Vol. 11 (1) Spring 2002 InterRidge · Sestri Levante, Italy. InterRidge MOMAR II Workshop The 2nd...

InterRidge News is published twice a year by the InterRidge Office, Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo 164-8639, Japan. Editors: Agnieszka Adamczewska and Marek Kaczmarz.

Tel: + 81 3 5351 6820; Fax: + 81 3 5351 6530; E-mail: [email protected] http://www.intridge.org

Spring 2002Vol. 11 (1)

InterRidgeNews

Initiative for international cooperation in ridge-crest studiesPrincipalMembers

FranceJapanUnited KingdomUnited States

AssociateMembers

CanadaGermanyItalyIndiaKoreaNorwayPortugal

CorrespondingMembers

AustraliaAustriaBrazilChinaDenmarkIcelandMauritiusMexicoMoroccoNew ZealandPhilippinesRussiaSOPACSouth AfricaSpainSwedenSwitzerland

ContentsInterRidge Office Updates

The InterRidge Wish List... .........................................................................................3Coordinator Update.....................................................................................................4InterRidge Publications...............................................................................................6InterRidge Web Page Overview...................................................................................7

InterRidge ProjectsOverview of InterRidge Working Groups...............................................................................................8Global Distribution of Hydrothermal Activity Working Group......................................................9Monitoring and Observatories Working Group..................................................................................10

Reports and announcements89th Dahlem Workshop...............................................................................................................................11Elizabeth Mann Borgese ..................................................................................................................11

International Ridge-Crest Research

Biological StudiesMAR-ECO - “Patterns and Processes of the ecosystems of the Northern Mid-Atlantic”;

an international project under the Census of Marine Life programme. Bergstad O. A..........12Towards unravelling the enigma of vent mussel reproduction on the Mid Atlantic

Ridge, or when ATOS met Cages. Dixon.D et al ................................................................14

Island arc/BABSubmarine Hydrothermal Mineralisations and Fluids off the Lesser Antilles Island

Arc – Initial Results from the CARIBFLUX Cruise SO 154. Halbach P. et al...................18Geophysical Experiments in the Mariana Region: Report of the YK01-11 cruise. Goto T. et al......22

OphiolitesHow back-arc basins evolved: tholeiite associations in the Kudi ophiolite of western Kunlun

Mountains, northwestern China. Zhihong W.......................................................................25

Continued over page ....

InterRidge News2

InterRidge Office Updates

Contents continued... International Ridge-Crest Research cont ...

Pacific-Antarctic RidgeWidespread Silicic Volcanism and Hydrothermal Activity on the Northern Pacific – Antarctic

Ridge. Stoffers P. et al............................................................................................................................................30

Mid-Ocean RidgeIsotope provinces of mid-ocean ridges. Pustovoy A.A. et al. ..........................................................................................33

Mid-Atlantic RidgeNew data on hydrothermal activity in the area of 12o57’N, MAR: initial results of the R/V Professor

Logatchev cruise 20. Bel’tenev V.Ye. et al...........................................................................................................38Sulphide mineralization, volcanic and tectonic activity of the MAR near Sierra Leone F.Z.: 10 cruise R/V

“Akademik Ioffe” (preliminary results). Skolotnev S. et al. ...............................................................................41

Indian RidgePreliminary results of a recent cruise to the Northern Central Indian Ridge. Drolia R.K. et al. ........................................43

World Ridge Cruise Map and Schedule, 2002................................................................................47National News...........................................................................................................................52

Calendar and Upcoming Meetings.................................................................................................58

National Correspondents and Steering Committee Members.........................................................63

You can use the online form to join our regular mailing list to receiveInterRidge News, or to be placed on our electronic mailing list, or to beput on the electronic directory on the web (http://www.intridge.org).Currently there are over 2800 scientists active in mid-ocean ridge researchon our mailing list. We are constatnly adding new entries to the electronicdirectory, which contains a listing of each researcher's field of interestand expertise as well as their full address information. Links are alsoprovided to personal or departmental web pages.

InterRidge Mailing ListSign up on the web at:

http://www.intridge.org/signup.htm

3Vol. 11(1), 2002

Request for: CHIMINEY SAMPLES

Samples of manganese encrusted chimneys as wellas hydrothermal or hydrogenous ferromanganese

samples and associated sediments collected from anyother midoceanic ridge system".

Contact: Ranadip Banerjee<[email protected]> or

<[email protected]>

SEARCH FOR GRAPHITE

Sediment trap deposits collected nearby vents, and/or grab samples of particulates from vents (0.0X to

1 gram quantities). Old collections are OK.If such materials are available in your drawers,

please contact: Jacques Jedwab<[email protected]>

I wish c uld getmy ands on .....

Would you like to get your hands on certain samples; be they rocks,crabs or tubeworms! Send your ‘wish list’ to the InterRidge officeand we will post it on the IR website andprint it in the next issue of IR news. Cooperation is the key to good science!


The InterRidge Wishhhhhh List....On suggestion of the IR Steering Committee, we have opened the InterRidge Wishhhhhhh list to

facilitate and poromote sample exchange between ridge scientists. Please submit requests forsamples, to the IR Office. Iwould like to encourage all ridge scientist to check the Wishhhh list andshare samples with your international colleagues. The success of this initiative is dependent on YOU!Below are three requests for samples. If you have such samples to share, please contact theappropriate scientists.

I wish I could get my hands on ........

Requested samples.....

ROCK SAMPLESRock samples from Laxmi Basin, Laxmicontinental block or any protruding seamountsin eastern Arabian sea for physical/chemical studiesContact: A. Shivaji ([email protected])

InterRidge News4


Coordinator's Update

Member NationsThe number of nations involved in

InterRidge activities continues togrow. This year, Mauritius has joinedInterRidge as a Corresponding Mem-ber nation. We welcome Dr. Daniel P.E. Marie from the Mauritius Oceanog-raphy Institute is the National Corre-spondent for Mauritius. This bringsthe total number of InterRidge mem-ber countries to twenty eight.

Upcoming InterRidge meetingsThis year is a very busy one for IR

meetings, there is something for eve-ryone! An ever increasing demand topool resources and expertise, on aninternational level, in order to maxim-ise research scope, quality and out-put, and at the same time minimisecosts for individual nations is the driv-ing force for organising more interna-tional meetings.

IR Steering Committee meetingThe next IR Steering Committee

meting will be hosted by Dr RiccardoTribuzio, 13-14th September 2002,Sestri Levante, Italy.

InterRidge MOMAR II WorkshopThe 2nd MOMAR workshop will

take place 15-17th June 2002, Horta,Azores (Portugal). The main goals ofthis workshop are to:1) establish a plan for the development

and installation of an ocean-bottomobservatory along the Mid AtlanticRidge south of the Azores, and

2) to identify the required scientificand technical support required tooperate and manage the projects,data and instruments involved inthe MOMAR observatory. Thelatest information about thisworkshop can be obtained fromthe IR website.

SWIR WorkshopA workshop to synthesise current

knowledge and identify areas, bothdisciplinarily and geographically that

require investigation and decide onfuture direction of research in thisarea is scheduled for 17-20th April,2002, at SOC, UK. The workshop is setto be a great success with over 70delegates from 13 countries register-ing to participate. A proceedings vol-ume from the meeting will be pub-lished as a “Theme” in the electronicjournal, G-cube (G3 http://g-cubed.org/). InterRidge is offering the“Outstanding student award” for thebest student presentation at this work-shop. The winner will be announcedin the next issue of IR news!

InterRidge Theoretical Institute(IRTI): Thermal Regime of OceanRidges and the Dynamics ofHydrothermal Circulation

The first IRTI will be held 9-13September 2002, at the University ofPavia, Italy. The IRTI is being jointlyorganized by the Hotspot-Ridge In-teractions working group and the Glo-bal Distribution of Hydrothermal Ac-tivity Working Group. The Institutewill take place over 4 1/2 days, and willcomprise of:1) a short course component, which

will focus on the modelling aspectsof the dynamics of hydrothermalcirculation in the crust,

2) a one day field excursion to studyhydrothermal alteration in thenorthern Apennine ophiolites and

3) a workshop component tosynthesize the current models,debate controversies, and outlinethe future directions forcollaborative research. For moreinformation see the back of thisissue of IR news or look on the IRwebsite.

Next Decade WorkshopThe Next Decade Workshop will

be held 10-12th June 2002, Bremen,Germany. The current InterRidge pro-gramme will come to an end of its 10year plan at the end of 2003. Thus, it istime for the international ridge com-

munity to convene together and sharetheir ideas about the direction of fu-ture ridge research. The aim of thisworkshop will be to exchange andpropose ideas for a new InterRidgeScience plan for the next decade ofinternational and multidisciplinaryresearch.

Representatives from Principal andAssociate member nations will de-velop the “Next Decade Project Plan”for InterRidge, based on the discus-sions during the workshop. The con-tinually increasing number of nationsactively involved in InterRidge willensure that a highly international ridgecommunity will utilise their expertiseto define and refine scientific ques-tions and focus interests, thereby,strengthening the InterRidge pro-gramme and the future “Project plan”.As a consequence, the highly interna-tional planning process is expected tobe of direct benefit to individual sci-entists and national programmes forthe nations involved. At the same timethe “Project plan” will provide oppor-tunities for the involvement of othernations.

All of the International Ridge Com-munity is encouraged to submit whitepapers, ideas and opinions to theInterRidge Office ([email protected]) with their views aboutthe "Next Decade" of internationalRidge research. For details about whatthe white papers should containplease refer to the IR website:http://www.intridge.org/ndir.htm

The InterRidge officeThe original IR Science Pro-

gramme plan will be finishing at theend of 2003. The IR office will remainin Tokyo until the end of the durationof the current Programme in 2003.From 2004 the IR office will move to anew Host country under the appoint-ment of a new Chair. Thus, at the endof this year, the IR office will be send-ing out a request for bids to host thenext IR office and for nominations for

5Vol. 11(1), 2002

Post your experimental site on the IR website

as a reserve now! Fill in the form at:

http://www.intridge.org/reser-f.htm

the new IR Chair. The period of tenureof the Chair is not precisely defined,but is normally expected to be threeyears. The final decision on the bidswill be made during the InterRidgeSteering Committee meeting in 2002.

The Next Decade workshop (seeabove) will be a crucial part of theoffice change over since the aim of theworkshop will be to create a documentoutlining the Science plan for IR forthe next decade. Input from the entireIR community is requested. See the IRwebsite for more information:http://www.intridge.org/ndir.htm

IR Steering Committee membersThank you to Kantaro Fujioka (Ja-

pan), Chris German (UK), Dave Kadko(USA), and Ranadhir Mukhopadhyay(India) who have finished their term asnational representatives on the IRSteering Committee. This year wewelcome Chuck Fisher, Chair of theUSA R2K program as a new USArepresentative, Masataka Kinoshitafrom JAMSTEC, Japan and AbhayMudholkar as the new Indian repre-sentative. The new national repre-sentative for UK will be announcedlater this year.

Additionally, thanks go to ChrisFox who has finished his term as theChair of the Event Detection and Re-sponse and Observatories WorkingGroup last year. We welcome two newad hoc steering committee members;Javier Escartin (France) and RicardoSantos (Azores, Portugal), as the newco-chairs of the “Monitoring and Ob-servations Working Group”.

Working GroupsThe SWIR workshop (see above)

is the last action of the SWIR work-ing group. The SWIR workshopwill end with a morning de-voted to discussion and de-bate about the future of re-search on the Indian ridge.After the publication of theproceedings from theSWIR workshop this work-ing group will be dis-solved. The outcomes ofthe discussions during

this workshop will be announced inthe next issue of IR news and on the IRwebsite.

Past and current information aboutIR working groups and projects canbe found on the IR website:http://www.intridge.org/act2.html

IR Outstanding Student PresentationThe IR Steering committee has decidedto encourage students involved inRidge research by awarding certificatesof Excellence and prize money to beststudent presentations at IR meetings.This year the IR Student Awards willbe handed out during the upcomingSWIR workshop (UK) and the IRTI(Italy). Background about studentsthat receive the IR award and abstractsof their presentations will appear in thenext issue of IR news. Students fromall countries are encouraged toparticipate in IR meetings and to presenttheir work!

InterRidge home pageWe are continuing to upgrade and

improve our web site to maximise in-formation transfer and make it userfriendly. To make our homepage moreinteractive we have divided it into twoframes. The latest information aboutIR meetings, announcements and anyother current, ridge related items isnow at your fingertips, accessible di-rectly from the left hand side frame onour homepage. The right hand sideframe contains the familiar menus withlots of ridge related information. Dueto the volume of information on ourwebsite a brief outline of what can be

found there is available on page 7 ofthis issue.

We have an alias for our website tomake the IR URL easy to remember,you can access the InterRidge homepage by simply typing:http://www.intridge.org

The IR databases are unique, theyprovide an international pool of infor-mation about all manner of issues re-lated to mid ocean ridges. The “Globalhydrothermal vents database” as wellas the “Ridge-Hot Spot InteractionReference Database” can be searchedby conventional method, by typing insearch words in any of the fields butalso these two databases contain in-teractive area maps to make searcheseasier. Thus, you can do your searchby location just by clicking on thedifferent areas on the globe. Thedatabases take a lot of work to main-tain but we relay on your input to keepthem up to date!

We are very pleased to see that theuse of the InterRidge website contin-ues to increase. As always, any com-ments and suggestions are welcomeand remember that I always like toreceive updates and new informationabout meetings and ridge relatedcruises, as well as job vacancies andother ridge related bits and peaces ofinformation. A brief summary of whatcan be found on the InterRidge websiteis also available at http://www.intridge.org/latest.htm

Agnieszka AdamczewskaInterRidge CoordinatorApril 2002


InterRidge News6


The following InterRidge publications are available upon request. Fill out anelectronic request from at http://www.intridge.org/act3.htmlor contact the InterRidge office by e-mail at [email protected].

InterRidge Publications

InterRidge News:Past issues of InterRidge News, are avalable starting with the first issue published in 1992 until the present. Informa-tion about the research articles published in each issue can be found on the InterRidge website:http://www.intridge.org/irn-toc.htm

The InterRidge News issues published from 2000 (ie. InterRidge News 9.1 and all following issues) are available asdownloadable PDF files from the same URL address on the InterRidge website, using Adobe Acrobat 4.0 or laterversions.

Workshop and Working Group Reports:

IR MOMAR (MOnitoring the Mid-Atlantic Ridge) workshop report, April, 1999.IR Mapping and Sampling the Arctic Ridges: A Project Plan, pp. 25, December 1998.ODP-IR -IAVCEI Workshop Rep.: The Oceanic Lithosphere and Scientific Drilling into the 21st Century, pp. 89.IR Global Working Group Workshop Report: Arctic Ridges: Results and Planning, pp. 78, October 1997.IR SWIR Project Plan, pp. 21, October 1997 (revised version).IR Meso-Scale Workshop Report: Quantification of Fluxes at Mid-Ocean Ridges: Design/Planning for the Segment

Scale Box Experiment, pp. 20, March 1996.IR Active Processes Working Group Workshop Report: Event Detection and Response & A Ridge Crest Observatory,

pp. 61, December 1996.IR Biological Ad Hoc Committee Workshop Report: Biological Studies at the Mid-Ocean Ridge Crest,

pp. 21, August 1996.IR Meso-Scale Workshop Report: 4-D Architecture of the Oceanic Lithosphere, pp. 15, May 1995.IR Meso-Scale Project Symposium and Workshops Reports, 1994: Segmentation and Fluxes at Mid-Ocean Ridges: A

Symposium and Workshops & Back-Arc Basin Studies: A Workshop, pp. 67, June 1994.IR Global Working Group Report 1993: Investigation of the Global System of Mid-Ocean Ridges, pp. 40, July 1994.IR Global Working Group Report 1994: Indian Ocean Planning Meeting Report, pp. 3, 1994.IR Meso-Scale Working Group Meeting Report, Cambridge, UK, pp.6, 1992.

Workshop and Symposium Abstract Volumes:

InterRidge Workshop: MOMAR (MOnitoring the Mid-Atlantic Ridge) Abstract Volume, pp. 82, Oct. 1998.InterRidge Workshop: Mapping and Sampling the Arctic Ridges Abstract Volume, pp. 30, Oct. 1998.First International Symposium on Deep-Sea Hydrothermal Vent Biology Abstract Volume, pp. 118, Oct. 1997.Fara-InterRidge Mid-Atlantic Ridge Symposium Results from 15°N to 40°N. J. Confer. Abs. 1(2), 1996.ODP-IR -IAVCEI Workshop: The Oceanic Lithosphere and Scientific Drilling into the 21st Century, pp. 126, 1996.

Steering Committee and Program Plan Reports:

IR STCOM Meeting Report, Kobe, Japan, 2001.IR STCOM Meeting Report, WHOI, USA, 2000.IR STCOM Meeting Report, Bergen, Norway, 1999.IR STCOM Meeting Report, Barcelona, Spain, 1998.IR STCOM Meeting Report, Paris, France, 1997.IR STCOM Meeting Report, Estoril, Portugal, 1996.IR STCOM Meeting Report, Kiel, Germany, pp. 22, 1995.IR STCOM Meeting Report, San Francisco, USA, 1994.IR STCOM Meeting Report, Tokyo, Japan, 1994.

IR STCOM Meeting Report, Seattle, USA, pp. 6, 1993.IR Meeting Report, York, UK, 1992.IR Meeting Report, Brest, France, pp. 39, 1990.IR Program Plan Addendum 1997, pp. 10, Jan. 1998.IR Program Plan Addendum 1996, pp. 10, April 1997.IR Program Plan Addendum 1995, pp.10, 1996.IR Program Plan Addendum 1994, pp.15, 1995.IR Program Plan Addendum 1993, pp. 9, 1994.IR Program Plan, pp. 26, 1994.

7Vol. 11(1), 2002


InterRidge Websitehttp://www.intridge.org/

The InterRidge office maintains an extensive website containing various types of information includingupcoming meetings, scheduled ridge related cruises,job vacancies as well as 9 different databases. Thesedatabases on the InterRidge website were initiated inresponse to a request by the international communityto have a ‘centralised’ clearing house for informationcollected by scientists all over the world so thatrelevant information is readily available to everybodyat one site. A brief summary of what can be found onthe InterRidge website is available at:

http://www.intridge.org/latest.htmWe are pleased that the use of the InterRdige

website is steadily increasing and we continue toencourage you make use of this resource and tocontinue to submit the latest information to our office.To make our homepage more interactive we have dividedit into two frames. On the left hand side frame you nowhave at your fingertips the latest information aboutmeetings, announcements and any other current, ridgerelated items. The right hand side frame contains thefamiliar menus, the general contents of which are outlinedbelow. As always any comments and suggestsions arealways welcome.

The alias for the IR website makes the URL easy toremember, you can now access the InterRidge homepage by simply typing http://www.intridge.org

1) Information sectionThis section provides links to Ridge related

meetings, cruises and other miscellaneousinformation, as well as a little bit about InterRidgestructure and its role, including: Latest ridge relatedNews; an introduction to what is InterRidge, with ashort description of the InterRidge programme,outlining the objectives of the programme as well asmanagement structure and national membership ofInterRidge; as well as a calendar of internationalconferences, meetings and workshops.

2) Activities sectionThis section is concerned with the scientific and

management structure of InterRidge. The 'Activities'section includes an outline of the scientific purposeof InterRidge. A description of the activities of the IRworking groups, which are responsible for directingdifferent aspects of ridge research with updates of

their activities can be found here. You can also findlinks to major projects that InterRidge is currentlyinvolved in and projects that are directly relevant toInterRidge activities - such as MOMAR and the MarineProtected Areas project. Additionally, in this section,you can find a list of all the publications distributedby the InterRidge office as well as a list of the InterRidgeNational Correspondents, and their contact details,from all of our Member Nations.

3) InterRidge databases sectionOne of the major objectives of InterRidge is to

facilitate the advancement of ongoing work ofindividuals, national and international groups byproviding centralised information and data-exchangeservices. Thus, we maintain a number of databasesthat contain data submitted from Ridge scientists fromaround the world. We rely on contributions fromindividuals to continuously update the information andincrease the number of records. I would like to takethis opportunity to encourage everyone to becomefamiliar with the databases on our website andcontribute information on a regular basis to ensurethat this important resource contains current and upto date information. A list of the databases maintainedby InterRidge with a brief introduction can be foundon our web site at:http://www.intridge.org/data1.html

The IR office also maintains a database with contactdetails of scientists involved in ridge reserach. To addyour name and contact details to the electronicdatabase just click on the “Mailing list sign up” on thehome page and fill in the signup form.

Furthermore, there is a neat little program, whichyou can use to calculate the spreading rate of the seafloor at any place around the globe!

Hydrothermal Ecological Reserves Page:http://www.intridge.org/reser-db.htm

This page lists all the current ecological reservesthat have been proposed at hydrothermal vents. Thesevary in breadth and scope; at Juan de Fuca theCanadian government has proposed the Endeavourvent field as a pilot marine protected area, while otherreserves consist of requests from individual scientistsconducting experiments in specific areas. There is alsoan on-line form to submit reserves to the page.

InterRidge News8

Overview of InterRidge Working GroupsMore information on working groups can be found on our website;

http://www.intridge.org/act2.html


Arctic RidgesObjective: Coordinate planning

efforts for mapping and samplingthe Arctic Ridges.

Current Activities: Coordination ofinternational cruise to the GakkelRidge in 2001.

Chair: Colin Devey (Germany)WG members: G. A. Cherkashov (Rus-

sia), B. J. Coakley (USA), K. Crane(USA), O. Dauteuil (France), V.Glebowsky (Russia), K. Gronvold(Iceland), H. R. Jackson (Canada),W. Jokat (Germany), Y.Kristoffersen (Norway), P. J.Michael (USA), K. J. Young (Ko-rea), N. C. Mitchell (UK), H. A.Roeser (Germany), H. Shimamura(Japan), Y. Nogi (Japan), C. L. VanDover (USA) .

Back-Arc BasinsObjectives: Summarize past work on

Back-Arc Basins and coordinatefuture studies.

Chair: Sang-Mook Lee (Korea)WG members: Ph. Bouchet (France),

J.-L. Charlou (France), K. Fujioka(Japan), E. Grácia (Spain), P. Herzig(Germany), J. Ishibashi (Japan), Y.Kido (Japan), S-M. Lee (Korea), R.Livermore (UK), S. Scott (Canada),R. J. Stern (USA), K. Tamaki (Japan),and B. Taylor (USA).

Biological StudiesObjectives: Objectives of the New

biology WG are outlined on theIR website.

Chairs: F Gaill (France) and S.K.Juniper (Canada).

WG members: M. Biscoito (Portugal),O. Gierre (Germany), J-H Hyun (S.Korea), A. Metaxas (Canada) T.Shank (USA), K. Takai (Japan), P.Tyler (UK) and F. Zal (France)

Global Digital DatabaseObjective: Establish a database of

global multibeam bathymetry andother data for mid-ocean ridgesand back-arc basins.

Current Activities: Compiling data.Chair: Philippe Blondel (UK)WG members: J. S. Cervantes (Spain),

C. Deplus (France), M. Jakobsson(Sweden), K. Okino (Japan), M.Ligi (Italy), R. Macnab (Canada),T. Matsumoto (Japan), K. A. K.Raju (India), W. Ryan (USA), andW. Weinrebe (Germany).

Global Distribution ofHydrothermal Activity

Objectives: Target key areas of theglobal MOR that should beexplored for hydrothermal activityand coordinate internationalcollaboration to explore them.

Current Activities: Organizing theInterRidge Theoretical Instituteon the Thermal regime of OceanRidges and the Dynamics of Hy-drothermal Circulation to be held9-13 Sept. 2002.

Chair: Chris R. German (UK)WG members: E. Baker (USA), Y. J.

Chen (USA), D. Cowan (UK), T.Gamo (Japan), E. Grácia (Spain),P. Halbach (Germany), S.-M. Lee(Korea), G. Massoth (N.Z), J.Radford-Knoery (France), A-L.Reysenbach (USA), D. S. Scheirer(USA), S. D. Scott (Canada), K. G.Speer (USA), C. A. Stein (USA),V. Tunnicliffe (Canada) and C. L.Van Dover (USA).

HotSpot-Ridge InteractionsObjectives: This WG was formed dur-

ing the 2000 Steering Committeemeeting to promote and facilitateglobal research to better under-stand the physical and chemicalinteractions between mantleplumes and mid-ocean ridges andtheir effects on seafloor geologi-cal, hydrothermal, and biologicalprocesses.

Current Activites: The agenda for thisnew WG is being developed.

Chair: J. Lin (USA)WG members: R.K. Drolia (India), J.

Dyment (France), J. Escartín(France), J. Freire Luis (Portugal),E. Grácia (Spain), D.W. Graham(USA), K. Hoernle (Germany), G.T.Ito (USA), L.M. MacGregor (UK)N. Seama (Japan), F. Sigmundsson(Iceland)

Monitoring and ObservatoriesObjectives: Develop detection

methods of transient ridge-crestseismic, volcanic and hydro-thermal events, and the logisticalresponses to them.

Current Activites: Organisation of thesecond MOMAR workshop. Ob-jectives of the workshop are listedon the InterRidge website.

Chairs: J. Escartin (France) and R.Santos (Azores, Portugual)

WG members: Chris Fox (USA), K.Mitsuzawa (Japan), Pierre-MarieSarradin (France), Adam Schultz(UK), Paul Snelgrove (USA), PaulTyler (UK).

SWIRObjective: Coordinate reconnais-

sance mapping and sampling ofthe Southwest Indian Ridge.

Current Activities: Organisation ofthe SWIR workshop.

Chair: Catherine Mével (France)WG members: M. Canals (Spain), C.

German (UK), N. Grindlay (USA),C. Langmuir (USA), A. Le Roex(South Africa), C. MacLeod (UK),J. Snow (Germany), T. Kanazawa(Japan) and C. L. Van Dover (USA).

Undersea TechnologyObjective: Foster the development of

undersea technology and dis-seminate information about it.

Chair: Spahr C. Webb (USA)WG members: J. R. Delaney (USA),

H. Momma (Japan), J. Kasahara(Japan), M. Kinoshita (Japan), A.Schultz (UK), D. S. Stakes (USA),P. Tarits (France) and H. Villinger(Germany).

9Vol. 11(1), 2002

Updates on InterRidge Projects

This is the first update for twoyears from this working group, firstestablished in late 1997. There is areason for the lack of an annual updatelast year – I was at sea for 70 days inthe Indian Ocean helping identify newsites of venting long the Central In-dian Ridge and wasn’t around to co-ordinate our Working Group’s input!!!

