Vol. 11 (1) Spring 2002 InterRidge News Initiative for international cooperation in ridge-crest studies Principal Members France Contents Japan United Kingdom InterRidge Office Updates United States The InterRidge Wish List...... 3 Coordinator Update...... 4 Associate InterRidge Publications...... 6 Members InterRidge Web Page Overview...... 7 Canada InterRidge Projects Italy Overview of InterRidge Working Groups...... 8 India Global Distribution of Hydrothermal Activity Working Group...... 9 Monitoring and Observatories Working Group...... 10 Korea Norway Reports and announcements Portugal 89th Dahlem Workshop...... 11 Elizabeth Mann Borgese ...... 11 Corresponding Members International Ridge-Crest Research Australia Biological Studies MAR-ECO - “Patterns and Processes of the ecosystems of the Northern Mid-Atlantic”; Brazil an international project under the Census of Marine Life programme. Bergstad O. A...... 12 China Towards unravelling the enigma of vent mussel reproduction on the Mid Atlantic Denmark Ridge, or when ATOS met Cages. Dixon.D et al ...... 14 Iceland Mauritius Island arc/BAB Mexico Submarine Hydrothermal Mineralisations and Fluids off the Lesser Antilles Island Morocco Arc – Initial Results from the CARIBFLUX Cruise SO 154. Halbach P. et al...... 18 New Zealand Geophysical Experiments in the Mariana Region: Report of the YK01-11 cruise. Goto T. et al...... 22 Philippines Russia Ophiolites SOPAC How back-arc basins evolved: tholeiite associations in the Kudi ophiolite of western Kunlun South Africa Mountains, northwestern China. Zhihong W...... 25 Spain Continued over page ....

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 2 InterRidge News

InterRidge Office Updates

Contents continued...

International Ridge-Crest Research cont ...

Pacific-Antarctic Ridge Widespread Silicic Volcanism and Hydrothermal Activity on the Northern Pacific – Antarctic Ridge.Stoffers P. et al...... 30

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

Mid-Atlantic Ridge New 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...... 38 Sulphide 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 Ridge Preliminary results of a recent cruise to the Northern Central Indian Ridge. Drolia R.K. et al...... 43

World Ridge Cruise Map and Schedule, 2002...... 47 National News...... 52 Calendar and Upcoming Meetings...... 58 National Correspondents and Steering Committee Members...... 63

InterRidge Mailing List Sign up on the web at: http://www.intridge.org/signup.htm

You can use the online form to join our regular mailing list to receive InterRidge News, or to be placed on our electronic mailing list, or to be put on the electronic directory on the web (http://www.intridge.org). Currently there are over 2800 scientists active in mid-ocean ridge research on our mailing list. We are constatnly adding new entries to the electronic directory, which contains a listing of each researcher's field of interest and expertise as well as their full address information. Links are also provided to personal or departmental web pages. Vol. 11(1), 2002 3

InterRidge Office Updates

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 for samples, to the IR Office. Iwould like to encourage all ridge scientist to check the Wishhhh list and share 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 the appropriate scientists. I wish I could get my hands on ...... Requested samples.....

Request for: CHIMINEY SAMPLES

Samples of manganese encrusted chimneys as well as hydrothermal or hydrogenous ferromanganese samples and associated sediments collected from any other midoceanic ridge system". Contact: Ranadip Banerjee or

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. ROCK SAMPLES If such materials are available in your drawers, Rock samples from Laxmi Basin, Laxmi please contact: Jacques Jedwab continental block or any protruding in eastern Arabian sea for physical/chemical studies Contact: A. Shivaji ([email protected])

I wish c uld get my 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 office and we will post it on the IR website and print it in the next issue of IR news. Cooperation is the key to good science! 4 InterRidge News

InterRidge Office Updates

Coordinator's Update

Member Nations require investigation and decide on munity to convene together and share The number of nations involved in future direction of research in this their ideas about the direction of fu- InterRidge activities continues to area is scheduled for 17-20th April, ture ridge research. The aim of this grow. This year, Mauritius has joined 2002, at SOC, UK. The workshop is set workshop will be to exchange and InterRidge as a Corresponding Mem- to be a great success with over 70 propose ideas for a new InterRidge ber nation. We welcome Dr. Daniel P. delegates from 13 countries register- Science plan for the next decade of E. Marie from the Mauritius Oceanog- ing to participate. A proceedings vol- international and multidisciplinary raphy Institute is the National Corre- ume from the meeting will be pub- research. spondent for Mauritius. This brings lished as a “Theme” in the electronic Representatives from Principal and the total number of InterRidge mem- journal, G-cube (G3 http://g- Associate member nations will de- ber countries to twenty eight. cubed.org/). InterRidge is offering the velop the “Next Decade Project Plan” “Outstanding student award” for the for InterRidge, based on the discus- Upcoming InterRidge meetings best student presentation at this work- sions during the workshop. The con- This year is a very busy one for IR shop. The winner will be announced tinually increasing number of nations meetings, there is something for eve- in the next issue of IR news! actively involved in InterRidge will ryone! An ever increasing demand to ensure that a highly international ridge pool resources and expertise, on an InterRidge Theoretical Institute community will utilise their expertise international level, in order to maxim- (IRTI): Thermal Regime of Ocean to define and refine scientific ques- ise research scope, quality and out- Ridges and the Dynamics of tions and focus interests, thereby, put, and at the same time minimise Hydrothermal Circulation strengthening the InterRidge pro- costs for individual nations is the driv- The first IRTI will be held 9-13 gramme and the future “Project plan”. ing force for organising more interna- September 2002, at the University of As a consequence, the highly interna- tional meetings. Pavia, Italy. The IRTI is being jointly tional planning process is expected to organized by the Hotspot-Ridge In- be of direct benefit to individual sci- IR Steering Committee meeting teractions working group and the Glo- entists and national programmes for The next IR Steering Committee bal Distribution of Hydrothermal Ac- the nations involved. At the same time meting will be hosted by Dr Riccardo tivity Working Group. The Institute the “Project plan” will provide oppor- Tribuzio, 13-14th September 2002, will take place over 4 1/2 days, and will tunities for the involvement of other Sestri Levante, Italy. comprise of: nations. 1) a short course component, which All of the International Ridge Com- InterRidge MOMAR II Workshop will focus on the modelling aspects munity is encouraged to submit white The 2nd MOMAR workshop will of the dynamics of hydrothermal papers, ideas and opinions to the take place 15-17th June 2002, Horta, circulation in the crust, InterRidge Office ([email protected] Azores (Portugal). The main goals of 2) a one day field excursion to study tokyo.ac.jp) with their views about this workshop are to: hydrothermal alteration in the the "Next Decade" of international 1) establish a plan for the development northern Apennine ophiolites and Ridge research. For details about what and installation of an ocean-bottom 3) a workshop component to the white papers should contain observatory along the Mid Atlantic synthesize the current models, please refer to the IR website: Ridge south of the Azores, and debate controversies, and outline http://www.intridge.org/ndir.htm 2) to identify the required scientific the future directions for and technical support required to collaborative research. For more The InterRidge office operate and manage the projects, information see the back of this The original IR Science Pro- data and instruments involved in issue of IR news or look on the IR gramme plan will be finishing at the the MOMAR observatory. The website. end of 2003. The IR office will remain latest information about this in Tokyo until the end of the duration workshop can be obtained from Next Decade Workshop of the current Programme in 2003. the IR website. The Next Decade Workshop will From 2004 the IR office will move to a be held 10-12th June 2002, Bremen, new Host country under the appoint- SWIR Workshop Germany. The current InterRidge pro- ment of a new Chair. Thus, at the end A workshop to synthesise current gramme will come to an end of its 10 of this year, the IR office will be send- knowledge and identify areas, both year plan at the end of 2003. Thus, it is ing out a request for bids to host the disciplinarily and geographically that time for the international ridge com- next IR office and for nominations for Vol. 11(1), 2002 5

InterRidge Office Updates

the new IR Chair. The period of tenure this workshop will be announced in found there is available on page 7 of of the Chair is not precisely defined, the next issue of IR news and on the IR this issue. but is normally expected to be three website. We have an alias for our website to years. The final decision on the bids Past and current information about make the IR URL easy to remember, will be made during the InterRidge IR working groups and projects can you can access the InterRidge home Steering Committee meeting in 2002. be found on the IR website: page by simply typing: The Next Decade workshop (see http://www.intridge.org/act2.html http://www.intridge.org above) will be a crucial part of the The IR databases are unique, they office change over since the aim of the IR Outstanding Student Presentation provide an international pool of infor- workshop will be to create a document The IR Steering committee has decided mation about all manner of issues re- outlining the Science plan for IR for to encourage students involved in lated to mid ocean ridges. The “Global the next decade. Input from the entire Ridge research by awarding certificates hydrothermal vents database” as well IR community is requested. See the IR of Excellence and prize money to best as the “Ridge-Hot Spot Interaction website for more information: student presentations at IR meetings. Reference Database” can be searched http://www.intridge.org/ndir.htm This year the IR Student Awards will by conventional method, by typing in be handed out during the upcoming search words in any of the fields but IR Steering Committee members SWIR workshop (UK) and the IRTI also these two databases contain in- Thank you to Kantaro Fujioka (Ja- (Italy). Background about students teractive area maps to make searches pan), Chris German (UK), Dave Kadko that receive the IR award and abstracts easier. Thus, you can do your search (USA), and Ranadhir Mukhopadhyay of their presentations will appear in the by location just by clicking on the (India) who have finished their term as next issue of IR news. Students from different areas on the globe. The national representatives on the IR all countries are encouraged to databases take a lot of work to main- Steering Committee. This year we participate in IR meetings and to present tain but we relay on your input to keep welcome Chuck Fisher, Chair of the their work! them up to date! USA R2K program as a new USA We are very pleased to see that the representative, Masataka Kinoshita InterRidge home page use of the InterRidge website contin- from JAMSTEC, Japan and Abhay We are continuing to upgrade and ues to increase. As always, any com- Mudholkar as the new Indian repre- improve our web site to maximise in- ments and suggestions are welcome sentative. The new national repre- formation transfer and make it user and remember that I always like to sentative for UK will be announced friendly. To make our homepage more receive updates and new information later this year. interactive we have divided it into two about meetings and ridge related Additionally, thanks go to Chris frames. The latest information about cruises, as well as job vacancies and Fox who has finished his term as the IR meetings, announcements and any other ridge related bits and peaces of Chair of the Event Detection and Re- other current, ridge related items is information. A brief summary of what sponse and Observatories Working now at your fingertips, accessible di- can be found on the InterRidge website Group last year. We welcome two new rectly from the left hand side frame on is also available at http:// ad hoc steering committee members; our homepage. The right hand side www.intridge.org/latest.htm Javier Escartin (France) and Ricardo frame contains the familiar menus with Santos (Azores, Portugal), as the new lots of ridge related information. Due Agnieszka Adamczewska co-chairs of the “Monitoring and Ob- to the volume of information on our InterRidge Coordinator servations Working Group”. website a brief outline of what can be April 2002

Working Groups The SWIR workshop (see above) is the last action of the SWIR work- ing group. The SWIR workshop will end with a morning de- voted to discussion and de- bate about the future of re- Post your experimental site on the IR website search on the Indian ridge. as a reserve now! Fill in the form at: After the publication of the proceedings from the http://www.intridge.org/reser-f.htm SWIR workshop this work- ing group will be dis- solved. The outcomes of the discussions during 6 InterRidge News

InterRidge Office Updates

InterRidge Publications The following InterRidge publications are available upon request. Fill out an electronic request from at http://www.intridge.org/act3.html or contact the InterRidge office by e-mail at [email protected]. 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 as downloadable PDF files from the same URL address on the InterRidge website, using Adobe Acrobat 4.0 or later versions. 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, Seattle, USA, pp. 6, 1993. IR STCOM Meeting Report, WHOI, USA, 2000. IR Meeting Report, York, UK, 1992. IR STCOM Meeting Report, Bergen, Norway, 1999. IR Meeting Report, Brest, France, pp. 39, 1990. IR STCOM Meeting Report, Barcelona, Spain, 1998. IR Program Plan Addendum 1997, pp. 10, Jan. 1998. IR STCOM Meeting Report, Paris, France, 1997. IR Program Plan Addendum 1996, pp. 10, April 1997. IR STCOM Meeting Report, Estoril, Portugal, 1996. IR Program Plan Addendum 1995, pp.10, 1996. IR STCOM Meeting Report, Kiel, Germany, pp. 22, 1995. IR Program Plan Addendum 1994, pp.15, 1995. IR STCOM Meeting Report, San Francisco, USA, 1994. IR Program Plan Addendum 1993, pp. 9, 1994. IR STCOM Meeting Report, Tokyo, Japan, 1994. IR Program Plan, pp. 26, 1994. Vol. 11(1), 2002 7

InterRidge Office Updates

InterRidge Website http://www.intridge.org/

The InterRidge office maintains an extensive web their activities can be found here. You can also find site containing various types of information including links to major projects that InterRidge is currently upcoming meetings, scheduled ridge related cruises, involved in and projects that are directly relevant to job vacancies as well as 9 different databases. These InterRidge activities - such as MOMAR and the Marine databases on the InterRidge website were initiated in Protected Areas project. Additionally, in this section, response to a request by the international community you can find a list of all the publications distributed to have a ‘centralised’ clearing house for information by the InterRidge office as well as a list of the InterRidge collected by scientists all over the world so that National Correspondents, and their contact details, relevant information is readily available to everybody from all of our Member Nations. at one site. A brief summary of what can be found on the InterRidge website is available at: 3) InterRidge databases section http://www.intridge.org/latest.htm One of the major objectives of InterRidge is to We are pleased that the use of the InterRdige facilitate the advancement of ongoing work of website is steadily increasing and we continue to individuals, national and international groups by encourage you make use of this resource and to providing centralised information and data-exchange continue to submit the latest information to our office. services. Thus, we maintain a number of databases To make our homepage more interactive we have divided that contain data submitted from Ridge scientists from it into two frames. On the left hand side frame you now around the world. We rely on contributions from have at your fingertips the latest information about individuals to continuously update the information and meetings, announcements and any other current, ridge increase the number of records. I would like to take related items. The right hand side frame contains the this opportunity to encourage everyone to become familiar menus, the general contents of which are outlined familiar with the databases on our website and below. As always any comments and suggestsions are contribute information on a regular basis to ensure always welcome. that this important resource contains current and up The alias for the IR website makes the URL easy to to date information. A list of the databases maintained remember, you can now access the InterRidge home by InterRidge with a brief introduction can be found page by simply typing http://www.intridge.org on our web site at: http://www.intridge.org/data1.html 1) Information section The IR office also maintains a database with contact This section provides links to Ridge related details of scientists involved in ridge reserach. To add meetings, cruises and other miscellaneous your name and contact details to the electronic information, as well as a little bit about InterRidge database just click on the “Mailing list sign up” on the structure and its role, including: Latest ridge related home page and fill in the signup form. News; an introduction to what is InterRidge, with a Furthermore, there is a neat little program, which short description of the InterRidge programme, you can use to calculate the spreading rate of the sea outlining the objectives of the programme as well as floor at any place around the globe! management structure and national membership of InterRidge; as well as a calendar of international Hydrothermal Ecological Reserves Page: conferences, meetings and workshops. http://www.intridge.org/reser-db.htm This page lists all the current ecological reserves 2) Activities section that have been proposed at hydrothermal vents. These This section is concerned with the scientific and vary in breadth and scope; at Juan de Fuca the management structure of InterRidge. The 'Activities' Canadian government has proposed the Endeavour section includes an outline of the scientific purpose vent field as a pilot marine protected area, while other of InterRidge. A description of the activities of the IR reserves consist of requests from individual scientists working groups, which are responsible for directing conducting experiments in specific areas. There is also different aspects of ridge research with updates of an on-line form to submit reserves to the page. 8 InterRidge News

InterRidge Office Updates

Overview of InterRidge Working Groups More information on working groups can be found on our website; http://www.intridge.org/act2.html

Arctic Ridges Current Activities: Compiling data. Dyment (France), J. Escartín Objective: Coordinate planning Chair: Philippe Blondel (UK) (France), J. Freire Luis (Portugal), efforts for mapping and sampling WG members: J. S. Cervantes (Spain), E. Grácia (Spain), D.W. Graham the Arctic Ridges. C. Deplus (France), M. Jakobsson (USA), K. Hoernle (Germany), G.T. Current Activities: Coordination of (Sweden), K. Okino (Japan), M. Ito (USA), L.M. MacGregor (UK) international cruise to the Gakkel Ligi (Italy), R. Macnab (Canada), N. Seama (Japan), F. Sigmundsson Ridge in 2001. T. Matsumoto (Japan), K. A. K. (Iceland) Chair: Colin Devey (Germany) Raju (India), W. Ryan (USA), and WG members: G. A. Cherkashov (Rus- W. Weinrebe (Germany). Monitoring and Observatories sia), B. J. Coakley (USA), K. Crane Objectives: Develop detection (USA), O. Dauteuil (France), V. Global Distribution of methods of transient ridge-crest Glebowsky (Russia), K. Gronvold Hydrothermal Activity seismic, volcanic and hydro- (Iceland), H. R. Jackson (Canada), Objectives: Target key areas of the thermal events, and the logistical W. Jokat (Germany), Y. global MOR that should be responses to them. Kristoffersen (Norway), P. J. explored for hydrothermal activity Current Activites: Organisation of the Michael (USA), K. J. Young (Ko- and coordinate international second MOMAR workshop. Ob- rea), N. C. Mitchell (UK), H. A. collaboration to explore them. jectives of the workshop are listed Roeser (Germany), H. Shimamura Current Activities: Organizing the on the InterRidge website. (Japan), Y. Nogi (Japan), C. L. Van InterRidge Theoretical Institute Chairs: J. Escartin (France) and R. Dover (USA) . on the Thermal regime of Ocean Santos (Azores, Portugual) Ridges and the Dynamics of Hy- WG members: Chris Fox (USA), K. Back-Arc Basins drothermal Circulation to be held Mitsuzawa (Japan), Pierre-Marie Objectives: Summarize past work on 9-13 Sept. 2002. Sarradin (France), Adam Schultz Back-Arc Basins and coordinate Chair: Chris R. German (UK) (UK), Paul Snelgrove (USA), Paul future studies. WG members: E. Baker (USA), Y. J. Tyler (UK). Chair: Sang-Mook Lee (Korea) Chen (USA), D. Cowan (UK), T. WG members: Ph. Bouchet (France), Gamo (Japan), E. Grácia (Spain), SWIR J.-L. Charlou (France), K. Fujioka P. Halbach (Germany), S.-M. Lee Objective: Coordinate reconnais- (Japan), E. Grácia (Spain), P. Herzig (Korea), G. Massoth (N.Z), J. sance mapping and sampling of (Germany), J. Ishibashi (Japan), Y. Radford-Knoery (France), A-L. the Southwest Indian Ridge. Kido (Japan), S-M. Lee (Korea), R. Reysenbach (USA), D. S. Scheirer Current Activities: Organisation of Livermore (UK), S. Scott (Canada), (USA), S. D. Scott (Canada), K. G. the SWIR workshop. R. J. Stern (USA), K. Tamaki (Japan), Speer (USA), C. A. Stein (USA), Chair: Catherine Mével (France) and B. Taylor (USA). V. Tunnicliffe (Canada) and C. L. WG members: M. Canals (Spain), C. Van Dover (USA). German (UK), N. Grindlay (USA), Biological Studies C. Langmuir (USA), A. Le Roex Objectives: Objectives of the New HotSpot-Ridge Interactions (South Africa), C. MacLeod (UK), biology WG are outlined on the Objectives: This WG was formed dur- J. Snow (Germany), T. Kanazawa IR website. ing the 2000 Steering Committee (Japan) and C. L. Van Dover (USA). Chairs: F Gaill (France) and S.K. meeting to promote and facilitate Juniper (Canada). global research to better under- Undersea Technology WG members: M. Biscoito (Portugal), stand the physical and chemical Objective: Foster the development of O. Gierre (Germany), J-H Hyun (S. interactions between mantle undersea technology and dis- Korea), A. Metaxas (Canada) T. plumes and mid-ocean ridges and seminate information about it. Shank (USA), K. Takai (Japan), P. their effects on seafloor geologi- Chair: Spahr C. Webb (USA) Tyler (UK) and F. Zal (France) cal, hydrothermal, and biological WG members: J. R. Delaney (USA), processes. H. Momma (Japan), J. Kasahara Global Digital Database Current Activites: The agenda for this (Japan), M. Kinoshita (Japan), A. Objective: Establish a database of new WG is being developed. Schultz (UK), D. S. Stakes (USA), global multibeam bathymetry and Chair: J. Lin (USA) P. Tarits (France) and H. Villinger other data for mid-ocean ridges WG members: R.K. Drolia (India), J. (Germany). and back-arc basins. Vol. 11(1), 2002 9