InterRidge Theoretical InstituteThe first item to bring to your

attention in this issue is the imminentdemise of the Working Group in 2002.This is in keeping with InterRidgedirectives on WGs amd their lifetimes– but fear not! We shall be bowingout not with a whimper, but a bang.Specifically, joint with the now-de-funct 4-D architecture working group,we shall be co-hosting the first everInterRidge Theoretical Institute tobe held in Pavia, Italy, September 9-13, 2002: “Thermal Structure of theOcean Crust and Dynamics of Hy-drothermal Circulation”. The meet-ing will comprise a 2-day shortcourse- with invited keynote papers plusample time for discussions and con-tributed poster presentations - fol-lowed by a field-trip to local hydro-thermally altered ophiolites and fin-ishing with a 2 day workshop identi-fying future directions for coordi-nated InterRidge research. From thisWG’s perspective, a clear objectivewill be to improve our understandingof the geological controls of seafloorhydrothermal venting.

Full details are available on theInterRidge web-site:

http://www.intridge.org/irti.htm

Global Distribution of HydrothermalActivity

It has always been the objectivethat ANY InterRidge Working Groupshould be able to make a significantcontribution to it’s chosen area offocus within the space of ca.5 years. I

am pleased to report that ours hasbeen no exception.

Hydrothermal ExplorationHighlights of field programmes

since early 2000 have included dis-covery of new hydrothermal fieldsalong three separate sections of ultra-slow spreading ridge-crest –1) the Atlantic portion of the SWIR (tobe reported by Bach et al. at theInterRidge SWIR workshop in April2002 – but look out, too, for the paperin G^3 any week now!);2) the Knipovich Ridge (see, e.g.,Tamaki, Cherkashov et al. (IR News 10.1pp 48-51, 2001); Connelly & German.EOS Trans AGU 83, OS205-206, 2002);3) most recently, the exciting discov-ery of abundant hydrothermal signalsalong the Gakkel Ridge in the ArcticOcean (see, e.g., Edmonds et al., EOSTrans AGU 82, F647, 2001). In parallel,a UK cruise to the southern Mid-Atlantic Ridge in late 2001 identifiedclear suspended particulate and dis-solved Mn anomalies at a range ofsites between 2 and 14 degrees South(C.R. German, unpubl. data) while therehave already been wide-ranging re-ports of the discoveries of first sites ofventing in the Indian Ocean during2000-2001 (Hashimoto et al, InterRidgeNews 10 (1) pp. 21-22; Van Dover etal., Science 294, 818-821, 2001). Inconcert, this makes for at least onevent-site now known to exist in everymajor ocean basin, worldwide, as wellas clear demonstration that hydro-thermal activity occurs in abundancealong even the slowest spreadingridges as well as along the fast andmedium-fast.

Global Vents Data-Base, On-LineAnother important achievement

of the WG, early on, was the establish-ment of a readily-updated electronicdata-base of every known hydrother-mal field – whether visited and sam-

pled on the seabed or just identifiedfrom water column anomalies. Boththe data-base and the update formscan be accessed directly from :http://www.intridge/vent.htmOnly time will tell whether this valu-able legacy is used to full advantageby you, the user!!

Vent BiogeographyFinally, as well as the IRTI leaving

the geological aspects of this Work-ing Group in good order (we have alsohad a very favourable initial responsefrom AGU about publishing a Geo-physical Monograph arising from theproceedings) the biogeographic as-pects of our work have also progressedwell and will be left in good health asthe Working Group itself is wound up.WG member Cindy van Dover recentlypublished an invited review article inScience (together with WG co-mem-bers Kevin Speer & Chris German,among others): “Evolution and bioge-ography of deep-sea vent and seepinvertebrates” Science 295, 1253-1257.That paper took the opportunity toidentify a range of key targets forfuture investigation, selecting spe-cific regions of the mid-ocean ridge-crest where discovery and biologicalcharacterisation of new vent-siteswould be of particular benefit. Fasterthan the current InterRidge WG candisband, therefore, I am pleased toreport the establishment of a new re-lated initiative supported by the SloanFoundation as part of the Census ofMarine Life programme. From Sum-mer 2002, Profs. Paul Tyler and ChrisGerman at SOC, UK, will co-host theinternational pilot office for a newprogramme, ChEss (ChemosyntheticEcosystem Studies) dedicated to de-signing and initiating surveys of lifein vent and seep communities on theocean floor. Funding is for three years,in the first instance; contact Paul Tyler([email protected]) for details.

Global Distribution of Hydrothermal Activity Working Group

Chris German

Challenger Division for Seafloor Processes, Southampton Oceanography Centre, UK

InterRidge News10

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Updates on InterRidge Projects

Monitoring of low-level seismicityon the Mid-Atlantic Ridge (MAR)using autonomous underwaterhydrophones will be continued andexpanded in the coming years. Theinitial effort, consisting of sixhydrophones moored in the region of15o-35o N (see InterRidge News 8.1,March, 1999), was deployed in March1999 by Debbie Smith (WHOI), MayaTolstoy (LDEO) and Chris Fox(NOAA/PMEL) and funded byUSRIDGE for two years of data collec-tion. After extending this initial effortto a third year, US RIDGE recentlyagreed to fund four additional years ofmonitoring in a more operational mode,with routine posting of derived seis-

mic source locations posted on theworld wide web and raw hydrophonesignals to be made available to thescientific community via FTP. PIs onthe extended effort are Bob Dziak(OSU), Haru Matsumoto (OSU),Debbie Smith (WHOI), and Chris Fox(NOAA/PMEL). The existing arrayprovides excellent coverage of theMAR from the equatorial region to theAzores, but bathymetric shadowingof the acoustic signals have not al-lowed monitoring of the MAR northof the Azores.

In May 2002, a French expedition(SIRENA) on the French researchvessel Le Suroit will deploy a newarray of six hydrophones around the

Monitoring and Observatories Working GroupExpanded Acoustic Monitoring of the Mid-Atlantic Ridge

Chris Fox

NOAA/PMEL/VENTS Program, Newport, USA

MAR between the Azores and theGibbs Fracture Zone (Fig. 1). The PIsfor this experiment are Jean Goslin(CNRS, Brest) and Chris Fox (NOAA/PMEL). The experiment is jointlyfunded by the French governmentand US NOAA. The array is onlyplanned for a one-year deploymentbut every attempt will be made tomaintain the array long-term, similarto the USRIDGE array to the south.Although the sensors will be locatedsouth of Gibbs, they should be able toroutinely detect activity from theReykjanes Ridge south of Iceland.This new data set, combined with datafrom the southern array, will provideexcellent coverage of the Azores plat-form and can be combined with seis-mic sensors on the Azores for a morecomplete picture of the seismicity ofthe hotspot. The first data set will berecovered in summer 2003.

Planning is underway to deployadditional acoustic sensors at otherlocations in the Atlantic and otherocean areas by the Sound in the Seaproject of NOAA's Ocean ExplorationProgramme (PI: C. Fox). One possibletarget area is along the equator in theAtlantic in conjunction with the exist-ing PIRATA array of surface weatherbuoys. The acoustic data sets de-scribed, while being collected for ridgecrest studies, provide valuable data toresearchers studying the distributionof large marine mammals in the openocean and the impact of manmade andnatural noise on marine life. Furtherinformation on these experiments,access to seismic source information,and access to raw data (still underdevelopment) can be found at:http://www.pmel.noaa.gov/vents/acoustics.html . All of these topicswill be discussed in detail at theupcoming MOMAR-II workshop June15-17 in Horta, Azores.

Figure 1. Plot of the planned hydrophone deployment, along with theexisting array.

11Vol. 11(1), 2002

Reports and announcements

What happens to the heat releasedwhen magma rises from within theEarth to generate new mid-ocean ridgecrust – a fundamental component ofplate tectonics? How does seawatertransport this heat to the oceans?How deep does water penetrate be-neath the seafloor; under what rangeof pressure and temperature condi-tions does it react; and with whichrock types? How do the resultingfluids rise to the surface and whatrange of mineral deposits do they pro-duce? How do the resultant fluxes ofenergy – both thermal and chemical –serve to support unique deep-seahydrothermal ecosystems? Is there avalid link to the origin of life? Whatimpact do hydrothermal fluxes haveon the chemical balance of the oceansand what is the fate of the materialsthey produce? Does a predicted~100km-wide high-productivity corri-dor – a larval superhighway – exist

along ridge-crests? Can we identifyhydrothermal signatures in the geo-logical (including paleontological)record; where do 100 million tonne oredeposits form in the modern day; andhave hydrothermal sediments playedan important role, throughout Earthhistory, in the transfer of material fromthe mantle to the continental crust?

These are just some of the ques-tions highlighted during a week-longmeeting of 38 international scientistsat the 89th Dahlem Workshop held atthe Freie Universität in Berlin, Oct.15-19, “Energy & Mass Transfer in Ma-rine Hydrothermal Systems”. Theethos of the Dahlem Workshops isunique – not to present what is al-ready known, but to highlight what wedo not yet know, what we need toknow, and why. The list, above, justskims the surface of the many newideas that were generated recentlywhen the field’s top researchers were

89th Dahlem Workshop update

Chris German

Southampton Oceanography Centre, UK

compressed together under the pres-sure-cooker conditions of an isolatedretreat. Full discourse of the varioussubjects highlighted above – includ-ing four completely new articles writ-ten during the course of the week’sproceedings – will be published inJune 2002*. As a more immediateresult, however, consensus has al-ready been reached on a new multi-branched and interlinking process-flow model – the Dahlem Hydrother-mal Reference Model (DaHRM) –which will be taken forward as the newinternational state-of-the-art for hy-drothermal fluxes at mid-ocean ridges,within the broader whole-EarthGeochemical Earth Reference Model(GERM).

* Energy and Mass Transfer inMarine Hydrothermal Systems, ed. P.Halbach, V. Tunnicliffe, and J. Hein.Berlin: Dahlem University Press.

Ecologist Elisabeth Mann Borgesedied at 83 Geneva, Switzerland —Elisabeth Mann Borgese, an activistfor protecting the world’s oceans andthe last surviving child of Germanliterary giant Thomas Mann, died of arespiratory infection in the early morn-ing hours of 8th February 2002 inSamedan, Switzerland, near St. Mo-ritz. Swiss press reports said sheskied the day before she died in spiteof her pneumonia. Her father, theGerman essayist, cultural critic, andnovelist, was awarded the Nobel Prizefor Literature in 1929.

Ms. Mann Borgese was an ecolo-

gist who fought for the preservationof the oceans, wrote numerous pa-pers and books and contributed toconferences on maritime issues. Shehad been dubbed “ambassador ofthe oceans.” She also was a univer-sity professor in Halifax, Nova Scotia,Canada; the founder of the Interna-tional Ocean Institute in Malta; andone of the founders of the Club ofRome, a group of scientists focusingon worldwide environmental prob-lems. In 1970, she organized a pio-neering conference, Peace in theOceans, concerning the Law of theSea. Since then, 30 similar confer-

ences have taken place worldwide.She is credited with helping bringabout a 1982 UN treaty on the Law ofthe Sea after more than a decade ofnegotiation. A Canadian later bychoice, Ms. Mann Borgese was bornin Munich, the second youngest ofMann’s six children. When she was15, she and her family left Nazi Ger-many for Switzerland, where shetrained as a concert pianist. She cameto the United States in 1938 with herparents and, a year later, marriedGiuseppe Antonio Borgese, a writerand art historian who had fled FascistItaly. He died in 1952.

Elizabeth Mann Borgese

InterRidge News12

International Research: Biological Studies

MAR-ECO – a North Atlantic biodi-versity study

Despite the wide distribution andextensive area of mid-ocean ridges(e.g. Garrison 1993), relatively fewprevious investigations have beendedicated to the study of the animalcommunities inhabiting these vastareas of the world ocean. Ridges mayhave characteristic faunas, but theymay also significantly influence theprocesses affecting the slope andshelf biota such as intercontinentalmigration and dispersion. On thisbackground, the project MAR-ECO(http://www.mar-eco.no/), focuss-ing on the macrofaunal communitiesassociated with the Mid-AtlanticRidge (MAR) between Iceland andthe Azores, has recently been estab-lished as an international ecosystemstudy under the Census of MarineLife (CoML, http://www.coml.org)programme. MAR-ECO targetsclassical food-chain organismsbut works in parallell with ChESs(http://www.wm.edu/coml/) , aCoML project studying chemosyn-thetic systems.

The overriding aim of MAR-ECOis to describe and understand thepatterns of distribution, abundanceand trophic relationships of the or-ganisms inhabiting the mid-oceanicNorth Atlantic (Fig. 1), and identifyand model ecological processes thatcause variability in these patterns.Fish, crustaceans, cephalopods, andgelatinous plankton and nekton havethe highest priority in the study, butthere will also be some effort devot-ed to epibenthic communities. Theproject will be carried out as a multi-

MAR-ECO - “Patterns and Processes of the ecosystems of the NorthernMid-Atlantic”; an international project under the Census of Marine Life

programme

Odd Aksel Bergstad

Institute of Marine Research, Flødevigen Marine Research Station, N-4817 His, Norway

Figure 1. The Mar-Eco area with sub-areas selected for detailed studies. Theexact locations are to be decided during the planning phase.

13Vol. 11(1), 2002

International Research: Biological Studies: Bergstad, cont...

International Steering Group to stim-ulate the network of experts to for-mulate component projects.

A first planning workshop washeld in the Alfred Wegener Institutfür Meeresforschung in Bremer-haven in early January 2002 to facil-itate presentation of the project andco-ordination of the componentproject building. Some 45 expertsfrom around the North Atlantic gath-ered to focus on component projectformulation. The following is a listof the working titles of MAR-ECOstudies now being fomulated, andfull outlines and updates will be pre-sented on the website in due course:

Zooplankton studies:Distribution, abundance and

species composition of zooplank-ton in cross-frontal and cross-ridgetransects of the Mid Atlantic Ridge.PI: Webjørn Melle, The Institute ofMarine Research, Norway.

Feeding behaviour and swim-ming mode of gelatinous zooplank-ton and nekton. PI: Ulf Båmstedt,the University of Bergen, Norway.

Time-scale distribution andtrophic structure of deep-water ge-latinous zooplankton and nekton.PI: Marsh Youngbluth, The HarborBranch Laboratory, USA.

Trophic structure of major cope-pods, euphausiids and fish larvaeacross the Mid Atlantic Ridge. PI:Astthor Gislason, Marine ResearchInstitute, Iceland.

Pelagic nekton:Longitudinal and latitudinal

changes in mesopelagic/ bathype-lagic nektonic fauna (fish, cephalo-pods and crustaceans) along MAR.PIs: Mike Vecchione, Kir Nesis,Sergey Evseenko, Peter Boyle, Mar-tin Collins, Von Westerhagen,Christian Pusch, Uwe Piatkowski,Filipe Porteiro, Ricardo Santos, JoãoPereira.

Interactions of mesopelagic andbathypelagic fauna with thebenthopelagic community associat-ed with MAR seamounts/ slopes.PI: Bernd Christiansen, Univ. ofHamburg, Germany.

ship operation in 2003-2005, withmost activity in 2004 centred arounda two-month cruise on the Norwe-gian RV G.O.Sars.

Scienc Plan, tasks and hypothesesThe Science Plan now available

(e.g. on the website http://www.mar-eco.no/) presents the three centraltasks of MAR-ECO and a compila-tion of hypotheses and suggestionsresulting from discussions duringand after an initial workshop held inBergen 12-13 February 2001:Task 1: Mapping of species

composition and distributionpatterns.

Theme 1: Identity and distributionpatterns of macrofauna.

Theme 2: Population genetics anddispersion studies.

Task 2: Identification of trophicinterrelationships and modellingof food web patterns

Task 3: Analyses of life historystrategiesThe three tasks are obviously

inter-related. Also, all the tasks relyon a thorough understanding of theabiotic environment (bathymetry,watermass properties and distribu-tions, circulation). A major challengeof the project is to overcome obser-vation difficulties at large depthsand in rugged terrain. A central aimis thus to utilise modern remote sens-ing technology (acoustics, optics)using advanced instrument carriers(e.g., towed vehicles, ROVs, AUVsetc.), in addition to more traditionalsamplers and observation methods.

Some basic overall hypothesesor questions to be addressed are:1) Are the MAR communities

extensions of the communitiesinhabiting the North Atlanticcontinental slope regions?

2) Is the MAR a barrier between thepelagic fauna of the east and westNorth Atlantic basins? Is there adifference in species occurrenceeither side of the MAR?

3) Do circulation features, e.g. the GulfStream, act as barriers between thenorthern and southern fauna? Inthe region of the Gulf Stream, whatis the effect of eastward drift and

import of material from the west?4) What is the significance of

seamounts within the ridgesystem?

5) Is the trophic structure of thenorthern mid-Atlantic ecosystemsimilar to that on the slope regionsof the eastern and western sides ofthe Atlantic?

Organisation and scheduleThe International Steering Group

organises and oversees the plan-ning, financing, and implementationof the project. Members of the groupare:Dr. Odd Aksel Bergstad, IMR,

Norway (chairman)Prof. Peter Boyle, Univ. Aberdeen,

UKDr. Olafur S. Astthorsson, MRI,

IcelandDr. Ricardo S. Santos, Univ. Azores,

PortugalDr. Uwe Piatkowski, Univ. Kiel,

GermanyProf. Michael Vecchione, NOAA,

NMFS, USADr. E.M. Burreson, Virginia Institute

of Marine Science (VIMS), USAProf. Ulf Båmstedt, University of

Bergen, NorwayDr Pascal Lorance, IFREMER, France

Norway has taken on the secre-tarial duties for the project, and theresponsible institution will be theInstitute of Marine Research (IMR)in collaboration with the Universityof Bergen. The new Norwegian re-search vessel R/V G.O. Sars will beat the disposal of the project activ-ities in 2004, and may form a centralfocus of international multi-vesseloperations.

The shedule and phases of MAR-ECO are the following:Planning phase: 2001-2003Field phase: 2003-2005Analysis, synthesis: 2004-2008Incorp. in OBIS: 2005-2008

Current statusThe status of MAR-ECO is that

the planning phase has been initiat-ed and a formal organisational struc-ture has been set up. A planninggrant recently awarded enables the

InterRidge News14

Effects of the Sub-polar Front onMAR pelagic communities. PIs: Pe-ter Boyle, Martin Collins, Universi-ty of Aberdeen, UK.

Life cycle strategies of selectedspecies living in different water mass-es. PIs: Roger Villaneuva, PeterBoyle, Christian Pusch.

Fertilisation experiments withfish and cephalopods for egg andlarvae description/ recognition. PI:Sergey Evseenko, Shirshov Insti-tute of Oceanology, Moscow.

Evaluation of global changescomparing catch of historical cruis-es with present day. PI: Filipe Portei-ro, Ricardo S. Santos, DOP, Horta,Portugal.

Demersal nekton studiesDistribution patterns and spe-

cies composition of demersal fishes

in relation to habitat variability onthe Mid-Atlantic Ridge. PI: FranzUiblein, Univ. of Salzburgh, Aus-tria.

Spatial genetic structure of com-mercially valuable deep-sea fish fromthe North Atlantic. PI: Rus Hoelzel,Univ. Of Durham, UK.

Epibenthic and Benthopelagic(Demersal) Invertebrate communi-ties, distribution and ecology. PI:David Billett, SOC, UK

Life history studies of demersalfishes. PI: Maurice Clarke, MarineFisheries Service, Ireland

The Mar-Eco visionThe MAR-ECO vision is that,

following the 2001-2008 project pe-riod, the identity, distribution pat-terns, food-webs, and life historypatterns of the macrofaunal commu-

nities of the northern Mid-AtlanticRidge and its flanks will be under-stood and well known both to thescientific community and the inter-ested public.

The website http://www.mar-eco.no/ is the main source of up-dates, contact information, and doc-uments relevant to the project.

International Research: Biological Studies: Bergstad, cont...

Towards unravelling the enigma of vent mussel reproduction on the MidAtlantic Ridge, or when ATOS met Cages!

David R. Dixon1, P.M. Sarradin2, L.R.J. Dixon1, A. Khripounoff 2, A. Colaçoand R. Serrao Santos3

1 Southampton Oceanography Centre, United Kingdom2 IFREMER Centre de Brest, France3 IMAR, University of the Azores, Horta, Portugal

During the recent EU-fundedATOS cruise (R/V L’Atalante, ROVVictor, June 22nd – July 21st 2001) toactive vent sites south-west of theAzores, two distinct yet complemen-tary types of benthic apparatus weredeployed to tackle the question ofthe timing of reproduction in thevent mussel Bathymodiolus azori-cus. The first were sediment traps ofthe type used previously during theEU-funded MARVEL cruise in Au-gust and September 1997 to trapsettlement stage (prodissoconch II)larvae of B. azoricus at the Rainbowand Menez Gwen vent sites (Comtetet al., 1998). The second were acous-tically retrievable cages describedrecently in IR news. Something of a

mystery surrounds the reproductivebehaviour of this dominant ventspecies since cruise collected sam-ples have so far failed to yield anyevidence of significant gonad de-velopment, which contrasts withexpectations based on the belief thatvents are aseasonal and thereforeable to provide a virtually unlimitedfood supply for the indigenous ventfauna (from bacterial chemosynthe-sis). Thus, given the high abun-dance of the species, particularly inthe Azores region, the reproductivebehaviour of the Atlantic musselremains something of an enigma.One supplementary aim of the EU-funded VENTOX cage study was tosample mussels outside the usual

cruise period, which is limited by thesummer weather window, so thattheir gonad condition during thewinter months could be assessedusing histological methods.

Sediment trapsAs part of the ATOS cruise ob-

jectives, measurements were carriedout of particulate and biological flux-es produced at two hydrothermalsites (Rainbow and Lucky Strike)located within the MAR segment.The experiment consisted of moor-ing two sediment traps (1m2) close tothe vents for 1 year’s duration inorder to follow the fluctuations inthe frequency of mussel larval set-tlement and general particulate emis-

15Vol. 11(1), 2002

Mytilid reproductionIn common with other mytilids,

B. azoricus lacks a true gonad andproduces gametes in a fleshy multi-purpose tissue, the mantle, whichlines the shell valves (Fig. 2). Inother mytilids, apart from acting as agonad, this tissue is also used tostore food reserves (lipid and glyco-gen) outside the breeding season,which are then used for the manu-facture of gametes later in the year.The sexes are normally separate inmytilids. In the best-studied mytilidspecies, the blue mussel Mytilusedulis, by the time that spawningtakes place, in the spring, the mantletissues are completely transformedinto mature gamete, sperms oroocytes, with very little or no evi-dence of any storage tissue (viz.adipogranular cells) remaining. Thefact that gamete mother cells areproduced de novo each season isanother reason why the mantle isconsidered not to be a true gonad;unlike the situation in mammalswhere in females a finite number ofoocytes is laid down at the embryostage. Taken together this alternat-ing pattern of tissue activity in themantle underpins a seasonal repro-ductive cycle, something that is typ-

ical of species living in environmentswhere food supply and/or other en-vironmental factors vary markedlyover the year, something that is notnormally associated with hydrother-mal vents.

In common with M. edulis, B.azoricus undoubtedly producesvast numbers of gametes that arereleased prior to fertilisation intothe vent plankton (Fig. 2). However,examination of several hundred adultmussels during three EU-fundedsummer cruises (MARVEL, PICOand ATOS) failed to reveal any ev-idence of ripe or, for that matter,discernible gametes in mantlesquashes (D. Dixon, unpublisheddata,) which conflicts with the ex-pected pattern if the Atlantic ventmussels were spawning continuous-ly (at least at the population level;Tyler and Young, 1999). A previoussediment trap study revealed thatlarval settlement occurred between24 August and 5 September 1997(Comtet et al., 1999). Loading aproportion of the collecting bucketswith a special high salt buffer al-lowed DNA confirmation of the iden-tity of these larvae (Dixon & Dixon,1998; Comtet et al., 1999). Previoushistological evidence also points toepisodic spawning behaviour in B.azoricus (Comtet & Desbruyères,1999). Clearly, this contrasts withour expectations for a species livingin a supposedly aseasonal deep-seavent environment, which is the rea-son why our aim now is to accumu-late additional histological evidenceof gonad condition in the winterperiod using the acoustically retriev-able cages and sediment traps. Thecage study will focus in particularon the winter period when there is anexpectation that a high proportionof individuals will contain develop-ing and/or ripe gametes. Tissue sam-ples from the recent ATOS cruiseand follow-up cage recovery studyare currently undergoing histologi-cal analysis and these have provid-ed additional supporting evidenceof a seasonal reproductive cycle inthis species (Dixon, Lowe, Villemin& Dixon, in preparation). The close-

International Research: Biological Studies Dixon et al., cont...

Figure 1. Diagram showing the design of the sediment trap described in thisarticle.

sions close to these two hydrother-mal sources. A third sediment trapwas deployed at a distance awayfrom any hydrothermal source toobtain a measurement of the back-ground pelagic flux to use as a refer-ence for the Azores region. As withthe cages, the design of the sedi-ment traps was modified to facilitatedeployment using the French ROVVictor 6000. Each trap unit (Fig. 1)consists of a PPS5 trap (©Techni-cap) modified by the addition of 7syntactic foam floats (©Euroshore).The dimensions of each trap are: 215cm height and 205 cm in diameter.The weight in air is 446kg with apositive buoyancy of 144kg. Anacoustic release (Posidonia type)which can be located by the ROVnavigation, is attached to the frame.A surface location system, consist-ing of an Argos beacon, flasher andradio beacons, was also fixed to thetop of the trap to aid recovery.

The two vent-located traps weredeployed close to the F5 marker atRainbow and Sintra at Lucky Strike,respectively. The position of thereference pelagic trap was N 36º 13.30,W 33º 52.7. The Portuguese R/VArquipélago is scheduled to recov-er all three traps in summer 2002.

InterRidge News16

ly related Bathymodiolus ther-mophilus from Pacific vents appearsto exhibit continuous reproduction,with a range of reproductive stagesbeing present in the gonadial tis-sues between May and December(Maria Baker, SOC, pers. com.).

What is the reason for this apparentseasonality?

It remains to be seen which eco-logical driver is responsible for theunexpected occurrence of seasonalreproduction in B. azoricus, but alikely candidate is the need for aparticulate food supply during thelarval dispersal phase. While thenutrition of the adult mussel ap-pears fully catered for by the sul-phide and methane in the vent emis-sions, its planktotrophic mussel lar-vae require a dependable source ofparticulate organic material to sus-tain them during the weeks ormonths while they are dispersing aspart of the plankton (Fig. 2). Sincethe surface waters over the MAR aregenerally considered to be oligo-trophic, it seems likely that the sur-vival of these microscopic larvaewill depend to a large extent on thesmall but nonetheless significantpeak in primary production that takesplace in the surface waters over theridge in the early spring (Fig. 3). It isour belief that it is only those larvaethat are released around the time ofthis spring peak that stand anychance of completing their larval de-velopment and thus successfully re-cruiting back into the adult popula-tions. Natural selection actingthrough the larval phase (somethingthat tends to be treated as a blackbox in ecological and evolutionarystudies) is likely to be the reasonwhy reproductive periodicity hasbeen selected for in at least onedominant MAR vent species, B. azo-ricus.

Previous work on seasonal re-production in the deep sea has em-phasised the role of phytodetrituson the feeding energetics of deep-sea benthic organisms, resulting inthe synchronisation of reproductiveactivity (e.g. Tyler et al., 1982). It has

International Research: Biological Studies: Dixon et al., cont...

Figure 2. Basic mytilid life-history pattern proposed for Bathymodiolus azoricus.This consists of a sedentary adult phase (A), external fertilisation (B),planktotrophic development (C), appearing in this case to be dependentupon the spring bloom in primary production, and larval settlement (D)shown to take place in the summer months leading to clearly recognisableadult size/age cohorts, evidence of a discontinuous recruitment pattern (VanDover et al., 1996; Comtet & Desbruyères, 1998).

already been demonstrated that sur-face-derived particulate matterreaches the vent environment onthe MAR (Dixon et al., 1995), andthere remains the possibility thatqualitative differences in the nutri-tional content of this photosynthet-ic versus the locally-produced,chemosynthetic-derived foodsource could provide the signal thatensures the synchronisation of re-productive development in the adultpopulations. Other evidence alsosuggests that surface-derived ma-terials can enter the deep-sea ventenvironment, sometimes in a largelyunmodified form (Fileman et al.,1998). Interestingly, in the Pacific(EPR) where Maria Baker conductedher studies on B. thermophilus,there is no evidence for a marked,seasonal peak in phytodetrital flux,which probably explains the lack ofreproductive synchrony in this spe-cies (M. Baker, pers. com.)

This proposed link between thereproductive behaviour of a domi-nant MAR vent organism and fluc-tuations in the levels of primary pro-duction in the surface waters con-flicts with the commonly stated be-lief that hydrothermal vents are anisolated, self-contained environ-ment, which was thought to be large-ly independent of processes goingon elsewhere in the rest of the ocean.The existence of seasonal reproduc-tion, if confirmed, in at least onedominant member of the Atlanticvent fauna, will force us to reconsid-er how we view metazoan life in theseislands of chemosynthetic produc-tivity in the deep ocean. Clearly,while vent bacteria may tell us some-thing about life on Mars, vent meta-zoans have their feet (byssus!) firm-ly anchored here on Earth!

It is intended to deploy the cag-es again this summer (2002) in col-laboration with colleagues at IMAR/

17Vol. 11(1), 2002

International Research: Biological Studies: Dixon et al, cont...

DOP and other Portuguese labora-tories. The plan is to recover themat intervals into the next winterperiod, something that can only beachieved using a small vessel, R/VArquipélago, operating opportun-istically out of Horta with respectto the mid Atlantic winter weatherconditions.

AcknowledgementsWe are extremely grateful to Si-

mon Partridge (Sonardyne Interna-tional Ltd.) for generously offeringto provide acoustic releases for thissummer’s cage study. This workrepresents part of the research pro-gramme of the EU-funded VENTOXproject (EVK3CT1999-00003) and isfunded in part by the UK NaturalEnvironment Research Council. Weare also extremely grateful for fundsprovided previously by the EUAMORES project (MAS3-CT95-0040; co-ordinator Dr Daniel Des-bruyères). Finally, we wish to ex-press our grateful thanks to the Cap-

tains and crews of the R/V l’Atalanteand the R/V Arquipélago, and to thepilots and technicians of ROV Vic-tor, without whom none of this workwould have been possible.

ReferencesComtet, T. & D. Desbruyères (1998).

Population structure andrecruitment in mytilid bivalves fromthe Lucky Strike and Menez Gwenhydrothermal vent fields (37º17’Nand 37º50’N on the Mid-AtlanticRidge). Marine Ecology ProgressSeries,163, 165-177.

Comtet, T., M. Le Pennec & D.Desbruyères (1999). Evidence of asexual pause in Bathymodiolusazoricus (Bivalvia: Mytlidae) fromhydrothermal vents of the Mid-Atlantic Ridge. J. Mar. Biol.Ass.U.K.,79, 1149-1150.

Dixon, D.R., D.A.S.B. Jollivet, L.R.J.Dixon, J.A. Nott & P.W.H. Holland(1995). The molecular identificationof early life-history stages ofhydrothermal vent organisms.

Figure 3. Monthly chlorophyll levels in the surface waters above the mid-Atlantic Ridge at 37ºN 31ºW derived from satelliteimagery (data supplied by Prof. Robin Pingree, University of Plymouth). It is clear that in the two years, Sept 1997-Sept 1999, there was a peak in primary production in the surface waters in the early spring that exceeded the winterbackground levels by between three and six-fold.

From Parson, L.M., Walker, C.L. &Dixon, D.R. (eds.), HydrothermalVents and Processes, GeologicalSociety Special Publication No. 87,343-350.

Dixon, D.R. & L.R.J. Dixon (1998).PLASMA: Planktonic LarvalSampler for Molecular Analysis –a progress report. BRIDGENewsletter15, 26- 29.

Fileman, T.W., Pond, D.W., Barlow,R.G. & Mantoura, R.F.C. (1998).Evidence for undegradeddiatomaceous materialsedimenting to the deep ocean inthe Bellingshausen Sea Antarctica.Deep Sea-Research I. 45, 333-346

Tyler, P.A., Grant, A., Pain, S.L. &Gage, J.D. (1982). Is annualreproduction in deep-seaechinoderms a response tovariability in their environment.Nature, London, 300, 747-749.

Tyler, P.A. & C.M. Young (1999).Reproduction and dispersal atvents and cold seeps. J. Mar.Biol.Ass. U.K.,79, 193-208.

InterRidge News18

International Research: Island arc/BAB

IntroductionIn comparison with other island

arcs such as those in the Mediterra-nean Sea and SW Pacific, there havebeen only few studies of submarinehydrothermal mineralisations in theCaribbean island arcs. Kang (1984)described some hydrothermal man-ganese deposits from the region andPolyak et al. (1992) reported on ahydrothermal water column anoma-ly between Montserrat and Guade-loupe. More recently, Johnson &Cronan (2001) have reported con-siderable metal enrichments in hy-drothermal fluids and metalliferoussediments off the central LesserAntilles volcanic arc. The elementsvariably enriched in the fluids as aresult of the hydrothermal activityare Fe, Mn, As, Si, B, Li and in thesediments are Fe, P, Mo, As, Sb, Hg,Cu and Pb. Variations in the concen-trations of these elements in bothfluids and sediments along the arcwere thought to result from a numberof factors, the most important ofwhich is the stage that each island’svolcano has reached in its eruptivecycle.

In order to investigate subma-rine hydrothermal mineralisationoff the Lesser Antilles in more de-tail, a research cruise (CARIB-FLUX) was carried out from Janu-ary 15 to February 8, 2001, with theGerman research vessel “R/VSonne” (SO 154). The main objec-tives of this cruise were to carryout measurements and water sam-pling in the water column and thenear-bottom water layer as well asthe study of local tectonics andthe recovery of hard rock and sed-

iment samples to look for indica-tions of recent to subrecent subma-rine hydrothermal activity in the areaof the Lesser Antilles island arc. Thewestern slope of the arc was select-ed as the main target area since thisarea has many nearshore shallowwater thermal springs (Johnson and

Cronan, 2001).Major target areas were the Ka-

houanne Basin and the MontserratRidge S and SW of the island ofMontserrat, the area W of Dominica,St. Lucia and the Kick’em Jennysubmarine volcano NW of Grenada(Fig. 1).

Submarine Hydrothermal Mineralisations and Fluidsoff the Lesser Antilles Island Arc –

Initial Results from the CARIBFLUX Cruise SO 154

P. Halbach1, H. Marbler1, D.S. Cronan2, A. Koschinsky1, E. Rahders1 and R. Seifert3

1 Freie University of Berlin, Department Geochemistry, Hydrogeology, Mineralogy, Berlin, Germany2 T.H. School of Environment, Earth Sci. and Eng., Imperial College of Sci., Tech. and Med., London, UK3 University of Hamburg, Institute of Biogeochemistry and Marine Chemistry, Hamburg, German

GRENADA

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Figure 1. Map of the Lesser Antilles with cruise track and target areas.

19Vol. 11(1), 2002

crusts appear metasomatic replace-ments of the limestone, includingabundant fossil shells as well asirregular enrichments of nontroniteand other clay minerals. The Mncontents for single layers can reach55 wt.%. The Mn/Fe ratio is veryhigh (up to 118) suggesting little orno input from normal seawater. Thecontents of most trace metals (Ni,Zn, Pb and Co) are very low (Table1) and the concentrations of the rareearth elements are less than 10 ppm.The outer layers and some internallayers of the crusts with distinctpetrographical and geochemicalcompositions indicate that the crustsprecipitated from distinct hydrother-mal episodes and are not a productof continuous deposition.

West of DominicaNear-shore investigations of

Soufriere Bay at the southern tip ofDominica showed that a supposedwater-covered continuation of ahydrothermally active caldera, whichoccurs on land, does not exist. OffNW Dominica, five seamounts wereinvestigated. The older ones are

Kahouanne BasinSample locations in the deepest

part of the Kahouanne Basin andclose to the Shoe-Rock-Spur (SRS)fault zone (western margin of thebasin) were chosen. Methane con-centrations in water samples in thatarea were generally below 3.5 nmol l-1,and values exceeding 1.5 nmol l-1

were restricted to the upper 400 m ofthe water column. Anomalous Znconcentrations in the lower watercolumn (earlier described by Polyaket al., 1992) could not be confirmed.

Sediments contained a few py-rite and chalcopyrite grains, rarelynontronite was found in the south-ern Kahouanne Basin, and in onedredge haul Mn-crusts of thickness-es up to 6 cm were sampled. Thispointed to subrecent hydrothermalactivity in this region: further dredgesampling led to the discovery of aninactive hydrothermal site on a smallplateau in the upper part of the SRSfault zone. These observations andsamplings suggest that a youngmassive sulphide deposit may existbeneath the sea floor. The post-cruise detailed geochemical and min-eralogical studies of the manganesecrusts, the nontronite samples andthe gossan fragments support thisin certain respects (e.g. high Pb-values in certain Mn-oxide-layers ofthe crusts).

The nontronite fragments are ofdark greenish to orange/reddishcolour (in the upper oxidised part)with thicknesses up to 10 cm. Be-side the predominant iron clay min-eral nontronite occur llite, musco-vite and small amounts of calcite.The content of total Fe (bulk) is upto 18 wt.% with depleted Mg, Ca andAl contents.

In the “gossan” fragments thevalues of total Fe reaches 17 wt.%.The Mn contents are up to 6.5 wt.%,which is relatively high for this typeof rocks. Values of trace metals in-cluding Ni, Pb, Zn and V are relative-ly low and range from 160 up to 300ppm. The mineral composition ofthese samples includes iron miner-als such as goethite (also a smallamount of hematite), nontronite,

aragonite and a low content of quartzand manganese oxides. No second-ary Cu or Pb minerals were deter-mined.

Montserrat RidgeAt the Montserrat Ridge, again

no clear indications of present hy-drothermal activity were found inthe water column. Hydrothermal Mncrusts up to 27 cm thickness weredredged, and Mn-cemented ashesare abundant along the ridge. Thecrusts from the Montserrat Ridgeare unique and are described herefor the first time from this part of theLesser Antilles Island arc. Theymight have the function of a caprock above a sulphide deposit.

Within the Mn crusts massivelayers occur which show very heter-ogeneous mineralogic composi-tions. Manganese minerals includ-ing todorokite, birnessite and psi-lomelane occur as thin layers (up to7 mm) alternating with layers (up to2.5 cm) of light calcitic and aragonit-ic sediments and layers of sediments(up to 1.5 cm) with a manganesecement in the outer parts. Within the

sample 18cd 52cd-a 52cd-b 83cd

W.depth m 1144 950 950 1252

Fe wt% 5,15 0,64 3,82 8,15

Mn wt% 40,8 55,3 29 23,6

Al O wt% 5,76 1,98 2,44 8,3

MgO wt% 1,58 3,42 3,23 3,95

CaO wt% 2,15 6,7 7,67 6,07

Cr ppm 9 13 4 19

Cu ppm 59 114 149 226

Ni ppm 57 308 714 657

Zn ppm 53 197 271 298

Ti ppm 864 457 1140 1830

Co ppm 21 26 345 67

Mo ppm 53 360 317 350

Li ppm 17 66 - 250

Pb ppm 140 11 1420 9

2 3

Sample description. 18cd: manganese cemented sediments (Kahouanne Basin);52cd: massive crust, -a: inner Mn oxide-layer, -b: outer Mn oxide-layer(Montserrat Ridge); 83cd: incrustation of volcanic rock (north of Dominica).Data from XRD and ICP-OES

Table 1. Chemical composition of manganese crusts

International Research: Island arc/BAB: Halbach et al., cont...

InterRidge News20

covered by Mn-oxides, and brecci-ated material often contained barite.Of particular interest are andesiticbreccias cemented by hydrothermalmanganese-oxyhydroxides. Meth-ane concentrations in the water col-umn were below 3.0 nmol l-1, withhighest concentrations in the bio-logically influenced upper waterbody, while in deeper water 1 nmol l-1

was not surpassed. However, fur-ther water analyses indicated localenrichments of reduced Cr speciesand Zn, which may indicate hydro-thermal contributions. The highlysensitive determination of Cr spe-cies has been shown to be an effec-tive means to trace hydrothermalsources (Sander and Koschinsky,2000) because the hydrothermalCr(III) signal is stable in the watercolumn. However, the various meas-urements revealed a strong variabil-ity, probably caused by strong localvariabilities in oceanographic pa-rameters and possibly several smallhydrothermal sources. As hotsprings are known to exist along thecoast and offshore Dominica (John-

son and Cronan, 2001), we assumethat the signals we identified are de-rived from various fluid sources atdifferent water depths off Dominica.

West of St. LuciaEnhanced methane concentra-

tions up to 13.8 nmol l-1 were foundin the St. Lucia Bay at water depthsbetween 50 and 100 m. Methane datacorrelate with a similar depth profileof Cr(III) and a maximum of Cr(III) atthe same depth. This input of reduc-ing waters can probably be relatedto the hydrothermal springs at thecoast of the bay. No hydrothermalsolid samples were recovered.

Kick’em JennyEnrichments of reduced Cr spe-

cies and of zinc were identified inmany water column profiles through-out the area; these enrichmentsmostly coincide with maxima of meth-ane and can be attributed to theinfluence of submarine hydrother-mal springs. The valley south of thevolcano contains small, step-likenormal faults. Fluids with methane

contents about 5-fold the back-ground concentration (about 14 nmoll-1 compared to 2-3 nmol l-1) as well aspositive anomalies of Zn (up to 120nmol l-1 in unfiltered samples) werediscovered in about 600 m waterdepth, indicating that low-tempera-ture hydrothermal fluids are emanat-ing from the faults. High resolutionsof the CTD sensor profiles revealedsmall negative salinity anomalies atvarious depths; however, tempera-ture anomalies could not be identi-fied clearly.

Unfortunately, we had no per-mission to sample the crater of thevolcano. Six water samples were tak-en directly at the seafloor on theflanks of the volcano with the HydroBottom Station (HBS) which is aninstrument especially designed tosample diffuse hydrothermal fluids(Halbach et al., 2001). These sam-ples showed increased concentra-tions of Si (up to 33 μmol l-1 com-pared to a background of 18 μmol l-1),methane (up to 22 nmol l-1), and ofseveral trace metals such as Zn, Cuand Ni. There is a significant deple-

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Figure 2. Chloride and silica concentrations in the water column profile of station 108 CTD and in the bottom water samplesof station 134 HBS at the southern flank of the Kick’em Jenny submarine volcano.


21Vol. 11(1), 2002

tion in Cl (0.48 mol l-1 compared tothe background of 0.59 mol l-1), sul-phate, Na, K and Mg compared tothe ambient bottom water. Very smallchemical signals were also visible inthe water column profiles at thisdepth range (Fig. 2). As mixing ofseawater with meteoric water canlargely be excluded, the reducedchlorinity of the samples may indi-cate boiling and phase separation inthe subseafloor. Boiling in hydro-thermal systems produces a vaporphase that is enriched in gases butdepleted in chloride and metal ionsand a brine phase that is highly sa-line and metal-rich (e.g., Butterfieldet al., 1990). Accordingly, our sam-ples would represent a condensedvapor phase. Measurements of sta-ble isotopes support this theory.

DiscussionAlthough hydrothermal mineral-

isation on the sea floor close to theislands is only low grade, it is hy-pothesised that phase separation inthe hydrothermal fluids at depthcould be leading to higher grademineralisation below the vent fieldsor the discharge of metal rich brineson the lower flanks of the volcanicislands.

The widespread occurrence ofmanganese precipitates on the west-ern side of the Lesser Antilles showsthat a fractionation process produc-ing low-temperature hydrothermalsolutions enriched in manganesehas taken place possibly at more orless the same geological timethroughout the study area. Addi-tional work on the manganese crustshas shown that ferromanganese pre-cipitation took place along faultsand fractures and on ridges, and waspromoted by the mixing of modifiedsea water (in a small amount) withhydrothermal fluid. The very lowtrace metal concentrations lead tothe conclusion, that the mineralis-ing fluid was mainly of hydrothermalorigin. In the ternary diagram afterUsui et al., 1992 (Fig. 3a) it is shownthat due to the low concentration ofNi, Cu and Zn, most of the analysedsamples plot in the hydrothermal

field. The diagram Mn/Fe vs. Codemonstrates that the hydrothermalsamples are characterised by highMn/Fe ratios and low Co concentra-tions (Fig. 3b); the three sampleswith higher Co concentrations indi-cate enhanced hydrogenetic input.

Because of the wide distributionof the manganese mineralisation incertain areas, it is thought to havebeen controlled by both focussedand diffuse hydrothermal flow. Anadditional but less important mech-anism of mineralisation is a diage-netic remobilisation and concentra-

tion of manganese by pore fluid inthe unconsolidated sediment.

It is clear from the above that thetwo main indicators of submarinehydrothermal activity in the regionas a whole are manganese crustsand water column anomalies.

Other minerals of hydrothermalorigin were only recovered betweenGuadeloupe and Montserrat, name-ly nontronite and sulphides. Thenontronites indicate low-tempera-ture hydrothermal activity whereaspyrite and chalcopyrite indicatehigher temperature hydrothermal-

Hydrogenrr etic

HyHyHHyydrddryyyy r hehehe allal

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Figure 3. Elemental relationships of all Mn oxide samples recovered duringcruise SO 154; (A) Ternary Diagram Fe– Mn (Cu+Ni+Zn) x 10 after Usuiet al. (1992); (B) Co vs. Mn/Fe


InterRidge News22

ism. Detailed geochemical analysesof the sediments have confirmed theenrichments.

Although the study area off theLesser Antilles was sampled in de-tail in all likely hydrothermal loca-tions, no massive sulphides werefound on the sea floor. There areindications, however, that they maybe present at shallow depth underthe sea floor, beneath a cover ofgossan or manganese crust. Never-theless overall hydrothermal activi-ty in the area appears to be less than,for example, in the western Pacificarcs.

AcknowledgementsCruise SO 154 and the project

CARIBFLUX (grant no. 03 G 0154)are funded by the German FederalMinistry of Education and Re-search (Bundesministerium fürBildung und Forschung BMBF).We thank the captain and crew ofR/V Sonne for the skilled support

during the cruise.

ReferencesButterfield, D.A., Massoth, G.J.,

McDuff, R.E., Lupton, J.E. andLilley, M.D. Geochemistry ofhydrothermal fluids from AxialSeamount hydrothermal emissionsstudy vent field, Juan de Fuca Ridge:Sub-seafloor boiling andsubsequent fluid-rock interaction.Journal of Geophysical Research,95(B8), 12895-12921, 1990.

Freie Universität Berlin and partners.Technical Cruise ReportCARIBFLUX with RV Sonne, cruiseno. SO 154, 2001.

Halbach, P., Holzbecher, E.,Koschinsky, A., Michaelis, W. andSeifert, R. Deep-sea hydrothermalmicroplume generation - a casestudy from the North Fiji Basin.Geomarine Letters, 21, 94-102, 2001.

Johnson, A. & Cronan, D.S.Hydrothermal metalliferoussediments and waters off the Lesser

Antilles. Marine Georesources &Geotechnology, 19, 65-83, 2001.

Kang, J.K. Les encroûtementsferromanganésifères sous-marinede l’est Caraïbe. These, Universited’Orleans, 1984.

Polyak, B.G., Bouysse, Ph., Kononov,V.I., Butuzova, G.Y. Evidence ofsubmarine hydrothermal dischargeto the northwest of GuadeloupeIsland (Lesser Antilles island arc).Journal of Volcanology &Geothermal Research, 54, 81-105,1992.

Sander, S. and Koschinsky, A.Onboard-ship redox speciation ofchromium in diffuse hydrothermalfluids from the North Fiji Basin.Marine Chemistry, 71, 83-102, 2000.

Usui, A. and Nishimura, A.Hydrothermal manganese oxidedeposits from the Izu-Ogasawara(Bonin)-Mariana Arc and adjacentareas. Bulletin of the GeologicalSurvey of Japan, vol. 43 (4), 257-284, 1992.


The Mariana region (Fig.1), theeastern part of the Philippine Sea, ischaracterized by several tectonicfeatures. The Mariana Trench is aresult of downward going of thesubducting Pacific plate. The Mar-iana Islands and the Mariana Troughare one of the typical island arc andbackarc, respectively. The MarianaTrough is a present active backarcbasin and the West Mariana Ridgeis considered as a remnant island

arc. In addition, serpentineseamounts formed by upwelling ser-pentine diapir are often found in theforearc area (e.g., Stern and Smoot,1998). Three upwellings from deepinterior of the earth probably existbelow this region; the Mariana Is-lands, Mariana Trough and the ser-pentine seamounts. These upwell-ings are related to create varioustectonic features in the Mariana re-gion. However, the dynamics of the

ocean bottom and the deep struc-ture beneath this region are stillunclear yet.

We conducted the YK01-11 re-search cruise by R/V Yokosuka,JAMSTEC in October 2001 to char-acterize tectonic features and toobtain a deep and dynamic image ofthe central Mariana region. Here, webriefly report the geophysical ex-periments in the YK01-11 cruise;1) Surface geophysical surveys,

Geophysical Experiments in the Mariana Region: Report of theYK01-11 cruise

T. Goto1, N. Seama2, H. Shiobara3, K. Baba4, M. Ichiki1, H. Iwamoto2, T. Matsuno2, K. Mochizuki3,Y. Nogi5, S. Oki3, K. Schwalenberg6, N. Tada2, K. Suyehiro1, H. Mikada1,

T. Kanazawa3, Y. Fukao3, and H. Utada3

1JAMSTEC, 2-15, Natsushima, Yokosuka, Kanagawa 237-0061, Japan.2Department of Earth and Planetary Sciences, Kobe University, Nada 657-8501, Kobe, Japan3Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan4Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA5National Institute of Polar Research, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan6Department of Physics, University of Toronto, 60, St.George Street, Toronto, M5S 1A7, Canada

23Vol. 11(1), 2002

2) long-term and semi-broadbandocean bottom seismometers (LT-OBSs) observation, and

3) ocean bottom electromagnetometers(OBEMs) observation.Surface geophysical surveys are

conducted to characterize the back-arc spreading evolution of the cen-tral Mariana Trough (16 N-19 N) andserpentine diapirs in the forearc (Fig.2). Multi-narrow beam bathymetry,gravity field, and magnetic field datawere collected. Gravity field datawere obtained from the shipboardgravimeter. Magnetic field data arecollected by the ship-towed protonprecession magnetometer and theshipboard three-component magne-tometers (STCMs: Isezaki, 1986),which can measure the vector of thegeomagnetic field. The Mariana re-gion is near the geomagnetic equa-tor and total intensity anomaly am-plitudes are often much reduceddepending on the orientation of theambient geomagnetic field and mag-

netic lineation (Isezaki, 1986). There-fore, the vector geomagnetic anom-aly field is especially useful to un-derstand its tectonics.

The morphology in the centralMariana Trough shows sevenspreading axis segmentations on thebasis of the present cruise and pre-vious ones (KH92-1, YK96-13, andYK99-11). The non-transform off-sets, that define the ridge segments,can be traced off-axis in the westernside. The direction of the spreadingfabric in the southern part of thisarea changes dramatically fromNNW-SSE to almost N-S trend; thatis interpreted as a result of thechange in the spreading direction.Further analysis combined with crus-tal age and thickness estimations byvector geomagnetic anomaly andgravity data would lead whole tec-tonic evolution in this area. In addi-tion, the morphologic feature in theforearc region indicates eight cones,and their magnetizations and densi-

ties will be estimated using gravityand geomagnetic anomalies. Theresults would lead to the sizes andthe characters of the serpentine di-apirs, which help us to understandthe mechanism of their formation inthe forearc region.

Ten LT-OBSs were deployed toinvestigate the image of deep struc-ture beneath the Mariana trough,how the Pacific plate slab is sub-ducting and stagnant. In addition,this seismic observation has a roleof the feasibility study to know thedeep seismic activity of this area,which has not been determined byon-land seismic observation net-works. For this purpose, three ofLT-OBSs (Fig. 1) are located off themain profile to surround the seismi-cally active area where 600 km deepevents are detected by a global seis-mic network. The LT-OBSs will berecovered in the winter of 2002 FY.

Electrical conductivity in themantle depends on its temperatureand/or existence of melts, so that theconductivity structure is useful toimage a hot mantle material, up-welling regions, and a cold subduct-ing plate. Therefore, ten ocean bot-tom electromagnetometers (OBEMs)were deployed in a line across thewhole Mariana region through thePacific plate, the trench, the arc andthe backarc area (Fig. 1) to revealregional and mantle conductivitystructure. The deep conductivitystructure beneath the slow spread-ing axis of the Mariana Trough isfocused on intensively in this study,so that four of OBEMs are locatedwithin 15 km width from the spread-ing axis. These OBEMs will be re-covered in the October of 2002.