Updates on InterRidge Projects

Global Distribution of Hydrothermal Activity Working Group

Chris German

Challenger Division for Seafloor Processes, Southampton Oceanography Centre, UK

This is the first update for two am pleased to report that ours has pled on the seabed or just identified years from this working group, first been no exception. from water column anomalies. Both established in late 1997. There is a the data-base and the update forms reason for the lack of an annual update Hydrothermal Exploration can be accessed directly from : last year – I was at sea for 70 days in Highlights of field programmes http://www.intridge/vent.htm the Indian Ocean helping identify new since early 2000 have included dis- Only time will tell whether this valu- sites of venting long the Central In- covery of new hydrothermal fields able legacy is used to full advantage dian Ridge and wasn’t around to co- along three separate sections of ultra- by you, the user!! ordinate our Working Group’s input!!! slow spreading ridge-crest – 1) the Atlantic portion of the SWIR (to Vent Biogeography InterRidge Theoretical Institute be reported by Bach et al. at the Finally, as well as the IRTI leaving The first item to bring to your InterRidge SWIR workshop in April the geological aspects of this Work- attention in this issue is the imminent 2002 – but look out, too, for the paper ing Group in good order (we have also demise of the Working Group in 2002. in G^3 any week now!); had a very favourable initial response This is in keeping with InterRidge 2) the Knipovich Ridge (see, e.g., from AGU about publishing a Geo- directives on WGs amd their lifetimes Tamaki, Cherkashov et al. (IR News 10.1 physical Monograph arising from the – but fear not! We shall be bowing pp 48-51, 2001); Connelly & German. proceedings) the biogeographic as- out not with a whimper, but a bang. EOS Trans AGU 83, OS205-206, 2002); pects of our work have also progressed Specifically, joint with the now-de- 3) most recently, the exciting discov- well and will be left in good health as funct 4-D architecture working group, ery of abundant hydrothermal signals the Working Group itself is wound up. we shall be co-hosting the first ever along the Gakkel Ridge in the Arctic WG member Cindy van Dover recently InterRidge Theoretical Institute to Ocean (see, e.g., Edmonds et al., EOS published an invited review article in be held in Pavia, Italy, September 9- Trans AGU 82, F647, 2001). In parallel, Science (together with WG co-mem- 13, 2002: “Thermal Structure of the a UK cruise to the southern Mid- bers Kevin Speer & Chris German, Ocean Crust and Dynamics of Hy- Atlantic Ridge in late 2001 identified among others): “Evolution and bioge- drothermal Circulation”. The meet- clear suspended particulate and dis- ography of deep-sea vent and seep ing will comprise a 2-day shortcourse solved Mn anomalies at a range of invertebrates” Science 295, 1253-1257. - with invited keynote papers plus sites between 2 and 14 degrees South That paper took the opportunity to ample time for discussions and con- (C.R. German, unpubl. data) while there identify a range of key targets for tributed poster presentations - fol- have already been wide-ranging re- future investigation, selecting spe- lowed by a field-trip to local hydro- ports of the discoveries of first sites of cific regions of the mid-ocean ridge- thermally altered ophiolites and fin- venting in the Indian Ocean during crest where discovery and biological ishing with a 2 day workshop identi- 2000-2001 (Hashimoto et al, InterRidge characterisation of new vent-sites fying future directions for coordi- News 10 (1) pp. 21-22; Van Dover et would be of particular benefit. Faster nated InterRidge research. From this al., Science 294, 818-821, 2001). In than the current InterRidge WG can WG’s perspective, a clear objective concert, this makes for at least one disband, therefore, I am pleased to will be to improve our understanding vent-site now known to exist in every report the establishment of a new re- of the geological controls of seafloor major ocean basin, worldwide, as well lated initiative supported by the Sloan hydrothermal venting. as clear demonstration that hydro- Foundation as part of the Census of Full details are available on the thermal activity occurs in abundance Marine Life programme. From Sum- InterRidge web-site: along even the slowest spreading mer 2002, Profs. Paul Tyler and Chris http://www.intridge.org/irti.htm ridges as well as along the fast and German at SOC, UK, will co-host the medium-fast. international pilot office for a new Global Distribution of Hydrothermal programme, ChEss (Chemosynthetic Activity Global Vents Data-Base, On-Line Ecosystem Studies) dedicated to de- It has always been the objective Another important achievement signing and initiating surveys of life that ANY InterRidge Working Group of the WG, early on, was the establish- in vent and seep communities on the should be able to make a significant ment of a readily-updated electronic ocean floor. Funding is for three years, contribution to it’s chosen area of data-base of every known hydrother- in the first instance; contact Paul Tyler focus within the space of ca.5 years. I mal field – whether visited and sam- ([email protected]) for details. 10 InterRidge News

Updates on InterRidge Projects

Monitoring and Observatories Working Group Expanded Acoustic Monitoring of the Mid-Atlantic Ridge

Chris Fox

NOAA/PMEL/VENTS Program, Newport, USA

Monitoring of low-level seismicity mic source locations posted on the MAR between the Azores and the on the Mid-Atlantic Ridge (MAR) world wide web and raw hydrophone Gibbs Fracture Zone (Fig. 1). The PIs using autonomous underwater signals to be made available to the for this experiment are Jean Goslin hydrophones will be continued and scientific community viaFTP. PIs on (CNRS, Brest) and Chris Fox (NOAA/ expanded in the coming years. The the extended effort are Bob Dziak PMEL). The experiment is jointly initial effort, consisting of six (OSU), Haru Matsumoto (OSU), funded by the French government hydrophones moored in the region of Debbie Smith (WHOI), and Chris Fox and US NOAA. The array is only 15o-35o N (see InterRidge News 8.1, (NOAA/PMEL). The existing array planned for a one-year deployment March, 1999), was deployed in March provides excellent coverage of the but every attempt will be made to 1999 by Debbie Smith (WHOI), Maya MAR from the equatorial region to the maintain the array long-term, similar Tolstoy (LDEO) and Chris Fox Azores, but bathymetric shadowing to the USRIDGE array to the south. (NOAA/PMEL) and funded by of the acoustic signals have not al- Although the sensors will be located USRIDGE for two years of data collec- lowed monitoring of the MAR north south of Gibbs, they should be able to tion. After extending this initial effort of the Azores. routinely detect activity from the to a third year, US RIDGE recently In May 2002, a French expedition Reykjanes Ridge south of Iceland. agreed to fund four additional years of (SIRENA) on the French research This new data set, combined with data monitoring in a more operational mode, vessel Le Suroit will deploy a new from the southern array, will provide with routine posting of derived seis- array of six hydrophones around the excellent coverage of the Azores plat- form and can be combined with seis-

60°W 30°W 0°E mic sensors on the Azores for a more complete picture of the seismicity of the hotspot. The first data set will be recovered in summer 2003. Planning is underway to deploy 60°N 60°N additional acoustic sensors at other locations in the Atlantic and other ocean areas by the Sound in the Sea project of NOAA's Ocean Exploration ^_ ^_ SIRENA Programme (PI: C. Fox). One possible Array ^_ ^_ target area is along the equator in the Atlantic in conjunction with the exist- ^_ ^_ ing PIRATA array of surface weather buoys. The acoustic data sets de- Azores ^_ scribed, while being collected for ridge ^_ crest studies, provide valuable data to 30°N 30°N researchers studying the distribution ^_ ^_ NSF of large marine mammals in the open Array ocean and the impact of manmade and ^_ ^_ natural noise on marine life. Further information on these experiments, access to seismic source information, and access to raw data (still under 0°N 0°N development) can be found at: http://www.pmel.noaa.gov/vents/ 60°W 30°W 0°E acoustics.html . All of these topics will be discussed in detail at the Figure 1. Plot of the planned hydrophone deployment, along with the upcoming MOMAR-II workshop June existing array. 15-17 in Horta, Azores. Vol. 11(1), 2002 11

Reports and announcements

89th Dahlem Workshop update

Chris German

Southampton Oceanography Centre, UK

What happens to the heat released along ridge-crests? Can we identify compressed together under the pres- when magma rises from within the hydrothermal signatures in the geo- sure-cooker conditions of an isolated Earth to generate new mid-ocean ridge logical (including paleontological) retreat. Full discourse of the various crust – a fundamental component of record; where do 100 million tonne ore subjects highlighted above – includ- plate tectonics? How does seawater deposits form in the modern day; and ing four completely new articles writ- transport this heat to the oceans? have hydrothermal sediments played ten during the course of the week’s How deep does water penetrate be- an important role, throughout Earth proceedings – will be published in neath the seafloor; under what range history, in the transfer of material from June 2002*. As a more immediate of pressure and temperature condi- the mantle to the continental crust? result, however, consensus has al- tions does it react; and with which These are just some of the ques- ready been reached on a new multi- rock types? How do the resulting tions highlighted during a week-long branched and interlinking process- fluids rise to the surface and what meeting of 38 international scientists flow model – the Dahlem Hydrother- range of mineral deposits do they pro- at the 89th Dahlem Workshop held at mal Reference Model (DaHRM) – duce? How do the resultant fluxes of the Freie Universität in Berlin, Oct.15- which will be taken forward as the new energy – both thermal and chemical – 19, “Energy & Mass Transfer in Ma- international state-of-the-art for hy- serve to support unique deep-sea rine Hydrothermal Systems”. The drothermal fluxes at mid-ocean ridges, hydrothermal ecosystems? Is there a ethos of the Dahlem Workshops is within the broader whole-Earth valid link to the origin of life? What unique – not to present what is al- Geochemical Earth Reference Model impact do hydrothermal fluxes have ready known, but to highlight what we (GERM). on the chemical balance of the oceans do not yet know, what we need to and what is the fate of the materials know, and why. The list, above, just * Energy and Mass Transfer in they produce? Does a predicted skims the surface of the many new Marine Hydrothermal Systems, ed. P. ~100km-wide high-productivity corri- ideas that were generated recently Halbach, V. Tunnicliffe, and J. Hein. dor – a larval superhighway – exist when the field’s top researchers were Berlin: Dahlem University Press.

Elizabeth Mann Borgese

Ecologist Elisabeth Mann Borgese gist who fought for the preservation ences have taken place worldwide. died at 83 Geneva, Switzerland — of the oceans, wrote numerous pa- She is credited with helping bring Elisabeth Mann Borgese, an activist pers and books and contributed to about a 1982 UN treaty on the Law of for protecting the world’s oceans and conferences on maritime issues. She the Sea after more than a decade of the last surviving child of German had been dubbed “ambassador of negotiation. A Canadian later by literary giant Thomas Mann, died of a the oceans.” She also was a univer- choice, Ms. Mann Borgese was born respiratory infection in the early morn- sity professor in Halifax, Nova Scotia, in Munich, the second youngest of ing hours of 8th February 2002 in Canada; the founder of the Interna- Mann’s six children. When she was Samedan, Switzerland, near St. Mo- tional Ocean Institute in Malta; and 15, she and her family left Nazi Ger- ritz. Swiss press reports said she one of the founders of the Club of many for Switzerland, where she skied the day before she died in spite Rome, a group of scientists focusing trained as a concert pianist. She came of her pneumonia. Her father, the on worldwide environmental prob- to the United States in 1938 with her German essayist, cultural critic, and lems. In 1970, she organized a pio- parents and, a year later, married novelist, was awarded the Nobel Prize neering conference, Peace in the Giuseppe Antonio Borgese, a writer for Literature in 1929. Oceans, concerning the Law of the and art historian who had fled Fascist Ms. Mann Borgese was an ecolo- Sea. Since then, 30 similar confer- Italy. He died in 1952. 12 InterRidge News

International Research: Biological Studies

MAR-ECO - “Patterns and Processes of the ecosystems of the Northern Mid-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

MAR-ECO – a North Atlantic biodi- versity study Despite the wide distribution and extensive area of mid-ocean ridges (e.g. Garrison 1993), relatively few previous investigations have been dedicated to the study of the animal communities inhabiting these vast areas of the world ocean. Ridges may have characteristic faunas, but they may also significantly influence the processes affecting the slope and shelf biota such as intercontinental migration and dispersion. On this background, the project MAR-ECO (http://www.mar-eco.no/), focuss- ing on the macrofaunal communities associated with the Mid-Atlantic Ridge (MAR) between Iceland and the Azores, has recently been estab- lished as an international ecosystem study under the Census of Marine Life (CoML, http://www.coml.org) programme. MAR-ECO targets classical food-chain organisms but works in parallell with ChESs (http://www.wm.edu/coml/), a CoML project studying chemosyn- thetic systems. The overriding aim of MAR-ECO is to describe and understand the patterns of distribution, abundance and trophic relationships of the or- ganisms inhabiting the mid-oceanic North Atlantic (Fig. 1), and identify and model ecological processes that cause variability in these patterns. Fish, crustaceans, cephalopods, and gelatinous plankton and nekton have the highest priority in the study, but there will also be some effort devot- ed to epibenthic communities. The Figure 1. The Mar-Eco area with sub-areas selected for detailed studies. The project will be carried out as a multi- exact locations are to be decided during the planning phase. Vol. 11(1), 2002 13

International Research: Biological Studies: Bergstad, cont... ship operation in 2003-2005, with import of material from the west? International Steering Group to stim- most activity in 2004 centred around 4) What is the significance of ulate the network of experts to for- a two-month cruise on the Norwe- seamounts within the ridge mulate component projects. gian RV G.O.Sars. system? A first planning workshop was 5) Is the trophic structure of the held in the Alfred Wegener Institut Scienc Plan, tasks and hypotheses northern mid-Atlantic ecosystem für Meeresforschung in Bremer- The Science Plan now available similar to that on the slope regions haven in early January 2002 to facil- (e.g. on the website http://www.mar- of the eastern and western sides of itate presentation of the project and eco.no/) presents the three central the Atlantic? co-ordination of the component tasks of MAR-ECO and a compila- project building. Some 45 experts tion of hypotheses and suggestions Organisation and schedule from around the North Atlantic gath- resulting from discussions during The International Steering Group ered to focus on component project and after an initial workshop held in organises and oversees the plan- formulation. The following is a list Bergen 12-13 February 2001: ning, financing, and implementation of the working titles of MAR-ECO Task 1: Mapping of species of the project. Members of the group studies now being fomulated, and composition and distribution are: full outlines and updates will be pre- patterns. Dr. Odd Aksel Bergstad, IMR, sented on the website in due course: Theme 1: Identity and distribution Norway (chairman) patterns of macrofauna. Prof. Peter Boyle, Univ. Aberdeen, Zooplankton studies: Theme 2: Population genetics and UK Distribution, abundance and dispersion studies. Dr. Olafur S. Astthorsson, MRI, species composition of zooplank- Task 2: Identification of trophic Iceland ton in cross-frontal and cross-ridge interrelationships and modelling Dr. Ricardo S. Santos, Univ. Azores, transects of the Mid Atlantic Ridge. of food web patterns Portugal PI: Webjørn Melle, The Institute of Task 3: Analyses of life history Dr. Uwe Piatkowski, Univ. Kiel, Marine Research, Norway. strategies Germany Feeding behaviour and swim- The three tasks are obviously Prof. Michael Vecchione, NOAA, ming mode of gelatinous zooplank- inter-related. Also, all the tasks rely NMFS, USA ton and nekton. PI: Ulf Båmstedt, on a thorough understanding of the Dr. E.M. Burreson, Virginia Institute the University of Bergen, Norway. abiotic environment (bathymetry, of Marine Science (VIMS), USA Time-scale distribution and watermass properties and distribu- Prof. Ulf Båmstedt, University of trophic structure of deep-water ge- tions, circulation). A major challenge Bergen, Norway latinous zooplankton and nekton. of the project is to overcome obser- Dr Pascal Lorance, IFREMER, France PI: Marsh Youngbluth, The Harbor vation difficulties at large depths Norway has taken on the secre- Branch Laboratory, USA. and in rugged terrain. A central aim tarial duties for the project, and the Trophic structure of major cope- is thus to utilise modern remote sens- responsible institution will be the pods, euphausiids and fish larvae ing technology (acoustics, optics) Institute of Marine Research (IMR) across the Mid Atlantic Ridge. PI: using advanced instrument carriers in collaboration with the University Astthor Gislason, Marine Research (e.g., towed vehicles, ROVs, AUVs of Bergen. The new Norwegian re- Institute, Iceland. etc.), in addition to more traditional search vessel R/V G.O. Sars will be samplers and observation methods. at the disposal of the project activ- Pelagic nekton: Some basic overall hypotheses ities in 2004, and may form a central Longitudinal and latitudinal or questions to be addressed are: focus of international multi-vessel changes in mesopelagic/ bathype- 1) Are the MAR communities operations. lagic nektonic fauna (fish, cephalo- extensions of the communities The shedule and phases of MAR- pods and crustaceans) along MAR. inhabiting the North Atlantic ECO are the following: PIs: Mike Vecchione, Kir Nesis, continental slope regions? Planning phase: 2001-2003 Sergey Evseenko, Peter Boyle, Mar- 2) Is the MAR a barrier between the Field phase: 2003-2005 tin Collins, Von Westerhagen, pelagic fauna of the east and west Analysis, synthesis: 2004-2008 Christian Pusch, Uwe Piatkowski, North Atlantic basins? Is there a Incorp. in OBIS: 2005-2008 Filipe Porteiro, Ricardo Santos, João difference in species occurrence Pereira. either side of the MAR? Current status Interactions of mesopelagic and 3) Do circulation features, e.g. the Gulf The status of MAR-ECO is that bathypelagic fauna with the Stream, act as barriers between the the planning phase has been initiat- benthopelagic community associat- northern and southern fauna? In ed and a formal organisational struc- ed with MAR seamounts/ slopes. the region of the Gulf Stream, what ture has been set up. A planning PI: Bernd Christiansen, Univ. of is the effect of eastward drift and grant recently awarded enables the Hamburg, Germany. 14 InterRidge News

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

Effects of the Sub-polar Front on in relation to habitat variability on nities of the northern Mid-Atlantic MAR pelagic communities. PIs: Pe- the Mid-Atlantic Ridge. PI: Franz Ridge and its flanks will be under- ter Boyle, Martin Collins, Universi- Uiblein, Univ. of Salzburgh, Aus- stood and well known both to the ty of Aberdeen, UK. tria. scientific community and the inter- Life cycle strategies of selected Spatial genetic structure of com- ested public. species living in different water mass- mercially valuable deep-sea fish from The website http://www.mar- es. PIs: Roger Villaneuva, Peter the North Atlantic. PI: Rus Hoelzel, eco.no/ is the main source of up- Boyle, Christian Pusch. Univ. Of Durham, UK. dates, contact information, and doc- Fertilisation experiments with Epibenthic and Benthopelagic uments relevant to the project. fish and cephalopods for egg and (Demersal) Invertebrate communi- larvae description/ recognition. PI: ties, distribution and ecology. PI: Sergey Evseenko, Shirshov Insti- David Billett, SOC, UK tute of Oceanology, Moscow. Life history studies of demersal Evaluation of global changes fishes. PI: Maurice Clarke, Marine comparing catch of historical cruis- Fisheries Service, Ireland es with present day. PI: Filipe Portei- ro, Ricardo S. Santos, DOP, Horta, The Mar-Eco vision Portugal. The MAR-ECO vision is that, following the 2001-2008 project pe- Demersal nekton studies riod, the identity, distribution pat- Distribution patterns and spe- terns, food-webs, and life history cies composition of demersal fishes patterns of the macrofaunal commu-

Towards unravelling the enigma of vent mussel reproduction on the Mid Atlantic 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 Kingdom 2 IFREMER Centre de Brest, France 3 IMAR, University of the Azores, Horta, Portugal

During the recent EU-funded mystery surrounds the reproductive cruise period, which is limited by the ATOS cruise (R/V L’Atalante, ROV behaviour of this dominant vent summer weather window, so that Victor, June 22nd – July 21st 2001) to species since cruise collected sam- their gonad condition during the active vent sites south-west of the ples have so far failed to yield any winter months could be assessed Azores, two distinct yet complemen- evidence of significant gonad de- using histological methods. tary types of benthic apparatus were velopment, which contrasts with deployed to tackle the question of expectations based on the belief that Sediment traps the timing of reproduction in the vents are aseasonal and therefore As part of the ATOS cruise ob- vent mussel Bathymodiolus azori- able to provide a virtually unlimited jectives, measurements were carried cus. The first were sediment traps of food supply for the indigenous vent out of particulate and biological flux- the type used previously during the fauna (from bacterial chemosynthe- es produced at two hydrothermal EU-funded MARVEL cruise in Au- sis). Thus, given the high abun- sites (Rainbow and Lucky Strike) gust and September 1997 to trap dance of the species, particularly in located within the MAR segment. settlement stage (prodissoconch II) the Azores region, the reproductive The experiment consisted of moor- larvae of B. azoricus at the Rainbow behaviour of the Atlantic mussel ing two sediment traps (1m2) close to and Menez Gwen vent sites (Comtet remains something of an enigma. the vents for 1 year’s duration in et al., 1998). The second were acous- One supplementary aim of the EU- order to follow the fluctuations in tically retrievable cages described funded VENTOX cage study was to the frequency of mussel larval set- recently in IR news. Something of a sample mussels outside the usual tlement and general particulate emis- Vol. 11(1), 2002 15

International Research: Biological Studies Dixon et al., cont... sions close to these two hydrother- Mytilid reproduction ical of species living in environments mal sources. A third sediment trap In common with other mytilids, where food supply and/or other en- was deployed at a distance away B. azoricus lacks a true gonad and vironmental factors vary markedly from any hydrothermal source to produces gametes in a fleshy multi- over the year, something that is not obtain a measurement of the back- purpose tissue, the mantle, which normally associated with hydrother- ground pelagic flux to use as a refer- lines the shell valves (Fig. 2). In mal vents. ence for the Azores region. As with other mytilids, apart from acting as a In common with M. edulis, B. the cages, the design of the sedi- gonad, this tissue is also used to azoricus undoubtedly produces ment traps was modified to facilitate store food reserves (lipid and glyco- vast numbers of gametes that are deployment using the French ROV gen) outside the breeding season, released prior to fertilisation into Victor 6000. Each trap unit (Fig. 1) which are then used for the manu- the vent plankton (Fig. 2). However, consists of a PPS5 trap (©Techni- facture of gametes later in the year. examination of several hundred adult cap) modified by the addition of 7 The sexes are normally separate in mussels during three EU-funded syntactic foam floats (©Euroshore). mytilids. In the best-studied mytilid summer cruises (MARVEL, PICO The dimensions of each trap are: 215 species, the blue mussel Mytilus and ATOS) failed to reveal any ev- cm height and 205 cm in diameter. edulis, by the time that spawning idence of ripe or, for that matter, The weight in air is 446kg with a takes place, in the spring, the mantle discernible gametes in mantle positive buoyancy of 144kg. An tissues are completely transformed squashes (D. Dixon, unpublished acoustic release (Posidonia type) into mature gamete, sperms or data,) which conflicts with the ex- which can be located by the ROV oocytes, with very little or no evi- pected pattern if the Atlantic vent navigation, is attached to the frame. dence of any storage tissue (viz. mussels were spawning continuous- A surface location system, consist- adipogranular cells) remaining. The ly (at least at the population level; ing of an Argos beacon, flasher and fact that gamete mother cells are Tyler and Young, 1999). A previous radio beacons, was also fixed to the produced de novo each season is sediment trap study revealed that top of the trap to aid recovery. another reason why the mantle is larval settlement occurred between The two vent-located traps were considered not to be a true gonad; 24 August and 5 September 1997 deployed close to the F5 marker at unlike the situation in mammals (Comtet et al., 1999). Loading a Rainbow and Sintra at Lucky Strike, where in females a finite number of proportion of the collecting buckets respectively. The position of the oocytes is laid down at the embryo with a special high salt buffer al- reference pelagic trap was N 36º 13.30, stage. Taken together this alternat- lowed DNA confirmation of the iden- W 33º 52.7. The Portuguese R/V ing pattern of tissue activity in the tity of these larvae (Dixon & Dixon, Arquipélago is scheduled to recov- mantle underpins a seasonal repro- 1998; Comtet et al., 1999). Previous er all three traps in summer 2002. ductive cycle, something that is typ- histological evidence also points to episodic spawning behaviour in B. azoricus (Comtet & Desbruyères, 1999). Clearly, this contrasts with our expectations for a species living in a supposedly aseasonal deep-sea vent environment, which is the rea- son why our aim now is to accumu- late additional histological evidence of gonad condition in the winter period using the acoustically retriev- able cages and sediment traps. The cage study will focus in particular on the winter period when there is an expectation that a high proportion of individuals will contain develop- ing and/or ripe gametes. Tissue sam- ples from the recent ATOS cruise and follow-up cage recovery study are currently undergoing histologi- cal analysis and these have provid- ed additional supporting evidence of a seasonal reproductive cycle in Figure 1. Diagram showing the design of the sediment trap described in this this species (Dixon, Lowe, Villemin article. & Dixon, in preparation). The close- 16 InterRidge News

International Research: Biological Studies: Dixon et al., cont... ly related Bathymodiolus ther- mophilus from Pacific vents appears to exhibit continuous reproduction, with a range of reproductive stages being present in the gonadial tis- sues between May and December (Maria Baker, SOC, pers. com.).