Synthetic calculations of elec-tromagnetic (EM) field on a priorimodels are carried out in order toknow how the EM measurements byOBEMs are sensitive to a deep con-ductivity structure below the Mari-ana region. We calculated time var-iation of sea-floor electric and mag-netic fields at arbitrary periods onseveral 2-dimensional conductivitymodels, and discussed a ratio and aphase difference between the elec-

140Ê 141Ê 142Ê 143Ê 144Ê 145Ê 146Ê 147Ê 148Ê 149Ê 150Ê

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Figure 1. OBEM and LT-OBS positions deployed in the YK01-11 cruise. Thebathymetry is based on a global database by Sandwell and Smith (1997) andSmith and Sandwell(1997).

International Research: Island arc/BAB: Goto et al., cont...

InterRidge News24

tric and the magnetic fields. Thecalculation results indicate severalimportant features:1) A high conductive mantle wedge at

the depth of 15 - 80 km will be wellconstrained by EM responses atthe period of 100 - 5000 sec.

2) A high conductive zone below theMariana Trough at the depth of 10- 80 km will be also imaged by EMresponses at the period of 100 -1000 sec.

3) The effect of the subducting slabdeeper than 100 km depth is notlarge, but it can be observed at theperiod greater than 5000 sec. Thesynthetic calculations encourageour OBEMs observation.These geophysical surveys also

have a role of pilot observation forlater Japan-US international coop-erative seismic and electromagneticexperiments planned in 2002-2005.Results of the surface geophysicalmapping in the YK01-11 cruise willgive us a model of an undergoing

tectonic process in the MarianaTrough. The deep seimic activitywill help to design future seismicobservation networks by densebroadband ocean bottom seismom-eters. Our seismic and electromag-netic experiments will give a coarsestructural image of the upper mantlein the Mariana region, which is a firststep to get further detailed images ofthe upper mantle, such as possibleplumes beneath the trough, and thePacific plate as subducting and stag-nant slab.

Acknowledgement We would like to thank Captain

O. Yukawa, the officers and the crewof R/V Yokosuka for their carefulconsideration for the ship and on-board operation. We discussed sci-entific targets with S. Kodaira, JAM-STEC. T. Kodera, S. Hosoya and Y.Maezawa, Nippon Marine Enterpris-es Ltd., compiled the obtained bathy-metric data on board. M. Shinohara,

T. Yamada, K. Nakahigashi of Earth-quake Research Institute, Univ.Tokyo, helped us to prepare LT-OBSs. H. Shimizu, T. Koyama and S.Asari of Earthquake Research Insti-tute, Univ. Tokyo, assisted withassembling of the OBEMs. R. Evans,J. Bailey, and A. D. Chave of WHOIhelped us to make electrodes for allthe OBEMs. N. Isezaki of ChibaUniversity kindly allows us to usehis STCM system. T. Yamazaki ofAIST and Y. Kido of JAMSTEC pro-vide information on previous sur-face geophysical data. Figures aremade with GMT software developedby Wessel, P. and W. H. F. Smith.

ReferencesStern, R. J. and N. C. Smoot, A

bathymetric overview of theMariana forearc, The Island Arc, 7,525-540, 1998.

Isezaki, N., A new shipboard three-component magnetometer, Geo-physics. 51, 1992-1998. 1986.

Figure 2. Bathymetric map obtained in the YK01-11 cruise.

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International Research: Island arc/BAB: Goto et al., cont...

25Vol. 11(1), 2002

Introduction and geological settingThe Kudi ophiolite, situated in

the northwest segment of the west-ern Kunlun orogenic belts, north-western China (Fig.1), is one of thewell-preserved ophiolite sequencesin the Kunlun Mountains. The ori-gin and tectonic implications for theKudi ophiolite have been previous-ly discussed (Jiang et al., 1992;Deng, 1995; Mattern et al., 1996).Recent studies have reached a con-sensus view that the ophiolite wasformed in a SSZ setting (Wang et al.,2001). The aim of this paper is toconstrain tectonic and magmaticevents of this SSZ ophiolite by de-tailed geochemistry and by compar-ing them with volcanic suites frommodern western Pacific arc-basinsystems. And furthermore, wepresent a model of evolution of aback-arc basin to enhance the un-derstanding of tectonic implicationsof the tholeiite associations.

The Kulun Mountains are com-posed of orogenic belts, in whichseveral ophiolite belts are exposedand regarded as suture zones be-tween blocks (e.g., Jiang et al., 1992).Two major tectonic fault belts in thewestern Kunlun Mountains, theWuyitak-Kudi-Subasi ophiolite beltand Kengxiwar fault zone, separatethe northern Kunlun, southern Kun-lun and Kara-Kunlun respectively(Fig.1). Detailed description of thesethree blocks and the Kengxiwar faultzone can be found in related refer-ences (e.g., Jiang et al., 1992; Mat-tern et al., 1996). There are four mainlithological and tectonic units in thestudied area: Proterozoic metamor-phic rocks, Sinian metavolcanitesand marbles, granitoids in differentages and the late Proterozoic-earlyPaleozoic Kudi ophiolite (Fig.1).

How back-arc basins evolved: tholeiite associations in the Kudi ophiolite ofwestern Kunlun Mountains, northwestern China

Wang Zhihong

Laboratory of Lithosphere Tectonic Evolution, Inst. of Geol. and Geoph., Chinese Acad. of Sci., Beijing, China

International Research: Ophiolites

Figure 1. Geological map and cross-section of the Kudi area along the Xinjiang-Tibet highway based on our field observations and mapping. The isotopicages are discussed in the text.

InterRidge News26

The Kudi ophioliteThe Kudi ophiolite is composed

of a series of oceanic crustal andmantle fragments, including maficand ultramafic rocks, volcanic rocks,the mafic dikes within the volcanicrocks and volcaniclastic flysch sed-iments and turbidites overlying onthe volcanic sequence. The litho-logic units of the mafic and ultrama-fic blocks are mainly harzburgites,dunites, cumulate dunites and py-roxenites, and cumulate and mas-sive gabbros which overlain on theultramafic rocks. Slightly serpenti-nized harzburgites and dunites wereintruded by pegmatitic dikes of py-roxenite and gabbro. The volcanicand volcaniclastic rocks of the Kudiophiolite are well-exposed in thenorth, and can be divided into threeparts according to their lithologicalcharacteristics: (1) the first part ismainly composed of massive andpillow basalts intruded by diabasedikes; (2) the second part is charac-terized by amygdaloidal, massivebasalts interlayered with andesiticbasalts and tuffites; and (3) the thirdpart is mainly composed of volcani-clastic flysch sediments, which con-tain basic volcanic lithic componentswith plagioclase phenocrysts (Mat-tern et al., 1996), and turbidites withBouma sequences. Most research-ers favor formation of the ophiolitein the late Proterozoic-early Palaeo-zoic (e.g., Deng, 1995; Mattern etal., 1996).

Petrology and mineralogyThe mantle peridotites from the

Kudi ophiolite are mainly harzbur-gites with minor dunites. The harz-burgites consists of olivine (Fo=90.9-91.7, 50-90 modal %), Cr-spinel (<5%)and orthopyroxene (En=90.3-91.9, 5-40%) with exsolution lamellae of di-opside and augite (En=48.7-53.3).Serpentinization is weak (generallyless than 10 modal %). The duniteconsists of olivine (Fo=90.3-90.5,about 95%), orthopyroxene(En=91.5-92.2, <5%) and Cr-spinel.The Cr-spinels in the Kudi mantleperidotites have high Cr number(Cr#=100Cr/(Cr+Al)=60-67), and are

of the III-type peridotite proposedby Dick and Bullen, indicating thatthe highly depleted mantle peridot-ites are of arc-related petrogenesisand formed in an environment asso-ciated with a subduction zone. Thepyroxenes in the harzburgites havelow Al2O3 contents (1.09-1.79wt%)and low TiO2 contents (0.01-0.09wt%), suggesting that the harz-burgites are residual mantle perido-tites after high degrees of partialmelting.

The Kudi cumulate complex iscomposed of pyroxenites and gab-bros with minor dunites. The Cr#and Mg# of spinels in the cumulatedunites are in the range of 49.1-52.8and 43.5-46.6 respectively. In theCr#-Mg# diagram, the spinels in thedunites plot near the back-arc basinfield. The pyroxenite is composed ofmainly clinopyroxene (60-80%) andorthopyroxene (<30%), and mostprimary minerals have been partly tocompletely replaced by amphiboleand chlorite. The gabbro mainlyconsists of plagioclase (40-60%) andpyroxene (20-40%) with minor mag-netite, and most fresh pyroxene isclinopyroxene. Amphibolitizationand chloritization also occur in thegabbros.

The Kudi diabases crop out asisolated dikes or as dike swarms. Theyare composed of plagioclase, pyrox-ene and minor olivine. Some primarypyroxenes have been replaced byamphibole and chlorite, while someplagioclases replaced by chlorite andepidote. Calcite veins occur locally.Massive basalts have diabasic tex-tures and are mainly composed ofpyroxene and plagioclase. Pillowbasalts are fine-grained and also com-posed of pyroxene and plagioclase.Primary minerals in massive and pil-low basalts are generally replaced bychlorite and epidote. Amygdales ofamygdaloidal basalts are mainly filledwith chlorite and fine-grained felsicminerals. Chloritization and epidoti-zation are also common in these rocks.

GeochemistryThe Kudi mantle peridotites have

high Mg# (91.1-91.9) and are highly

depleted peridotites. The Al2O3 andCaO contents in the rocks are low,0.62-1.15 wt% and 0.3-0.95wt% re-spectively. The TiO2 content of themantle peridotites varies from 0.003to 0.014 wt%, lower than those ofmid-ocean-ridge mantle rocks (0.1-0.4 wt%) and similar to those ofmantle rocks from ophiolites formedin supra-subduction zone environ-ments (<0.1 wt%) (Pearce et al., 1984).

Relative to primitive mantle val-ues, the Kudi mantle peridotites areslightly richer in Th and U (1-10´prim-itive mantle) and poorer in Ti (0.1-1´primitive mantle). The Kudi mantleperidotites display LREE-enrichedchondrite-normalized rare-earth-el-ement patterns with LREE/HREE=3.2-5.6 and (La/Yb)n=2.1-3.4(Wang et al., 2001).

The contents of Al2O3, CaO, SiO2and TiO2 increase from the mantleperidotites to pyroxenites and togabbros. The Al2O3, CaO and FeO*contents in the pyroxenites havewide ranges, reflecting the variabil-ity of pyroxene mode and composi-tions. The gabbros are high in Al2O3and low in FeO*, though both havelimited ranges.

Chondrite-normalized trace ele-ment patterns for the cumulate py-roxenites and gabbros exhibitmarked negative Nb and Ti anoma-lies (Wang et al., 2001). The pyrox-enites have flat REE patterns andthe REE concentrations are 1-10´chondrite (Wang et al., 2001).The REE patterns for the gabbrosare also flat (Wang et al., 2001).

TiO2 contents clearly separatethe extrusive rocks into three differ-ent magmatic suites. Group 1 basaltsare characterized by moderate TiO2contents (0.8-1wt%), and group 2basalts have higher TiO2 contents(1-1.6 wt%, most of them are higherthan 1.1 wt%), while group 3 basaltshave lowest TiO2 contents (0.16-0.38wt%). The TiO2 contents of the dia-bases are similar to that of group 2basalts.

Group 1 basalts disply similar N-MORB normalized trace elementpatterns with that of the Tofua arc,and more enriched in La and Ce also

International Research: Ophiolites: Zhihong, cont...

27Vol. 11(1), 2002

LREE-depleted chondrite-normal-ized REE patterns with low levelsof HREE (Fig.2c). In conclusion,the Kudi extrusive rocks are com-posed of three different tholeiiteassociations.

Magma sources for the tholeiiteassociations

On the TiO2-Zr diagram, Group 3basalts plot in and near the fields ofHunter Ridge and IBM forearc bon-inites, while group 2 basalts mimicthe MORB trend (Ti/Zr=102), andTi/Zr values of group 1 basalts aremostly in the range of 75-100. Thesethree groups of basalts are clearlyseparated on the diagram of La/Sm-TiO2 (Fig.3). Group 1 basalts plot inthe field of Mariana arc and muchLREE-enriched area, group 2 basaltsin the field of Lau Basin, and group3 basalts in and near the fields ofHunter Ridge and IBM forearc bon-inites. On the Hf/3-Th-Nb/16 dia-gram, group 1 and 2 basalts indicatea clear supra-subduction zone (SSZ)signiture. Conclusively, we interpretgroup 1 basalts to be LREE-enrichedisland arc tholeiites (IAT), group 2basalts to be back-arc basin (BAB)tholeiites, and group 3 basalts to below-Ti island arc tholeiites (IAT).

Tectonic evolution of the KudiophioliteAn upper mantle and crustal sectionof a back-arc basin

The mantle peridotites are rich inMg and Ni and poor in Al and Ca;and the pyroxene is low in Al and Ti,and the spinel is high in Cr#(Cr#>0.6), indicating that they arehighly depleted mantle residues andsimilar to those of mantle rocks fromSSZ ophiolites. The cumulate py-roxenites and gabbros are Nb and Tidepleted and are of arc affinity.These cumulate rocks have flat REEpatterns as that of group 2 basalts.The cumulate gabbros together withthe diabase and group 2 basaltsdefine a clear cogenetic trend in theHf-Th-Nb diagram. As discussedearlier, the diabase dikes and group2 basalts have indistinguishablegeochemistry with that of tholeiites

as shown by their LREE-enrichedchondrite-normalized REE patterns(Fig.2a). On N-MORB normalizedtrace element patterns, group 2 ba-salt display marked negative Nbanomalies. Furthermore, these ba-salts have slightly LREE-depletedor flat chondrite-normalized REEpatterns (Fig.2b). Diabase dikes aresimilar to group 2 basalts both intrace and rare-earth elments geo-

chemistry (Fig.2b), as their majorelements. Group 3 basalts have lowTiO2 (0.16-0.38 wt%), P2O5 (0.01-0.03wt%), Zr (4-30 ppm) and Y (7-11ppm); and high Mg (Mg#=62-72)and Cr (300-500 ppm). They displaysimilar N-MORB normalized trace el-ement patterns (low levels of HFSE)with that of the boninites from theBonin Islands (even more enrichedin LILE) and slightly U-shaped or

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Figure 2. Chondrite-normalized rare-earth-element patterns for the tholeiiteassociations from the Kudi- ophiolite. (A)-LREE-enriched group 1 basalts;(B)-LREE-depleted and flat group 2 basalts (solid circles for the diabasedikes); (C)-U-shaped group 3 basalts. Normalizing values are from Sun andMcDonough (1989).


InterRidge News28

from back-arc basins. In summary,the main parts of the Kudi ophiolite,namely the SSZ-type mantle perido-tites, cumulate complex with arc tho-leiite affinity, and BABB-type dia-base dikes and group 2 basalts con-stitute an upper mantle and crustalsection of a back-arc basin in a SSZenvironment.

Petrogenetic scenario for the low-Tiisland arc tholeiites (IAT)

Group 3 basalts share lots ofcommon geochemical characteris-tics with the modern boninites, i.e.,low Ti and HFSE, high Cr, and slight-ly U-shaped or LREE-depleted chon-drite-normalized REE patterns withlow levels of HREE, especially withthe boninites from the Hunter Ridgeand IBM forearc (Fig. 3). The geo-chemistry of the low-Ti IAT indi-cates that they represent melts de-rived from a depleted mantle sourceregion modified compositionally byfluids and/or melts during subduc-tion metasomatism. The occurrenceof calc-alkaline volcanics and vol-caniclastic sediments above theKudi ophiolite, which is normallyrestricted to mature intraoceanicarcs, implies that these low-Ti IATwere not produced during the initi-ation of an island arc or not associ-ated with the initiation of subduc-

tion. Field observations indicate thatthe low-Ti IAT generally overlay theBAB tholeiites and/or are interlay-ered with the BAB tholeiites locally,suggesting that they could haveformed after the BAB tholeiites orapproximately the same time. In oth-er words, the low-Ti IAT producedduring extension of the back-arcbasin. We present here an interac-tion model between subduction andextension of a back-arc basin forinterpreting tectonic and magmaticevents responsible for the origin ofthe low-Ti IAT.

Intraoceanic subduction gener-ally and firstly results in slab devol-atilization, with focussed fluid effluxinto the convecting mantle wedgetriggering partial melting, and con-sequently arc volcanism is devel-oped (Fig.4a). Geophysical investi-gation of marginal basins in thewestern Pacific suggested that initi-ation of inter-arc basin extension isresulted from mantle diapir ratherthan a change of subduction zoneconfiguration (e.g., trench rollback).The coupling of MORB-type mantleupwelling with fluid efflux from slabdevolatilization would permit forma-tion of BABB-type magmatism bywhich floored the extensional back-arc basin (Fig.4b). Continued mantleupwelling and consequent extension

would possibly give birth to propa-gating of back-arc basin spreadingridge into a protoarc along the trend.Hydrous fluids enriched in LILEemanate from the subducting lithos-pheric slab into the formerly deplet-ed (extraction of BABB magma) andhot refractory mantle (newly formedupper mantle in the back-arc basin),triggering partial re-melting, andconsequently the low-Ti IAT mag-ma formed. If the magma extruderight at the bottom of the back-arcbasin, the low-Ti IAT will cover theformer floored BAB tholeiites. If themagmas extrude into the propagat-ing tip of the back-arc basin, the IATwill interlayer with the BAB tholei-ites following continued basin ex-tension (Fig.4b).

Tectonic implication of the LREE-enriched IAT

It is different to distinguish thesecond-stage arc magma from thefirst-stage arc magma forming theprotoarc (Fig.4a). Group 1 basalts inthe Kudi ophiolite are more enrichedin LILE and LREE than the basaltsfrom typical arcs (e.g., Fig.3), sug-gesting that voluminous fluid effluxhad entered into the mantle wedgepossibly due to devolatilization oftwo subducting slabs (Fig.4c) and/or much close to a subduction zone.The interaction occurred betweenthe parental magma of group 1 ba-salts and the mantle peridotites fromthe mantle wedge and formerly theupper mantle of the back-arc basin(Wang et al., 2001), spatially andtemporally eliminating the possibil-ities of protoarc magmatism for group1 basalts. This implies that a newsubduction zone, indicative of clo-sure of the back-arc basin, hademerged within the Kudi palaeo-back-arc basin, permitting hydrousfluids and/or melts from devolatili-zation of the back-arc basin lithos-phere subducting slab to interactwith the rocks in a newly formedmantle wedge (Fig.4c).

ConclusionsWe developed an evolution mod-

el of a back-arc basin to explain tec-

Figure 3. Comparison of La/Sm and TiO2 for group 1 basalts (solid squares),group 2 basalts (solid circles) and group 3 basalts (open circles) from the Kudiophiolite and modern arc systems.


29Vol. 11(1), 2002

tonic and magmatic events of theearly Paleozoic Kudi SSZ ophioliteinvolving the production of threetypes of tholeiite associations.

The SSZ-type mantle peridot-ites, cumulate complex with arc tho-leiite affinity, and BABB-type dia-base dikes and basalts constitute anupper mantle and crustal section ofa back-arc basin formed by couplingof MORB-type mantle upwellingwith fluid efflux from slab devolatil-ization. The low-Ti IAT representmelts derived from a depleted mantlesource region (extraction of BABBmagma) modified compositionally byfluids and/or melts from the sub-ducting lithospheric slab duringpropagation and extension of theback-arc basin. The emergence ofthe LREE-enriched IAT and the in-teraction between the parental mag-ma of the IAT and the mantle wedgerocks indicate the closure of theback-arc basin.

AcknowledgmentsWe are indebted to Chen H L,

Xiao W J, Zhang G C, Zhou H, FangA M, Yuan C, and Wei X S for theirfield help. This research was sup-ported by the National 305 Project.

ReferencesDeng, W.M., Geological features of

ophiolite and tectonic significancein the Karakorum-west KunlunMts, Acta Petrologica Sinica, 11,98-111, 1995 (in Chinese withEnglish abstract).

Jiang, C.F., J.S.Yang, B.G.Feng,Z.Z.Zhu, M.Zhao, Y.C.Chai,X.D.Shi, H.D.Wang, and J.Q.Hu,Opening-closing tectonics of theKunlun mountains, Geol.Memoirs.5(12), pp.224, GeologicalPublishing House, Beijing, 1992(in Chinese with English abstract).

Mattern, F., W.Schneider, Y.Li, andX.Li, A traverse through thewestern Kunlun (Xinjiang, China):tentative geodynamic implicationsfor the Paleozoic and Mesozoic,Geol. Rundsch,85, 705-722, 1996.

Pearce, J.A., S.J.Lippard, andS.Roberts, Characteristics andtectonic significance of supra-

subduction zone ophiolites, InMarginal Basin Geology, editedby B.P.Kokelaar, and M.F.Howells,Geol. Soc. London Spec. Publ., 16,77-94, 1984.

Wang, Z.H., S.Sun, Q.L.Hou, and J.L.Li,

Effect of melt-rock interaction ongeochemistry in the Kudi ophiolite(western Kunlun Mountains,northwestern China): implicationfor ophiolite origin, Earth Planet.Sci.Lett., 191, 33-48, 2001.

2

2

2

Figure 4. Schematic diagram illustrating the evolution of a back-arc basin andproduction of three tholeiite associations. (A) A first-stage arc system (theprotoarc). (B) Propagation and extension of a back-arc basin. The symbol ofa star with in a round circle represents the low-Ti IAT generally overlaid theBAB tholeiites which floored the basin; and the star symbol represents thelow-Ti IAT commonly interlayered with the BAB tholeiites at the propagatingtip of the back-arc basin. (C) A second-stage arc magmatism related toformation of the LREE-enriched IAT during the closure of the back-arc basin,arousing the interaction between the arc magma and the mantle rocks. Seetext for detailed discussion.


InterRidge News30

International Research: Pacific-Antarctic Ridge

The Foundation seamount chainwas first visited during 1995 by theR/V SONNE, and subsequently in1997 by the R/V L’ATALANTE. Geo-chemical and geophysical data fromthese cruises have shown that theFoundation seamounts formed dur-ing the passage of the Pacific Plate

Widespread Silicic Volcanism and Hydrothermal Activity on theNorthern Pacific – Antarctic Ridge

P. Stoffers1, T. Worthington1, R. Hekinian1, S. Petersen2, M. Hannington3, M. Türkay4, D.Ackermand1, C. Borowski5, S. Dankert2, S. Fretzdorff1, K. Haase1, A. Hoppe1, I. Jonasson3, T.

Kuhn2, R. Lancaster3, T. Monecke2, A. Renno2, J. Stecher4, L. Weiershäuser6

1 Institut für Geowissenschaften, Universität Kiel, Germany2 Institut für Mineralogie, Technische Universität Bergakademie Freiberg, Germany3 Natural Resources Canada, Ottawa, Canada4 Forschungsinstitut Senckenberg, Frankfurt, Germany5 Zoologisches Institut, Universität Hamburg, Germany6 Department of Geology, University of Toronto, Canada

over a mantle plume, and that thisplume is presently located 35 kmwest of the Pacific–Antarctic Ridge(PAR) near 37°25’S (Fig. 1; Maia etal., 2000; 2001; O’Connor et al.,2001). Surprisingly, silicic lavas (upto 64 wt.% SiO2) were recovered fromthe PAR crest adjacent to the young-

est Foundation seamounts (Hekini-an et al., 1997; 1999). Silicic volcan-ism (>55 wt.% SiO2) on mid-oceanridges is rare, but does occur on thenorthern East Pacific Rise (10.5°N;Thompson et al., 1989) and the 095°propagator of the Galapagos Spread-ing Centre (Clague et al., 1981).

The prime objectives of theFOUNDATION III cruise (R/VSONNE- SO 157) in mid-2001 were todetermine the extent of the siliciclavas along the PAR and to investi-gate associated hydrothermal activ-ity. We examined a 630 km-long seg-ment of the northern PAR boundedby large left-stepping overlappingspreading centres (OSCs) near 36.5°Sand 41.5°S (Fig. 1). Detailed bathy-metric data was collected using thenewly installed SIMRAD EM120onboard the R/V SONNE, and 65 sta-tions were devoted to recoveringseafloor samples in conjunction withvideo observations of hydrothermalactivity and vent fauna.

The PAR at 37.5 – 41.5°SIn the northern part of the sur-

veyed area, the PAR axis forms aseries of short (~15 km-long) non-overlapping segments (Fig. 2). Smallright-stepping non-transform dis-continuites offset each segment by~1 km, although a more complexwestward bending occurs aroundan off-axis seamount near 38°15’S.Each segment is dome-shaped, withthe elevation decreasing gently

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31Vol. 11(1), 2002

was video surveyed by the R/VL’ATALANTE in early 1997. The newlava covers an area of 3.5 km x 200 m,and was erupted from a series ofpartly buried fissures whose loca-tion is marked by collapse pits. Amore varied lava suite was recov-ered from the lower flanks of thedome, where the dominant litholo-gies were glass-encrusted sparselyphyric pillow andesite and basalt.Light dustings of MnOx suggestmost of these lower lavas are older.

To the south of 38°15’S, the PARaxis continues at an almost constantdepth of 2220–2250 m. Pillow andsheet flows of sparsely phyric an-desite and basalt characterise this120 km-long section. The section isterminated by two 120 m-high axialdomes constructed near 39°20’S and

39°27’S (Fig. 1). The crest of thesouthern dome at 2090 m-depth iscapped by a fresh 4 km-long tabularflow of glassy aphyric andesite withskeletal pyroxene and plagioclasecrystals. Strongly elongated flow-aligned vesicles often containedpyrite-cubanite crystals, and re-leased H2S when cut.

Further south, a series of 40–50km-long ridge segments (each 40–50km-long) are separated by left-step-ping OSCs at 39°48’, 40°09’, 40°34’,40°55’, and 41°19’S (Fig. 1). The ridgeaxis is offset by 4–5 km at each ofthese discontinuities, and the over-lap distance varies from 5–22 km.MORB-like pillow lavas were recov-ered from these segments. Our sur-vey terminated at the large left-step-ping OSC near 41°22’S, where theridge crest is offset by 18 km and theoverlap extends for 10 km. An isolat-ed 500 m-high seamount with a well-developed summit crater has beenbuilt in the overlap basin. Fresh aphy-ric basalt, older MnOx-stained sparse-ly phyric basalt and dolerite wererecovered from the summit crater.

Hydrothermal activity and vent faunaActive hydrothermal vents, to-

gether with abundant vent faunaand fossil sulphide deposits, werelocated during video sled and TV-controlled grab surveys. These sur-veys provided comprehensive cov-erage of the 37°40’S and 37°48’Saxial domes. The high-temperaturesulphide deposits and vent faunaare the first reported occurrencesfrom high latitudes on southernhemisphere spreading ridges.

Widespread diffuse venting(near-bottom water temperatureanomalies up to 0.25°C) is associat-ed with the young silicic flows in thecleft of the 37°40’S dome. Both thecleft walls and recovered rocks werecommonly stained with Fe-hydrox-ides. Two partly talus-covered sul-phide outcrops occur along the east-ern cleft wall. Both are 30 m in diam-eter, and comprise sulphide rubblewith halos of metalliferous sedimentand Fe-hydroxide staining. Free-standing sulphide spires were seen

along strike towards its ends. Thedomes are better developed north ofthe off-axis seamount, where theyrise ~100 m above the segment ends.Graben-like clefts up to 200 m-wideand 50 m-deep cut through some ofthe domes.

The 37°40’S dome was selectedfor a detailed petrological and hy-drothermal study. This dome risesto 2120 m-depth, and is cut by a cleftfilled with fresh glassy lavas andtalus from adjacent pillow mounds.Lavas from the summit and cleft in-clude aphyric dacite and andesite,and have glass crusts >5 mm thick.Conchoidal fractures, together withnumerous strongly elongate andflow-aligned vesicles, characterisethese silicic lavas. At least one lavaflow was emplaced since the area

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International Research: Pacific-Antarctic Ridge: Stoffers et al., cont...

InterRidge News32

at the northernmost site. Three areasof dark, dusty hydrothermal sedi-ment, interpreted as recent plumefallout, coincided with weak temper-ature anomalies. One was near a clamfield seen during the 1995 R/VSONNEcruise, and another extended for 100m over the post-1997 glassy siliciclava at the southern end of the cleft.

The 37°48’S axial dome consistsof partly sediment-covered lavasburied by younger sediment-freeflows, and lacks a central cleft. Nev-ertheless, near-bottom water tem-perature anomalies (up to 0.25°C)occur at deep fissures cutting theyounger lavas on the southern domeflank. White hydrothermal fluid wasobserved near a sulphide outcrop 10m across at one fissure, and thefissures are surrounded by a vesico-myid clam bed 50 m in diameter andabundant vent fauna. A fossil sul-phide outcrop 30 m across occurs1.7 km north of the clam field, andincludes two large sulphide spiresup to 3 m high. There, an old sul-phide mound has been partly buriedand disrupted by young lavas.Abundant sulphide talus has beenramped onto the young lavas, andsulphide windows outcrop betweenpillows. The talus is strongly al-tered, and stained with bright redFe-hydroxides, yellow jarosite, andbright green atacamite. Recoveredsulphide blocks consisted of coa-lesced pyrite chimneys, massive re-crystallised sphalerite and chalcop-yrite, and included sulphide-pseu-domorphed clams and large wormtubes up to 1.5 cm in diameter.

The faunal communities aroundthe active hydrothermal vents are

dominated by Bathymodiolus andNeolepas, and mobile animals in-clude bythograeid crabs, Munidop-sis, and zoarcid fish. Unlike B. ther-mophilus found near sulphide-richvent fluids elsewhere, the gills ofour recovered Bathymodiolus spec-imens were only moderately hyper-trophic and H2S was not releasedwhen the shells were opened. Poly-chaete worms and snails were col-lected from the vent sites, and densebeds of dead vesicomyid clams wereseen in the peripheral zone. Filter-feeders at the active vents and in theperipheral zone were hexactinellidsponges and sessile crinoids, where-as the more distal zones were dom-inated by large assemblages of ser-pulid tubes, actinians, coryphaenidfish and swimming crinoids. Theabundance of swimming crinoids atthe PAR is possibly unique, andthey were a useful indicator of near-by hydrothermal venting.

SummarySilicic lavas have now been re-

covered from the upper flanks ofPAR axial domes between 37°11’Sand 39°48’S, a distance of 290 km.These lavas outcrop on the upperflanks and summits of the axialdomes, whereas less silicic lavas arefound on the lower dome flanks (Fig.3). Widespread hydrothermal activ-ity and sulphide deposits are asso-ciated with the silicic volcanism, andmay reflect the high heat flow avail-able from fractionating magma.

AcknowledgementsWe thank Captain Henning Pap-

enhagen, his officers and the crew

onboard R/V SONNE cruise 157 fortheir expert help. This project is fund-ed by BMBF Grant 03G0157A.

ReferencesClague, D.A., F.A. Frey, G. Thompson,

and S. Rindge. Minor and tracegeochemistry of volcanic rocksdredged from the GalapagosSpreading Center: role of crystalfractionation and mantleheterogeneity. J. Geophys. Res.,86, 9469–9482, 1981.

Hekinian, R., P. Stoffers, C. Devey, D.Ackermand, C. Hémond, J.O’Connor, N. Binard, and M. Maia.Intraplate versus ridge volcanismon the Pacific–Antarctic Ridge near37°S - 111°W. J. Geophys. Res.,102, 12265–12286, 1997.

Hekinian, R., P. Stoffers, D.Ackermand, S. Révillon, M. Maia,and M. Bohn. Ridge–hotspotinteraction: the Pacific–AntarcticRidge and the Foundationseamounts. Mar. Geol., 160, 199–223, 1999.

Maia, M., D. Ackermand, G.A.Dehghani, P. Gente, R. Hekinian,D. Naar, J. O’Connor, K. Perrot, J.Phipps Morgan, G. Ramillien, S.Révillon, A. Sabetian, D. Sandwell,and P. Stoffers. The Pacific–Antarctic Ridge–Foundationhotspot interaction: a case studyof a ridge approaching a hotspot.Mar. Geol., 167, 61–84, 2000.

Maia, M., C. Hémond, and P. Gente.Contrasted interactions betweenplume, upper mantle, andlithosphere: Foundation chaincase.Geochem. Geophys. Geosyst.,2, #2000GC000117, 2001.

O’Connor, J.M., P. Stoffers, and J.R.Wijbrans. En echelon volcanicelongate ridges connectingintraplate Foundation Chainvolcanism to the Pacific–Antarcticspreading center. Earth Planet.Sci. Lett., 192, 633–648, 2001.

Thompson, G., W.B. Bryan, and S.E.Humphris. Axial volcanism on theEast Pacific Rise, 10–12°N, in:Magmatism in the Ocean Basins,eds. A.D. Saunders and M.J. Norry.Geol. Soc. Spec. Publ., 42,181–200, 1989.

36˚S 37˚S 38˚S 39˚S 40˚S 41˚S 42˚S

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Silicic lavas on PA R axial domesdredge sitesilicic dome

Figure 3. Bathymetric profile of the northern PAR. Silicic lavas predominate onthe axial domes between 37°11’S and 39°48’S.

International Research: Pacific-Antarctic Ridge: Stoffers et al., cont...

33Vol. 11(1), 2002

IntroductionNumerous previous studies have

reliably established regional andlocal variations of isotope composi-tions for mid-ocean ridge basalts(MORBs). As early as in 1987, E. Itoand co-workers in their review em-phasized the fact that Indian Oceanbasalts are enriched in radiogenic Srand Pb isotopes with respect to Pa-cific and Atlantic MORBs. At rough-

ly the same time, “enriched” MORBswere detected in the South Atlantic.This enabled S. Hart to establish theDUPAL anomaly of the SouthernHemisphere, so named after B. Du-pre and C. Allegre, prominent re-searchers in the field of isotope ge-ochemistry. The limited size of thispaper compels us to refer hereinaf-ter to the review (Hofmann, 1997).Besides, there exist a huge number

of published work that address finervariations in MORB compositionwithin specific regions. In most cas-es, MORB isotope systematics drawin one way or another on the “mantletetrahedron” of A. Zindler and S.Hart (1986). Its corners are made bythe so-called end members whichinclude DM (depleted mantle),HIMU (high μ mantle, where μ is238U/204Pb), and two types of en-riched mantle, EM1 and EM2. Someauthors believe that the DUPALanomaly is easiest to explain by in-troducing a certain “composite” endmember, LOMU (“low μ mantle”),which is a mixture of EM1 and EM2(Douglass and Schilling, 1999). Be-sides, in use are a number of within-tetrahedron components (FOZO,PREMA, C, etc.) (Hofmann, 1997),one of which (C, or “common”) isviewed as being common to MORBsfrom different oceans (Hanan andGraham, 1996). Many workers notethe similarity of within-tetrahedroncomponents and use them as indica-tors of lower-mantle plumes (Hof-mann, 1997). However, distinctionsbetween these components are greatenough. This results in considera-ble uncertainty and, not infrequent-ly, inconsistency in systematics andinterpretations of one and the samefeature. This makes direct compila-tion of conclusions obtained by dif-ferent workers rather hard. Our studypresents results from data generali-zation for MORB compositions us-ing all-embracing Sr–Nd–Pb isotopesystematics, modified by means ofmultidimensional statistics.

Methods usedThe entire data set (820 published

analyses) was convoluted using amultidimensional data agglomera-tion technique of our own, which

Isotope provinces of mid-ocean ridges

A.A. Pustovoy1, Yu.V. Mironov2, and V.M. Ryakhovsky2

1 Shirshov Institute of Oceanology RAS, Atlantic Branch, Kaliningrad, Russia2 Vernadsky State Geological Museum RAS, Moscow, Russia

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Figure 1. MORB isotope systematic. 1-3 - the average isotope compositions forclusters of: normal (1); DUPAL (2) and “singular” MORB (3); 4 - individualcompositions of “singular” MORB from Arctic province; 5 – flood basaltsfrom Eastern Greenland.

International Research: Mid-Ocean Ridge

InterRidge News34

affords the identification of compo-sitional clusters in multidimension-al space. A reference frame for thespace under study was provided bythe customarily used radiogenic/non-radiogenic isotope ratios (87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb). To systematizethe MORB clusters identified, weused our own modification of the“mantle tetrahedron” (Fig. 1)(Rundqvist et al., 2000). Its crucial

classification element, along withthe end members, is the F (“focal”)within-tetrahedron component. Itwas derived as the mean composi-tion of an independent cluster in thecourse of a similar analysis of data,dominantly from intraplate oceanicstructures. The component F turnedout to be close in composition to themean for all the within-tetrahedroncomponents known so far, includ-ing C. We regard the component F as

a general characteristic for within-tetrahedron components, con-strained using multidimensional sta-tistics techniques. Previously, vari-ance of MORB isotope compositionwas shown to be due principally tomixing of the component F with DM(Rundqvist et al., 2000). For thisreason, for the purposes of MORBsystematics, we used an additionalclassification element, the join F–DM (Mironov et al., 2000).

MORB types and isotope provincesof mid-ocean ridges

Based on how mean composi-tions of the clusters plot with re-spect to the mixing line F + DM, threeprincipal types of MORB can be iden-tified (Fig. 1). These types are spa-tially discrete and compose exten-sive provinces (Fig. 2). The first type,the counterpart to “normal” MORB,is featured by the presence of HIMU(F + DM + HIMU field). This type is

Figure 2. Isotope heterogeneity of World Ocean. Mid-ocean ridge isotope provinces: Pacific (I), Central Atlantic (II), RedSea – Aden (III), South Atlantic (IV), Indian Ocean (V), Arctic (VI), and Transitional Indian-Atlantic (VII). Normal MORBsuites: DM+HIMU (1) and DM+F+(HIMU) (2); DUPAL MORB suites: DM+F+(EM1) (3) and DM+F+EM1 (4);“Singular” MORB suite DM+F+(ARC) (5); isotope rock types from intraplate structures: F+HIMU (6), F+EM1 (7) andF+DM+(ARC) (8) (after Mironov et al., 2000). The boundaries of the isotope mid-ocean ridge provinces (9).

International Research: Mid-Ocean Ridge: Pustovoy, et al., cont...

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35Vol. 11(1), 2002

widespread in the Central Atlantic,Pacific, and Red Sea–Aden provinc-es. The second type is developedwithin the DUPAL anomaly. Its hall-mark is the presence of EM1 (F + DM+ EM1 field). The South Atlantic andIndian Ocean provinces, which liewithin the DUPAL anomaly, are sep-arated by the Transitional (Indian–Atlantic) province, where both nor-

mal and DUPAL-MORB coexist. Inaddition to these rather well-knowntypes, we established a third type ofMORB, which defines the singular-ity of the Arctic province. The latterencompasses the ridges of the NorthAtlantic and the Norwegian–Green-land Basin, including the northernReykjanes Ridge on the south andthe Gakkel Ridge on the north. As

noted earlier, Gakkel Ridge basaltsare isotopically similar to DUPAL-MORB (Muhe et al., 1997). Indeed,in terms of most isotope characteris-tics, such as 206Pb/204Pb vs. 87Sr/86Sr(Fig. 1), 206Pb/204Pb vs. 143Nd/144Nd.,and 206Pb/204Pb vs. 208Pb/204Pb varia-tions, this type is analogous toDUPAL-MORB. However, in termsof 206Pb/204Pb vs. 207Pb/204Pb varia-tions, it matches normal MORB (Fig.1). This peculiarity cannot be due toEM1 admixture, as in the southernDUPAL anomaly. The most likelyexplanation is a certain degree ofcontamination of oceanic lithos-phere in this region by another com-ponent, which, for the time being,we term tentatively ARC (“Arctic”).This component is located far be-yond the “mantle tetrahedron,” inthe region of extremely low 206Pb/204Pb and 207Pb/204Pb values.

Boundaries of isotope provinc-es for mid-ocean ridges fit in withthose of E–W transoceanic hetero-geneities delineated earlier basedon isotope compositions of volcan-ites on intraplate rises and islands(Fig. 2) (Rundqvist, 2000). Remarka-bly, the MORB signature of a givenprovince is defined by the sameadmixture (EM1 or HIMU) that pre-vails in volcanic compositions onlatitudinally close rises and islands,where it forms quasi-binary mixtureswith the component F (Mironov etal., 2000). In this respect, the Arcticprovince is somewhat different.Here, the component ARC, criticalto the recognition of the province,makes only a minor admixture in mix-ing products of F and DM not solelyin mid-ocean ridges, but on islandsas well. At the same time, quasi-binary mixing of F and ARC is re-corded only in the continental floodvolcanites, which preceded the open-ing of the North Atlantic (Fig. 1).

Comparative characteristics of iso-tope provinces

Cluster frequency histogramsshow that provinces composed ofthe same MORB type still differ fromeach other to some extent (Fig. 3).Thus, the Central Atlantic province

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Figure 3. Frequency of occurrence of normal (I), “singular” (II), and DUPAL (III)MORB in mid-ocean ridge provinces.


InterRidge News36

(unlike the Pacific one) is character-ized by the presence of “normal”MORB varieties with a high propor-tion of F and HIMU components.This and other distinctions are morereadily evident in a section of themantle tetrahedron (Fig. 4). In theCentral Atlantic province, twoMORB suites are distinguishedclearly. One suite, widespread in thenorthern segment of the province(Fig. 2), originates from mixing of Fand DM with a minor HIMU admix-ture. A similar suite is developed inthe Red Sea–Aden province. Thesecond suite, intrinsic to the south-ern segment of the Central Atlanticprovince (24°N–24°S), is more con-sistent with direct mixing of the twoend members, DM and HIMU (witha minor F admixture). Compositionalrange of this MORB suite accommo-dates all MORB compositions fromthe Pacific province as well, withPacific basalts having a much nar-rower range, tending towards DM.

No less clear distinctions existbetween the Indian Ocean and SouthAtlantic provinces, composed ofDUPAL-MORB (Fig. 4). Variance ofIndian MORB is due mainly to mix-ing of DM and F (with EM1 admix-ture). Compositional variations ofSouth Atlantic MORB can be ex-plained by mixing of two “compos-ite” components. One of these cor-responds roughly to the mean com-position of Indian MORB. The othercomponent is closely similar to the

LOMU

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Figure 4. Isotope suites of normal (A) and DUPAL (B) MORB. Isotope mid-ocean ridge provinces: Central Atlantic, northern segment (1), Red Sea -Aden (2), Central Atlantic, southern segment (3), Pacific (4), Indian Ocean(5), South Atlantic (6); intraplate structures, data from which were used fordefinition of component LOMU: Africa and Australia (7), Gough, Tristan daCunha, Discovery (8), Afanasy Nikitin (9) (after Douglass, Schilling, 1999);other intraplate DUPAL structures (10).


Editor's Note

The articles appearing in InterRidge News are intended to disseminate as quickly as possiblepreliminary results on recent mid-ocean ridge and back arc ocean cruises. Articles are notpeer-reviewed and should not be cited as peer reviewed articles. The InterRidge office doesedit the articles and strives to correct any grievous errors however all responsibility forscientific accuracy rests with the authors. Comments on articles that have appeared inInterRidge News are always welcome.

Agnieszka AdamczewskaInterRidge News Editor

37Vol. 11(1), 2002

volcanites of the neighboring hotspots (Gough, Tristan da Cunha,Discovery). Compositions of theseand most other within-plate volcan-ites of the South Atlantic and IndianOcean cluster along the mixing lineof F and a component which is bestapproximated by EM1, of the knownend members. In this context, itwould stand to reason to modifyEM1, which is used conventionallyin isotope studies, toward somewhatgreater 87Sr/86Sr ratios (roughly,0.7065–0.7075). An EM1 componentso refined has the same meaning asLOMU (antithetical to HIMU), pro-posed recently in explanation of thesingularity of the DUPAL anomaly(Douglass and Schilling, 1999). How-ever, the trend that stretches from aplume component P, and on whosebasis LOMU was recognized—and,accordingly, LOMU itself—are dis-placed perceptibly from the mixingline of F and the refined EM1 into aregion with still greater 87Sr/86Sr val-ues (Fig. 4). This might be due to thefact that the slope of the trend wasdetermined chiefly from data pointsfor Gough, Tristan da Cunha, andDiscovery rocks, which differ fromthe other within-plate DUPAL struc-tures in having somewhat higher87Sr/86Sr. Precise characteristics ofLOMU as the center of a rathervaguely delimited region of Africanand Australian kimberlitic and lam-proitic compositions are quite hardto obtain. At the same time, the re-fined EM1 is consistent with realrocks dredged from the AfanasyNikitin Rise, Indian Ocean.

SummaryIn the framework of our own

modification of A.Zindler andS.Hart’s Sr–Nd–Pb isotope system-atics, mid-ocean ridge basalts aredefined dominantly as products ofmixing of depleted mantle with amantle reservoir F, which is involvedin both rift-related and intraplateoceanic magmageneses. This reser-voir is close to the average compo-sition of all the components earlierproposed (C, FOZO, PREMA, etc.)within the mantle tetrahedron. MORB

types that have distinctive admix-ture components are spatially dis-crete and form extensive isotopeprovinces of mid-oceanic ridges. Inaddition to the known MORB types,normal (with HIMU admixture) andDUPAL-MORB (with EM1 admix-ture), a “singular” type is recog-nized. The latter, in terms of mostparameters, is a counterpart ofDUPAL-MORB, but it has 206Pb/204Pb and 207Pb/204Pb ratios similar tonormal MORB. This type is charac-teristic of the ridges of the NorthAtlantic and Norwegian–GreenlandBasin, which are recognized as con-stituting a separate Arctic province.Boundaries of isotope provinces formid-ocean ridges fit in with those ofE–W transoceanic heterogeneitiesidentified earlier by our study onisotope compositions of rocks onintraplate rises and islands.

AcknowledgmentsOur study was carried out with-

in the frames of the project to cre-ate the Electronic GeodynamicGlobe, headed by AcademicianD.V. Rundqvist, on the basis of asoftware package developed at theDepartment of Geo-InformationTechnologies, SGM, RussianAcademy of Sciences. This workwas supported by the RussianFoundation for Basic Research(project numbers: 00-15-98535, 00-07-90000, 01-05-65497, 01-05-64182, 02-07-90140) and the Feder-al programme “World Ocean” (Min-istry of Sciences of Russian Feder-

ation and the Russian Academy ofSciences).

ReferencesDouglass, J., and J.-G. Schilling,. Plume

- ridge interactions of theDiscovery and Shona mantleplumes with the southern Mid-Atlantic Ridge (40o-55oS). J.Geophys. Res., 104, B2, 2941-2962,1999.

Hanan, B.B., and D.W. Graham. Leadand helium isotope evidence fromoceanic basalts for a common deepsource of mantle plumes. Science,272, 991-995, 1996.

Hofmann A.W. Mantle geochemistry:the message from oceanic volcanism.Nature, 385, 219-229, 1997.

Mironov, Yu.V., V.M. Rhyakhovskii,and A.A. Pustovoi A.A. Sr–Nd–Pb Isotopic Zoning in the WorldOcean and Mantle Plumes.Geochemistry International, 38,Suppl. 1, 20-27, 2000.

Muhe, R., H. Bohrmann, D. Garbe-Schonberg, and H. Kassens. E-MORB glasses from the GakkelRidge (Arctic Ocean) at 87oN:evidence for the Earth‘s mostnortherly volcanic activity. EarthPlanet. Sci. Let., 152, 1-4, 1-9, 1997.

Rundqvist, D.V., V.M. Ryakhovskii,Yu.V. Mironov, and A.A. Pustovoi.Whether There Is a Universal Sr–Nd –Pb Isotope Tracer of the LowerMantle Plumes. Doklady EarthSciences, 370 (1), 110-113, 2000.

Zindler, A., and S. Hart. Chemicalgeodynamics. Ann. Rev. EarthPlanet Sci., 14, 493-571, 1986.


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InterRidge News38

IntroductionIn September-November 2001,

during the cruise of R/V ProfessorLogatchev, the Polar Marine Geosur-vey Expedition (PMGE) in associa-tion with VNIIOkeangeologia con-ducted comprehensive investiga-tions in the axial MAR segment be-tween 13o and 18oN. The goal to besought was to reveal evidence ofrecent and ancient hydrothermal ac-tivity and to discern areas perspec-

tive for massive sulphides. One ofthe sites is located 20 km north of theMarathon Fault which is situated at12o48’-13o04’N and 44o44’-45o00’W.

The presence of stockwork sul-phide mineralization on the cornerrise located at the rift valley/ Mara-thon Fault junction at 12o48’N wasmentioned by P.A.Rona (1986) andlater confirmed during cruise 9 of theR/V Akademik Nikolai Strakhov(Raznitsyn et al., 1991).

The basis for the investigationswas provided by the results of R/VGeolog Fersman 10-th cruise (1991-1992) and by new data obtained incruises of R/V Yuzhmorgeologia(Sudarikov et al., 2001) and R/V At-lantis (Sudarikov and Zhirnov, 2001).During these expeditions, anoma-lies were recorded in bottom watersof western side of the rift valleybetween 12o54’-12o56’N and 44o52,5’-44o55,5’W (the Neptune’s Beardarea), rock samples with sulphidestringers and dissemination wererecovered from dike rocks in thesoutheastern corner rise and highcontents of iron hydroxides wererecorded in the surface layer of bot-tom sediments. These data were theevidence for the presence of an ac-tive hydrothermal source in the studyarea.

ResultsThe site is of complex structure

comprising of intensively dislocat-ed volcanic and plutonic rocksthroughout the section of the oce-anic crust from mantle restite peri-dotites up to basalts. The latter arecommon in the valley floor and insouthern part of the site, plutonicrocks – in its northern part, thoughbasalts, gabbroids and peridotitesoften meet in one dredge.

Bedrocks showing hydrother-mal-metamorphic alteration withinthe site are confined to three struc-tural elements (Fig. 1):1) a steep slope in lower part of eastern

side of the rift valley;2) a gentle slope in western side of the

valley, dividing the floor andtectonic step;

New data on hydrothermal activity in the area of 12o57’N, MAR: initialresults of the R/V Professor Logatchev cruise 20.

V.Ye.Bel’tenev1, I.I.Rozhdestvenskaya1, A.V.Nescheretov1, G.A.Cherkashev2, S.M.Sudarikov2,A.B.Rumyantsev1, V.F.Markov1, A.G.Krotov1, E.A.Zhirnov2

1Polar Marine Geosurvey Expedition, 34 Pobedy Str., Lomonosov, Russia2VNIIOkeangeologia, 1 Angliysky Pr., St.Petersburg, 190121, Russia

Figure 1. Structures and indications of hydrothermal activity. 1 - valley floor;2 - axis neovolcanic rise; 3 - slopes of the rift valley; 4 - tectonic steps of riftvalley slopes; 5 - rift mountains; 6 – tectonic faults; 7 - scarps; 8 – volcanicmounds; 9 - hydrothermal-altered rocks; 10 - sulphide dissemination; 11 - Fe-Mn crusts; 12 - anomalies in bottom water

International Research: Mid-Atlantic Ridge

39Vol. 11(1), 2002

3) a steep bench in upper part of westernside of the rift valley over thetectonic step.Within these structures the evi-

dence of hydrothermal-metamorphicrock recrystallization is associatedwith submeridional faults embracingthe rift valley floor or dividing sometectonic steps on the valley sides.

The evidence of stockwork sul-phide mineralization (pyrite and pyr-rhotite) was recorded in one of thefragments of serpentinized peridot-ites. Silvery yellow-shaded sul-phides are present in the rock asrounded prolate grains, up to 3 mmin size. In metabasalts from two sta-tions, dispersed sulphide minerali-zation was recorded as rare quartz-sulphide veins or minor accumula-tions, 2-4 mm in size.

The easily observable sulphidemineralization may be considered inmetabasalts and especially in peri-dotites as the direct evidence ofhydrothermal activity within the site.It should be especially noted that allthe rocks with sulphide mineraliza-tion were sampled from the westernside of the rift valley from a smallarea (Fig. 1) located at 12o56’-12o59’Nand 44o53’-44o56’W.

Based on evidence from CTD andhydrochemical investigations, themost promising location of hydrother-mal activity is the northwestern areaof the site, showing evidence of ahydrothermal plume (Fig.1).

On one of the stations turbidityis 0.003-0.006 NTU and 0.012 NTU,more than background values in lay-ers 3660-3880 m and 3740-3780 m,

respectively (Fig. 2a). Local maxi-mum of turbidity in layer 3757 m is0.055 NTU, that is 6 times more thanbackground values. The anomaly ofturbidity was recorded both down-ward and upward CTD, the turbiditybeing slightly higher downward. Itis of interest that temperature at theturbidity anomaly level is lower thanthat of surrounding water (Fig. 2b),and concentrations of dissolvedmanganese are anomalous (4 timeshigher than background values).

On the second station located 2km north of previous, in layer 3900-3950 m, turbidity increases up to0.032 NTU (Fig.3a), this is more than3 times higher than background val-ues. A local maximum temperature isobserved in layer 3760 m (Fig. 3b)and concentrations of dissolvedmanganese and methane are anom-alous (7 and 5 times higher thanbackground values, respectively).

The preliminary data show thesource of hydrothermal plume to belocated northwest of these stationswhereby hydrothermal products aretransported southward by deep cur-rents.