What is the reason for this apparent seasonality? It remains to be seen which eco- logical driver is responsible for the unexpected occurrence of seasonal reproduction in B. azoricus, but a likely candidate is the need for a particulate food supply during the larval dispersal phase. While the nutrition 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 of particulate organic material to sus- Figure 2. Basic mytilid life-history pattern proposed for Bathymodiolus azoricus. tain them during the weeks or This consists of a sedentary adult phase (A), external fertilisation (B), months while they are dispersing as planktotrophic development (C), appearing in this case to be dependent part of the plankton (Fig. 2). Since upon the spring bloom in primary production, and larval settlement (D) the surface waters over the MAR are shown to take place in the summer months leading to clearly recognisable generally considered to be oligo- adult size/age cohorts, evidence of a discontinuous recruitment pattern (Van trophic, it seems likely that the sur- Dover et al., 1996; Comtet & Desbruyères, 1998). vival of these microscopic larvae will depend to a large extent on the small but nonetheless significant peak in primary production that takes already been demonstrated that sur- This proposed link between the place in the surface waters over the face-derived particulate matter reproductive behaviour of a domi- ridge in the early spring (Fig. 3). It is reaches the vent environment on nant MAR vent organism and fluc- our belief that it is only those larvae the MAR (Dixon et al., 1995), and tuations in the levels of primary pro- that are released around the time of there remains the possibility that duction in the surface waters con- this spring peak that stand any qualitative differences in the nutri- flicts with the commonly stated be- chance of completing their larval de- tional content of this photosynthet- lief that hydrothermal vents are an velopment and thus successfully re- ic versus the locally-produced, isolated, self-contained environ- cruiting back into the adult popula- chemosynthetic-derived food ment, which was thought to be large- tions. Natural selection acting source could provide the signal that ly independent of processes going through the larval phase (something ensures the synchronisation of re- on elsewhere in the rest of the ocean. that tends to be treated as a black productive development in the adult The existence of seasonal reproduc- box in ecological and evolutionary populations. Other evidence also tion, if confirmed, in at least one studies) is likely to be the reason suggests that surface-derived ma- dominant member of the Atlantic why reproductive periodicity has terials can enter the deep-sea vent vent fauna, will force us to reconsid- been selected for in at least one environment, sometimes in a largely er how we view metazoan life in these dominant MAR vent species, B. azo- unmodified form (Fileman et al., islands of chemosynthetic produc- ricus. 1998). Interestingly, in the Pacific tivity in the deep ocean. Clearly, Previous work on seasonal re- (EPR) where Maria Baker conducted while vent bacteria may tell us some- production in the deep sea has em- her studies on B. thermophilus, thing about life on Mars, vent meta- phasised the role of phytodetritus there is no evidence for a marked, zoans have their feet (byssus!) firm- on the feeding energetics of deep- seasonal peak in phytodetrital flux, ly anchored here on Earth! sea benthic organisms, resulting in which probably explains the lack of It is intended to deploy the cag- the synchronisation of reproductive reproductive synchrony in this spe- es again this summer (2002) in col- activity (e.g. Tyler et al., 1982). It has cies (M. Baker, pers. com.) laboration with colleagues at IMAR/ Vol. 11(1), 2002 17

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

DOP and other Portuguese labora- tains and crews of the R/V l’Atalante From Parson, L.M., Walker, C.L. & tories. The plan is to recover them and the R/V Arquipélago, and to the Dixon, D.R. (eds.), Hydrothermal at intervals into the next winter pilots and technicians of ROV Vic- Vents and Processes, Geological period, something that can only be tor, without whom none of this work Society Special Publication No. 87, achieved using a small vessel, R/V would have been possible. 343-350. Arquipélago, operating opportun- Dixon, D.R. & L.R.J. Dixon (1998). istically out of Horta with respect References PLASMA: Planktonic Larval to the mid Atlantic winter weather Comtet, T. & D. Desbruyères (1998). Sampler for Molecular Analysis – conditions. Population structure and a progress report. BRIDGE recruitment in mytilid bivalves from Newsletter15, 26- 29. Acknowledgements the Lucky Strike and Menez Gwen Fileman, T.W., Pond, D.W., Barlow, We are extremely grateful to Si- hydrothermal vent fields (37º17’N R.G. & Mantoura, R.F.C. (1998). mon Partridge (Sonardyne Interna- and 37º50’N on the Mid-Atlantic Evidence for undegraded tional Ltd.) for generously offering Ridge). Marine Ecology Progress diatomaceous material to provide acoustic releases for this Series,163, 165-177. sedimenting to the deep ocean in summer’s cage study. This work Comtet, T., M. Le Pennec & D. the Bellingshausen Sea Antarctica. represents part of the research pro- Desbruyères (1999). Evidence of a Deep Sea-Research I. 45, 333-346 gramme of the EU-funded VENTOX sexual pause in Bathymodiolus Tyler, P.A., Grant, A., Pain, S.L. & project (EVK3CT1999-00003) and is azoricus (Bivalvia: Mytlidae) from Gage, J.D. (1982). Is annual funded in part by the UK Natural hydrothermal vents of the Mid- reproduction in deep-sea Environment Research Council. We Atlantic Ridge. J. Mar. Biol.Ass. echinoderms a response to are also extremely grateful for funds U.K.,79, 1149-1150. variability in their environment. provided previously by the EU Dixon, D.R., D.A.S.B. Jollivet, L.R.J. Nature, London, 300, 747-749. AMORES project (MAS3-CT95- Dixon, J.A. Nott & P.W.H. Holland Tyler, P.A. & C.M. Young (1999). 0040; co-ordinator Dr Daniel Des- (1995). The molecular identification Reproduction and dispersal at bruyères). Finally, we wish to ex- of early life-history stages of vents and cold seeps. J. Mar. press our grateful thanks to the Cap- hydrothermal vent organisms. Biol.Ass. U.K.,79, 193-208.

Figure 3. Monthly chlorophyll levels in the surface waters above the mid-Atlantic Ridge at 37ºN 31ºW derived from satellite imagery (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 winter background levels by between three and six-fold. 18 InterRidge News

International Research: Island arc/BAB

Submarine Hydrothermal Mineralisations and Fluids off 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, Germany 2 T.H. School of Environment, Earth Sci. and Eng., Imperial College of Sci., Tech. and Med., London, UK 3 University of Hamburg, Institute of Biogeochemistry and Marine Chemistry, Hamburg, German

Introduction iment samples to look for indica- Cronan, 2001). In comparison with other island tions of recent to subrecent subma- Major target areas were the Ka- arcs such as those in the Mediterra- rine hydrothermal activity in the area houanne Basin and the Montserrat nean Sea and SW Pacific, there have of the Lesser Antilles island arc. The Ridge S and SW of the island of been only few studies of submarine western slope of the arc was select- Montserrat, the area W of Dominica, hydrothermal mineralisations in the ed as the main target area since this St. Lucia and the Kick’em Jenny Caribbean island arcs. Kang (1984) area has many nearshore shallow NW of Grenada described some hydrothermal man- water thermal springs (Johnson and (Fig. 1). ganese deposits from the region and Polyak et al. (1992) reported on a hydrothermal water column anoma-

ly between Montserrat and Guade- ANTIGUA Cuba loupe. More recently, Johnson & Montserrat Puerto Ridge MONTSERRAT 20 N Rico Jamaica Cronan (2001) have reported con- Kahouanne Basin Dom.Rep siderable metal enrichments in hy- AREA 1 Caribbean Sea drothermal fluids and metalliferous GUADELOUPE

sediments off the central Lesser 10 N 16 Antilles . The elements N V E N E Z U E L A variably enriched in the fluids as a MARIE GALANTE 70 W 60 W

result of the hydrothermal activity N-Dominica DOMINICA are Fe, Mn, As, Si, B, Li and in the AREA 2 sediments are Fe, P, Mo, As, Sb, Hg, Soufriere Bay Cu and Pb. Variations in the concen- trations of these elements in both fluids and sediments along the arc MARTINIQUE were thought to result from a number of factors, the most important of C A R I B B E A N S E A which is the stage that each island’s 14 AREA 3 volcano has reached in its eruptive N ST. LUCIA cycle. In order to investigate subma- rine hydrothermal mineralisation ST.VINCENT off the Lesser Antilles in more de- BARBADOS tail, a research cruise (CARIB-

FLUX) was carried out from Janu- Kick' em ary 15 to February 8, 2001, with the Jenny German research vessel “R/V AREA 4 RONDE ISLAND 0 100 km NW-Grenadada Sonne” (SO 154). The main objec- 12 GRENADA tives of this cruise were to carry N out measurements and water sam- pling in the water column and the 62 W 60 W near-bottom water layer as well as the study of local tectonics and the recovery of hard rock and sed- Figure 1. Map of the Lesser Antilles with cruise track and target areas. Vol. 11(1), 2002 19

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

Kahouanne Basin aragonite and a low content of quartz crusts appear metasomatic replace- Sample locations in the deepest and manganese oxides. No second- ments of the limestone, including part of the Kahouanne Basin and ary Cu or Pb minerals were deter- abundant fossil shells as well as close to the Shoe-Rock-Spur (SRS) mined. irregular enrichments of nontronite fault zone (western margin of the and other clay minerals. The Mn basin) were chosen. Methane con- Montserrat Ridge contents for single layers can reach centrations in water samples in that At the Montserrat Ridge, again 55 wt.%. The Mn/Fe ratio is very area were generally below 3.5 nmol l-1, no clear indications of present hy- high (up to 118) suggesting little or and values exceeding 1.5 nmol l-1 drothermal activity were found in no input from normal seawater. The were restricted to the upper 400 m of the water column. Hydrothermal Mn contents of most trace metals (Ni, the water column. Anomalous Zn crusts up to 27 cm thickness were Zn, Pb and Co) are very low (Table concentrations in the lower water dredged, and Mn-cemented ashes 1) and the concentrations of the rare column (earlier described by Polyak are abundant along the ridge. The earth elements are less than 10 ppm. et al., 1992) could not be confirmed. crusts from the Montserrat Ridge The outer layers and some internal Sediments contained a few py- are unique and are described here layers of the crusts with distinct rite and chalcopyrite grains, rarely for the first time from this part of the petrographical and geochemical nontronite was found in the south- Lesser Antilles Island arc. They compositions indicate that the crusts ern Kahouanne Basin, and in one might have the function of a cap precipitated from distinct hydrother- dredge haul Mn-crusts of thickness- rock above a sulphide deposit. mal episodes and are not a product es up to 6 cm were sampled. This Within the Mn crusts massive of continuous deposition. pointed to subrecent hydrothermal layers occur which show very heter- activity in this region: further dredge ogeneous mineralogic composi- West of Dominica sampling led to the discovery of an tions. Manganese minerals includ- Near-shore investigations of inactive hydrothermal site on a small ing todorokite, birnessite and psi- Soufriere Bay at the southern tip of plateau in the upper part of the SRS lomelane occur as thin layers (up to Dominica showed that a supposed fault zone. These observations and 7 mm) alternating with layers (up to water-covered continuation of a samplings suggest that a young 2.5 cm) of light calcitic and aragonit- hydrothermally active , which massive sulphide deposit may exist ic sediments and layers of sediments occurs on land, does not exist. Off beneath the sea floor. The post- (up to 1.5 cm) with a manganese NW Dominica, five seamounts were cruise detailed geochemical and min- cement in the outer parts. Within the investigated. The older ones are eralogical studies of the manganese crusts, the nontronite samples and the gossan fragments support this in certain respects (e.g. high Pb- Table 1. Chemical composition of manganese crusts values in certain Mn-oxide-layers of sample the crusts). 18cd 52cd-a 52cd-b 83cd The nontronite fragments are of W.depth m 1144 950 950 1252 dark greenish to orange/reddish Fe wt% 5,15 0,64 3,82 8,15 colour (in the upper oxidised part) Mn wt% 40,8 55,3 29 23,6 wt% with thicknesses up to 10 cm. Be- Al 2 O3 5,76 1,98 2,44 8,3 side the predominant iron clay min- MgO wt% 1,58 3,42 3,23 3,95 eral nontronite occur llite, musco- CaO wt% 2,15 6,7 7,67 6,07 vite and small amounts of calcite. Cr ppm 9 13 4 19 The content of total Fe (bulk) is up Cu ppm 59 114 149 226 to 18 wt.% with depleted Mg, Ca and Ni ppm 57 308 714 657 Al contents. Zn ppm 53 197 271 298 In the “gossan” fragments the Ti ppm 864 457 1140 1830 values of total Fe reaches 17 wt.%. Co ppm 21 26 345 67 The Mn contents are up to 6.5 wt.%, Mo ppm which is relatively high for this type 53 360 317 350 ppm of rocks. Values of trace metals in- Li 17 66 - 250 ppm cluding Ni, Pb, Zn and V are relative- Pb 140 11 1420 9 ly low and range from 160 up to 300 ppm. The mineral composition of Sample description. 18cd: manganese cemented sediments (Kahouanne Basin); these samples includes iron miner- 52cd: massive crust, -a: inner Mn oxide-layer, -b: outer Mn oxide-layer als such as goethite (also a small (Montserrat Ridge); 83cd: incrustation of volcanic rock (north of Dominica). amount of hematite), nontronite, Data from XRD and ICP-OES 20 InterRidge News

International Research: Island arc/BAB: Halbach et al., cont... covered by Mn-oxides, and brecci- son and Cronan, 2001), we assume contents about 5-fold the back- ated material often contained barite. that the signals we identified are de- ground concentration (about 14 nmol Of particular interest are andesitic rived from various fluid sources at l-1 compared to 2-3 nmol l-1) as well as breccias cemented by hydrothermal different water depths off Dominica. positive anomalies of Zn (up to 120 manganese-oxyhydroxides. Meth- nmol l-1 in unfiltered samples) were ane concentrations in the water col- West of St. Lucia discovered in about 600 m water umn were below 3.0 nmol l-1, with Enhanced methane concentra- depth, indicating that low-tempera- highest concentrations in the bio- tions up to 13.8 nmol l-1 were found ture hydrothermal fluids are emanat- logically influenced upper water in the St. Lucia Bay at water depths ing from the faults. High resolutions body, while in deeper water 1 nmol l-1 between 50 and 100 m. Methane data of the CTD sensor profiles revealed was not surpassed. However, fur- correlate with a similar depth profile small negative salinity anomalies at ther water analyses indicated local of Cr(III) and a maximum of Cr(III) at various depths; however, tempera- enrichments of reduced Cr species the same depth. This input of reduc- ture anomalies could not be identi- and Zn, which may indicate hydro- ing waters can probably be related fied clearly. thermal contributions. The highly to the hydrothermal springs at the Unfortunately, we had no per- sensitive determination of Cr spe- coast of the bay. No hydrothermal mission to sample the crater of the cies has been shown to be an effec- solid samples were recovered. volcano. Six water samples were tak- tive means to trace hydrothermal en directly at the seafloor on the sources (Sander and Koschinsky, Kick’em Jenny flanks of the volcano with the Hydro 2000) because the hydrothermal Enrichments of reduced Cr spe- Bottom Station (HBS) which is an Cr(III) signal is stable in the water cies and of zinc were identified in instrument especially designed to column. However, the various meas- many water column profiles through- sample diffuse hydrothermal fluids urements revealed a strong variabil- out the area; these enrichments (Halbach et al., 2001). These sam- ity, probably caused by strong local mostly coincide with maxima of meth- ples showed increased concentra- variabilities in oceanographic pa- ane and can be attributed to the tions of Si (up to 33 μmol l-1 com- rameters and possibly several small influence of submarine hydrother- pared to a background of 18 μmol l-1), hydrothermal sources. As hot mal springs. The valley south of the methane (up to 22 nmol l-1), and of springs are known to exist along the volcano contains small, step-like several trace metals such as Zn, Cu coast and offshore Dominica (John- normal faults. Fluids with methane and Ni. There is a significant deple-

Concentration Cl (g/l) . Concentration Si (mg/l) . Cl Si 15.0 17.5 20.0 22.5 25.0 0.00.2 0.4 0.6 0.81.0 0 0

100 100 108 CTD 108 CTD 134 HBS 134 HBS 200 200

300 300

400 400

500 500 ater depth (m) ater depth (m) W W 600 600

700 700

800 800

900 900

Figure 2. Chloride and silica concentrations in the water column profile of station 108 CTD and in the bottom water samples of station 134 HBS at the southern flank of the Kick’em Jenny submarine volcano. Vol. 11(1), 2002 21

International Research: Island arc/BAB: Halbach et al., cont... tion in Cl (0.48 mol l-1 compared to field. The diagram Mn/Fe vs. Co tion of manganese by pore fluid in the background of 0.59 mol l-1), sul- demonstrates that the hydrothermal the unconsolidated sediment. phate, Na, K and Mg compared to samples are characterised by high It is clear from the above that the the ambient bottom water. Very small Mn/Fe ratios and low Co concentra- two main indicators of submarine chemical signals were also visible in tions (Fig. 3b); the three samples hydrothermal activity in the region the water column profiles at this with higher Co concentrations indi- as a whole are manganese crusts depth range (Fig. 2). As mixing of cate enhanced hydrogenetic input. and water column anomalies. seawater with meteoric water can Because of the wide distribution Other minerals of hydrothermal largely be excluded, the reduced of the manganese mineralisation in origin were only recovered between chlorinity of the samples may indi- certain areas, it is thought to have Guadeloupe and Montserrat, name- cate boiling and phase separation in been controlled by both focussed ly nontronite and sulphides. The the subseafloor. Boiling in hydro- and diffuse hydrothermal flow. An nontronites indicate low-tempera- thermal systems produces a vapor additional but less important mech- ture hydrothermal activity whereas phase that is enriched in gases but anism of mineralisation is a diage- pyrite and chalcopyrite indicate depleted in chloride and metal ions netic remobilisation and concentra- higher temperature hydrothermal- and a brine phase that is highly sa- line and metal-rich (e.g., Butterfield et al., 1990). Accordingly, our sam- ples would represent a condensed vapor phase. Measurements of sta- (Cu+Ni+Zn) x10 ble isotopes support this theory. A Discussion Although hydrothermal mineral- isation on the sea floor close to the islands is only low grade, it is hy- pothesised that phase separation in the hydrothermal fluids at depth could be leading to higher grade Hydrrogenetic mineralisation below the vent fields or the discharge of metal rich brines on the lower flanks of the volcanic islands. The widespread occurrence of HyHydrdr hehe alal manganese precipitates on the west- Fe Mn ern side of the Lesser Antilles shows that a fractionation process produc- ing low-temperature hydrothermal B solutions enriched in manganese Mn/Fe - Co has taken place possibly at more or Co (ppm) less the same geological time 600 throughout the study area. Addi- tional work on the manganese crusts 500 has shown that ferromanganese pre- 400 cipitation took place along faults Hydrogenetic and fractures and on ridges, and was 300 promoted by the mixing of modified 200 sea water (in a small amount) with 100 hydrothermal fluid. The very low Hydrothermal trace metal concentrations lead to 0 the conclusion, that the mineralis- 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 ing fluid was mainly of hydrothermal Mn/Fe origin. In the ternary diagram after Usui et al., 1992 (Fig. 3a) it is shown that due to the low concentration of Figure 3. Elemental relationships of all Mn oxide samples recovered during Ni, Cu and Zn, most of the analysed cruise SO 154; (A) Ternary Diagram Fe– Mn (Cu+Ni+Zn) x 10 after Usui samples plot in the hydrothermal et al. (1992); (B) Co vs. Mn/Fe 22 InterRidge News

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

ism. Detailed geochemical analyses during the cruise. Antilles. Marine Georesources & of the sediments have confirmed the Geotechnology, 19, 65-83, 2001. enrichments. References Kang, J.K. Les encroûtements Although the study area off the Butterfield, D.A., Massoth, G.J., ferromanganésifères sous-marine Lesser Antilles was sampled in de- McDuff, R.E., Lupton, J.E. and de l’est Caraïbe. These, Universite tail in all likely hydrothermal loca- Lilley, M.D. Geochemistry of d’Orleans, 1984. tions, no massive sulphides were hydrothermal fluids from Axial Polyak, B.G., Bouysse, Ph., Kononov, found on the sea floor. There are hydrothermal emissions V.I., Butuzova, G.Y. Evidence of indications, however, that they may study vent field, Juan de Fuca Ridge: submarine hydrothermal discharge be present at shallow depth under Sub-seafloor boiling and to the northwest of Guadeloupe the sea floor, beneath a cover of subsequent fluid-rock interaction. Island (Lesser Antilles island arc). gossan or manganese crust. Never- Journal of Geophysical Research, Journal of Volcanology & theless overall hydrothermal activi- 95(B8), 12895-12921, 1990. Geothermal Research, 54, 81-105, ty in the area appears to be less than, Freie Universität Berlin and partners. 1992. for example, in the western Pacific Technical Cruise Report Sander, S. and Koschinsky, A. arcs. CARIBFLUX with RV Sonne, cruise Onboard-ship redox speciation of no. SO 154, 2001. chromium in diffuse hydrothermal Acknowledgements Halbach, P., Holzbecher, E., fluids from the North Fiji Basin. Cruise SO 154 and the project Koschinsky, A., Michaelis, W. and Marine Chemistry, 71, 83-102, 2000. CARIBFLUX (grant no. 03 G 0154) Seifert, R. Deep-sea hydrothermal Usui, A. and Nishimura, A. are funded by the German Federal microplume generation - a case Hydrothermal manganese oxide Ministry of Education and Re- study from the North Fiji Basin. deposits from the Izu-Ogasawara search (Bundesministerium für Geomarine Letters, 21, 94-102, 2001. (Bonin)-Mariana Arc and adjacent Bildung und Forschung BMBF). Johnson, A. & Cronan, D.S. areas. Bulletin of the Geological We thank the captain and crew of Hydrothermal metalliferous Survey of Japan, vol. 43 (4), 257- R/V Sonne for the skilled support sediments and waters off the Lesser 284, 1992.

Geophysical Experiments in the Mariana Region: Report of the YK01-11 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, Japan 3Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan 4Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA 5National Institute of Polar Research, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan 6Department of Physics, University of Toronto, 60, St.George Street, Toronto, M5S 1A7, Canada

The Mariana region (Fig.1), the arc. In addition, serpentine ocean bottom and the deep struc- eastern part of the Philippine Sea, is seamounts formed by upwelling ser- ture beneath this region are still characterized by several tectonic pentine diapir are often found in the unclear yet. features. The Mariana Trench is a forearc area (e.g., Stern and Smoot, We conducted the YK01-11 re- result of downward going of the 1998). Three upwellings from deep search cruise by R/V Yokosuka, subducting Pacific plate. The Mar- interior of the earth probably exist JAMSTEC in October 2001 to char- iana Islands and the Mariana Trough below this region; the Mariana Is- acterize tectonic features and to are one of the typical island arc and lands, Mariana Trough and the ser- obtain a deep and dynamic image of backarc, respectively. The Mariana pentine seamounts. These upwell- the central Mariana region. Here, we Trough is a present active backarc ings are related to create various briefly report the geophysical ex- basin and the West Mariana Ridge tectonic features in the Mariana re- periments in the YK01-11 cruise; is considered as a remnant island gion. However, the dynamics of the 1) Surface geophysical surveys, Vol. 11(1), 2002 23

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

22Ê ties will be estimated using gravity and geomagnetic anomalies. The results would lead to the sizes and 21Ê OBEM LT-OBS the characters of the serpentine di- apirs, which help us to understand 20Ê the mechanism of their formation in the forearc region. Ten LT-OBSs were deployed to 19Ê investigate the image of deep struc- ture beneath the Mariana trough, 18Ê how the Pacific plate slab is sub- ducting and stagnant. In addition, 17Ê this seismic observation has a role of the feasibility study to know the deep seismic activity of this area, 16Ê which has not been determined by on-land seismic observation net- 15Ê works. For this purpose, three of LT-OBSs (Fig. 1) are located off the

14Ê main profile to surround the seismi- 140Ê 141Ê 142Ê 143Ê 144Ê 145Ê 146Ê 147Ê 148Ê 149Ê 150Ê cally active area where 600 km deep events are detected by a global seis- mic network. The LT-OBSs will be Depth(m) recovered in the winter of 2002 FY. -8000 -4000 0 Electrical conductivity in the Figure 1. OBEM and LT-OBS positions deployed in the YK01-11 cruise. The mantle depends on its temperature bathymetry is based on a global database by Sandwell and Smith (1997) and and/or existence of melts, so that the Smith and Sandwell(1997). conductivity structure is useful to image a hot mantle material, up- welling regions, and a cold subduct- ing plate. Therefore, ten ocean bot- 2) long-term and semi-broadband netic lineation (Isezaki, 1986). There- tom electromagnetometers (OBEMs) ocean bottom seismometers (LT- fore, the vector geomagnetic anom- were deployed in a line across the OBSs) observation, and aly field is especially useful to un- whole Mariana region through the 3) ocean bottom electromagnetometers derstand its tectonics. Pacific plate, the trench, the arc and (OBEMs) observation. The morphology in the central the backarc area (Fig. 1) to reveal Surface geophysical surveys are Mariana Trough shows seven regional and mantle conductivity conducted to characterize the back- spreading axis segmentations on the structure. The deep conductivity arc spreading evolution of the cen- basis of the present cruise and pre- structure beneath the slow spread- tral Mariana Trough (16 N-19 N) and vious ones (KH92-1, YK96-13, and ing axis of the Mariana Trough is serpentine diapirs in the forearc (Fig. YK99-11). The non-transform off- focused on intensively in this study, 2). Multi-narrow beam bathymetry, sets, that define the ridge segments, so that four of OBEMs are located gravity field, and magnetic field data can be traced off-axis in the western within 15 km width from the spread- were collected. Gravity field data side. The direction of the spreading ing axis. These OBEMs will be re- were obtained from the shipboard fabric in the southern part of this covered in the October of 2002. gravimeter. Magnetic field data are area changes dramatically from Synthetic calculations of elec- collected by the ship-towed proton NNW-SSE to almost N-S trend; that tromagnetic (EM) field on a priori precession magnetometer and the is interpreted as a result of the models are carried out in order to shipboard three-component magne- change in the spreading direction. know how the EM measurements by tometers (STCMs: Isezaki, 1986), Further analysis combined with crus- OBEMs are sensitive to a deep con- which can measure the vector of the tal age and thickness estimations by ductivity structure below the Mari- geomagnetic field. The Mariana re- vector geomagnetic anomaly and ana region. We calculated time var- gion is near the geomagnetic equa- gravity data would lead whole tec- iation of sea-floor electric and mag- tor and total intensity anomaly am- tonic evolution in this area. In addi- netic fields at arbitrary periods on plitudes are often much reduced tion, the morphologic feature in the several 2-dimensional conductivity depending on the orientation of the forearc region indicates eight cones, models, and discussed a ratio and a ambient geomagnetic field and mag- and their magnetizations and densi- phase difference between the elec- 24 InterRidge News

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

tric and the magnetic fields. The tectonic process in the Mariana T. Yamada, K. Nakahigashi of Earth- calculation results indicate several Trough. The deep seimic activity quake Research Institute, Univ. important features: will help to design future seismic Tokyo, helped us to prepare LT- 1) A high conductive mantle wedge at observation networks by dense OBSs. H. Shimizu, T. Koyama and S. the depth of 15 - 80 km will be well broadband ocean bottom seismom- Asari of Earthquake Research Insti- constrained by EM responses at eters. Our seismic and electromag- tute, Univ. Tokyo, assisted with the period of 100 - 5000 sec. netic experiments will give a coarse assembling of the OBEMs. R. Evans, 2) A high conductive zone below the structural image of the upper mantle J. Bailey, and A. D. Chave of WHOI Mariana Trough at the depth of 10 in the Mariana region, which is a first helped us to make electrodes for all - 80 km will be also imaged by EM step to get further detailed images of the OBEMs. N. Isezaki of Chiba responses at the period of 100 - the upper mantle, such as possible University kindly allows us to use 1000 sec. plumes beneath the trough, and the his STCM system. T. Yamazaki of 3) The effect of the subducting slab Pacific plate as subducting and stag- AIST and Y. Kido of JAMSTEC pro- deeper than 100 km depth is not nant slab. vide information on previous sur- large, but it can be observed at the face geophysical data. Figures are period greater than 5000 sec. The Acknowledgement made with GMT software developed synthetic calculations encourage We would like to thank Captain by Wessel, P. and W. H. F. Smith. our OBEMs observation. O. Yukawa, the officers and the crew These geophysical surveys also of R/V Yokosuka for their careful References have a role of pilot observation for consideration for the ship and on- Stern, R. J. and N. C. Smoot, A later Japan-US international coop- board operation. We discussed sci- bathymetric overview of the erative seismic and electromagnetic entific targets with S. Kodaira, JAM- Mariana forearc, The Island Arc, 7, experiments planned in 2002-2005. STEC. T. Kodera, S. Hosoya and Y. 525-540, 1998. Results of the surface geophysical Maezawa, Nippon Marine Enterpris- Isezaki, N., A new shipboard three- mapping in the YK01-11 cruise will es Ltd., compiled the obtained bathy- component magnetometer, Geo- give us a model of an undergoing metric data on board. M. Shinohara, physics. 51, 1992-1998. 1986.

141ûE 142ûE 143ûE 144ûE 145ûE 146ûE 147ûE 148ûE 149ûE 20ûN 20ûN miles 0 50 100

Site.11 19ûN Site.13 19ûN -3000

Site.14 Site.10 Site.9 Site.7 Site.5 Site.8 Site.4Site.6 18ûN Site.3 18ûN Site.12 Site.2

Site.1 17ûN 17ûN

-4000

-4000 16ûN 16ûN 141ûE 142ûE 143ûE 144ûE 145ûE 146ûE 147ûE 148ûE 149ûE

-7500 -6875 -6250 -5625 -5000 -4375 -3750 -3125 -2500 -1875 -1250 Depth[m]

Figure 2. Bathymetric map obtained in the YK01-11 cruise. Vol. 11(1), 2002 25

International Research: Ophiolites

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

Wang Zhihong

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

Introduction and geological setting The Kudi ophiolite, situated in the northwest segment of the west- ern Kunlun orogenic belts, north- western China (Fig.1), is one of the well-preserved ophiolite sequences in the Kunlun Mountains. The ori- gin and tectonic implications for the Kudi 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 was formed in a SSZ setting (Wang et al., 2001). The aim of this paper is to constrain tectonic and magmatic events of this SSZ ophiolite by de- tailed geochemistry and by compar- ing them with volcanic suites from modern western Pacific arc-basin systems. And furthermore, we present a model of evolution of a back-arc basin to enhance the un- derstanding of tectonic implications of the tholeiite associations. The Kulun Mountains are com- posed of orogenic belts, in which several ophiolite belts are exposed and regarded as suture zones be- tween blocks (e.g., Jiang et al., 1992). Two major tectonic fault belts in the western Kunlun Mountains, the Wuyitak-Kudi-Subasi ophiolite belt and Kengxiwar fault zone, separate the northern Kunlun, southern Kun- lun and Kara-Kunlun respectively (Fig.1). Detailed description of these three blocks and the Kengxiwar fault zone can be found in related refer- ences (e.g., Jiang et al., 1992; Mat- ternet al., 1996). There are four main lithological and tectonic units in the studied area: Proterozoic metamor- phic rocks, Sinian metavolcanites and marbles, granitoids in different Figure 1. Geological map and cross-section of the Kudi area along the Xinjiang- ages and the late Proterozoic-early Tibet highway based on our field observations and mapping. The isotopic Paleozoic Kudi ophiolite (Fig.1). ages are discussed in the text. 26 InterRidge News

International Research: Ophiolites: Zhihong, cont...

The Kudi ophiolite of the III-type peridotite proposed depleted peridotites. The Al2O3 and The Kudi ophiolite is composed by Dick and Bullen, indicating that CaO contents in the rocks are low, of a series of oceanic crustal and the highly depleted mantle peridot- 0.62-1.15 wt% and 0.3-0.95wt% re- mantle fragments, including mafic ites are of arc-related petrogenesis spectively. The TiO2 content of the and ultramafic rocks, volcanic rocks, and formed in an environment asso- mantle peridotites varies from 0.003 the mafic dikes within the volcanic ciated with a subduction zone. The to 0.014 wt%, lower than those of rocks and volcaniclastic flysch sed- pyroxenes in the harzburgites have mid-ocean-ridge mantle rocks (0.1- iments and turbidites overlying on 0.4 wt%) and similar to those of low Al2O3 contents (1.09-1.79wt%) the volcanic sequence. The litho- mantle rocks from ophiolites formed and low TiO2 contents (0.01- logic units of the mafic and ultrama- 0.09wt%), suggesting that the harz- in supra-subduction zone environ- fic blocks are mainly harzburgites, burgites are residual mantle perido- ments (<0.1 wt%) (Pearce et al., 1984). dunites, cumulate dunites and py- tites after high degrees of partial Relative to primitive mantle val- roxenites, and cumulate and mas- melting. ues, the Kudi mantle peridotites are sive gabbros which overlain on the The Kudi cumulate complex is slightly richer in Th and U (1-10´prim- ultramafic rocks. Slightly serpenti- composed of pyroxenites and gab- itive mantle) and poorer in Ti (0.1- nized harzburgites and dunites were bros with minor dunites. The Cr# 1´primitive mantle). The Kudi mantle intruded by pegmatitic dikes of py- and Mg# of spinels in the cumulate peridotites display LREE-enriched roxenite and gabbro. The volcanic dunites are in the range of 49.1-52.8 chondrite-normalized rare-earth-el- and volcaniclastic rocks of the Kudi and 43.5-46.6 respectively. In the ement patterns with LREE/ ophiolite are well-exposed in the Cr#-Mg# diagram, the spinels in the HREE=3.2-5.6 and (La/Yb)n=2.1-3.4 north, and can be divided into three dunites plot near the back-arc basin (Wang et al., 2001). parts according to their lithological field. The pyroxenite is composed of The contents of Al2O3, CaO, SiO2 characteristics: (1) the first part is mainly clinopyroxene (60-80%) and and TiO2 increase from the mantle mainly composed of massive and orthopyroxene (<30%), and most peridotites to pyroxenites and to pillow intruded by diabase primary minerals have been partly to gabbros. The Al2O3, CaO and FeO* dikes; (2) the second part is charac- completely replaced by amphibole contents in the pyroxenites have terized by amygdaloidal, massive and chlorite. The gabbro mainly wide ranges, reflecting the variabil- basalts interlayered with andesitic consists of plagioclase (40-60%) and ity of pyroxene mode and composi- basalts and tuffites; and (3) the third pyroxene (20-40%) with minor mag- tions. The gabbros are high in Al2O3 part is mainly composed of volcani- netite, and most fresh pyroxene is and low in FeO*, though both have clastic flysch sediments, which con- clinopyroxene. Amphibolitization limited ranges. tain basic volcanic lithic components and chloritization also occur in the Chondrite-normalized trace ele- with plagioclase phenocrysts (Mat- gabbros. ment patterns for the cumulate py- ternet al., 1996), and turbidites with The Kudi diabases crop out as roxenites and gabbros exhibit Bouma sequences. Most research- isolated dikes or as dike swarms. They marked negative Nb and Ti anoma- ers favor formation of the ophiolite are composed of plagioclase, pyrox- lies (Wang et al., 2001). The pyrox- in the late Proterozoic-early Palaeo- ene and minor olivine. Some primary enites have flat REE patterns and zoic (e.g., Deng, 1995; Mattern et pyroxenes have been replaced by the REE concentrations are 1- al., 1996). amphibole and chlorite, while some 10´chondrite (Wang et al., 2001). plagioclases replaced by chlorite and The REE patterns for the gabbros Petrology and mineralogy epidote. Calcite veins occur locally. are also flat (Wang et al., 2001).

The mantle peridotites from the Massive basalts have diabasic tex- TiO2 contents clearly separate Kudi ophiolite are mainly harzbur- tures and are mainly composed of the extrusive rocks into three differ- gites with minor dunites. The harz- pyroxene and plagioclase. Pillow ent magmatic suites. Group 1 basalts burgites consists of olivine (Fo=90.9- basalts are fine-grained and also com- are characterized by moderate TiO2 91.7, 50-90 modal %), Cr-spinel (<5%) posed of pyroxene and plagioclase. contents (0.8-1wt%), and group 2 and orthopyroxene (En=90.3-91.9, 5- Primary minerals in massive and pil- basalts have higher TiO2 contents 40%) with exsolution lamellae of di- low basalts are generally replaced by (1-1.6 wt%, most of them are higher opside and augite (En=48.7-53.3). chlorite and epidote. Amygdales of than 1.1 wt%), while group 3 basalts

Serpentinization is weak (generally amygdaloidal basalts are mainly filled have lowest TiO2 contents (0.16-0.38 less than 10 modal %). The dunite with chlorite and fine-grained felsic wt%). The TiO2 contents of the dia- consists of olivine (Fo=90.3-90.5, minerals. Chloritization and epidoti- bases are similar to that of group 2 about 95%), orthopyroxene zation are also common in these rocks. basalts. (En=91.5-92.2, <5%) and Cr-spinel. Group 1 basalts disply similar N- The Cr-spinels in the Kudi mantle Geochemistry MORB normalized trace element peridotites have high Cr number The Kudi mantle peridotites have patterns with that of the Tofua arc, (Cr#=100Cr/(Cr+Al)=60-67), and are high Mg# (91.1-91.9) and are highly and more enriched in La and Ce also Vol. 11(1), 2002 27

International Research: Ophiolites: Zhihong, cont... as shown by their LREE-enriched chemistry (Fig.2b), as their major LREE-depleted chondrite-normal- chondrite-normalized REE patterns elements. Group 3 basalts have low ized REE patterns with low levels of HREE (Fig.2c). In conclusion, (Fig.2a). On N-MORB normalized TiO2 (0.16-0.38 wt%), P2O5 (0.01-0.03 trace element patterns, group 2 ba- wt%), Zr (4-30 ppm) and Y (7-11 the Kudi extrusive rocks are com- salt display marked negative Nb ppm); and high Mg (Mg#=62-72) posed of three different tholeiite anomalies. Furthermore, these ba- and Cr (300-500 ppm). They display associations. salts have slightly LREE-depleted similar N-MORB normalized trace el- or flat chondrite-normalized REE ement patterns (low levels of HFSE) Magma sources for the tholeiite patterns (Fig.2b). Diabase dikes are with that of the boninites from the associations similar to group 2 basalts both in Bonin Islands (even more enriched On the TiO2-Zr diagram, Group 3 trace and rare-earth elments geo- in LILE) and slightly U-shaped or basalts plot in and near the fields of Hunter Ridge and IBM forearc bon- inites, while group 2 basalts mimic the MORB trend (Ti/Zr=102), and Ti/Zr values of group 1 basalts are A mostly in the range of 75-100. These three groups of basalts are clearly separated on the diagram of La/Sm-

TiO2 (Fig.3). Group 1 basalts plot in the field of Mariana arc and much LREE-enriched area, group 2 basalts in the field of Lau Basin, and group 3 basalts in and near the fields of Hunter Ridge and IBM forearc bon- inites. On the Hf/3-Th-Nb/16 dia- gram, group 1 and 2 basalts indicate a clear supra-subduction zone (SSZ) signiture. Conclusively, we interpret B group 1 basalts to be LREE-enriched island arc tholeiites (IAT), group 2 basalts to be back-arc basin (BAB) tholeiites, and group 3 basalts to be low-Ti island arc tholeiites (IAT).