Bottom sediments are very com-mon in the study area and assigned tocarbonate coccolith-foraminiferal ooz-es. In order to reveal distribution ha-loes of minerals (indicators of hydro-thermal supply), mineralogical analy-sis of surface layer (0-5 cm) of bottomsediment samples (0.5 l in volume)were performed onboard the ship.Immersion method was used for siltyand sandy fractions. The sedimentsfrom central part of the site were stud-ied thoroughly, where the anomalycentre had been recorded during theR/V Yuzhmorgeologia cruise at13o54.9’N and 44o53’W (Sudarikov etal., 2001).

The surface layer of sedimentscontains minerals-indicators of hy-drothermal activity: pyrite, chalko-pyrite, pyrrhotite, native copper,atacamite, barite, intermetals and ironhydroxides. Pyrite, barite and ironhydroxides prevail. Single signs ofthese minerals are present in most ofthe sediment samples, but their high-est concentrations in the surface

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Figure3. Water transmissivity (A) and temperature (B) at the depth 3910m

International Research: Mid-Atlantic Ridge: Bel’tenev, et al., cont...

InterRidge News40

layer are recorded in sediments fromthe terrace of western side of thevalley in the site centre (12o56’-12o58’N and 44o54’-44o56’W). Fig-ure 4 shows distribution of pyrite,barite and iron hydroxides in thesurface sedimentary layer. Signs ofthese minerals regularly increase inamount westwards to the slope foot;direct correlation being observedbetween pyrite and iron hydroxidessuggesting a common source theyare supplied from. A source of theseminerals is probably located in thefoot or on the slope of upper west-ern side of the rift valley. High con-centrations of barite in the sedimentsprobably suggest the presence of alow-temperature hydrothermal ventin the immediate vicinity.

On four stations in central part ofthe site low-temperature manganesecrusts were sampled (Fig. 1); theyrepresent unconsolidated sooty for-mations of ellipsoidal or flattenedshapes, 1-2 cm up to 10-16 cm insizes. In some instances they formon sediments, in others, on bothsediments and basalt fragments.

Conclusions1) The vicinity of the transform fault

determines the morphological andstructural features of the studyarea; numerous tectonicdislocations of different strikesform a blocky structure and

suggest tectonic activity. In turn,conditions favorable for deeppenetration of water forminghydrothermal fluid are created intectonically active zones.

2) The source of hydrothermal plumein bottom waters is probablylocated on the rift valley side innorthwestern part of the study area.

3) In the central part of the site (12o56’-12o58’N and 44o54’-44o56’W) in thesurface sedimentary layer of theterrace of western valley side stabledispersion haloes of hydrothermalminerals are observed, indicatorsinclude: pyrite, barite and ironhydroxides. Low-temperature Fe-Mn formations were sampled hereon four stations.

4) Rocks showing evidence ofhydrothermal-metamorphicrecrystallization associated withsubmeridional faults; sulphidemineralization in metabasalts andperidotites suggest hydrothermalactivity.

5) The authors hereof consider mostpromising for massive sulphidesthe foot and the slope of the uppervalley side above the terrace withcoordinates 12o56.5’-13o00’N and44o55.5’-44o57.5’W.

AcknowledgementsThe authors are thankful to the

crew of R/V Professor Logatchev,and to the research staff of the expe-

dition for helpful participation in theresearch and in the book preparation.

This work was partly supportedby the Russian Foundation for BasicResearch, project no. 99-05-65258.

ReferencesRona P.A. Hydrothermal mineralization

at seafloor spreading centers.Moscow, Mir, 1986, 160 pp.[Russian translation]

Raznitsyn Yu.N., S.G. Skolotnev, N.N.Turko, A.O. Mazarovitch, A.A.Peive , L.E. Shterenberg. Thejunction zone of the Marathon faultwith the rift valley north segment:structure, rock composition, sulfidemineralization (Central Atlantic).Doklady Akademii Nauk, 320 (4),952-956, 1991. [In Russian]

Sudarikov S.M., M. P. Davydov, G. A.Cherkashev, V. V. Gubenkov, O. A.Pivovarchuk, V. F. Kazachenok,and A. L. Mikhailov. A New Areaof Hydrothermal Activity in theRift Zone of the Mid-AtlanticRidge, 13o N. Doklady AkademiiNauk, 381 (5), 1-5, 2001. [InRussian.Translated in English inDoklady of Earth Sciences]

Sudarikov S. and Zhirnov E.Hydrothermal Plumes along theMid-Atlantic Ridge: PreliminaryResults of CTD Investigationsduring the DIVERSExpedition (July2001). InterRidge News Vol. 10 (2),pp. 33-36. 2001.

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Figure 4. Distribution of hydrothermal minerals in surface sediments: (A) Fe-hydroxides; (B) Pyrite; (C) Barite. Crosses- location of sampling stations. The grey scale corresponds to amount of mineral grains (per 1 liter of sediment).

International Research: Mid-Atlantic Ridge: Bel’tenev, et al., cont...

41Vol. 11(1), 2002

The 10th cruise of R/V“Akademik Ioffe” took place in theCentral Atlantic from 3 October to 2November 2001. This was a contin-uation of the previous expedition ofthe 22nd cruise R/V “AkademikNikolaj Strakhov” to 5º - 7º N MAR(Sierra Leone F.Z. area) (Peyve etal., 2000), where mapping by a multi-

beam EM 12S echosounder and ex-tensive dredging were carried out.

It was shown that this segment iscut by only one major transform fault- 7º10' (Bogdanov*), which dividesthis area from the segment to thenorth which has different structure(Peyve et al., 2001). In the 5º - 7º Narea, the MAR rift valley is displaced

by dextral faults including the SierraLeone F.Z. Rift segments with ob-lique spreading and overlapping riftvalleys are typical to this part of theMAR. The axial part of the MAR isasymmetrical in this region. Elon-gated ridges predominate to the westfrom the rift valley, to the east thesea bottom has a chaotic morpholo-gy and consists of separate isomet-ric highs and ridges. Several deepbasins, including Markov* hole(5º55' N, 33º11' W), about 5000 mdeep, were found in the rift valley(Fig. 1). According to the dredgingresults the rift valley floor, its rampsand nearby ridge slopes are com-posed of serpentinous peridotitesand gabbro. Basalts are locally dis-tributed. All these peculiaritiesspeak for the predominance of thetectonic processes upon magmaticin this MAR area. Dolerites withsulphide minerogenesis (cubanite,chalcopyrite and pyrrhotite) weredredged in one of the overlappingsegments just north from Sierra Leo-ne F.Z. (Mazarovich et al., 2001).

The current expedition set outwith the following aims:- to dredge different morphostructures

of the Bogdanov F.Z.,- to specify rock distribution in the

MAR axial part, especially in thearea with sulphide minerogenesisand

- to study flanks of the MAR crestusing multibeam ECHOS XDechosounder and high frequencyprofiler PARASOUND.

Sulphide mineralization, volcanic and tectonic activity of the MAR nearSierra Leone F.Z.:

10 cruise R/V “Akademik Ioffe” (preliminary results)

S.Skolotnev1, A.Peyve1, N.Bortnikov2, N.Tsukanov3, S.Lyapunov1, V.Kolobov4, A. Mochalov2, D.Krinov2, E.Sharkov2, N.Razdolina2, M.Stoliarov2, A.Cipriani5

1Geological Institute, Russian Academy of Sciences, Moscow, Russia2Institute of Geol. of Ore Deposits, Petrography, Mineralogy and Geochem., Russian Acad. of Sci., Moscow, Russia3Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia4United Institute of Geology, Geophysics and Mineralogy, Russian Academy of Sciences, Novosibirsk, Russia5Instituto di Geologia Marina CNR, Bologna, Italy

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International Research: Mid-Atlantic Ridge

InterRidge News42

We have found that basalts com-pose huge neovolocanic highs(dredge stations S2246, I1039, I1045)on the east rift flank (Fig. 1). Thesefeatures indicate that powerful im-pulses of volcanic activity are tak-ing place along with predominatingtectonic processes. Only basaltswere dredged from the flanks of theMAR crest (dredges I1009, I1010,I1012, I1016, I1029, I1030, I1034,I1036, I1037, I1046) (Fig. 1). Chaotictopography change to regular ridg-es on the east flank. These data letus think that geodynamic conditionsof normal spreading with domina-tion of magmatic processes, changednot far ago to geodynamic regimewith the domination of tectonic proc-esses. This happened approximate-ly 2 ma ago, judging from the spread-ing rate and distance from the riftaxis to the area with different mor-phology and composition.

Basalts with quartz veins (up to5 mm) containing pyrite, chalcopy-rite and atacamite (?), as well asamphibole – chlorite metasomaticrocks, containing pyrite (dredgeI1025) were collected near the pointwhere dolerites with sulphides werefound in 22 expedition of “AkademikNikolaj Strakhov” (Fig. 1). Gabbroand numerous metasomatic rockswith sulphide inclusions, quartz andbarite veins with sulphide grains(sphalerite?) and non-oxidized mas-sive sulphide ore fragments werecollected from the east flank of theMarkov hole (dredge I1032) (Fig. 1).Petrographyñ studies have shownthat metasomatic rocks were formedafter cataclastic gabbros. Accord-ing to X-ray diffraction studiesmetasomatic rocks are composed ofprehnite, epidote, chlorite and am-phibole and ore is composed of chal-

copyrite with some epidote and chlo-rite. New data (Bazilevskaya, Skol-otnev, in press) has shown that thinFe-Mn oxide films on basalt surfac-es from Markov hole (dredge I1043),are fertilized in Cu, Zn, Fe è Mn2+, incomparison to Fe-Mn crusts fromneighboring regions. These datamake it possible to think that recent-ly or maybe today “black smoker”type ore formation is taking place inthe Markov hole. If this finding willbe confirmed by more detailed stud-ies this will prove the validity ofobservation made by (Mazarovich,Sokolov, 1998) that ore deposits like“black smoker” are situated in MARareas with reduced seismicity. TheMAR between 5º - 7ºN is also char-acterized by low seismicity. Ourobservations let us think that com-bination of intensive tectonic proc-esses and powerful impulsive mag-matic activity is favourable for cre-ation of sulphide deposits.

Dredging of the Bogdanov F.Z.has showed that serpentinous peri-dotites and gabbro predominatethere, which is typical of the major-ity of transform faults.

Study of the sediments structurein depressions on the flanks of theMAR crest with profiler “PARA-SOUND” has shown that sedimentsare deformed there by numeroushorst structures. This is evidence ofwidespread distribution of verticalintraplate deformations in this seg-ment of the MAR.

AcknowledgementsWe are grateful to technicians:

V. Velinskiy, A. Nosov, V. Kuznets-ov, S. Dremutchev, V. Rastorguev;captain V. Sazonov and crew of thevessel “Akademik Ioffe”.

* Name approved by the Four-

teenth meeting of the GEBCO, 17-20April 2001.

ReferencesBazilevskaya E., Skolotnev S. Fe-Mn

crusts of the Sierra Leone F.Z. area(Equatorial Atlantic) DokladyAkademii Nayk (translated inEnglish in Doklady of EarthSciences), in press.

Mazarovich A., Sokolov S. Tectonicposition of hydrothermal areas onthe Mid-Atlantic Ridge. Litologiai poleznye iskopaemye, 4, 436-439,1998.

Mazarovich A., Simonov V., Peyve A.,Kovyazin S., Tretyakov G.,Raznitsin Ju., Savelieva G.,Skolotnev S., Sokolov S., Turko N.Hydrothermal mineralization on theSierra Leone fracture zone (CentralAtlantic). Litologia i poleznyeiskopaemye,5, 526-533, 2001.

Peyve A., Bonatti E., Brunelli D.,Chilikov A., Cipriani A.,Dobrolubova K., Efimov V.,Erofeev S., Ferrante V., GasperiniL., Hekinian R., Ligi M., MaurizioG., Mazarovich A., Perfiliev A.,Raznitsin Ju., Savelieva G., SichlerB., Simonov V., Skolotnev S.,Sokolov S., Turko N. New data onsome major MAR structures:preliminary results of R/VAkademic Nikolaj Strakhov 22cruise.InterRidge News, 9, 28, 2000.

Peyve A., Dobrolubova K., Efimov V.,Cipriani A., Mazarovich A.,Perfiliev A., Raznitsin Ju.,Savelieva G., Simonov V.,Skolotnev S., Sokolov S., Turko N.Structural peculiarities of the SierraLeone fracture zone (CentralAtlantic).Doklady Akademii Nayk(translated in English in Dokladyof Earth Sciences) 377, 6, .803-806,2001.

International Research: Mid-Atlantic Ridge: Skolotnev, et al., cont...

MOMAR webpage:http://www.intridge.org/momar/index.html

MOMAR II Workshop - 15-17 June 2002, Horta, Azores

http://www.ipgp.jussieu.fr/~escartin/MOMAR.html

43Vol. 11(1), 2002

IntroductionThe Northern Central Indian

Ridge (NCIR) spans from 12° to 2°S(Fig. 1) and constitutes an importantregime of accreting plate bounda-ries of Australia-Africa in the south

and India-Africa plate in the northseparated by the intersection of CIRand WDZ (Wide Deformation Zone).Except the interpretation of few mag-netic lines in the Vema Transformarea (Kamesh Raju et al., 1997) and

the discussion of tectonic implica-tion of bathymetric and magneticdata of Vema region (Drolia et al.,2000), results of reconnaissancesurvey during 28th cruise of R/VSonne (1983), no data of significanceis available from the study areas.

In the NCIR lacunae exist con-cerning plate kinematics, segmenta-tion pattern, petrologic variationsand the influence of Ridge – Trans-form Interactions (RTI) on plate ge-ometry or on the formation of triplejunction. The complex structural fea-tures and magmatic processes con-strain the formation of the new crustalong the CIR and probably play amajor role in geochemical and ther-mal evolution of the study region.Further, probable hydrothermal flu-id circulation along this ridge con-tributes in regulating ocean chemis-try. This is probably one of the fewareas in the world ocean where thekinematics of slow accreting plateboundaries and associated triplejunction formation with low seismicactivity remains poorly known.

A 35 days expedition, on boardR/V Sagar Kanya (Cruise SK-165,28th May to 2nd July, 2001) was under-taken under the InRidge programme.This was the 2nd cruise to visit NCIRafter the one in July-Aug. 1997. Thethree fold objectives of the presentcruise were1) to establish the complexly faulted

and segmented nature of the NCIRbetween the region 3.5°S-10.5°S,66-66°E,

2) to obtain evidence for the nascent

Preliminary results of a recent cruise to the Northern Central Indian Ridge

Drolia R.K.1, Sridhar D.Iyer5, Chakraborty B.5, Kodagali V.N.5, Mukhopadhyay R.5, Nanyasi S.K.5,Sarma K.V.L.N.S5, Rajasekhar R.P.5, Misra S.2, Ray D.3, Andrade R4. Lasitha S.4,Varghese J.4,

Jacob J5, Sukumaran N. P1, Pednekar A5, Furtado R5, Nair A.5

1 National Geophysical Research Institute, Uppal Road, Hyderabad-5000072 Department of Geology and Geophysics, IIT, Kharagpur, India3Department of geology, Calcutta University, Kolkatta, India4Department of Marine Geology and Geophysics, CUSAT, Cochin5 National Institute of Oceanography, Dona Paula, Goa-403004

Figure 1. Location map of the study areas : Sealark (SL), Vityaz (VT) and Vema(VM). NW-SE oriented double lines are ridge segments. NE-SW trendingsolid balck lines are Transform faults.

International Research: Indian Ridge

InterRidge News44

triple junction in the region southof Vityaz and North of VemaTransforms and

3) to search for signatures ofhydrothermal activity.

Data Acquisition and processingThe coverage consists of forty

five 110-160 km long profiles, orient-ed N50°E across seven ridge seg-ments on either side of Sealark, Vit-yaz and Vema Transform faults be-tween latitudes 3°S – 10°S. We havecollected high quality multi-beamswath bathymetric, gravity and mag-netic data over three intersectingregions of Sealark Transform Fault(TF)-NCIR (SL area), Vityaz TF-NCIR(VT area) and VemaTF-NCIR (VMarea). Integrated and Global Posi-tioning system (GPS) was used fornavigation. The digital magneticdata and analog bathymetric chartswere acquired using Geometric Pro-ton Magnetometer and a Honewell-Elac deep Sea Wide beam EchoSounder. The estimated accuracy ofthe recorded average depth was 10 m.The multi-beam Hydrosweep sys-tem (STN Atlas Electronik GmbH)was used to obtain swath bathymet-ric data in the survey area. The sys-tem was operated at 15.5 kHz andmakes use of 59 Pre Formed Beams(PFBs) with an average beam widthof 2.3°, providing swath coverage oftwice the water depth. For 100%coverage (insonification), interline

spacing of two nautical miles wasused during the survey.

Three major TFs, Sealark, Vityazand Vema were mapped in detail forthe first time. Additionally theTransform just north of Vema TF(christened as Ehrlich Transform)was mapped in detail. Rocks andwater samples from axial valley,Ridge-Transform Interaction (RTI)and near-axis seamounts were re-covered.

Post-cruise processing involveddigitization of echograms and inter-polation of magnetic data at 1- minuteintervals, and merging of the mag-netic filed intensity data with bathy-metric data. Mathew’s correctionwas applied to the bathymetric datato get corrected depth. In case ofany discrepancy we had retainedCentral beam depths provided bymulti beam data. We interpolatedthe magnetic and bathymetric dataat 1-km intervals. The magnetic anom-aly was computed by subtractingIGRF 2000 from the observed inter-polated total intensity data. We haveused the revised ridge-transformgeometry of northern CIR (Fig. 1)based on latest satellite – derivedgravity map (Sandwell and Smith,1997). To facilitate the discussion ofthe accretionary units the ridge seg-ments have been numbered I to IXand the transform faults / Fracturezones as D1 to D9 from south tonorth.

Using the reversal time-scale ofCande and Kent (1995), we havemodeled the observed magnetic pro-files and identified the anomalies.We have taken an average spread-ing rate of 18mm /yr, magnetizedlayer thickness of 500m and suscep-tibility contrast of 0.01 c.g.s. units.We were able to identify magneticanomalies 1 to 3.

Multibeam Swath Bathymetricdata were processed to obtainBathymetric maps of the three re-gions in the study area. The tectonicelements of the Transform Faults:i.e. Transform Tectonized Zone(TTZ), Transform Fault Zone (TFZ)and Principal Transform Displace-ment Zone (PTDZ); have been esti-mated by analyzing the multi-beamswath data. The Transform azimuthfrom trends of the Transform Val-leys was measured.

Results and DiscussionThe study region is characterized

by seven short ridge-segments andsix offsets with the longest offsetbeing the 255 km Vema Transform.The ridge segments are shorter thantransform segments with the senseof ridge offsets along the fracturezones being uniformly right lateral.

Our results show that the seafloor depths vary from 1500 to 6200mbut are generally in the order of 2500-4000m. The ridge segments are char-acterized by along-axis depth varia-tions: deepening at segment endsand swallowing at the central por-tion. In Vema and Vityaz region theridge segment deepens at centre andshallows towards RTI. The VityazTF shallow and narrows towards SWas its width varies from 11 km in NEto 7 km in SW. The maximum –re-corded depth is 5400 m in NE part ofthe TF. The Vema TF is character-ized by undulating valley floor hav-ing wavelength of 50 km and ampli-tude varying between 400 and 450 m.The width of the TF varies from 20km in SW to 35 km in NE with 6-15 kmwide floor humps of 200-300 m highin the central part. These humps maysuggest that magma is upwellingthrough discreet feeder channels.

International Research: Indian Ridge: Drolia, et al., cont...

SWIR Workshop17-19 April 2002

SOC, UK

Workshop targets :- synthesise most recent results obtained on the SWIR- develop plans for future study of the Indian ocean ridge system

Papers from this meeting will be incorporated into a proceedingsvolume in the electronic journal, G-cube:

(G3 http://g-cubed.org/).

http://www.intridge.org/swirwksp.htm

45Vol. 11(1), 2002

The average depth of the TF floor is6000m, which shallows to 4615m to-wards NE with the maximum depth of6500m recorded on the flanks in thecentral region.

The characteristics of the RTI,axial valley and TFs including theoccurrence of neo-volcanic zonesalong 29 ridge-normal profiles sug-gest predominance of tectono-mag-matic activities in VT and VM areasand dominance of tectonic activitiesin SL area.

The Ehrlich Transform (TF justnorth of Vema TF) reveals a complexmorphotectonic characters compris-ing of alternating trough (4800m)and crests (2300m) suggestive ofintense deformation. Detailed anal-ysis of the forces responsible forthis deformation may provide someclue about the dynamics of triplejunction evolution.

MagneticsMagnetic anomalies up to chron 3

have been identified across the ridgesegments III to IX on various pro-files (Fig. 2) in the three regions. Themedian valley is characterized bybroad amplitude anomaly of 200-400nT in the three regions. Magnet-ic anomalies associated with frac-ture zones are relatively subdued.The anomaly amplitude is less than200nT across the deepest part of theVema Fracture zone. We have esti-mated spreading rates along theAfrica / India and Africa / Australiaplate margins since the time of anom-aly 3. The ridge-axis and anomaly 3have been used for computing theflank spreading rates after matchingthe observed anomaly shape withthe synthetic one. The mean half-spreading rate of 1.8cm/yr in theSealark and Vityaz regions increas-es to 2.1 cm/yr to south of the VemaTransform. The nature of intra- andinter-segmental variations in mag-netic anomalies suggest that theregion between south of Vityaz TFand north of Vema Transform seemto have distinct signatures of Africa-India / Africa-Australia plate mo-tion which could be possibly due toevolving triple junction in the re-gion.

PetrologyBasalts from the axial valley are

fresh, with a coating of glass (0.5 to50mm) and contain abundant phen-ocrysts of plagioclase but rarely ofolivine. Dredging the RTI yieldedvariably altered basalt and ferroman-ganese crusts and nodules and in-tensely bioturbated calcareous ma-terial with thick coating of Fe-Mnoxide (Mukhopadhyay et al., 1998).During the SK 165, rocks from near-axis seamounts (Station 9DG onwestern side of segment III) wererecovered. These are dominantlycolumnar while few are pillow ba-salts, suggesting the probability oferuption of two types of lava flow inthe past. The first flow probablyformed pillow basalts while the latereruption with columnar structurewas emplaced as dyke. The pres-ence of two types of basalts mayhelp explain the rise and fall of tem-

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InterRidge News46

perature across the Curie point andconsequently the observed over-print magnetization of the oceaniccrust (Drolia et al., 2000). The sam-ples mainly have plagioclase thatoccurs as phenocrysts but mostlyas laths and tabular forms. Olivine isless abundant and in some casesempty vesicles are very common.The occurrence of amphiboles inone sample is intriguing. The basal-tic fragments of another near-axisseamount (24DG) are aphric tosparsely phyric and altered.

The manganese nodules with lowMn/Fe ratio (<1) and low values ofCu and Ni than those from basinalregions indicate their possible hy-drothermal-hydrogenous origin.

SummaryThe high quality multi-beam

swath bathymetric, gravity, magnet-ic and bathymetric data were col-lected over three intersecting regionsof Northern Central Indian Ridge(NCIR) during a recent cruise onboard ORV SagarKanya. Preliminaryresults suggest along-axis depthvariations: deepening at segmentends and shallowing at the segment

centre in Vema and Vityaz regionwhereas Sealark region depicts deep-ening at the segment end and shal-lowing at the segment centre. TheEhrlich Transform (TF just north ofVema TF) reveals a complex mor-photectonic character suggestive ofintense deformation. The nature ofintra- and inter-segmental variationsin magnetic anomalies suggest thatthe region between south of VityazTF and north of Vema Transformseem to have distinct signatures ofAfrica-India / Africa-Australia platemotion which could be possibly dueto on evolving triple junction in theregion.

AcknowledgementsWe acknowledge the Department

of Ocean Development, New Delhifor kindly making R/V SagaKanyaavailable for the cruise and the De-partment of Science and Technolo-gy for partial funding (grant # ESS/23/VES/060/99). We thank Dr. M.Sudhakar of National Centre of Ant-arctic and Ocean Research, forscheduling the cruise and logisticsupport and the Captain and crew ofSK165 cruise for rendering all help.

This paper is published with thepermission of the Directors of NIOand NGRI. The project is funded bythe United States India Fund throughONR Grant # N 00014-97-I-0925.

ReferencesCande S.C. and Kent D.V. 1995,

Revised calibration of thegeomagnetic polarity time scalefor the late Cretaceous andCenozoic, Jour. Geophys. Res,100, 6093-6095.

Drolia R.K. et al 2000, Magnetic andbathymetric investigations overthe vema region of the CentralIndian Ridge:Tectonicimplications, Marine Geology,167,413-423.

Kamesh Raju K A et al 1997,Geophysical investigations overa segment of Central Indian Ridge,Indian Ocean, Geo-Marine Letters,17,195-201

Mukhopadhyay R et al 1998, CurrentScience, 75,1157-1161

Sandwell DT and Smith WHF 1997,Marine gravity anomaly fromGeosat and ERS1 satellitealtimetry, Journal of GeophysicalResearch, 102, 10039-10054.


A SPECIAL ISSUE ON ANCIENT AND MODERN SEAFLOORVOLCANOGENIC MASSIVE SULFIDE DEPOSITS

A special double issue of the journal, Exploration and Mining Geology, was published on March 21, 2001 (Vol.8, Nr 3 and 4, Jul. and Oct. 1999), dedicated to the memory of the eminent Russian ocean ridge geologist SergeyKrasnov (1952-1996). The special issue accesses for the first time new Chinese work on volcanogenic massivesulfide (VMS) deposits, as well as related seafloor hydrothermal research by the international community. TheChinese papers report a surge in exploration for and discovery of ancient VMS deposits in P.R. China stimulatedby discoveries of active systems at ocean ridges and volcanic island arcs.

Peter A. Rona and Zengqian Hou, Guest Editors Preface

The issue include: Ancient Volcanogenic Massive Sulfide Deposits In China and Modern Seafloor HydrothermalDeposits (Volcanic Island Arcs and Ocean Ridges)

More detailed information about the contents of this special issue can be obtained from the InterRidge homepageat: http://www.intridge.org/emg.pdf

The special issue may be ordered from the publisher: The Geological Society of the Canadian Institute of Mining,Metallurgy and Petroleum, Suite 1210, 3400 de Maisonneuve Blvd. W., Montreal, Quebec, H3Z 3B8, CanadaTel.: (514) 939-2710, ext. 320; Fax: (514) 939-2714; e-mail: [email protected] .