Tectonic evolution of the Kudi ophiolite An upper mantle and crustal section of a back-arc basin The mantle peridotites are rich in Mg and Ni and poor in Al and Ca; and the pyroxene is low in Al and Ti, C and the spinel is high in Cr# (Cr#>0.6), indicating that they are highly depleted mantle residues and similar to those of mantle rocks from SSZ ophiolites. The cumulate py- roxenites and gabbros are Nb and Ti depleted and are of arc affinity. These cumulate rocks have flat REE patterns as that of group 2 basalts. The cumulate gabbros together with the diabase and group 2 basalts Figure 2. Chondrite-normalized rare-earth-element patterns for the tholeiite define a clear cogenetic trend in the associations from the Kudi- ophiolite. (A)-LREE-enriched group 1 basalts; Hf-Th-Nb diagram. As discussed (B)-LREE-depleted and flat group 2 basalts (solid circles for the diabase earlier, the diabase dikes and group dikes); (C)-U-shaped group 3 basalts. Normalizing values are from Sun and 2 basalts have indistinguishable McDonough (1989). geochemistry with that of tholeiites 28 InterRidge News

International Research: Ophiolites: Zhihong, cont...

would possibly give birth to propa- gating of back-arc basin spreading ridge into a protoarc along the trend. Hydrous fluids enriched in LILE emanate from the subducting lithos- pheric slab into the formerly deplet- ed (extraction of BABB magma) and hot refractory mantle (newly formed upper mantle in the back-arc basin), triggering partial re-melting, and consequently the low-Ti IAT mag- ma formed. If the magma extrude right at the bottom of the back-arc basin, the low-Ti IAT will cover the former floored BAB tholeiites. If the magmas extrude into the propagat- ing tip of the back-arc basin, the IAT will interlayer with the BAB tholei- 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 Kudi ites following continued basin ex- ophiolite and modern arc systems. tension (Fig.4b).

Tectonic implication of the LREE- tion. Field observations indicate that from back-arc basins. In summary, enriched IAT the low-Ti IAT generally overlay the the main parts of the Kudi ophiolite, It is different to distinguish the BAB tholeiites and/or are interlay- namely the SSZ-type mantle perido- second-stage arc magma from the ered with the BAB tholeiites locally, tites, cumulate complex with arc tho- first-stage arc magma forming the suggesting that they could have leiite affinity, and BABB-type dia- protoarc (Fig.4a). Group 1 basalts in formed after the BAB tholeiites or base dikes and group 2 basalts con- the Kudi ophiolite are more enriched approximately the same time. In oth- stitute an upper mantle and crustal in LILE and LREE than the basalts er words, the low-Ti IAT produced section of a back-arc basin in a SSZ from typical arcs (e.g., Fig.3), sug- during extension of the back-arc environment. gesting that voluminous fluid efflux basin. We present here an interac- had entered into the mantle wedge tion model between subduction and Petrogenetic scenario for the low-Ti possibly due to devolatilization of extension of a back-arc basin for island arc tholeiites (IAT) two subducting slabs (Fig.4c) and/ interpreting tectonic and magmatic Group 3 basalts share lots of or much close to a subduction zone. events responsible for the origin of common geochemical characteris- The interaction occurred between the low-Ti IAT. tics with the modern boninites, i.e., the parental magma of group 1 ba- Intraoceanic subduction gener- low Ti and HFSE, high Cr, and slight- salts and the mantle peridotites from ally and firstly results in slab devol- ly U-shaped or LREE-depleted chon- the mantle wedge and formerly the atilization, with focussed fluid efflux drite-normalized REE patterns with upper mantle of the back-arc basin into the convecting mantle wedge low levels of HREE, especially with (Wang et al., 2001), spatially and triggering partial melting, and con- the boninites from the Hunter Ridge temporally eliminating the possibil- sequently arc volcanism is devel- and IBM forearc (Fig. 3). The geo- ities of protoarc magmatism for group oped (Fig.4a). Geophysical investi- chemistry of the low-Ti IAT indi- 1 basalts. This implies that a new gation of marginal basins in the cates that they represent melts de- subduction zone, indicative of clo- western Pacific suggested that initi- rived from a depleted mantle source sure of the back-arc basin, had ation of inter-arc basin extension is region modified compositionally by emerged within the Kudi palaeo- resulted from mantle diapir rather fluids and/or melts during subduc- back-arc basin, permitting hydrous than a change of subduction zone tion metasomatism. The occurrence fluids and/or melts from devolatili- configuration (e.g., trench rollback). of calc-alkaline volcanics and vol- zation of the back-arc basin lithos- The coupling of MORB-type mantle caniclastic sediments above the phere subducting slab to interact upwelling with fluid efflux from slab Kudi ophiolite, which is normally with the rocks in a newly formed devolatilization would permit forma- restricted to mature intraoceanic mantle wedge (Fig.4c). arcs, implies that these low-Ti IAT tion of BABB-type magmatism by which floored the extensional back- were not produced during the initi- Conclusions arc basin (Fig.4b). Continued mantle ation of an island arc or not associ- We developed an evolution mod- upwelling and consequent extension ated with the initiation of subduc- el of a back-arc basin to explain tec- Vol. 11(1), 2002 29

International Research: Ophiolites: Zhihong, cont... tonic and magmatic events of the subduction zone ophiolites, In Effect of melt-rock interaction on early Paleozoic Kudi SSZ ophiolite Marginal Basin Geology, edited geochemistry in the Kudi ophiolite involving the production of three by B.P.Kokelaar, and M.F.Howells, (western Kunlun Mountains, types of tholeiite associations. Geol. Soc. London Spec. Publ., 16, northwestern China): implication The SSZ-type mantle peridot- 77-94, 1984. for ophiolite origin, Earth Planet. ites, cumulate complex with arc tho- Wang, Z.H., S.Sun, Q.L.Hou, and J.L.Li, Sci.Lett., 191, 33-48, 2001. leiite affinity, and BABB-type dia- base dikes and basalts constitute an upper mantle and crustal section of a back-arc basin formed by coupling of MORB-type mantle upwelling with fluid efflux from slab devolatil- ization. The low-Ti IAT represent melts derived from a depleted mantle source region (extraction of BABB magma) modified compositionally by fluids and/or melts from the sub- 2 ducting lithospheric slab during propagation and extension of the back-arc basin. The emergence of the LREE-enriched IAT and the in- teraction between the parental mag- ma of the IAT and the mantle wedge rocks indicate the closure of the back-arc basin.

Acknowledgments We are indebted to Chen H L, Xiao W J, Zhang G C, Zhou H, Fang A M, Yuan C, and Wei X S for their 2 field help. This research was sup- ported by the National 305 Project.

References Deng, W.M., Geological features of ophiolite and tectonic significance in the Karakorum-west Kunlun Mts, Acta Petrologica Sinica, 11, 98-111, 1995 (in Chinese with English abstract). Jiang, C.F., J.S.Yang, B.G.Feng, 2 Z.Z.Zhu, M.Zhao, Y.C.Chai, X.D.Shi, H.D.Wang, and J.Q.Hu, Opening-closing tectonics of the Kunlun mountains, Geol.Memoirs. 5(12), pp.224, Geological Publishing House, Beijing, 1992 (in Chinese with English abstract). Figure 4. Schematic diagram illustrating the evolution of a back-arc basin and Mattern, F., W.Schneider, Y.Li, and production of three tholeiite associations. (A) A first-stage arc system (the X.Li, A traverse through the protoarc). (B) Propagation and extension of a back-arc basin. The symbol of western Kunlun (Xinjiang, China): a star with in a round circle represents the low-Ti IAT generally overlaid the tentative geodynamic implications BAB tholeiites which floored the basin; and the star symbol represents the for the Paleozoic and Mesozoic, low-Ti IAT commonly interlayered with the BAB tholeiites at the propagating Geol. Rundsch,85, 705-722, 1996. tip of the back-arc basin. (C) A second-stage arc magmatism related to Pearce, J.A., S.J.Lippard, and formation of the LREE-enriched IAT during the closure of the back-arc basin, S.Roberts, Characteristics and arousing the interaction between the arc magma and the mantle rocks. See tectonic significance of supra- text for detailed discussion. 30 InterRidge News

International Research: Pacific-Antarctic Ridge

Widespread Silicic Volcanism and Hydrothermal Activity on the Northern 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, Germany 2 Institut für Mineralogie, Technische Universität Bergakademie Freiberg, Germany 3 Natural Resources Canada, Ottawa, Canada 4 Forschungsinstitut Senckenberg, Frankfurt, Germany 5 Zoologisches Institut, Universität Hamburg, Germany 6 Department of Geology, University of Toronto, Canada

The Foundation seamount chain over a mantle plume, and that this est Foundation seamounts (Hekini- was first visited during 1995 by the plume is presently located 35 km anet al., 1997; 1999). Silicic volcan-

R/V SONNE, and subsequently in west of the Pacific–Antarctic Ridge ism (>55 wt.% SiO2) on mid-ocean 1997 by the R/V L’ATALANTE. Geo- (PAR) near 37°25’S (Fig. 1; Maia et ridges is rare, but does occur on the chemical and geophysical data from al., 2000; 2001; O’Connor et al., northern East Pacific Rise (10.5°N; these cruises have shown that the 2001). Surprisingly, silicic lavas (up Thompson et al., 1989) and the 095° Foundation seamounts formed dur- propagator of the Galapagos Spread- to 64 wt.% SiO2) were recovered from ing the passage of the Pacific Plate the PAR crest adjacent to the young- ing Centre (Clague et al., 1981). The prime objectives of the

120˚W 110˚W 100˚W 112˚W 111˚W 110˚W FOUNDATION III cruise (R/V

2800 SONNE- SO 157) in mid-2001 were to

0

280 determine the extent of the silicic 10˚S 0 0

6 37˚S 3000 2 lavas along the PAR and to investi-

2 gate associated hydrothermal activ- 000 acific Rise P ity. We examined a 630 km-long seg- 20˚S 37˚40'S dome East 37˚48'S dome ment of the northern PAR bounded ts EM m oun 38˚S r Sea by large left-stepping overlapping E a ste 38˚15'S off axis seamounts s spreading centres (OSCs) near 36.5°S

30˚S high l and 41.5°S (Fig. 1). Detailed bathy- ia

JFM ax metric data was collected using the

n 2 3000 o F oundation 800 s 2400 newly installed SIMRAD EM120 Seamounts 00 39˚S va 800 2 3 0 2 la 0 SO 6 157 2 onboard the R/V SONNE, and 65 sta- 40˚S work ic are a ilic S 39˚27'S dome tions were devoted to recovering 3000

39˚48'S seafloor samples in conjunction with video observations of hydrothermal idge 40˚S cR activity and vent fauna. cti 50˚S

0

60

SO 157 Foundation III 2 2

acific-Antar The PAR at 37.5 – 41.5°S

6 P 0

Contour interval 500 m 0

2800 In the northern part of the sur- 3000 SO 157 Foundation III 41˚S veyed area, the PAR axis forms a

0 Statio n site 0 series of short (~15 km-long) non- 28 Foundatio n plume geoid anomal y overlapping segments (Fig. 2). Small 41˚22'S (Mai a et al., 2000) overlap basin Contour interval 200 m right-stepping non-transform dis- continuites offset each segment by Figure 1. Tectonic setting and bathymetry of the northern PAR. Left- location ~1 km, although a more complex of the SO 157 work area and major tectonic features (EM = Easter Microplate, westward bending occurs around JFM = Juan Fernandez Microplate). Right- SO 157 station sites along the PAR an off-axis seamount near 38°15’S. crest and features referred to in the text. Black bars indicate the extent of silicic Each segment is dome-shaped, with lavas along the PAR crest. the elevation decreasing gently Vol. 11(1), 2002 31

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

111o 30'W 111o 20'W 111o 10'W 111o 00'W 110o 50'W 110o 40'W

230 39°27’S (Fig. 1). The crest of the

0 37o 30'S southern dome at 2090 m-depth is capped by a fresh 4 km-long tabular flow of glassy aphyric andesite with

Central 2550 skeletal pyroxene and plagioclase Foundation 37˚40'S Axial o crystals. Strongly elongated flow- chain 37 40'S Dom e aligned vesicles often contained pyrite-cubanite crystals, and re- 2400 2450 leased H S when cut. 37˚48'S 2 Axial Further south, a series of 40–50 Dom 37o 50'S e km-long ridge segments (each 40–50 50 2

0 2

0 24 km-long) are separated by left-step- ping OSCs at 39°48’, 40°09’, 40°34’, 40°55’, and 41°19’S (Fig. 1). The ridge 38o 00'S axis is offset by 4–5 km at each of these discontinuities, and the over- lap distance varies from 5–22 km. MORB-like pillow lavas were recov- Southern 38o 10'S ered from these segments. Our sur-

Foundation 0 chain 245 vey terminated at the large left-step- ping OSC near 41°22’S, where the

0

5

4 ridge crest is offset by 18 km and the 2 38˚15'S Off overlap extends for 10 km. An isolat- axis o Seamount 38 20'S ed 500 m-high seamount with a well- s developed summit crater has been

0 5 26 built in the overlap basin. Fresh aphy- ric , older MnOx-stained sparse- SO 157 Foundation III 38o 30'S ly phyric basalt and dolerite were

Dredgesite, SO 157 recovered from the summit crater.

0 Dredgesite, SO 100

260 01020 2300 Hydrothermal activity and vent fauna km Contourinterval 50 m 38o 40'S Active hydrothermal vents, to- gether with abundant vent fauna Figure 2. Detailed bathymetry and dredge stations in the northern part of the and fossil sulphide deposits, were work area. located during video sled and TV- controlled grab surveys. These sur- along strike towards its ends. The was video surveyed by the R/V veys provided comprehensive cov- domes are better developed north of L’ATALANTE in early 1997. The new erage of the 37°40’S and 37°48’S the off-axis seamount, where they lava covers an area of 3.5 km x 200 m, axial domes. The high-temperature rise ~100 m above the segment ends. and was erupted from a series of sulphide deposits and vent fauna Graben-like clefts up to 200 m-wide partly buried fissures whose loca- are the first reported occurrences and 50 m-deep cut through some of tion is marked by collapse pits. A from high latitudes on southern the domes. more varied lava suite was recov- hemisphere spreading ridges. The 37°40’S dome was selected ered from the lower flanks of the Widespread diffuse venting for a detailed petrological and hy- dome, where the dominant litholo- (near-bottom water temperature drothermal study. This dome rises gies were glass-encrusted sparsely anomalies up to 0.25°C) is associat- to 2120 m-depth, and is cut by a cleft phyric pillow andesite and basalt. ed with the young silicic flows in the filled with fresh glassy lavas and Light dustings of MnOx suggest cleft of the 37°40’S dome. Both the talus from adjacent pillow mounds. most of these lower lavas are older. cleft walls and recovered rocks were Lavas from the summit and cleft in- To the south of 38°15’S, the PAR commonly stained with Fe-hydrox- clude aphyric and andesite, axis continues at an almost constant ides. Two partly talus-covered sul- and have glass crusts >5 mm thick. depth of 2220–2250 m. Pillow and phide outcrops occur along the east- Conchoidal fractures, together with sheet flows of sparsely phyric an- ern cleft wall. Both are 30 m in diam- numerous strongly elongate and desite and basalt characterise this eter, and comprise sulphide rubble flow-aligned vesicles, characterise 120 km-long section. The section is with halos of metalliferous sediment these silicic lavas. At least one lava terminated by two 120 m-high axial and Fe-hydroxide staining. Free- flow was emplaced since the area domes constructed near 39°20’S and standing sulphide spires were seen 32 InterRidge News

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

depth (m) dredge site onboard R/V SONNE cruise 157 for Silicic lavas on PA R axial domes 2000 silicic dome their expert help. This project is fund-

2200 ed by BMBF Grant 03G0157A.

2400 References

dome

dome 2600 Clague, D.A., F.A. Frey, G. Thompson,

37˚40'S 39˚27'S and S. Rindge. Minor and trace 2800

SC geochemistry of volcanic rocks 3000 OSC O 36˚S 37˚S 38˚S 39˚S 40˚S 41˚S 42˚S dredged from the Galapagos Spreading Center: role of crystal Figure 3. Bathymetric profile of the northern PAR. Silicic lavas predominate on fractionation and mantle the axial domes between 37°11’S and 39°48’S. heterogeneity. J. Geophys. Res., 86, 9469–9482, 1981. at the northernmost site. Three areas dominated by Bathymodiolus and Hekinian, R., P. Stoffers, C. Devey, D. of dark, dusty hydrothermal sedi- Neolepas, and mobile animals in- Ackermand, C. Hémond, J. ment, interpreted as recent plume clude bythograeid crabs, Munidop- O’Connor, N. Binard, and M. Maia. fallout, coincided with weak temper- sis, and zoarcid fish. Unlike B. ther- Intraplate versus ridge volcanism ature anomalies. One was near a clam mophilus found near sulphide-rich on the Pacific–Antarctic Ridge near field seen during the 1995 R/VSONNE vent fluids elsewhere, the gills of 37°S - 111°W. J. Geophys. Res., cruise, and another extended for 100 our recovered Bathymodiolus spec- 102, 12265–12286, 1997. m over the post-1997 glassy silicic imens were only moderately hyper- Hekinian, R., P. Stoffers, D. lava at the southern end of the cleft. trophic and H2S was not released Ackermand, S. Révillon, M. Maia, The 37°48’S axial dome consists when the shells were opened. Poly- and M. Bohn. Ridge–hotspot of partly sediment-covered lavas chaete worms and snails were col- interaction: the Pacific–Antarctic buried by younger sediment-free lected from the vent sites, and dense Ridge and the Foundation flows, and lacks a central cleft. Nev- beds of dead vesicomyid clams were seamounts. Mar. Geol., 160, 199– ertheless, near-bottom water tem- seen in the peripheral zone. Filter- 223, 1999. perature anomalies (up to 0.25°C) feeders at the active vents and in the Maia, M., D. Ackermand, G.A. occur at deep fissures cutting the peripheral zone were hexactinellid Dehghani, P. Gente, R. Hekinian, younger lavas on the southern dome sponges and sessile crinoids, where- D. Naar, J. O’Connor, K. Perrot, J. flank. White hydrothermal fluid was as the more distal zones were dom- Phipps Morgan, G. Ramillien, S. observed near a sulphide outcrop 10 inated by large assemblages of ser- Révillon, A. Sabetian, D. Sandwell, m across at one fissure, and the pulid tubes, actinians, coryphaenid and P. Stoffers. The Pacific– fissures are surrounded by a vesico- fish and swimming crinoids. The Antarctic Ridge–Foundation myid clam bed 50 m in diameter and abundance of swimming crinoids at hotspot interaction: a case study abundant vent fauna. A fossil sul- the PAR is possibly unique, and of a ridge approaching a hotspot. phide outcrop 30 m across occurs they were a useful indicator of near- Mar. Geol., 167, 61–84, 2000. 1.7 km north of the clam field, and by hydrothermal venting. Maia, M., C. Hémond, and P. Gente. includes two large sulphide spires Contrasted interactions between up to 3 m high. There, an old sul- Summary plume, upper mantle, and phide mound has been partly buried Silicic lavas have now been re- lithosphere: Foundation chain and disrupted by young lavas. covered from the upper flanks of case.Geochem. Geophys. Geosyst., Abundant sulphide talus has been PAR axial domes between 37°11’S 2, #2000GC000117, 2001. ramped onto the young lavas, and and 39°48’S, a distance of 290 km. O’Connor, J.M., P. Stoffers, and J.R. sulphide windows outcrop between These lavas outcrop on the upper Wijbrans. En echelon volcanic pillows. The talus is strongly al- flanks and summits of the axial elongate ridges connecting tered, and stained with bright red domes, whereas less silicic lavas are intraplate Foundation Chain Fe-hydroxides, yellow jarosite, and found on the lower dome flanks (Fig. volcanism to the Pacific–Antarctic bright green atacamite. Recovered 3). Widespread hydrothermal activ- spreading center. Earth Planet. sulphide blocks consisted of coa- ity and sulphide deposits are asso- Sci. Lett., 192, 633–648, 2001. lesced pyrite chimneys, massive re- ciated with the silicic volcanism, and Thompson, G., W.B. Bryan, and S.E. crystallised sphalerite and chalcop- may reflect the high heat flow avail- Humphris. Axial volcanism on the yrite, and included sulphide-pseu- able from fractionating magma. East Pacific Rise, 10–12°N, in: domorphed clams and large worm Magmatism in the Ocean Basins, tubes up to 1.5 cm in diameter. Acknowledgements eds. A.D. Saunders and M.J. Norry. The faunal communities around We thank Captain Henning Pap- Geol. Soc. Spec. Publ., 42,181– the active hydrothermal vents are enhagen, his officers and the crew 200, 1989. Vol. 11(1), 2002 33

International Research: Mid-Ocean Ridge

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, Russia 2 Vernadsky State Geological Museum RAS, Moscow, Russia

Introduction ly the same time, “enriched” MORBs of published work that address finer Numerous previous studies have were detected in the South Atlantic. variations in MORB composition reliably established regional and This enabled S. Hart to establish the within specific regions. In most cas- local variations of isotope composi- DUPAL anomaly of the Southern es, MORB isotope systematics draw tions for mid-ocean ridge basalts Hemisphere, so named after B. Du- in one way or another on the “mantle (MORBs). As early as in 1987, E. Ito pre and C. Allegre, prominent re- tetrahedron” of A. Zindler and S. and co-workers in their review em- searchers in the field of isotope ge- Hart (1986). Its corners are made by phasized the fact that Indian Ocean ochemistry. The limited size of this the so-called end members which basalts are enriched in radiogenic Sr paper compels us to refer hereinaf- include DM (depleted mantle), and Pb isotopes with respect to Pa- ter to the review (Hofmann, 1997). HIMU (high μ mantle, where μ is cific and Atlantic MORBs. At rough- Besides, there exist a huge number 238U/204Pb), and two types of en- riched mantle, EM1 and EM2. Some authors believe that the DUPAL anomaly is easiest to explain by in- ARC troducing a certain “composite” end member, LOMU (“low μ mantle”),

Sr/0.706 Sr which is a mixture of EM1 and EM2 87 86 (Douglass and Schilling, 1999). Be- EM1 sides, in use are a number of within- tetrahedron components (FOZO, 0.704 F PREMA, C, etc.) (Hofmann, 1997), + one of which (C, or “common”) is + HIMU viewed as being common to MORBs from different oceans (Hanan and 0.702 DM Graham, 1996). Many workers note the similarity of within-tetrahedron 15.9 components and use them as indica- HIMU HIM U tors of lower-mantle plumes (Hof- mann, 1997). However, distinctions F between these components are great

Pb/ Pb + enough. This results in considera-

20715.5 204 EM1 + ble uncertainty and, not infrequent- DM ly, inconsistency in systematics and interpretations of one and the same feature. This makes direct compila- 15.1 tion of conclusions obtained by dif- ferent workers rather hard. Our study presents results from data generali- zation for MORB compositions us- ing all-embracing Sr–Nd–Pb isotope 14.7 ARC systematics, modified by means of 15 16 17 18 19 20 206Pb/ 204 Pb multidimensional statistics. + 1 2 34 5 Methods used Figure 1. MORB isotope systematic. 1-3 - the average isotope compositions for The entire data set (820 published clusters of: normal (1); DUPAL (2) and “singular” MORB (3); 4 - individual analyses) was convoluted using a compositions of “singular” MORB from Arctic province; 5 – flood basalts multidimensional data agglomera- from Eastern Greenland. tion technique of our own, which 34 InterRidge News

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

Figure 2. Isotope heterogeneity of World Ocean. Mid-ocean ridge isotope provinces: Pacific (I), Central Atlantic (II), Red Sea – Aden (III), South Atlantic (IV), Indian Ocean (V), Arctic (VI), and Transitional Indian-Atlantic (VII). Normal MORB suites: 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) and F+DM+(ARC) (8) (after Mironov et al., 2000). The boundaries of the isotope mid-ocean ridge provinces (9). affords the identification of compo- classification element, along with a general characteristic for within- sitional clusters in multidimension- the end members, is the F (“focal”) tetrahedron components, con- al space. A reference frame for the within-tetrahedron component. It strained using multidimensional sta- space under study was provided by was derived as the mean composi- tistics techniques. Previously, vari- the customarily used radiogenic/ tion of an independent cluster in the ance of MORB isotope composition non-radiogenic isotope ratios (87Sr/ course of a similar analysis of data, was shown to be due principally to 86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/ dominantly from intraplate oceanic mixing of the component F with DM 204Pb, 208Pb/204Pb). To systematize structures. The component F turned (Rundqvist et al., 2000). For this the MORB clusters identified, we out to be close in composition to the reason, for the purposes of MORB used our own modification of the mean for all the within-tetrahedron systematics, we used an additional “mantle tetrahedron” (Fig. 1) components known so far, includ- classification element, the join F– (Rundqvist et al., 2000). Its crucial ing C. We regard the component F as DM (Mironov et al., 2000).

MORB types and isotope provinces of mid-ocean ridges InterRidge Publications Based on how mean composi- tions of the clusters plot with re- The latest issue of InterRidge News, as well as a spect to the mixing line F + DM, three principal types of MORB can be iden- number of other IR meeting and workshop reports and tified (Fig. 1). These types are spa- publications, are now available as downloadable PDF tially discrete and compose exten- files from the InterRidge Website. Just visit: sive provinces (Fig. 2). The first type, the counterpart to “normal” MORB, http://www.intridge.org/act3.htm is featured by the presence of HIMU (F + DM + HIMU field). This type is Vol. 11(1), 2002 35

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

n,% noted earlier, Gakkel Ridge basalts 50 are isotopically similar to DUPAL- 102 an. MORB (Muhe et al., 1997). Indeed, Arctic in terms of most isotope characteris- 10 tics, such as 206Pb/204Pb vs. 87Sr/86Sr (Fig. 1), 206Pb/204Pbvs. 143Nd/144Nd., 35 and 206Pb/204Pb vs. 208Pb/204Pb varia- 294 an. tions, this type is analogous to 15 Central Atlantic DUPAL-MORB. However, in terms of 206Pb/204Pb vs. 207Pb/204Pb varia- tions, it matches normal MORB (Fig. 60 1). This peculiarity cannot be due to 183 an. Pacific EM1 admixture, as in the southern 20 DUPAL anomaly. The most likely explanation is a certain degree of 40 contamination of oceanic lithos- 62 an. phere in this region by another com- 20 Red Sea - Aden ponent, which, for the time being, we term tentatively ARC (“Arctic”). 0 This component is located far be- 25 40 an. yond the “mantle tetrahedron,” in Transitional the region of extremely low 206Pb/ 204Pb and 207Pb/204Pb values. 5 Boundaries of isotope provinc- 60 es for mid-ocean ridges fit in with Indian Ocean those of E–W transoceanic hetero- 83 an. geneities delineated earlier based 20 on isotope compositions of volcan- ites on intraplate rises and islands 45 (Fig. 2) (Rundqvist, 2000). Remarka- 57 an. South Atlantic bly, the MORB signature of a given 25 province is defined by the same 5 admixture (EM1 or HIMU) that pre- vails in volcanic compositions on latitudinally close rises and islands, where it forms quasi-binary mixtures with the component F (Mironov et al., 2000). In this respect, the Arctic province is somewhat different. Here, the component ARC, critical

DM+F F+(DM)+(EM1) F+DM+(HIMU) F+EM1+(DM) F+(DM)+(HIMU) DM+EM1+( F) F+HIMU+(DM) F+DM+(ARC) F+DM+(EM1) to the recognition of the province, I II III makes only a minor admixture in mix- ing products of F and DM not solely Figure 3. Frequency of occurrence of normal (I), “singular” (II), and DUPAL (III) in mid-ocean ridges, but on islands MORB in mid-ocean ridge provinces. as well. At the same time, quasi- binary mixing of F and ARC is re- corded only in the continental flood widespread in the Central Atlantic, mal and DUPAL-MORB coexist. In volcanites, which preceded the open- Pacific, and Red Sea–Aden provinc- addition to these rather well-known ing of the North Atlantic (Fig. 1). es. The second type is developed types, we established a third type of within the DUPAL anomaly. Its hall- MORB, which defines the singular- Comparative characteristics of iso- mark is the presence of EM1 (F + DM ity of the Arctic province. The latter tope provinces + EM1 field). The South Atlantic and encompasses the ridges of the North Cluster frequency histograms Indian Ocean provinces, which lie Atlantic and the Norwegian–Green- show that provinces composed of within the DUPAL anomaly, are sep- land Basin, including the northern the same MORB type still differ from arated by the Transitional (Indian– Reykjanes Ridge on the south and each other to some extent (Fig. 3). Atlantic) province, where both nor- the Gakkel Ridge on the north. As Thus, the Central Atlantic province 36 InterRidge News

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

EM2 A (unlike the Pacific one) is character- 0.705 EM1 ized by the presence of “normal” MORB varieties with a high propor- tion of F and HIMU components. 0.704 Sr F C This and other distinctions are more 86 HIMU readily evident in a section of the Sr/

87 0.703 mantle tetrahedron (Fig. 4). In the Central Atlantic province, two MORB suites are distinguished 0.702 DM clearly. One suite, widespread in the northern segment of the province 16 17 18 19 20 206Pb/204Pb (Fig. 2), originates from mixing of F and DM with a minor HIMU admix- B 0.713 W. Australia ture. A similar suite is developed in Lamproites the Red Sea–Aden province. The LOMU 0.711 second suite, intrinsic to the south- Micaceous Group 2 Kimberlites EM2 ern segment of the Central Atlantic Kimberlites province (24°N–24°S), is more con- 0.709 sistent with direct mixing of the two Sr

86 Afanasy end members, DM and HIMU (with 0.707 Nikitin Sr/ a minor F admixture). Compositional 87 range of this MORB suite accommo- Lamproites EM1? 0.705 Smoky Butte dates all MORB compositions from P the Pacific province as well, with C HIMU Pacific basalts having a much nar- 0.703 F rower range, tending towards DM. DM No less clear distinctions exist 0.701 between the Indian Ocean and South 16 17 18 19 20 206 204 Pb/ Pb Atlantic provinces, composed of DUPAL-MORB (Fig. 4). Variance of 135672 4 8910 Indian MORB is due mainly to mix- ing of DM and F (with EM1 admix- Figure 4. Isotope suites of normal (A) and DUPAL (B) MORB. Isotope mid- ture). Compositional variations of ocean ridge provinces: Central Atlantic, northern segment (1), Red Sea - South Atlantic MORB can be ex- Aden (2), Central Atlantic, southern segment (3), Pacific (4), Indian Ocean plained by mixing of two “compos- (5), South Atlantic (6); intraplate structures, data from which were used for ite” components. One of these cor- definition of component LOMU: Africa and Australia (7), Gough, Tristan da responds roughly to the mean com- Cunha, Discovery (8), Afanasy Nikitin (9) (after Douglass, Schilling, 1999); position of Indian MORB. The other other intraplate DUPAL structures (10). component is closely similar to the

Editor's Note

The articles appearing in InterRidge News are intended to disseminate as quickly as possible preliminary results on recent mid-ocean ridge and back arc ocean cruises. Articles are not peer-reviewed and should not be cited as peer reviewed articles. The InterRidge office does edit the articles and strives to correct any grievous errors however all responsibility for scientific accuracy rests with the authors. Comments on articles that have appeared in InterRidge News are always welcome. Agnieszka Adamczewska InterRidge News Editor Vol. 11(1), 2002 37

International Research: Mid-Ocean Ridge: Pustovoy, et al., cont... volcanites of the neighboring hot spots (Gough, Tristan da Cunha, Discovery). Compositions of these The deadline for and most other within-plate volcan- InterRidge News 11(2) is: ites of the South Atlantic and Indian Ocean cluster along the mixing line of F and a component which is best 14 October, 2002 approximated by EM1, of the known end members. In this context, it • Format specifications can be found at would stand to reason to modify EM1, which is used conventionally http://www.intridge.org/irn.htm in isotope studies, toward somewhat • Send submissions by e-mail or by diskette via the greater 87Sr/86Sr ratios (roughly, 0.7065–0.7075). An EM1 component post to the InterRidge Office. so refined has the same meaning as LOMU (antithetical to HIMU), pro- posed recently in explanation of the types that have distinctive admix- ation and the Russian Academy of singularity of the DUPAL anomaly ture components are spatially dis- Sciences). (Douglass and Schilling, 1999). How- crete and form extensive isotope ever, the trend that stretches from a provinces of mid-oceanic ridges. In References plume component P, and on whose addition to the known MORB types, Douglass, J., and J.-G. Schilling,. Plume basis LOMU was recognized—and, normal (with HIMU admixture) and - ridge interactions of the accordingly, LOMU itself—are dis- DUPAL-MORB (with EM1 admix- Discovery and Shona mantle placed perceptibly from the mixing ture), a “singular” type is recog- plumes with the southern Mid- line of F and the refined EM1 into a nized. The latter, in terms of most Atlantic Ridge (40o-55oS). J. region with still greater 87Sr/86Sr val- parameters, is a counterpart of Geophys. Res., 104, B2, 2941-2962, ues (Fig. 4). This might be due to the DUPAL-MORB, but it has 206Pb/ 1999. fact that the slope of the trend was 204Pb and 207Pb/204Pb ratios similar to Hanan, B.B., and D.W. Graham. Lead determined chiefly from data points normal MORB. This type is charac- and helium isotope evidence from for Gough, Tristan da Cunha, and teristic of the ridges of the North oceanic basalts for a common deep Discovery rocks, which differ from Atlantic and Norwegian–Greenland source of mantle plumes. Science, the other within-plate DUPAL struc- Basin, which are recognized as con- 272, 991-995, 1996. tures in having somewhat higher stituting a separate Arctic province. Hofmann A.W. Mantle geochemistry: 87Sr/86Sr. Precise characteristics of Boundaries of isotope provinces for the message from oceanic volcanism. LOMU as the center of a rather mid-ocean ridges fit in with those of Nature, 385, 219-229, 1997. vaguely delimited region of African E–W transoceanic heterogeneities Mironov, Yu.V., V.M. Rhyakhovskii, and Australian kimberlitic and lam- identified earlier by our study on and A.A. Pustovoi A.A. Sr–Nd– proitic compositions are quite hard isotope compositions of rocks on Pb Isotopic Zoning in the World to obtain. At the same time, the re- intraplate rises and islands. Ocean and Mantle Plumes. fined EM1 is consistent with real Geochemistry International, 38, rocks dredged from the Afanasy Acknowledgments Suppl. 1, 20-27, 2000. Nikitin Rise, Indian Ocean. Our study was carried out with- Muhe, R., H. Bohrmann, D. Garbe- in the frames of the project to cre- Schonberg, and H. Kassens. E- Summary ate the Electronic Geodynamic MORB glasses from the Gakkel In the framework of our own Globe, headed by Academician Ridge (Arctic Ocean) at 87oN: modification of A.Zindler and D.V. Rundqvist, on the basis of a evidence for the Earth‘s most S.Hart’s Sr–Nd–Pb isotope system- software package developed at the northerly volcanic activity. Earth atics, mid-ocean ridge basalts are Department of Geo-Information Planet. Sci. Let., 152, 1-4, 1-9, 1997. defined dominantly as products of Technologies, SGM, Russian Rundqvist, D.V., V.M. Ryakhovskii, mixing of depleted mantle with a Academy of Sciences. This work Yu.V. Mironov, and A.A. Pustovoi. mantle reservoir F, which is involved was supported by the Russian Whether There Is a Universal Sr– in both rift-related and intraplate Foundation for Basic Research Nd –Pb Isotope Tracer of the Lower oceanic magmageneses. This reser- (project numbers: 00-15-98535, 00- Mantle Plumes. Doklady Earth voir is close to the average compo- 07-90000, 01-05-65497, 01-05- Sciences, 370 (1), 110-113, 2000. sition of all the components earlier 64182, 02-07-90140) and the Feder- Zindler, A., and S. Hart. Chemical proposed (C, FOZO, PREMA, etc.) al programme “World Ocean” (Min- geodynamics. Ann. Rev. Earth within the mantle tetrahedron. MORB istry of Sciences of Russian Feder- Planet Sci., 14, 493-571, 1986. 38 InterRidge News

International Research: Mid-Atlantic Ridge

New data on hydrothermal activity in the area of 12o57’N, MAR: initial results 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, Russia 2VNIIOkeangeologia, 1 Angliysky Pr., St.Petersburg, 190121, Russia

Introduction tive for massive sulphides. One of The basis for the investigations In September-November 2001, the sites is located 20 km north of the was provided by the results of R/V during the cruise of R/V Professor Marathon Fault which is situated at Geolog Fersman 10-th cruise (1991- Logatchev, the Polar Marine Geosur- 12o48’-13o04’N and 44o44’-45o00’W. 1992) and by new data obtained in vey Expedition (PMGE) in associa- The presence of stockwork sul- cruises of R/V Yuzhmorgeologia tion with VNIIOkeangeologia con- phide mineralization on the corner (Sudarikov et al., 2001) and R/V At- ducted comprehensive investiga- rise located at the rift valley/ Mara- lantis (Sudarikov and Zhirnov, 2001). tions in the axial MAR segment be- thon Fault junction at 12o48’N was During these expeditions, anoma- tween 13o and 18oN. The goal to be mentioned by P.A.Rona (1986) and lies were recorded in bottom waters sought was to reveal evidence of later confirmed during cruise 9 of the of western side of the rift valley recent and ancient hydrothermal ac- R/V Akademik Nikolai Strakhov between 12o54’-12o56’N and 44o52,5’- tivity and to discern areas perspec- (Raznitsyn et al., 1991). 44o55,5’W (the Neptune’s Beard area), rock samples with sulphide stringers and dissemination were recovered from dike rocks in the southeastern corner rise and high contents of iron hydroxides were recorded in the surface layer of bot- tom sediments. These data were the evidence for the presence of an ac- tive hydrothermal source in the study area.

Results The site is of complex structure comprising of intensively dislocat- ed volcanic and plutonic rocks throughout the section of the oce- anic crust from mantle restite peri- dotites up to basalts. The latter are common in the valley floor and in southern part of the site, plutonic rocks – in its northern part, though basalts, gabbroids and peridotites often meet in one dredge. Bedrocks showing hydrother- mal-metamorphic alteration within the site are confined to three struc- tural elements (Fig. 1): Figure 1. Structures and indications of hydrothermal activity. 1 - valley floor; 1) a steep slope in lower part of eastern 2 - axis neovolcanic rise; 3 - slopes of the rift valley; 4 - tectonic steps of rift side of the rift valley; valley slopes; 5 - rift mountains; 6 – tectonic faults; 7 - scarps; 8 – volcanic 2) a gentle slope in western side of the mounds; 9 - hydrothermal-altered rocks; 10 - sulphide dissemination; 11 - Fe- valley, dividing the floor and Mn crusts; 12 - anomalies in bottom water tectonic step; Vol. 11(1), 2002 39

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

3) a steep bench in upper part of western The easily observable sulphide respectively (Fig. 2a). Local maxi- side of the rift valley over the mineralization may be considered in mum of turbidity in layer 3757 m is tectonic step. metabasalts and especially in peri- 0.055 NTU, that is 6 times more than Within these structures the evi- dotites as the direct evidence of background values. The anomaly of dence of hydrothermal-metamorphic hydrothermal activity within the site. turbidity was recorded both down- rock recrystallization is associated It should be especially noted that all ward and upward CTD, the turbidity with submeridional faults embracing the rocks with sulphide mineraliza- being slightly higher downward. It the rift valley floor or dividing some tion were sampled from the western is of interest that temperature at the tectonic steps on the valley sides. side of the rift valley from a small turbidity anomaly level is lower than The evidence of stockwork sul- area (Fig. 1) located at 12o56’-12o59’N that of surrounding water (Fig. 2b), phide mineralization (pyrite and pyr- and 44o53’-44o56’W. and concentrations of dissolved rhotite) was recorded in one of the Based on evidence from CTD and manganese are anomalous (4 times fragments of serpentinized peridot- hydrochemical investigations, the higher than background values). ites. Silvery yellow-shaded sul- most promising location of hydrother- On the second station located 2 phides are present in the rock as mal activity is the northwestern area km north of previous, in layer 3900- rounded prolate grains, up to 3 mm of the site, showing evidence of a 3950 m, turbidity increases up to in size. In metabasalts from two sta- hydrothermal plume (Fig.1). 0.032 NTU (Fig.3a), this is more than tions, dispersed sulphide minerali- On one of the stations turbidity 3 times higher than background val- zation was recorded as rare quartz- is 0.003-0.006 NTU and 0.012 NTU, ues. A local maximum temperature is sulphide veins or minor accumula- more than background values in lay- observed in layer 3760 m (Fig. 3b) tions, 2-4 mm in size. ers 3660-3880 m and 3740-3780 m, and concentrations of dissolved manganese and methane are anom- alous (7 and 5 times higher than ABbackground values, respectively). The preliminary data show the 0.022 2.08 source of hydrothermal plume to be 0.012 13o00 839 0.021 2.07 located northwest of these stations 2.06 0.02 whereby hydrothermal products are 0.012 914 2.05 0.019 transported southward by deep cur- 0.012 904 2.04 0.018 12o58' rents. 2.03 0.017 Bottom sediments are very com-

0.018 0.011 0.023 838 902 2.02 0.016 873 mon in the study area and assigned to 2.01 0.015 carbonate coccolith-foraminiferal ooz- 0.012 903 2 12o56' 0.014 es. In order to reveal distribution ha- 1.99 0.012 894 loes of minerals (indicators of hydro- 0.013 1.98 0.012 893 0.013 0.012 820 821 822 thermal supply), mineralogical analy- 0.012 1.97 0.014 sis of surface layer (0-5 cm) of bottom 0.011 12o54' 1.96 44o54 52 50 44o54 52 50 sediment samples (0.5 l in volume) were performed onboard the ship. Figure2. Water transmissivity (A) and temperature (B) at the depth 3750m Immersion method was used for silty and sandy fractions. The sediments ABfrom central part of the site were stud- ied thoroughly, where the anomaly 0.023 1.94 centre had been recorded during the 0.022 13o00 1.935 R/V Yuzhmorgeologia cruise at 0.021 13o54.9’N and 44o53’W (Sudarikov et 0.02 1.93 al., 2001). 0.019 1.925

0.018 o The surface layer of sediments 12 58' 1.92 0.017 contains minerals-indicators of hy- 1.915 0.016 drothermal activity: pyrite, chalko- 0.015 1.91 pyrite, pyrrhotite, native copper, 0.014 12o56' 1.905 atacamite, barite, intermetals and iron 0.013 1.9 hydroxides. Pyrite, barite and iron 0.012 1.895 hydroxides prevail. Single signs of 0.011 these minerals are present in most of 0.01 12o54' 1.89 44o54 52 50 44o54 52 50 the sediment samples, but their high- Figure3. Water transmissivity (A) and temperature (B) at the depth 3910m est concentrations in the surface 40 InterRidge News

International Research: Mid-Atlantic Ridge: Bel’tenev, et al., cont... layer are recorded in sediments from suggest tectonic activity. In turn, dition for helpful participation in the the terrace of western side of the conditions favorable for deep research and in the book preparation. valley in the site centre (12o56’- penetration of water forming This work was partly supported 12o58’N and 44o54’-44o56’W). Fig- hydrothermal fluid are created in by the Russian Foundation for Basic ure 4 shows distribution of pyrite, tectonically active zones. Research, project no. 99-05-65258. barite and iron hydroxides in the 2) The source of hydrothermal plume surface sedimentary layer. Signs of in bottom waters is probably References these minerals regularly increase in located on the rift valley side in Rona P.A. Hydrothermal mineralization amount westwards to the slope foot; northwestern part of the study area. at seafloor spreading centers. direct correlation being observed 3) In the central part of the site (12o56’- Moscow, Mir, 1986, 160 pp. between pyrite and iron hydroxides 12o58’N and 44o54’-44o56’W) in the [Russian translation] suggesting a common source they surface sedimentary layer of the Raznitsyn Yu.N., S.G. Skolotnev, N.N. are supplied from. A source of these terrace of western valley side stable Turko, A.O. Mazarovitch, A.A. minerals is probably located in the dispersion haloes of hydrothermal Peive , L.E. Shterenberg. The foot or on the slope of upper west- minerals are observed, indicators junction zone of the Marathon fault ern side of the rift valley. High con- include: pyrite, barite and iron with the rift valley north segment: centrations of barite in the sediments hydroxides. Low-temperature Fe- structure, rock composition, sulfide probably suggest the presence of a Mn formations were sampled here mineralization (Central Atlantic). low-temperature hydrothermal vent on four stations. Doklady Akademii Nauk, 320 (4), in the immediate vicinity. 4) Rocks showing evidence of 952-956, 1991. [In Russian] On four stations in central part of hydrothermal-metamorphic Sudarikov S.M., M. P. Davydov, G. A. the site low-temperature manganese recrystallization associated with Cherkashev, V. V. Gubenkov, O. A. crusts were sampled (Fig. 1); they submeridional faults; sulphide Pivovarchuk, V. F. Kazachenok, represent unconsolidated sooty for- mineralization in metabasalts and and A. L. Mikhailov. A New Area mations of ellipsoidal or flattened peridotites suggest hydrothermal of Hydrothermal Activity in the shapes, 1-2 cm up to 10-16 cm in activity. Rift Zone of the Mid-Atlantic sizes. In some instances they form 5) The authors hereof consider most Ridge, 13o N. Doklady Akademii on sediments, in others, on both promising for massive sulphides Nauk, 381 (5), 1-5, 2001. [In sediments and basalt fragments. the foot and the slope of the upper Russian.Translated in English in valley side above the terrace with Doklady of Earth Sciences] Conclusions coordinates 12o56.5’-13o00’N and Sudarikov S. and Zhirnov E. 1) The vicinity of the transform fault 44o55.5’-44o57.5’W. Hydrothermal Plumes along the determines the morphological and Mid-Atlantic Ridge: Preliminary structural features of the study Acknowledgements Results of CTD Investigations area; numerous tectonic The authors are thankful to the during the DIVERSExpedition (July dislocations of different strikes crew of R/V Professor Logatchev, 2001). InterRidge News Vol. 10 (2), form a blocky structure and and to the research staff of the expe- pp. 33-36. 2001.