Price: CDN$40.00/US$27.00 PREPAYMENT REQUIRED IN CANADIAN OR U.S. FUNDS

47Vol. 11(1), 2002

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A listing of international ridge cruises can be found on the following pages. Each cruise is coded with anumber, which represents it's location on the map below. The list of world cruises is organised by date. Pleasesubmit scheduled and upcoming cruises by filling in the online form at: http://www.intridge.org/cruisefm.htm

48InterRidge N

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idge Cruise Schedule, 2002, continued...

Map

No.Country PI Institution Cruise ID/Location Research Objectives Ship Dates

Japan MatsumotoSouthwest Indian Ridge

Atlantis II FZ

Shinkai 6500 submersible dives at lower

crust and mantle outcropYokosuka

Dec 21, '01 -

Jan 15, '02JAMSTEC2

Japan

USAOhara

Hydrogr.

Dept. Japan

Parece Vela Basin

Philippine Sea

Petrological investigation of the Parece Vela

backarc basin spreading center. Kairei

Jan 6 -

Jan 25, '023

USA Von Damm UNH East Pacific Rise

East Pacific Rise Hydrothermal Systems:

Continued Chemical Instability at 9-10

degrees N vs. Stability at 21 degrees N

Atlantis

Alvin

Jan 6 -

Feb 10, '021

USA Cochran Southeast Indian Ridge

Effects of Changes in Mantle Temperature on

Melt Supply and Crustal Accretion: An MCS

Reflection and OBH Refraction Study of the

Southeast Indian Ridge

Maurice

EwingJan 26, '02LDEO6

Japan Shinohara Australia-Antarctica DiscordanceCrustal study by OBMs and high resolution

deep-tow magnetometerHakuho Maru

Jan 27 -

Feb 12, '027 ERI

USA Cowen Guaymas Basin

The Fate and Implications of Removal of

Hydrothermally-Injected NH4+ from Plume

Waters

Atlantis

Alvin

Apr 26 -

May 11, '02U of HI9

URIUSA Larson Southwest Pacific Basin

Mid-Cretaceous Tectonic Evolution of the

Tongareva Triple Junction in the Southwest

Pacific Basin

MelvilleMar 24 -

Apr 13, '028

Japan Takai JAMSTEC Rodriguez triple junctionShinkai 6500 submersible dives at

hydrothermal sitesYokosuka

Jan 21 -

Feb, '025

USA

Childress

Fisher

Van Dover

UCSB

Penn State

Wm&Mary

East Pacific Rise

Physiological Ecology of Hydrothermal Vent

Chemoautotrophic Symbioses. Species

Composition and Biodiversity in Mussel Bed

Communities of Hydrothermal Vents

Dec 9, '01 -

Jan 1, '021 Atlantis

Japan ArimaYokohama

Ntnl. Univ.Mariana Trough and Mariana Arc

Sediments and microbio sampling at a

hydrothermal areaKairei

Jan 8 -

Feb 24, '024

49Vol. 11(1), 2002

World R


Germany

Iceland

Devey

ScholtenU. Bremen Tjoernes Fracture Zone

Volcanology of spreading north of Iceland

Hydrothermalism of the Grimsey field

Geochemistry of the plume-ridge transition

PoseidonJun 26 -

Jul 14, '0215

ORIJapan

Tokuyama

Okino

Tamaki

Southern Okinawa Trough High resolution deep-tow sonar mapping

with geochemical sensors Hakuho-maru

Jun 10 Ð

Jun, 24, '0210

USA Spiess SIO Juan de Fuca RidgeJuan de Fuca Plate Geodesy: Juan de Fuca

Ridge and Cascadia Subduction ZoneRoger Revelle

Jun 8 -

Jun 22, '0214

New

Zealand

Ronde

Massoth

GNS

NOAA

U. Kiel

Kyushu Univ.

Southern Kermadec Arc, 35-30 S

CTD and in situ chemical mapping and fluid

sampling if hydrothermal plumes associated

with active volcanoes

TangaroaJun 16 -

Jun 29, '0213

France

US

Portugal

J. Goslin U. BrestAzores-Gibralter

(SIRENA - North Atlantic)

Deployment of six moored autonomous

hydrophones 1) to monitor the seismicity of

the MAR between the Azores and Gibbs FZ;

2) to produce a high-resolution tomographic

model of the upper mantle below a ridge in

a ridge/hotspot context

May 23 -

Jun 10, '0211

USA

Hammond

Embley

Fornari

Shank

Galapagos Rift Galapagos 25th AnniversaryMay 24 -

Jun 4, '02

NOAA

WHOI12

Atlantis

Alvin

New

ZealandWright

NIWA

U. Kiel

VUW

Southern Kermadec Arc, 35-30 S

Multibeam mapping, rock dredging, seafloor

photography, and epibenthic fauna sample

along volcanoes of the arc front

May 24 -

Jun 14, '0213 Tangaroa

Japan Tamaki Southern Okinawa TroughDeep tow sidescan sonar survey of the

rift zoneHakuho Maru

May 7 -

Jun 24, '02ORI10

Japan Fujikura Southern Okinawa Trough Vent biology by Submersible Shinkai 2000 Natsushima May 13 Ð

Jul 5, '02

JAMSTEC10

East Pacific Rise

Central Anomaly Magnetization High:

Constraints on the Volcanic Construction and

Architecture of Young Upper Oceanic Crust

USA

Schouten

Tivey

Fornari

Madonald

Atlantis

Alvin/ABE

May 14 -

May 23, '02

WHOI

UCSB1

FranceGaill

BrisEast Pacific Rise - PHARE

In-situ experiments and

biogeochemical interactions

L'Atalante

ROV VictorMay '021 U. Pierre

Le Suroit

50InterRidge N

ews

World R


Map

No.Country PI Institution Cruise ID/Location Research Objectives Ship Dates

Korea S-M Lee

Daeyang Program 2002 Leg 1

Western Bismark Sea volcanoes,

PACMANUS

Geophysical, multichannel seismic, near

bottom observation, and geochemical

and biological investigations of

New Ireland Forearc Basin,

OnnuriAug 24 -

Sep 9, '02KORDI16

OnnuriSep 10 -

Sep 27, '02

Seafloor mapping and geophysical

investigation of the eastern boundary of the

Caroline Plate and Sorol Trough,

equatorial western Pacific.

16

Japan Kinoshita Ogasawara (Bonin) Arc Longterm observatory at vent sites by

Submersible Shinkai 2000 and ROV Natsushima

Aug 22 -

Sep 18, '02 JAMSTEC17

Korea K-Y Lee KORDI North Fiji Basin KODOS 2002 - Reconnaissance survey of

hydrothermal vents.Onnuri

Jul 14 -

Aug 15, '0218

USA Klein Hess deep

Collaborative Research: Geochemical and

Geological Investigation of the Incipient Rift

at 2o40'N, east of the East Pacific Rise

MelvilleAug 5 -

Sep 2, '02Duke Univ.12

Japan Urabe GSJIzu-Bonin Arc

Suiyo Seamount

Shallow drilling at hydrothermal site of

Suiyo Seamount, Izu-Bonin Arc for

sub-vent biosphere

Hakurei-MaruJul 17 -

Jul 27, '0217

USA Cowen U of HIJuan de Fuca Ridge

Endeavour

The Fate and Implications of Removal of

Hydrothermally-Injected NH4+ from

Plume Waters

Atlantis

Alvin

Aug 4 -

Aug 25, '0214

Japan IshibashiKyushu

Univ.

Izu-Bonin Arc

Western Pacific

Sampling of fluid, microbes and sediments

from Suiyo Seamount, Archaean Park Shinsei-Maru

Aug 3 -

Aug 15, '0217

USA

Johnson

Sharma

Voight

Juan de Fuca Ridge

Collaborative Research: Direct Sampling of

the Oceanic Sub-Surface Biosphere at Old

and Young Seamounts.

Atlantis

Jason II

Aug 29 -

Sep 23, '02

UW

Dartmouth

Field Museum

14

USA Carbotte LDEO Juan de Fuca RidgeNew Content and Functionality for the

RIDGE Multibeam Synthesis

Jul 8 -

Aug 7, '0214

Maurice

Ewing

Daeyang Program 2002 Leg 2

Sorol Trough and Caroline PlateKORDIS-M LeeKorea

51Vol. 11(1), 2002

World R


USA

USA

USA

USA

USA

Voight

Childress

Fisher

Becker

Childress

UCSB

Penn State

U Miami

UCSB

Brown Univ.

Gorda Ridge

Monterey Fan Valley seeps

Biological collections at vents and seeps,

chemical and geological studies, mapping

Atlantis

Alvin200314

Oct 20 -

Nov 16, '0214

Japan Seama

Cary

Taylor

Cavanaugh

Lizarralde

Mariana Trough Upper mantle structure by electromagnetic

studyKairei

Oct 28 Ð

Nov 12, '02

Field Museum

U Delaware

WHOI

NOAA

4

USA Forsyth East Pacific Rise

Collaborative Research: Investigation of the

Origin of Non-hotspot, Intraplate,Volcanic

Ridges and Cross-Grain Gravity Lineations

MelvilleNov 2 -

Dec 5, '02

Kobe Univ.

1

Gulf of CaliforniaMaurice

Ewing

Sep 17 -

Nov 4, '029

Margins: Collaborative Research: Seismic

and Geologic Study of Gulf of California

Rifting and Magmatism

Germany

Canada

UK

USA

Herzig

Hannington

Skinner

Shallow drilling (5m) of an epithermal (gold)

mineralization on top of Conical SeamountSonne

Sep 13 -

Oct 11, '0216

New Ireland Basin

SO-166, CONDRILL

Georgia Tech

Freiberg

Juan de Fuca Ridge

East Pacific RiseNew Horizon

(w/Atlantis)

Nov 9, '01 -

Jan 3, '021

Collaborative Research: Studies on the


Chemoautotrophic Symbioses

Costa Rica RiftAtlantis

Alvin

Nov 20 -

Nov 26, '0212

Long-Term Monitoring of Off-Axis

Hydrogeology on the Costa Rica

Rift Using an Instrumented Wireline

Multi-Packer System

East Pacific RiseAtlantis

Alvin

Nov 30 -

Dec 22, '021

Collaborative Research: Studies on the


Chemoautotrophic Symbioses

Atlantis

Lexen, Alvin

Collaborative Research: Eurythermal

Adaptations to an Extreme Environment by

the Symbionts of the Hydrothermal Vent

Polychaete, Alvinella Pompejana.

Microbiology and Ecology of Filamentous

Sulfur Formation.

52 InterRidge News

National News....

United KingdomAn important first piece of news

from the UK is that we have recentlysecured a transition for funding ofUK membership of InterRidge fromthe now disbanded BRIDGE pro-gramme to its host funding agency,the Natural Environment ResearchCouncil.

With the current subscriptions fi-nally in place, Chris German will nowstand down as one of the UK’s twonational representatives. Paul Dandowill continue in that role and a newsecond representative will be an-nounced shortly (watch this space!)

From a research perspective, wehave four items of news worthy ofparticular mention:-

1) 6500m ROV.The contract for a deep-diving

6500m ROV was placed by SOC, onbehalf of the UK research community,with the Woods Hole OceanographicInstitution in late 2001. A team of UKengineers have now begun work withthe Woods Hole team in the USA andcompletion of the build is scheduledfor January 2003. Shiptime for deliv-ery and training cruises is currentlybeing negotiated for Spring/Sum-mer 2003 with first research expedi-tions anticipated in 2004. For furtherdetails, contact Prof.Paul Tyler atSOC: [email protected] orcheck the website at: http://www.soc.soton.ac.uk/OED/ROV/index.php#

2) Seafloor Observatories.A submission was presented to

the NERC in late 2001 to support a UKobservatories initiative (B-DEOS) withvarious mid-ocean ridge interests.Although this proposal, coordinatedby Prof.Adam Schultz at the Univer-sity of Cardiff, was not funded in thefirst instance, NERC have acceptedthe scientific merits of the case pro-posed and have adopted the B-DEOSinitiative as an important future pro-gramme deserving of support. Animportant part of current UK thinkingis that this may be an initiative bestserved through collaborative fundinge.g. through a wider EC initiative linkedto the MOMAR concept (note theInterRidge MOMAR II workshop inHorta, 15-17 June). Further details:[email protected] .

3) Census of Marine Life/Chemosynthetic Ecosystems - ChEss.

On March 26th 2002, the SloanFoundation Board met to review theCensus of Marine Life (CoML) pro-gramme in its entirety, and among itdeliberations approved funding of apilot study “ChEss” to design and

initiate surveys of life in vent and seepcommunities on the ocean floor. Theinitial stages of this internationalproject – which, clearly, will have sig-nificant interest to many members ofInterRidge – will be co-hosted by Profs.Paul Tyler and Chris German at SOC,UK. Funding is for three years, in thefirst instance, commencing summer2002. For further details, please con-tact Prof.Paul Tyler:[email protected] .

4) Vent Aqauria. An aquarium system for hydro-

thermal vent animals from the Mid-Atlantic Ridge has been developed,with funding from the EU VENTOXproject, at the School of Ocean Sci-ences, University of Wales-Bangor.Cooled seawater tanks, in a quaran-tine facility, are supplied with bothsulphide and methane. Vent musselshave maintained their symbionts forover 8 months in the system which, itis hoped, will provide a long-termsource of living animals for biologicalstudies. For further details, pleasecontact Prof. Paul Dando:[email protected] .

Dr. Chris German, National Correspondent

Challenger Div. for Seafloor ProcessesSouthampton Oceanography CentreEuropean Way, Empress DockSouthampton, SO14 3ZH,United Kingdom

Tel: + 44 1703 596 542Fax: + 44 1703 596 554E-mail: [email protected]

InterRidge - Japan

Archaean Park (AP) project (PI: T.Urabe) has been successfully pursuedsince its start in 2000. For the purposeof interdisciplinary characterization ofsubseafloor biosphere, the project plan,in 2001, involved drilling by BMS (Bor-ing Machine System) and taking of

many samples from the caldera of SuiyoSeamount, a hydrothermally activevolcano of the Izu-Bonin Arc in thePhilippine Sea. Some of the preliminaryresults on geological, geophysical,geochemical, and microbiological stud-ies were presented as six lectures and

five posters at the Ocean ScienceMeeting (AGU and ASLO) held atHonolulu on 11-15 February 2002 (http:// w w w . a g u . o r g / m e e t i n g s /os02top.html). There were two ses-sions OS32O and OS31F (Physical,chemical, and biological processes

53Vol. 11(1), 2002

National News....

associated with active submarinevolcanism in the Pacific I (co-chairedby T. Urabe) and II (co-chaired by M.Kinoshita) for their presentations.

Targets of the Japan InterRidge-related projects of this year (2002) arechiefly in the northwestern PacificOcean close to Japan as describedbelow.

The AP project will continue theinvestigations at Suiyo Seamountbetween July and September this year.Plans are to drill deeper holes and todeploy many more instruments forlong term monitoring than last year.There are three cruises planned; byR/V #2 Hakurei Maru for BMS drill-ing (PI: T. Urabe), R/V Shinsei Maru(with ROV Hakuyo 2000; PI: J.Ishibashi), and R/V Natsushima (with15 dives by DSRV Shinkai 2000; PI:M. Kinoshita) of JAMSTEC.

Investigations of ridge processeswill also be carried out in the OkinawaTrough backarc basin, southwest of

Japan. Two cruises (with five legs) ofR/V Natsushima (with DSRV Shinkai2000; PIs: F. Inagaki, M. Tokeshi, andK. Fujikura) and a cruise by R/VHakuho Maru of ORI, Univ. of Tokyo,are planned in April to July 2002.Shinkai 2000 will dive both in the mid-Okinawa Trough and in the south-western most Okinawa Trough wheremany high temperature fluid ventingsites have been located. The HakuhoMaru cruise (PI: H. Tokuyama) willutilize high resolution deep-tow side-scan sonar system WADATSUMI(ORI, Univ. Tokyo) together with ahigh quality SeaBeam 2120 system for

bathymetric surveys. For a detailedhydrothermal plume mapping, severalMAPRs (Miniature AutonomousPlume Recorder) of NOAA/PMEL (PI:E. Baker) will be attached toWADATSUMI as a collaborativestudy between Japan and US RIDGE.After the WADATSUMI surveys,CTD hydrocasts (PI: T. Gamo), heatflow measurements (PI: M. Yamano),and rock dredges (PI: R. Shinjo) will beperformed to get geophysical andgeochemical data of the ridge activity.

Toshitaka GamoHokkaido University

Korea

Two research cruises in backarcbasin will be conducted by KORDIthis year. The first is a short recon-naissance survey of the North FijiBasin, which will be led by Dr. Kyoung-Yong Lee. During this cruise, scien-tists will collect rock samples in orderto understand the hydrothermal min-eralisation process in the backarc en-vironment. This survey will be con-ducted from August 8 to 15 and uponcompletion of the surveys R/V Onnuriwill make port call at Suva, Fiji onAugust 16-17. The second will con-sist of survey at three different sites inPapua New Guinea as part of DaeyangProgram 2002. The three sites are NewIreland forearc basin south of LihirIsland, PACMANUS hydrothermalvent fields, and seamounts in thewestern Bismark Sea. The chief scien-tist of this cruise is Dr. Sang-MookLee. This cruise will take place from

August 24 to September 9 with portcalls at Rabaul and Madang, PapuaNew Guinea. The objectives of thiscruise are as follows. First, in the NewIreland forearc basin multichannelseismic profiling will be conductedover the Conical, TUBAF and Edisonseamounts and the Horst Structure,which are the sites for an IODP pro-posal. Second, a deep-tow magneticsurvey is planned over the sites drill-ing during ODP Leg 193 in order toresolve the detailed magnetic struc-ture of felsic hydrothermal mound.

Third, a multibeam bathymetric sur-vey will be performed over severalseamounts, which form the westernBismark arc. From September 10 to 25,R/V Onnuri will also make a number ofobservations in the Philippine Sea andCaroline Sea on the way back to Ko-rea. These include reconnaissancesurvey of the eastern boundary of theCaroline Plate and geophysical inves-tigation of the Sorol Trough. Scien-tists from Australia, Germany, USA,and Papua New Guinea are expectedto be involved in the second cruise.

Sang-Mook Lee, National CoorespondentDeep-Sea Resources Research CenterKorea Ocean Research and Development InstituteAnsan, P.O. Box 29Seoul 425-600, KOREA

Tel: + 82 345 400 6363Fax: + 82 345 418 8772Email: [email protected]

For more information on InterRidge-Japan contact:Kensaku TamakiOcean Research Institute,University of Tokyo1-15-1 Minamidai, Nakano,Tokyo 164-8639, Japan

Tel: + 81 3 5351 6443Fax: + 81 3 5351 6445E-mail: [email protected]

54 InterRidge News

National News....

USA: RIDGE

The Ridge 2000 programme (R2K)is a new, US National Science Founda-tion (NSF) sponsored research initia-tive to understand the Earth’s spread-ing ridge system as an integratedwhole, from its inception in the mantleto its manifestations in the biosphereand the water column. The R2K Pro-gramme was conceived to promote anintegrated approach towards the studyof mid-ocean ridges. Emerging fromcommunity workshops over the pasttwo years, R2K builds directly on thescientific and technological successesof the RIDGE Programme. The scien-tific motivation for the R2K Programmeis encapsulated in the phrase “frommantle to microbes” that expressesthe inextricable linkages between proc-esses of planetary renewal in the deepocean and the origin, evolution andsustenance of life in the absence ofsunlight. R2K is at the beginning of ananticipated 12-year programme.

The R2K Science Plan aims for acomprehensive understanding of therelationships among the geologicalprocesses of plate spreading at mid-ocean ridges and the seafloor andsub-surface ecosystems that theysupport. Research carried out underthis new programme will be structuredwithin an integrated, whole-systemapproach that will encompass a widerange of disciplines. Specific geo-graphic areas will be the focus of de-tailed studies to yield new insightsinto the linkages among the biologi-cal, chemical and geological processesthat are involved in crustal accretionand subsequent ridge crest processes.The R2K Programme will support twomain research themes: Time-CriticalStudies and Integrated Studies.

Time-Critical StudiesThe goal of the Time-Critical Stud-

ies element is to understand the na-ture, frequency, distribution andgeobiological impacts of magmatic and

tectonic events along the global mid-ocean ridge system. To this end, thetheme focuses on the immediate bio-logical, chemical and geological con-sequences of active processes on theseafloor. Such processes generallyoccur as transient events and includevolcanic eruptions and intrusions ofmagma at the ridge axis and faultingrelated to seafloor spreading.

Since 1993, event detection andresponse efforts have focused on twoshort ridge systems (the Juan de Fucaand Gorda Ridges, northeastern Pa-cific Ocean) and have revolutionizedour understanding of these activeprocesses. The field response toevents detected using the SOSUS ar-ray (the Navy’s cabled hydrophonesystem in the northeastern PacificOcean) has provided fundamental newinformation about the linkages be-tween volcanic events at the seafloor,the development of hydrothermalplumes in the ocean above the ridgecrest, hydrothermal circulation andvent biota.

Under the R2K Programme, Time-Critical Studies are dedicated to facili-tating rapid-response missions thatcan observe, record and sample thesecritical transient phenomena in theocean above the mid-ocean ridge aswell as on the seafloor itself. In theinitial phases of this element, the pro-gramme will be restricted to the north-east Pacific where real time detectionis possible through the SOSUS arrayand where the facilities are availablefor a rapid response.

Integrated StudiesThe Integrated Studies theme of

R2K is intended as a programme offocused, whole system research ofglobal mid-ocean ridge processes.This component addresses the com-plex, interlinked array of processesthat support life at and beneath theseafloor as a consequence of the flow

of energy and material from Earth’sdeep mantle, through the volcanic andhydrothermal systems of the oceaniccrust, to the overlying ocean. Moreo-ver, this part of the programme recog-nizes that the complex linkages be-tween life and planetary processes atmid-ocean ridges can only be under-stood through coordinated studiesthat span a broad range of disciplines.Thus, Integrated Studies will consistof multidisciplinary research that isfocused on a small number of pre-selected “type” areas that are designedto characterize segments of the mid-ocean ridge system. The objective ofIntegrated Studies is to develop quan-titative, whole-system modelsthrough coordinated and interdisci-plinary experiments. It will be neces-sary for scientists to understand theinteractions and linkages between thevolcanic, tectonic, geochemical andbiological systems to achieve thisgoal.

The Integrated Studies theme willinitially focus on three sites that werechosen on the basis of a communityvote and a review by a special R2KIntegrated Site Selection Panel( h t t p : / / R 2 K . b i o . p s u . e d u /ISPANELRPT.htm). These sites willbe centered on a portion of:- 9-10°N segment of the East Pacific

Rise;- The Endeavour Segment of the Juan

de Fuca Ridge;- Either the East or Central Lau Basin

Spreading Center.

Programme StatusThe R2K Programme officially be-

gan October 15, 2001, when the officeopened at Penn State University.Charles Fisher, a professor of biologyat Penn State University is chairingthe Steering Committee for the pro-gramme with guidance from an Execu-tive Committee consisting of DeborahSmith from WHOI, James Cowen from

55Vol. 11(1), 2002

National News....

For more information contact:RIDGE Office208 Mueller LaboratoryThe Pennsylvania State UniversityUniversity Park, PA 16802,USA

Tel: + 1 814 865 3365Fax: + 1 814 865 9131E-mail: [email protected]: http://R2K.bio.psu.edu

the University of Hawaii, and DavidChristie from Oregon State Univer-sity. In addition to Fisher, the R2Kprogramme office has three full timestaff members. Deborah Hassler is theRidge 2000 programme coordinator.She is a graduate of the MIT/WHOIJoint Programme in Oceanography,and joined the programme followingher NSF sponsored Postdoctoral Fel-lowship at Harvard University withRoberta Rudnick. Patty Nordstrom isthe new programme assistant. Pattyhas a MS degree in extension educa-tion and brings a wealth of organiza-tional, web, and practical experienceto the office. Liz Goehring is the edu-cation and outreach coordinator forthe programme. Liz had 10 years ofexperience as a systems engineer withIBM, before she obtained a MS de-gree in ecology, became involved insecondary education outreach activi-ties and then taught for several yearsin the public school system.

Two workshops were conductedin early 2002, one for scientific back-ground and one for planning. Theseworkshops were designed to provideopportunities for a broad cross-sec-tion of scientists and engineers toshare information about the IntegratedStudy sites and to participate in plan-ning the implementation of the re-search programme.

The Community Education Work-shop was held in Long Beach, CA Feb.25-27, 2002. Approximately 110 peo-ple attended. The primary purpose ofthis workshop was to provide a forumfor community education and the shar-ing of data among all investigatorswishing to write proposals for work atone of the Integrated Study sites. Eachday was devoted to one IntegratedStudy site and featured several in-

vited speakers, a discussion led by aninterdisciplinary panel after each talk,and general poster sessions. Speakernotes and figures, white papers, avail-able data sets, maps, publications,and bibliographies from the workshopcan be found at the R2K website.

Implementation plans for each ofthe initial Integrated Study sites weredeveloped at an open ImplementationPlan Workshop on April 7-8, 2002 inAlbuquerque, NM. These plans iden-tified the geographic focus aboutwhich the nested components of eachIntegrated Study will be centered andprovided the guidelines for the com-ponents that will constitute the set ofIntegrated Studies necessary at eachsite.

The NSF Programme Announce-ment for R2K is available on the NSFand R2K websites and proposals forfunding work at the three IntegratedStudy sites will be considered begin-ning with the August 15, 2002 OceanSciences (OCE) target date. The re-sults of the Community Education andImplementation Plan Workshops arealso available on the web site. R2Kproposals are subject to the normalpeer-review process and will be re-viewed by the regular NSF OceanScience Division Panels. Addition-ally, the R2K Steering Committee willperform a relevancy review of all R2Kproposals.

An important component of theR2K programme is a strong commit-

ment to data management and therapid dissemination of metadata anddata. Sharing data will maximize tech-nology transfer across the programme,encourage integration of science, co-ordination of research, and the con-struction and testing of hypotheses.R2K is a time limited programme, thusall data collected will be rapidly re-leased for maximum benefit to all. Adraft statement regarding this policyis available on the R2K web site forcomment.

Along with the programme ele-ments discussed above, R2K is spon-soring a postdoctoral fellowship pro-gramme. The fellowship is intended tofoster cross-disciplinary fertilizationby providing opportunities for indi-viduals to broaden their research ex-pertise as well as to expand the breadthof ridge science.

Contact Us

To join the mailing list, for timeta-bles, data, upcoming meetings andworkshops, contacts and other infor-mation about the programme, email usat [email protected], see thewebsite at http://R2K.bio.psu.edu orcall 814-865-RIDG.