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44°57' 44°56' 44°54' 44°52' 44°57' 44°56' 44°54' 44°52' 44°57' 44°56' 44°54' 44°52' 13° 13° 13° 13° 00' 00' 00' 00'

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54' 54' 0 54' 54' 44°57' 44°56'44°54' 44°52' 44°57' 44°56'44°54' 44°52' 44°57' 44°56'44°54' 44°52' ABC 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). Vol. 11(1), 2002 41

International Research: Mid-Atlantic Ridge

Sulphide mineralization, volcanic and tectonic activity of the MAR near Sierra 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, Russia 2Institute of Geol. of Ore Deposits, Petrography, Mineralogy and Geochem., Russian Acad. of Sci., Moscow, Russia 3Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia 4United Institute of Geology, Geophysics and Mineralogy, Russian Academy of Sciences, Novosibirsk, Russia 5Instituto di Geologia Marina CNR, Bologna, Italy

The 10th cruise of R/V beam EM 12S echosounder and ex- by dextral faults including the Sierra “Akademik Ioffe” took place in the tensive dredging were carried out. Leone F.Z. Rift segments with ob- Central Atlantic from 3 October to 2 It was shown that this segment is lique spreading and overlapping rift November 2001. This was a contin- cut by only one major transform fault valleys are typical to this part of the uation of the previous expedition of - 7º10' (Bogdanov*), which divides MAR. The axial part of the MAR is the 22nd cruise R/V “Akademik this area from the segment to the asymmetrical in this region. Elon- Nikolaj Strakhov” to 5º - 7º N MAR north which has different structure gated ridges predominate to the west (Sierra Leone F.Z. area) (Peyve et (Peyve et al., 2001). In the 5º - 7º N from the rift valley, to the east the al., 2000), where mapping by a multi- area, the MAR rift valley is displaced sea bottom has a chaotic morpholo- gy and consists of separate isomet- ric highs and ridges. Several deep I1003 I1005I1006 I1011 basins, including Markov* hole Bogdanov F.Z. I1007 I1009 (5º55' N, 33º11' W), about 5000 m I1002 deep, were found in the rift valley 7°N I1012 I1010 (Fig. 1). According to the dredging results the rift valley floor, its ramps

I1029 I1030 and nearby ridge slopes are com- I1016 posed of serpentinous peridotites 6.6 and gabbro. Basalts are locally dis- tributed. All these peculiarities I1027I1026 speak for the predominance of the I1025 I1020 I1019 I1022 tectonic processes upon magmatic 6.2 I1028 in this MAR area. Dolerites with Sierra Leone F.Z. Markov hole sulphide minerogenesis (cubanite, I1031 chalcopyrite and pyrrhotite) were I1032 dredged in one of the overlapping I1043 I1042 5.8 I1041 segments just north from Sierra Leo- 30 I1040 ne F.Z. (Mazarovich et al., 2001). I1039 The current expedition set out 20 with the following aims: I1036 - to dredge different morphostructures 5.4 10 I1034 I1037 of the Bogdanov F.Z., 0 - to specify rock distribution in the S. America MAR axial part, especially in the I1044 -10 -70 -50 -30 -10 I1046 area with sulphide minerogenesis 5 I1045 and 34.5 34 33.5 33°W - to study flanks of the MAR crest using multibeam ECHOS XD Figure1. Bathymetric map of the study area. Circles - dredge stations; white echosounder and high frequency dotted line - axis of the ridge; black line - PARASOUND tracks profiler PARASOUND. 42 InterRidge News

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

We have found that basalts com- copyrite with some epidote and chlo- teenth meeting of the GEBCO, 17-20 pose huge neovolocanic highs rite. New data (Bazilevskaya, Skol- April 2001. (dredge stations S2246, I1039, I1045) otnev, in press) has shown that thin on the east rift flank (Fig. 1). These Fe-Mn oxide films on basalt surfac- References features indicate that powerful im- es from Markov hole (dredge I1043), Bazilevskaya E., Skolotnev S. Fe-Mn pulses of volcanic activity are tak- are fertilized in Cu, Zn, Fe è Mn2+, in crusts of the Sierra Leone F.Z. area ing place along with predominating comparison to Fe-Mn crusts from (Equatorial Atlantic) Doklady tectonic processes. Only basalts neighboring regions. These data Akademii Nayk (translated in were dredged from the flanks of the make it possible to think that recent- English in Doklady of Earth MAR crest (dredges I1009, I1010, ly or maybe today “black smoker” Sciences), in press. I1012, I1016, I1029, I1030, I1034, type ore formation is taking place in Mazarovich A., Sokolov S. Tectonic I1036, I1037, I1046) (Fig. 1). Chaotic the Markov hole. If this finding will position of hydrothermal areas on topography change to regular ridg- be confirmed by more detailed stud- the Mid-Atlantic Ridge. Litologia es on the east flank. These data let ies this will prove the validity of i poleznye iskopaemye, 4, 436-439, us think that geodynamic conditions observation made by (Mazarovich, 1998. of normal spreading with domina- Sokolov, 1998) that ore deposits like Mazarovich A., Simonov V., Peyve A., tion of magmatic processes, changed “black smoker” are situated in MAR Kovyazin S., Tretyakov G., not far ago to geodynamic regime areas with reduced seismicity. The Raznitsin Ju., Savelieva G., with the domination of tectonic proc- MAR between 5º - 7ºN is also char- Skolotnev S., Sokolov S., Turko N. esses. This happened approximate- acterized by low seismicity. Our Hydrothermal mineralization on the ly 2 ma ago, judging from the spread- observations let us think that com- Sierra Leone fracture zone (Central ing rate and distance from the rift bination of intensive tectonic proc- Atlantic). Litologia i poleznye axis to the area with different mor- esses and powerful impulsive mag- iskopaemye,5, 526-533, 2001. phology and composition. matic activity is favourable for cre- Peyve A., Bonatti E., Brunelli D., Basalts with quartz veins (up to ation of sulphide deposits. Chilikov A., Cipriani A., 5 mm) containing pyrite, chalcopy- Dredging of the Bogdanov F.Z. Dobrolubova K., Efimov V., rite and atacamite (?), as well as has showed that serpentinous peri- Erofeev S., Ferrante V., Gasperini amphibole – chlorite metasomatic dotites and gabbro predominate L., Hekinian R., Ligi M., Maurizio rocks, containing pyrite (dredge there, which is typical of the major- G., Mazarovich A., Perfiliev A., I1025) were collected near the point ity of transform faults. Raznitsin Ju., Savelieva G., Sichler where dolerites with sulphides were Study of the sediments structure B., Simonov V., Skolotnev S., found in 22 expedition of “Akademik in depressions on the flanks of the Sokolov S., Turko N. New data on Nikolaj Strakhov” (Fig. 1). Gabbro MAR crest with profiler “PARA- some major MAR structures: and numerous metasomatic rocks SOUND” has shown that sediments preliminary results of R/V with sulphide inclusions, quartz and are deformed there by numerous Akademic Nikolaj Strakhov 22 barite veins with sulphide grains horst structures. This is evidence of cruise.InterRidge News, 9, 28, 2000. (sphalerite?) and non-oxidized mas- widespread distribution of vertical Peyve A., Dobrolubova K., Efimov V., sive sulphide ore fragments were intraplate deformations in this seg- Cipriani A., Mazarovich A., collected from the east flank of the ment of the MAR. Perfiliev A., Raznitsin Ju., Markov hole (dredge I1032) (Fig. 1). Savelieva G., Simonov V., Petrographyñ studies have shown Acknowledgements Skolotnev S., Sokolov S., Turko N. that metasomatic rocks were formed We are grateful to technicians: Structural peculiarities of the Sierra after cataclastic gabbros. Accord- V. Velinskiy, A. Nosov, V. Kuznets- Leone fracture zone (Central ing to X-ray diffraction studies ov, S. Dremutchev, V. Rastorguev; Atlantic).Doklady Akademii Nayk metasomatic rocks are composed of captain V. Sazonov and crew of the (translated in English in Doklady prehnite, epidote, chlorite and am- vessel “Akademik Ioffe”. of Earth Sciences) 377, 6, .803-806, phibole and ore is composed of chal- * Name approved by the Four- 2001.

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 Vol. 11(1), 2002 43

International Research: Indian Ridge

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-500007 2 Department of Geology and Geophysics, IIT, Kharagpur, India 3Department of geology, Calcutta University, Kolkatta, India 4Department of Marine Geology and Geophysics, CUSAT, Cochin 5 National Institute of Oceanography, Dona Paula, Goa-403004

Introduction and India-Africa plate in the north the discussion of tectonic implica- The Northern Central Indian separated by the intersection of CIR tion of bathymetric and magnetic Ridge (NCIR) spans from 12° to 2°S and WDZ (Wide Deformation Zone). data of Vema region (Drolia et al., (Fig. 1) and constitutes an important Except the interpretation of few mag- 2000), results of reconnaissance regime of accreting plate bounda- netic lines in the Vema Transform survey during 28th cruise of R/V ries of Australia-Africa in the south area (Kamesh Raju et al., 1997) and Sonne (1983), no data of significance is available from the study areas. In the NCIR lacunae exist con- cerning plate kinematics, segmenta- tion pattern, petrologic variations and the influence of Ridge – Trans- form Interactions (RTI) on plate ge- ometry or on the formation of triple junction. The complex structural fea- tures and magmatic processes con- strain the formation of the new crust along the CIR and probably play a major 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 few areas in the world ocean where the kinematics of slow accreting plate boundaries and associated triple junction formation with low seismic activity remains poorly known. A 35 days expedition, on board R/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 NCIR after the one in July-Aug. 1997. The three fold objectives of the present cruise were 1) to establish the complexly faulted and segmented nature of the NCIR Figure 1. Location map of the study areas : Sealark (SL), Vityaz (VT) and Vema between the region 3.5°S-10.5°S, (VM). NW-SE oriented double lines are ridge segments. NE-SW trending 66-66°E, solid balck lines are Transform faults. 2) to obtain evidence for the nascent 44 InterRidge News

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

triple junction in the region south spacing of two nautical miles was Using the reversal time-scale of of Vityaz and North of Vema used during the survey. Cande and Kent (1995), we have Transforms and Three major TFs, Sealark, Vityaz modeled the observed magnetic pro- 3) to search for signatures of and Vema were mapped in detail for files and identified the anomalies. hydrothermal activity. the first time. Additionally the We have taken an average spread- Transform just north of Vema TF ing rate of 18mm /yr, magnetized Data Acquisition and processing (christened as Ehrlich Transform) layer thickness of 500m and suscep- The coverage consists of forty was mapped in detail. Rocks and tibility contrast of 0.01 c.g.s. units. five 110-160 km long profiles, orient- water samples from axial valley, We were able to identify magnetic ed N50°E across seven ridge seg- Ridge-Transform Interaction (RTI) anomalies 1 to 3. ments on either side of Sealark, Vit- and near-axis seamounts were re- Multibeam Swath Bathymetric yaz and Vema Transform faults be- covered. data were processed to obtain tween latitudes 3°S – 10°S. We have Post-cruise processing involved Bathymetric maps of the three re- collected high quality multi-beam digitization of echograms and inter- gions in the study area. The tectonic swath bathymetric, gravity and mag- polation of magnetic data at 1- minute elements of the Transform Faults: netic data over three intersecting intervals, and merging of the mag- i.e. Transform Tectonized Zone regions of Sealark Transform Fault netic filed intensity data with bathy- (TTZ), Transform Fault Zone (TFZ) (TF)-NCIR (SL area), Vityaz TF-NCIR metric data. Mathew’s correction and Principal Transform Displace- (VT area) and VemaTF-NCIR (VM was applied to the bathymetric data ment Zone (PTDZ); have been esti- area). Integrated and Global Posi- to get corrected depth. In case of mated by analyzing the multi-beam tioning system (GPS) was used for any discrepancy we had retained swath data. The Transform azimuth navigation. The digital magnetic Central beam depths provided by from trends of the Transform Val- data and analog bathymetric charts multi beam data. We interpolated leys was measured. were acquired using Geometric Pro- the magnetic and bathymetric data ton Magnetometer and a Honewell- at 1-km intervals. The magnetic anom- Results and Discussion Elac deep Sea Wide beam Echo aly was computed by subtracting The study region is characterized Sounder. The estimated accuracy of IGRF 2000 from the observed inter- by seven short ridge-segments and the recorded average depth was 10 m. polated total intensity data. We have six offsets with the longest offset The multi-beam Hydrosweep sys- used the revised ridge-transform being the 255 km Vema Transform. tem (STN Atlas Electronik GmbH) geometry of northern CIR (Fig. 1) The ridge segments are shorter than was used to obtain swath bathymet- based on latest satellite – derived transform segments with the sense ric data in the survey area. The sys- gravity map (Sandwell and Smith, of ridge offsets along the fracture tem was operated at 15.5 kHz and 1997). To facilitate the discussion of zones being uniformly right lateral. makes use of 59 Pre Formed Beams the accretionary units the ridge seg- Our results show that the sea (PFBs) with an average beam width ments have been numbered I to IX floor depths vary from 1500 to 6200m of 2.3°, providing swath coverage of and the transform faults / Fracture but are generally in the order of 2500- twice the water depth. For 100% zones as D1 to D9 from south to 4000m. The ridge segments are char- coverage (insonification), interline north. acterized by along-axis depth varia- tions: deepening at segment ends and swallowing at the central por- tion. In Vema and Vityaz region the SWIR Workshop ridge segment deepens at centre and shallows towards RTI. The Vityaz 17-19 April 2002 TF shallow and narrows towards SW SOC, UK as its width varies from 11 km in NE to 7 km in SW. The maximum –re- http://www.intridge.org/swirwksp.htm corded depth is 5400 m in NE part of the TF. The Vema TF is character- Workshop targets : ized by undulating valley floor hav- - synthesise most recent results obtained on the SWIR ing wavelength of 50 km and ampli- - develop plans for future study of the Indian ocean ridge system tude varying between 400 and 450 m. The width of the TF varies from 20 km in SW to 35 km in NE with 6-15 km Papers from this meeting will be incorporated into a proceedings wide floor humps of 200-300 m high volume in the electronic journal, G-cube: in the central part. These humps may (G3 http://g-cubed.org/). suggest that magma is upwelling through discreet feeder channels. Vol. 11(1), 2002 45

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

The average depth of the TF floor is The Ehrlich Transform (TF just have been identified across the ridge 6000m, which shallows to 4615m to- north of Vema TF) reveals a complex segments III to IX on various pro- wards NE with the maximum depth of morphotectonic characters compris- files (Fig. 2) in the three regions. The 6500m recorded on the flanks in the ing of alternating trough (4800m) median valley is characterized by central region. and crests (2300m) suggestive of broad amplitude anomaly of 200- The characteristics of the RTI, intense deformation. Detailed anal- 400nT in the three regions. Magnet- axial valley and TFs including the ysis of the forces responsible for ic anomalies associated with frac- occurrence of neo-volcanic zones this deformation may provide some ture zones are relatively subdued. along 29 ridge-normal profiles sug- clue about the dynamics of triple The anomaly amplitude is less than gest predominance of tectono-mag- junction evolution. 200nT across the deepest part of the matic activities in VT and VM areas Vema Fracture zone. We have esti- and dominance of tectonic activities Magnetics mated spreading rates along the in SL area. Magnetic anomalies up to chron 3 Africa / India and Africa / Australia plate margins since the time of anom- aly 3. The ridge-axis and anomaly 3 66û 67û 68û 69û 70û have been used for computing the -3û -3û flank spreading rates after matching the observed anomaly shape with the synthetic one. The mean half- spreading rate of 1.8cm/yr in the -4û -4û Sealark and Vityaz regions increas- es to 2.1 cm/yr to south of the Vema Transform. The nature of intra- and inter-segmental variations in mag- netic anomalies suggest that the -5û -5û region between south of Vityaz TF and north of Vema Transform seem to have distinct signatures of Africa- India / Africa-Australia plate mo- tion which could be possibly due to -6û -6û evolving triple junction in the re- gion.

Petrology -7û -7û Basalts from the axial valley are fresh, with a coating of glass (0.5 to 50mm) and contain abundant phen- ocrysts of plagioclase but rarely of olivine. Dredging the RTI yielded -8û -8û variably altered basalt and ferroman- ganese crusts and nodules and in- tensely bioturbated calcareous ma- terial with thick coating of Fe-Mn -9û -9û oxide (Mukhopadhyay et al., 1998). During the SK 165, rocks from near- axis seamounts (Station 9DG on western side of segment III) were recovered. These are dominantly -10û -10û columnar while few are pillow ba- salts, suggesting the probability of eruption of two types of lava flow in the past. The first flow probably formed pillow basalts while the later -11û -11û eruption with columnar structure 66û 67û 68û 69û 70û was emplaced as dyke. The pres- Figure 2. Plot of magnetic anomalies perpendicular to cruise track lines in the ence of two types of basalts may study area. help explain the rise and fall of tem- 46 InterRidge News

International Research: Indian Ridge: Drolia, et al., cont... perature across the Curie point and centre in Vema and Vityaz region This paper is published with the consequently the observed over- whereas Sealark region depicts deep- permission of the Directors of NIO print magnetization of the oceanic ening at the segment end and shal- and NGRI. The project is funded by crust (Drolia et al., 2000). The sam- lowing at the segment centre. The the United States India Fund through ples mainly have plagioclase that Ehrlich Transform (TF just north of ONR Grant # N 00014-97-I-0925. occurs as phenocrysts but mostly Vema TF) reveals a complex mor- as laths and tabular forms. Olivine is photectonic character suggestive of References less abundant and in some cases intense deformation. The nature of Cande S.C. and Kent D.V. 1995, empty vesicles are very common. intra- and inter-segmental variations Revised calibration of the The occurrence of amphiboles in in magnetic anomalies suggest that geomagnetic polarity time scale one sample is intriguing. The basal- the region between south of Vityaz for the late Cretaceous and tic fragments of another near-axis TF and north of Vema Transform Cenozoic, Jour. Geophys. Res, seamount (24DG) are aphric to seem to have distinct signatures of 100, 6093-6095. sparsely phyric and altered. Africa-India / Africa-Australia plate Drolia R.K. et al 2000, Magnetic and The manganese nodules with low motion which could be possibly due bathymetric investigations over Mn/Fe ratio (<1) and low values of to on evolving triple junction in the the vema region of the Central Cu and Ni than those from basinal region. Indian Ridge:Tectonic regions indicate their possible hy- implications, Marine Geology, drothermal-hydrogenous origin. Acknowledgements 167,413-423. We acknowledge the Department Kamesh Raju K A et al 1997, Summary of Ocean Development, New Delhi Geophysical investigations over The high quality multi-beam for kindly making R/V SagaKanya a segment of Central Indian Ridge, swath bathymetric, gravity, magnet- available for the cruise and the De- Indian Ocean, Geo-Marine Letters, ic and bathymetric data were col- partment of Science and Technolo- 17,195-201 lected over three intersecting regions gy for partial funding (grant # ESS/ Mukhopadhyay R et al 1998, Current of Northern Central Indian Ridge 23/VES/060/99). We thank Dr. M. Science, 75,1157-1161 (NCIR) during a recent cruise on Sudhakar of National Centre of Ant- Sandwell DT and Smith WHF 1997, board ORV SagarKanya. Preliminary arctic and Ocean Research, for Marine gravity anomaly from results suggest along-axis depth scheduling the cruise and logistic Geosat and ERS1 satellite variations: deepening at segment support and the Captain and crew of altimetry, Journal of Geophysical ends and shallowing at the segment SK165 cruise for rendering all help. Research, 102, 10039-10054.