Previous updates from various Nations can be found on the IR web siteunder the menu "Member Nations" or by going directly to:

http://www.intridge.org/act4.html

56 InterRidge News

National News....

By creating the Mauritius Ocea-nographic Institute (MOI) in January2000, Mauritius has expressed its deep-est interest towards ocean explora-tion and research. The idea of settingup such an institute was triggered bythe fact that the Republic of Mauritiushas an EEZ which is 1.9 million km2

and, by the time of its creation, therewas an urgent need to submit a claimto the United Nation Commission onthe Limits of the Continental Shelf(UNCLCS).

The interest of the MOI to under-take ridge research was born from thefact that part of the Central IndianRidge (CIR) falls within the EEZ of theRepublic of Mauritius. Furthermore,ridge research is in its burgeoningstage and joining with the rest of theinternational community could only

be beneficial to the Mauritian scien-tists in terms of training and experi-ence in that new area of research.

The academic and economic ben-efit that could be extracted from un-dertaking ridge research are signifi-cant to motivate and arouse the en-thusiasm of Mauritian scientists to beamong those in the front row of suchscientific activities.

The increasing interest of the gov-ernment of the Republic of Mauritiustowards marine research, particularlyridge research, is visible in its action:

three foreign scientific cruises ob-tained the approval of the Govern-ment of Mauritius to run scientificexpedition on the part of the CIR fall-ing in our EEZ. We are presently work-ing on bathymetric and magnetic datacollected from the area limited by 18°S and 20.6° S along the CIR.

With the above-mentioned inter-est towards ridge research and par-ticularly on the CIR, Mauritius is in theprocess of forming a national ridgeresearch initiative: the Mauritius RidgeResearch Group.

Daniel MARIEMauritius Oceanography Institute4th Floor France CentreVictoria AvenueQuatre BornesMAURITIUS

Tel: + 230 427 4434Fax: + 230 427 4433Email: [email protected]

As planned, the Dorsales pro-gramme has ended last December, af-ter 8 years of existence. The fundingagencies (CNRS and IFREMER) arenot suggesting that the French com-munity should stop working on mid-ocean ridges. But they encourage thecommunity to spend some time think-ing about what should be our neworientations, and to propose a newplan for 2003 with focused objec-tives. In that sense, 2002 is a year oftransition, during which France re-mains a principal member of InterRidge.

Several workshops have been or-ganized during the passed six monthsto discuss these future issues.

At the first workshop held inRoscoff, in October 2001, the Frenchcommunity has agreed to concentrateefforts on long term observation andmonitoring of active processes at mid-ocean ridges. This new orientation is

in agreement with the internationalcontext. Canada, Japan and the UShave initiated long term observationprogrammes and are ready to installseafloor observatories.

Two further workshops (in Marchand April respectively) discussedpossible targets. The first target willbe the Mid-Atlantic Ridge south ofAzores (MOMAR area). This area hasthe advantage of including three majorhydrothermal fields (Menez Gwen,Lucky Strike and Rainbow) whichcover various depths and lithologies.

French scientists have been very ac-tive is this area during the last decade,in the context of European pro-grammes. Moreover, this site has beenselected by InterRidge. The secondtarget will be the East Pacific Rise at13°N. This area will be more inten-sively targeted by biological studies,since the French biologists want tobenefit from their record of 20 years ofobservation. In parallel, some activitywill be maintained in the southernEPR, which corresponds to the fastestportion of the global ridge system.

For more information on the French programme contact:

Catherine Mével,Laboratoire de Geosciences MarinesUniversité Pierre et Marie Curie4 Place Jussieu, Tour 26, 3ème étage75252 Paris Cedex 05, FRANCE

Tel: 33-1-44-27-51-93Fax: 33-1-44-27-39-11E-mail: [email protected]

France

MauRidge

57Vol. 11(1), 2002

National News....

Canadian ridge scientists and stu-dents will be participating in two fieldprograms in the Northeast Pacific inSummer 2002, both using the ROPOSremotely-operated submersible. Thefirst (July 12 to August 5, 2002) will bea collaborative cruise with the NOAAVENTS program in which ROPOS willbe mobilised on the University ofWashington research vessel ThomasG. Thompson. Along with NOAA andUniversity of Washington colleagues,a Canadian team led by Prof. SteveScott of the University of Toronto willfirst complete work at Axial Volcanoon the Juan de Fuca Ridge, as part ofthe NeMO (New Millenium Observa-tory) program, which began in thesummer of 1998. The focus of theNeMO program has been the docu-mentation of the geological and bio-logical events that followed a January1998 seafloor eruption in the easternportion of the Axial caldera. Followingthe work at Axial Volcano the cruisewill move north to Explorer Ridge, aspreading ridge located to the north ofthe Juan de Fuca Ridge. Hydrothermalactivity was first discovered on twoCanadian cruises to Explorer Ridge in1984, and portions of the ridge wererevisited with ROPOS in the mid-

1990’s. Several very large, hydrother-mally active, polymetallic sulphidemounds have been found along aportion of the ridge that shoals to<2000m. While the area’s notoriouslybad weather has hampered extensiveexploration, it is hoped that the larger,more stable platform offered by theThompson will permit more extensivemapping and sampling of the ExplorerRidge fauna and sulphide depositsduring the 12 days that the vessel willbe on site.

Upon it’s return to port in Victoria,British Columbia on August 5, ROPOSand it’s deep-sea winch will be trans-ferred from the deck of the Thomas G.Thompson directly to the deck of theCanadian vessel John P. Tully. TheTully will then set sail for a week ofdiving and exploration on a gas hy-drate site on the Vancouver Islandmargin with a group headed by Prof.

Ross Chapman of the University ofVictoria. On August 12, Prof.Chapman’s group will be replaced bya new scientific party, led by Prof. KimJuniper of the Université du Québec àMontréal. The Tully will then sail forthe Endeavour Segment of the Juan deFuca Ridge for sample collections,and the deployment and recovery oflong-term faunal colonisation andmineral weathering experiments. Op-erations at Endeavour Segment will bemixed with dives at several nearbyODP drill sites, where ROPOS will beused for in situ downloading of datafrom instruments in sealed drill holes.One area of particular interest is Mid-dle Valley where it is hoped that in-struments in CORKed holes recordedlast winter’s major seimic event atMiddle Valley. The Tully cruise willend in Victoria, British Columbia onAugust 22.

For more information on CanRidge contact:S. Kim Juniper, Canadian InterRidge CorrespondentGEOTOPUniversité du Québec à MontréalP.O. Box 8888, Station AMontréal, Québec, H3C 3P8Canada

Tel: + 1 514 987-3000 ext. 6603Fax: + 1 514 987 4647E-mail: [email protected]

Canada: CanRidge

Marine Protected Areas in Canada

University of Qubebec, Endeavour hot vents area:http://www.er.uqam.ca/nobel/oasis/index2.html

One of ten areas of interest set up as part of theMarine Protected Areas programme:

http://www.dfo-mpo.gc.ca/oceanscanada/newenglish/htmdocs/mpas/endeavour.htmhttp://www.pac.dfo-mpo.gc.ca/oceans/mpa/pilots.htm

The Remotely Operated Platform for Ocean Science: http://ropos.com/

58 InterRidge News

Calendar of MOR Research related events (2002)

More details about all of the following meetings can be found via theMeetings menu on the InterRidge homepage:

http://www.intridge.org/info3.html

Upcoming Meetings and Workshops

11-15 February 2002 Ocean Sciences Meeting. Honolulu, Hawaii

5-8 March, 2002 Oceanology International 2002. London, UK

16-19 April, 2002 Underwater Technology 2002 International Symposium.Tokyo, Japan

17-19 April, 2002 SWIR Workshop. SOC, UK

20-25 April, 2002 "Minerals Of The Ocean" - International Conference.St. Petersburg, Russia

21-26 April, 2002 European Geophysical Society. Nice, France

28 May - 1 June, 2002 AGU Spring Meeting. Washington, DC USA

10-12 June 2002 IR Next Decade Workshop. Bremen, Germany

15-17 June 2002 MOMAR Workshop, Horta (Azores, Portugal)

9-12 July, 2002 Western Pacific Geophysics Meeting.Wellington, New Zealand

4 - 7 September, 2002 Plume Magmatism. Petrozavodsk, Russia

13-14 September 2002 Steering Committee Meeting. Italy

9 - 13 September, 2002 InterRidge Theoretical Institute (IRTI) Thermal Regimeof Ocean Ridges and Dynamics of Hydrothermal Circulation. University of Pavia, Italy.

25-26 September, 2002 Unmanned Underwater Vehicle Showcase. SOC, UK

6-10 December, 2002 AGU 2002 Fall Meeting. San Francisco, USA

7-11 April, 2003 EGS-AGU-EUG Joint Assembly. Nice, France

Email the InterRidge Office ([email protected]) with informationon upcoming international ridge related meetings. We will publish them inIR news and add also post the latest information on the IR website.

59Vol. 11(1), 2002

InterRidge Next Decade WorkshopCall for white papers!

10-12 June 2002, Bremen, Germany

http://www.intridge.org/ndir.htm

Organiser: Colin Devey (Germany)

InterRidge Initiative will reach the end of its first 10 year period in 2003, providing an opportunityto assess what has been achieved and to plan for the next decade of ridge research.

This assessment and planning will take various formats, but a very important part of the processis this workshop The aim of this workshop is to establish the goals for InterRidge for the next decadeand to determine the organisational structure necessary to reach them.For the workshop to be successful it is imperative that the views of the whole InterRidge communityare incorporated into its planning and execution. Please take the time now to access the WorkshopWeb page and register yourself for participation at the workshop. If you cannot make room in yourschedule to attend, please submit a summary of what you think InterRidge should try and achievein the next decade in the form of a white paper (all information about what you might want to includeare on the website).

Provisional AgendaJune 10thVision statements from leaders in the fields of spreading axis biology, geology, geophysics andtechnology. The aim of this session is to set the framework for the workshop and to provide acommon basis for the working group discussions

Discussions in discipline-orientated working groups (Biology, Geology, Geophysics, Technol-ogy...). The aim of these discussions is for each discipline to formulate and rank in terms ofimportance and feasibility their visions and aims for the next decade.

June 11thReport session of disciplinary ry working groups. Discussion on the present InterRidge WorkingGroup structure: are all working groups necessary, how long should they exist, do we need new one?

Interdisciplinary discussion in ad hoc working groups (if neessary) to define structure/organisationof InterRidge for the next decade and the finances necessary

June 12th

Plenary wrap-up, presentation of the draft plan for InterRidge Next Decade, division of responsi-bility and time plan for finishing official Next Decade plan

Working group leaders (both from the discipline-defined groups and the structure and financegroups if created) to write up texts for the Project Plan

Your participation in the future of InterRidge is important. Please make an input however you can.We look forward to seeing you in June!


60 InterRidge News


South West Indian Ridge Workshop (SWIR)17-19 April 2002


Organising Committee:C. Mével, Co-chair ([email protected]),L. Parson, Co-chair ([email protected]),A. M. Adamczewska ([email protected])H.J.B. Dick ([email protected]),D. Sauter ([email protected]),K. Tamaki ([email protected]),

Papers from this meeting will be incorporated into a proceedingsvolume in the electronic journal, G-cube: (G3 http://g-cubed.org/).

http://www.intridge.org/swirwksp.htm

Mantle Plumes and MetallogenyInternational Symposium

September 4–7, 2002, Petrozavodsk, Russia

http://www.intridge.org/plume02.pdfProposed Symposium topics:

General issues of mantle plume evolutionMantle plumes and chemical geodynamicsPlumes and rifting, including pre-rift regimeRecent and Cenozoic mantle plumes in continental and oceanic lithospheresMantle plumes in the Phanerozoic and PrecambrianMantle plumes as manifest in geophysical fields and deep structureNumerical modeling of inception and development of mantle plumesMantle plumes and metallogenyPlumes and biological catastrophes in the Earth’s history

Pre- and post-Symposium field trips will introduce you to unique manifestations of plumemagmatism in the Early Proterozoic of Karelia and Devonian magmatism of the KolaPeninsula and to the geological setup of Archean greenstone belts.

61Vol. 11(1), 2002


MOMAR II Workshop15-17 June 2002, Horta (Azores, Portugal)

Organisers: Javier Escartin, France, ([email protected]) Ricardo Serrão Santos, Azores ([email protected])

Workshop Objectives:a) define the scientific objectives to be pursued in the next 5-10 years: integration of biological,

volcanic, tectonic, hydrothermal and oceanographic processes in time and spaceb) identify technologies/instrumentation available for observatory-related studies, and future

developments required: AUVs, moorings, ROVs, submersibles, data collection/storage/transmission, etc.

c) define the type of experiments to carry out in the future and establish a realistic implementa-tion plan based on the scientific goals, as well as technological and funding constrains

d) define the procedures for management and integration of scientific datae) establish links with existing national and international observatory-related projects: data and

connector standards, transfer of technologyf) discuss and evaluate management proposals of study sites, and aspects related with scientific

interpretation and dissemination for the general publicg) discuss and evaluate possibilities and strategies for funding of the observatory.

Towards planning of seafloor observatory programs for the MAR regionFor the latest information go to: http://www.intridge.org/

The Fourth Unmanned Underwater Vehicle Showcase25-26 September 2002,


The Exhibition: the showcase for leading manufacturers of vehicles and subsystems fromaround the world.

The Conference: a leading edge technical programme put together by a committee of industryexperts featuring presentations from global leaders in the industry

The Demonstrations: see the vehicles and systems in operation in the dockside watersadjacent to SOC.

http://www.uuvs.net/

62 InterRidge News

Organising Committee: C. German (Co-Chair), J. Lin (Co-Chair),A. Fisher, M. Cannat, R. Tribuzio & A. Adamczewska

We are pleased to announce the first IRTI to be held in Italy in September 2002.The principal objectives of this theoretical institute will be:

(1) To foster exchange of information on recent progress in observational, experimental, andmodeling studies of hydrothermal circulation and their implications for thermal evolutionof the oceanic lithosphere.

(2) To identify key scientific issues that could be addressed in coming years and discuss ageneral plan for more focused international collaboration in this important research field.

(3) To educate a broad spectrum of international researchers, post-docs, and graduatestudents on the state-of-the-art research approaches, especially experimental and theoreticalmodeling capabilities.

The Institute will take place over 4 1/2 days’ duration comprising 2 days’ short-course andone day’s field excursion to study hydrothermal alteration in the northern Apennine ophiolitesfollowed by a further 1 1/2 days’ workshop for a subset of the short-course/field tripparticipants.

We have arranged for 19 Invited Speakers and Discussion Leaders from across theinternational community to lead the proposed short-course.

The short-course will be held in the historic lecture theatre of the University of Pavia, situatedapproximately 30miles/50km south of Milano. The field course will be to the northernApennine ophiolites, where exceptional hydrothermal alteration exposures can be observed.The workshop will be held at Sestri Levante.

Participation: We anticipate 50-100 attendees for the short course and field excursion andabout 30 attendees for the workshop. Because space is likely to be limited, those interestedin participating, either to the short-course and field excursion or for the full duration of thewhole IRTI, should register their interests with Agnieszka Adamczewska at ([email protected]).

We look forward to seeing you in Italy!Chris German ([email protected]) & Jian Lin ([email protected])

1st InterRidge Theoretical Institute (IRTI)Thermal Regime of Ocean Ridges and Dynamics of

Hydrothermal Circulation9-13 September 2002, University of Pavia, Italy


Latest information about registration can be found at:http://www.intridge.org/irti.htm

63Vol. 11(1), 2002

InterRidge National Correspondents

AustraliaDr. Trevor FalloonGeology DepartmentUniversity of TasmaniaGPO Box 252C, HobartTasmania 7001, AustraliaE-mail: [email protected]

AustriaDr. Monika BrightMarine Biol., Institute for Ecologyand Conservation BiologyUniversity of Vienna, Althanstr. 14,A-1090 Vienna , AustriaE-mail: [email protected]

BrazilDr. Suzanna SichelDept. de Geologia - Lagemar UFFAv. Litorânea s/nº 4° andarCEP: 24210-340Gragoatá Niterói RJ BrazilE-mail: [email protected]

CanadaDr. Kim JuniperGEOTOPUniversite du Québec à MontréalP.O. Box 8888, succursale Centre Ville,Montréal, Québec, H3C 3P8, CanadaE-mail: [email protected]

andDr. Kathryn M. GillisSchool of Earth and Ocean SciencesUniversity of Victoria, MS 4015Victoria, BC V8W 2Y2, CanadaE-mail: [email protected]

ChinaDr. Wang ZhihongLaboratory of Lithosphere TectonicEvolutionInstitute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029, P.R. ChinaE-mail: [email protected]

DenmarkDr. John HopperDanish Lithosphere CentreOester Voldgade 10, KobenhavnDK-1350, DenmarkE-mail: [email protected]

FranceDr. Catherine MévelLaboratoire de Geosciences MarinesIPGP - Université Pierre et Marie CurieCase 110, 4 place Jussieu,75252 Paris cedex 05, FranceE-mail: [email protected]

GermanyDr. Colin DeveyFachbereich 5 GeowissenschaftenUniversität BremenPostfach 330440D-28334 Bremen, GermanyE-mail: [email protected]

IcelandDr. Karl GronvoldNordic Volcanological InstituteUniversity of IcelandGrensasvegur 50IS 108 Reykjavik, IcelandE-mail: [email protected]

PhilippinesDr. Graciano P. Yumul, Jr.National Institute of Geological SciencesUniversity of the PhilippinesDiliman, Quezon City, 1101, PhilippinesE-mail: [email protected]

PortugalProf. Fernando BarrigaDepartamento de GeologiaFacul. de CienciasUniversidade de LisboaEdificio C2, Piso 5, Campo GrandePT 1700 Lisboa, PortugalE-mail: [email protected]

RussiaDr. Sergei A. SilantyevVernadsky Inst. of GeochemistryRussian Academy of Sciences19, Kosygina StreetMoscow 117975, RussiaE-mail: [email protected]

SOPACDr. Russell HoworthSOPAC,Private Mail Bag,Suva, FijiE-mail: [email protected]

South AfricaDr. Anton P. le RoexDepartment of Geological SciencesUniversity of Cape TownRondebosch 7700, South AfricaE-mail: [email protected]

SpainDr. Juan José DañobeitiaInst. Jaime Almera de Ciencias de laTierra, CSICC/Lluis Sole i Sabaris s/n08028 Barcelona, SpainE-mail: [email protected]

SwedenDr. Nils HolmDept. of Geology and GeochemistryUniversity of StockholmS-106 91 Stockholm, SwedenE-mail: [email protected]

SwitzerlandDr. Gretchen Früh-GreenDepartment of Earth SciencesETH-Z, Sonneggstr. 5CH-8092 Zurich, SwitzerlandE-mail: [email protected]

United KingdomDr. Chris GermanChallenger Division for Seafloor ProcessesSouthampton Oceanography CentreEuropean Way, Empress DockSouthampton, SO14 3ZH, UKE-mail: [email protected]

USADr. Charles Fisher, RIDGE ChairRIDGE OfficeDepartment of Biology,Pennsylvania State University,208 Mueller Laboratory,University Park PA 16802, USAE-mail: [email protected]

IndiaDr. Sridhar D. IyerE-mail: [email protected] andDr. K.A. Kamesh RajuE-mail: [email protected] Institute of OceanographyH.O. Dona PaulaGoa 403 004, India

ItalyProf. Enrico BonattiInstituto di Geologia Marina C.N.R.,Universita di Bologna,Via P. Gobetti 101,I-40129 Bologna, ItalyE-mail: [email protected]

andDr. Paola TartarottiDipartimento di Geologia, Paleontologia e Geofisica, Universita di Padova,Via Giotto 1, 1-35137 Padova, ItalyE-mail: [email protected]

JapanProf. Nobuhiro IsezakiDepartment of Earth Sciences,Faculty of Science, Chiba University,Yayoi-cho 1-33, Inage-ku, Chiba-shi,Chiba 260, JapanE-mail: [email protected]

KoreaDr. Sang-Mook LeeMarine Geology and Geophysics DivisionKORDI, Ansan, P.O. Box 29Seoul 425-600, KoreaE-mail: [email protected]

MauritiusDr. Daniel P. E. MarieMauritius Oceanography Institute4th Floor, France CentreVictoria Avenue, Quatre Bornes, MauritiusE-mail: [email protected]

MexicoDr. J. Eduardo Aguayo-CamargoInst. de Ciencias del Mar y LimnologiaU. Nacional Autonoma de MexicoApartado Postal 70-305Mexico City, 04510, MexicoE-mail: [email protected]

MoroccoProf. Jamal AuajjarUniversite Mohammed VAgdal Ecole Mahammadia des IngenieursDepat. de Genie Mineral, Avenue Ibn Sina,BP 765, Agdal, Rabat 10 000, MoroccoE-mail: [email protected]

New ZealandDr. Ian WrightNat. Inst. of Water and AtmosphericResearch, P.O. Box 14-901Wellington 3, New ZealandE-mail: [email protected]

NorwayProf. Rolf PedersenInstitute of Solid Earth PhysicsUniversity of BergenAllegt. 41, 5007 Bergen, NorwayE-mail: [email protected]

64 InterRidge News

InterRidge Steering Committee

Dr. Kensaku TamakiInterRidge ChairOcean Research Institute,University of Tokyo1-15-1 Minamidai, Nakano,Tokyo 164-8639, JapanTel: + 81 3 5351 6443Fax: + 81 3 5351 6445E-mail: [email protected]

Prof. Fernando BarrigaDepartamento de GeologiaFacul. de CienciasUniversidade de LisboaEdificio C2, Piso 5, Campo GrandePT 1700 Lisboa, PortugalTel: +351 1 750 0066Fax: +351 1 759 9380E-mail: [email protected]

Dr. Phillippe Blondel, ad hocDepartment of PhysicsUniversity of BathBath BA2 7AY, UKTel: + 44 1225 826 826Fax: + 44 1225 826 110E-mail: [email protected]

Prof. Enrico BonattiInstituto di Geologia Marina C.N.R.Universita di BolognaVia P. Gobetti 101I-40129 Bologna, ItalyTel: + 39 51 639 8935Fax: + 39 51 639 8939E-mail: [email protected]

Dr. Dave M. ChristieCOAS, Oregon State University104 Oceanography Adm. BuildingCorvallis, OR 97331-5503, USATel: + 1 541 737 5205Fax: + 1 541 737 2064E-mail: [email protected]

Prof. Paul R. DandoSchool of Ocean SciencesUniversity of Wales-Bangor,Menai BridgeAnglesey, LL59 5EY, UKTel: + 44 1248 382 904Fax: + 44 1248 382 620E-mail: [email protected]

Dr. Colin W. DeveyFachbereich 5 GeowissenschaftenUniversität BremenPostfach 330440D-28334 Bremen, GermanyTel: + 49 421 218 9205Fax: + 49 421 218 9460E-mail: [email protected]

Dr. Jérôme DymentCNRS UMR 6538Institut Univ. Europeen de la MerUniversite de Bretagne Occidentale1 Place Nicolas Copernic29280 Plouzane, FranceTel : + 33 2 9849 8720Fax : + 33 2 9849 8760E-mail : [email protected]

Dr. Javier Escartín, ad hocLaboratoire de Geosciences MarinesIPGP - Université Pierre et Marie CurieCase 89, 4 place Jussieu,75252 Paris cedex 05, FranceTel: + 33 1 4427 4601Fax: + 33 1 4427 3911E-mail: [email protected]

Dr. Charles FisherDepartment of Biology,Pennsylvania State University,208 Mueller Laboratory,University Park PA 16802, USATel: +1 814 865 3365Fax: +1 814 865 9131E-mail: [email protected]

Dr. Françoise Gaill, ad hocLaboratoire de Biologie MarineCNRS UPR 7622Université Pierre et Marie Curie(Paris 6), 7 Quai Saint-BernardF-75252 Paris Cédex 05, FranceTel: + 33 1 44 27 30 63Fax: + 33 1 44 27 52 50E-mail: [email protected]

Prof. Toshitaka GamoDivision of Earth and PlanetarySciences Graduate School of ScienceHokkaido UniversityN10 W8Sapporo, 060-0810, JapanTel: +81 11 706 2725Fax: +81 11 746 0394E-mail: [email protected]

Dr. Christopher R. German, ad hocChallenger Div. for Seafloor ProcessesSouthampton Oceanography CentreSouthampton, SO14 3ZH, UKTel: + 44 1703 596 542Fax: + 44 1703 596 554E-mail: [email protected]

Dr. Kim JuniperGEOTOPUniversité du Québec à MontréalP.O. Box 8888, Station AMontréal, Québec, H3C 3P8, CanadaTel: + 1 514 987 3000 ext. 6603Fax: + 1 514 987 4647E-mail: [email protected]

Dr. Masataka KinoshitaDeep Sea Research DepartmentJAMSTEC, 2-15 NatsushimaYokosuka, 237-0061, JapanTel: +81 468 67 9323Fax: +81 468 67-9315E-mail: [email protected]

Dr. Jian Lin, ad hocDepartment of Geology & GeophysicsWoods Hole Oceanographic InstitutionWoods Hole, MA 02543-1541, USATel: + 1 508 289 2576Fax: + 1 508 457 2187E-mail: [email protected]

Dr. Sang-Mook LeeDeep-Sea Resources Research CenterKORDI, Ansan, P.O. Box 29Seoul 425-600, Republic of KoreaTel: +82 31 400 6363Fax: +82 31 418 8772Email: [email protected]

Dr. Catherine MévelIPGP - Université Pierre et Marie CurieCase 110, 4 place Jussieu,75252 Paris cedex 05, FranceTel: + 33 1 4427 5193Fax: + 33 1 4427 3911E-mail: [email protected]

Dr. Abhay MudholkarNational Institute of OceanographyDona Paula, GOA 403 004, IndiaTel: + 91-832 221-322 ex 4322Fax: + 91-832-223-340E-mail: [email protected]

Prof. Rolf PedersenInstitute of Solid Earth PhysicsUniversity of Bergen, Allegaten 41,N-5007 Bergen, NorwayTel: + 47 5558 3517Fax: + 47 5558 9416E-mail: [email protected]

Dr. Ricardo Santos, ad hocUniversity of the AzoresDept. of Oceanography and FisheriesPT- 9901-862 Horta (Azores), Portugaltel: +351 292 292 944fax: +351 292 292 659e-mail: [email protected]

Dr. Spahr C. Webb, ad hocLamont Doherty Earth Observatory,Columbia UniversityNew York 10964, USATel: + 1 845-365-8439Fax: + 1 845-365-8150E-mail: [email protected]

Vol. 11 (1) Spring 2002 InterRidge · Sestri Levante, Italy. InterRidge MOMAR II Workshop The 2nd...

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