A SPECIAL ISSUE ON ANCIENT AND MODERN SEAFLOOR VOLCANOGENIC 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 Sergey Krasnov (1952-1996). The special issue accesses for the first time new Chinese work on volcanogenic massive sulfide (VMS) deposits, as well as related seafloor hydrothermal research by the international community. The Chinese papers report a surge in exploration for and discovery of ancient VMS deposits in P.R. China stimulated by 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 Hydrothermal Deposits (Volcanic Island Arcs and Ocean Ridges)

More detailed information about the contents of this special issue can be obtained from the InterRidge homepage at: 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, Canada Tel.: (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 Vol. 11(1), 2002 47

World Ridge Cruise Map, 2002

A listing of international ridge cruises can be found on the following pages. Each cruise is coded with a number, which represents it's location on the map below. The list of world cruises is organised by date. Please submit scheduled and upcoming cruises by filling in the online form at: http://www.intridge.org/cruisefm.htm 0E 30N 30S 13 8 18 60N 60S 4 16 17 3 10 180E 180E 7 6 120E 120E 5

2

60E 60E

120E 60E 60E 60E 0E 0E 0E 180E 15

11

120W 120W 120W

60W Ridge Cruises 2002 60W 60W 6 120W 120W 12 9 1 14 180E 180E 60S 60N 30S 30N 0E 48 InterRidge News

World Ridge Cruise Schedule, 2002, continued... Jan 8 - Feb 24, '02 Dec 9, '01 - Dec 9, '01 Jan 1, '02 Jan 21 - Feb, '02 Mar 24 - Apr 13, '02 Jan 6 - Jan 25, '02 Apr 26 - '02 May 11, Jan 6 - Feb 10, '02 Jan 27 - Feb 12, '02 Dec 21, '01 - Jan 15, '02 Jan 26, '02 Kairei Atlantis Yokosuka Melville Atlantis Alvin Kairei Atlantis Alvin Hakuho Maru Yokosuka Maurice Ewing Sediments and microbio sampling at a hydrothermal area Physiological Ecology of Hydrothermal Vent Vent Ecology of Hydrothermal Physiological Species Symbioses. Chemoautotrophic in Mussel Bed and Biodiversity Composition Vents Communities of Hydrothermal Shinkai 6500 submersible dives at hydrothermal sites Mid-Cretaceous Tectonic Evolution of the Tectonic Mid-Cretaceous in the Southwest Junction Triple Tongareva Pacific Basin Petrological investigation of the Parece Vela Vela of the Parece Petrological investigation center. backarc basin spreading Systems: East Pacific Rise Hydrothermal Instability at 9-10 Continued Chemical at 21 degrees N degrees N vs. Stability The Fate and Implications of Removal of The Fate and Implications of Removal Hydrothermally-Injected NH4+ from Plume Waters Shinkai 6500 submersible dives at lower Shinkai 6500 submersible crust and mantle outcrop Crustal study by OBMs and high resolution Crustal study by OBMs and high resolution deep-tow magnetometer Effects of Changes in Mantle Temperature on Temperature of Changes in Mantle Effects An MCS Accretion: Melt Supply and Crustal of the Reflection and OBH Refraction Study Southeast Indian Ridge Mariana Trough and Mariana Arc and Mariana Trough Mariana East Pacific Rise East Pacific Parece Vela Basin Parece Vela Philippine Sea Southwest Indian Ridge Atlantis II FZ Yokohama Yokohama Ntnl. Univ. UCSB Penn State Wm&Mary URI U of HI Hydrogr. Dept. Japan JAMSTEC LDEO Ohara Childress Fisher Dover Van USA USA Larson Southwest Pacific Basin USA Damm Von UNH East Pacific Rise USA Cowen Guaymas Basin USA Cochran Ridge Southeast Indian Japan Arima Japanjunction Takaitriple JAMSTEC Rodriguez Japan Matsumoto Japan USA Japan Shinohara Discordance Australia-Antarctica Country PI Institution ID/Location Cruise Objectives Research Ship Dates 1 5 8 9 3 7ERI 2 6 4 1 Map No. Vol. 11(1), 2002 49

World Ridge Cruise Schedule, 2002, continued... May '02 May 24 - Jun 4, '02 May 23 - Jun 10, '02 Jun 16 - Jun 29, '02 Jun 8 - Jun 22, '02 Jun 10 Ð Jun, 24, '02 Jun 26 - Jul 14, '02 Jul 5, '02 May 14 - May 23, '02 May 7 - Jun 24, '02 May 24 - Jun 14, '02 Le Suroit L'Atalante Victor ROV Atlantis Alvin Tangaroa Roger Revelle Hakuho-maru Poseidon Atlantis Alvin/ABE Hakuho Maru Tangaroa In-situ experiments and In-situ experiments interactions biogeochemical Deployment of six moored autonomous Deployment of six moored the seismicity of hydrophones 1) to monitor FZ; Azores and Gibbs the MAR between the 2) to produce a high-resolution tomographic in model of the upper mantle below a ridge a ridge/hotspot context CTD and in situ chemical mapping and fluid CTD and in situ chemical mapping and sampling if hydrothermal plumes associated with active volcanoes Juan de Fuca Plate Geodesy: Juan de Fuca Juan de Fuca Plate Geodesy: Juan de Fuca Ridge and Cascadia Subduction Zone High resolution deep-tow sonar mapping High resolution deep-tow sonar mapping with geochemical sensors Volcanology of spreading north of Iceland Volcanology Hydrothermalism of the Grimsey field Geochemistry of the plume-ridge transition Central Anomaly Magnetization High: Anomaly Magnetization Central Construction and Volcanic Constraints on the Upper Oceanic Crust Young Architecture of Multibeam mapping, rock dredging, seafloor Multibeam mapping, rock dredging, seafloor fauna sample and epibenthic photography, along volcanoes of the arc front Deep tow sidescan sonar survey of the sidescan sonar survey Deep tow rift zone Galapagos RiftAnniversary Galapagos 25th East Pacific Rise - PHARE East Pacific Arc, 35-30 S Southern Kermadec Azores-Gibralter Atlantic) North - (SIRENA Southern Kermadec Arc, 35-30 S Southern Kermadec Southern Okinawa Trough Trough Southern Okinawa Southern Okinawa Trough Trough Southern Okinawa biology by Submersible Shinkai 2000 Vent Natsushima 13 Ð May East Pacific Rise NIWA U. Kiel VUW NOAA WHOI GNS NOAA U. Kiel Kyushu Univ. ORI U. Bremen Tjoernes Fracture Zone JAMSTEC WHOI UCSB ORI Hammond Embley Fornari Shank Gaill Bris Wright J. Goslin U. Brest Ronde Massoth Tokuyama Okino Tamaki Devey Scholten Fujikura Schouten Tivey Fornari Madonald USA France New Zealand France US Portugal New Zealand USA Spiess SIO Juan de Fuca Ridge Japan Germany Iceland USA Japan Japan TamakiTrough Southern Okinawa 1 U. Pierre 11 1 12 13 14 10 15 10 13 10 50 InterRidge News

World Ridge Cruise Schedule, 2002, continued... Jul 8 - Aug 7, '02 Jul 17 - Jul 27, '02 Aug 3 - Aug 15, '02 Aug 4 - Aug 25, '02 Aug 5 - Sep 2, '02 Jul 14 - Aug 15, '02 Aug 22 - Sep 18, '02 Sep 10 - Sep 27, '02 Aug 24 - Sep 9, '02 Aug 29 - Sep 23, '02 Hakurei-Maru Shinsei-Maru Atlantis Alvin Melville Onnuri Natsushima Onnuri Onnuri Atlantis Jason II Maurice Ewing New Content and Functionality for the and Functionality New Content Synthesis RIDGE Multibeam Shallow drilling at hydrothermal site of Shallow drilling at hydrothermal Arc for Suiyo Seamount, Izu-Bonin sub-vent biosphere and sediments Sampling of fluid, microbes Archaean Park from Suiyo Seamount, of Removal of The Fate and Implications Hydrothermally-Injected NH4+ from Plume Waters Collaborative Research: Geochemical and Collaborative Research: Geochemical and Rift Geological Investigation of the Incipient at 2o40'N, east of the East Pacific Rise Seafloor mapping and geophysical the investigation of the eastern boundary of Trough, Caroline Plate and Sorol equatorial western Pacific. KODOS 2002 - Reconnaissance survey of - Reconnaissance KODOS 2002 hydrothermal vents. Longterm observatory at vent sites by Submersible Shinkai 2000 and ROV Geophysical, multichannel seismic, near bottom observation, and geochemical and biological investigations of New Ireland Forearc Basin, Collaborative Research: Direct Sampling of Collaborative Research: Direct Sampling the Oceanic Sub-Surface Biosphere at Old Seamounts. and Young Izu-Bonin Arc Suiyo Seamount Izu-Bonin Arc Pacific Western Juan de Fuca Ridge Endeavour Daeyang Program 2002 Leg 1 Bismark Sea volcanoes, Western PACMANUS Juan de Fuca Ridge Daeyang Program 2002 Leg 2 Plate and Caroline Trough Sorol Kyushu Univ. Duke Univ. JAMSTEC KORDI UW Dartmouth Field Museum KORDI Johnson Sharma Voight S-M Lee USA Carbotte LDEO Juan de Fuca Ridge USA USA Cowen U of HI Japan Ishibashi Japan Urabe GSJ USA Klein Hess deep Japan Kinoshita Ogasawara (Bonin) Arc (Bonin) Japan Kinoshita Ogasawara Korea Lee K-Y KORDI North Fiji Basin Korea S-M Lee Korea Country PI Institution Cruise ID/Location Objectives Research Ship Dates 14 14 17 17 14 12 18 17 16 16 Map No. Vol. 11(1), 2002 51

World Ridge Cruise Schedule, 2002, continued... 2003 Oct 20 - Nov 16, '02 Oct 28 Ð Nov 12, '02 Nov 2 - Dec 5, '02 Sep 17 - Nov 4, '02 Sep 13 - '02 Oct 11, Nov 9, '01 - Jan 3, '02 Nov 20 - Nov 26, '02 Nov 30 - Dec 22, '02 Atlantis Alvin Kairei Melville Maurice Ewing Sonne New Horizon (w/Atlantis) Atlantis Alvin Atlantis Alvin Atlantis Lexen, Alvin Biological collections at vents and seeps, chemical and geological studies, mapping Collaborative Research: Investigation of the Collaborative Research: Investigation of Origin of Non-hotspot, Intraplate,Volcanic Ridges and Cross-Grain Gravity Lineations Upper mantle structure by electromagnetic Upper mantle structure by electromagnetic study Shallow drilling (5m) of an epithermal (gold) (5m) of an epithermal Shallow drilling Seamount on top of Conical mineralization Research: Seismic Collaborative Margins: of Gulf of California and Geologic Study Rifting and Magmatism Collaborative Research: Studies on the Collaborative Research: Studies on the Vent Physiological Ecology of Hydrothermal Chemoautotrophic Symbioses Long-Term Monitoring of Off-Axis Monitoring of Off-Axis Long-Term Hydrogeology on the Costa Rica Wireline Rift Using an Instrumented Multi-Packer System Collaborative Research: Eurythermal Collaborative Research: Environment by Adaptations to an Extreme Vent Hydrothermal the Symbionts of the Polychaete, Alvinella Pompejana. of Filamentous Microbiology and Ecology Sulfur Formation. Collaborative Research: Studies on the Vent Physiological Ecology of Hydrothermal Chemoautotrophic Symbioses Gulf of California Gorda Ridge seeps Valley Monterey Fan Mariana Trough Mariana Trough East Pacific Rise New Ireland Basin New Ireland SO-166, CONDRILL Juan de Fuca Ridge Costa Rica Rift East Pacific Rise Brown Univ. UCSB U Miami UCSB Penn State Field Museum U Delaware WHOI NOAA Kobe Univ. Kobe Univ. Freiberg Tech Georgia Lizarralde Cary Taylor Cavanaugh Becker Childress Fisher Voight Herzig Hannington Skinner Childress USA USA USA ForsythUSA East Pacific Rise USA USA Japan Seama Germany Canada UK USA 4 14 1 14 9 16 1 12 1 52 InterRidge News

National News....

United Kingdom

An important first piece of news 2) Seafloor Observatories. initiate surveys of life in vent and seep from the UK is that we have recently A submission was presented to communities on the ocean floor. The secured a transition for funding of the NERC in late 2001 to support a UK initial stages of this international UK membership of InterRidge from observatories initiative (B-DEOS) with project – which, clearly, will have sig- the now disbanded BRIDGE pro- various mid-ocean ridge interests. nificant interest to many members of gramme to its host funding agency, Although this proposal, coordinated InterRidge – will be co-hosted by Profs. the Natural Environment Research by Prof.Adam Schultz at the Univer- Paul Tyler and Chris German at SOC, Council. sity of Cardiff, was not funded in the UK. Funding is for three years, in the With the current subscriptions fi- first instance, NERC have accepted first instance, commencing summer nally in place, Chris German will now the scientific merits of the case pro- 2002. For further details, please con- stand down as one of the UK’s two posed and have adopted the B-DEOS tact Prof.Paul Tyler: national representatives. Paul Dando initiative as an important future pro- [email protected] . will continue in that role and a new gramme deserving of support. An second representative will be an- important part of current UK thinking 4) Vent Aqauria. nounced shortly (watch this space!) is that this may be an initiative best An aquarium system for hydro- From a research perspective, we served through collaborative funding thermal vent animals from the Mid- have four items of news worthy of e.g. through a wider EC initiative linked Atlantic Ridge has been developed, particular mention:- to the MOMAR concept (note the with funding from the EU VENTOX InterRidge MOMAR II workshop in project, at the School of Ocean Sci- 1) 6500m ROV. Horta, 15-17 June). Further details: ences, University of Wales-Bangor. The contract for a deep-diving [email protected] . Cooled seawater tanks, in a quaran- 6500m ROV was placed by SOC, on tine facility, are supplied with both behalf of the UK research community, 3) Census of Marine Life/ sulphide and methane. Vent mussels with the Woods Hole Oceanographic Chemosynthetic Ecosystems - ChEss. have maintained their symbionts for Institution in late 2001. A team of UK On March 26th 2002, the Sloan over 8 months in the system which, it engineers have now begun work with Foundation Board met to review the is hoped, will provide a long-term the Woods Hole team in the USA and Census of Marine Life (CoML) pro- source of living animals for biological completion of the build is scheduled gramme in its entirety, and among it studies. For further details, please for January 2003. Shiptime for deliv- deliberations approved funding of a contact Prof. Paul Dando: ery and training cruises is currently pilot study “ChEss” to design and [email protected] . being negotiated for Spring/Sum- mer 2003 with first research expedi- Dr. Chris German, National Correspondent tions anticipated in 2004. For further Challenger Div. for Seafloor Processes details, contact Prof.Paul Tyler at Southampton Oceanography Centre SOC: [email protected] or European Way, Empress Dock check the website at: http:// Tel: + 44 1703 596 542 Southampton, SO14 3ZH, www.soc.soton.ac.uk/OED/ROV/ Fax: + 44 1703 596 554 United Kingdom index.php# E-mail: [email protected]

InterRidge - Japan

Archaean Park (AP) project (PI: T. many samples from the caldera of Suiyo five posters at the Ocean Science Urabe) has been successfully pursued Seamount, a hydrothermally active Meeting (AGU and ASLO) held at since its start in 2000. For the purpose volcano of the Izu-Bonin Arc in the Honolulu on 11-15 February 2002 (http:/ of interdisciplinary characterization of Philippine Sea. Some of the preliminary /www.agu.org/meetings/ subseafloor biosphere, the project plan, results on geological, geophysical, os02top.html). There were two ses- in 2001, involved drilling by BMS (Bor- geochemical, and microbiological stud- sions OS32O and OS31F (Physical, ing Machine System) and taking of ies were presented as six lectures and chemical, and biological processes Vol. 11(1), 2002 53

National News.... associated with active submarine Japan. Two cruises (with five legs) of bathymetric surveys. For a detailed volcanism in the Pacific I (co-chaired R/V Natsushima (with DSRV Shinkai hydrothermal plume mapping, several by T. Urabe) and II (co-chaired by M. 2000; PIs: F. Inagaki, M. Tokeshi, and MAPRs (Miniature Autonomous Kinoshita) for their presentations. K. Fujikura) and a cruise by R/V Plume Recorder) of NOAA/PMEL (PI: Targets of the Japan InterRidge- Hakuho Maru of ORI, Univ. of Tokyo, E. Baker) will be attached to related projects of this year (2002) are are planned in April to July 2002. WADATSUMI as a collaborative chiefly in the northwestern Pacific Shinkai 2000 will dive both in the mid- study between Japan and US RIDGE. Ocean close to Japan as described Okinawa Trough and in the south- After the WADATSUMI surveys, below. western most Okinawa Trough where CTD hydrocasts (PI: T. Gamo), heat The AP project will continue the many high temperature fluid venting flow measurements (PI: M. Yamano), investigations at Suiyo Seamount sites have been located. The Hakuho and rock dredges (PI: R. Shinjo) will be between July and September this year. Maru cruise (PI: H. Tokuyama) will performed to get geophysical and Plans are to drill deeper holes and to utilize high resolution deep-tow side- geochemical data of the ridge activity. deploy many more instruments for scan sonar system WADATSUMI long term monitoring than last year. (ORI, Univ. Tokyo) together with a Toshitaka Gamo There are three cruises planned; by high quality SeaBeam 2120 system for Hokkaido University R/V #2 Hakurei Maru for BMS drill- ing (PI: T. Urabe), R/V Shinsei Maru (with ROV Hakuyo 2000; PI: J. For more information on InterRidge-Japan contact: Ishibashi), and R/V Natsushima (with Kensaku Tamaki 15 dives by DSRV Shinkai 2000; PI: Ocean Research Institute, M. Kinoshita) of JAMSTEC. University of Tokyo Tel: + 81 3 5351 6443 Investigations of ridge processes 1-15-1 Minamidai, Nakano, Fax: + 81 3 5351 6445 will also be carried out in the Okinawa Tokyo 164-8639, Japan E-mail: [email protected] Trough backarc basin, southwest of

Korea

Two research cruises in backarc August 24 to September 9 with port Third, a multibeam bathymetric sur- basin will be conducted by KORDI calls at Rabaul and Madang, Papua vey will be performed over several this year. The first is a short recon- New Guinea. The objectives of this seamounts, which form the western naissance survey of the North Fiji cruise are as follows. First, in the New Bismark arc. From September 10 to 25, Basin, which will be led by Dr. Kyoung- Ireland forearc basin multichannel R/V Onnuri will also make a number of Yong Lee. During this cruise, scien- seismic profiling will be conducted observations in the Philippine Sea and tists will collect rock samples in order over the Conical, TUBAF and Edison Caroline Sea on the way back to Ko- to understand the hydrothermal min- seamounts and the Horst Structure, rea. These include reconnaissance eralisation process in the backarc en- which are the sites for an IODP pro- survey of the eastern boundary of the vironment. This survey will be con- posal. Second, a deep-tow magnetic Caroline Plate and geophysical inves- ducted from August 8 to 15 and upon survey is planned over the sites drill- tigation of the Sorol Trough. Scien- completion of the surveys R/V Onnuri ing during ODP Leg 193 in order to tists from Australia, Germany, USA, will make port call at Suva, Fiji on resolve the detailed magnetic struc- and Papua New Guinea are expected August 16-17. The second will con- ture of felsic hydrothermal mound. to be involved in the second cruise. sist of survey at three different sites in Papua New Guinea as part of Daeyang Program 2002. The three sites are New Sang-Mook Lee, National Coorespondent Ireland forearc basin south of Lihir Deep-Sea Resources Research Center Island, PACMANUS hydrothermal Korea Ocean Research and Development Institute vent fields, and seamounts in the Ansan, P.O. Box 29 Tel: + 82 345 400 6363 western Bismark Sea. The chief scien- Seoul 425-600, KOREA Fax: + 82 345 418 8772 tist of this cruise is Dr. Sang-Mook Email: [email protected] Lee. This cruise will take place from 54 InterRidge News

National News....

USA: RIDGE

The Ridge 2000 programme (R2K) tectonic events along the global mid- of energy and material from Earth’s is a new, US National Science Founda- ocean ridge system. To this end, the deep mantle, through the volcanic and tion (NSF) sponsored research initia- theme focuses on the immediate bio- hydrothermal systems of the oceanic tive to understand the Earth’s spread- logical, chemical and geological con- crust, to the overlying ocean. Moreo- ing ridge system as an integrated sequences of active processes on the ver, this part of the programme recog- whole, from its inception in the mantle seafloor. Such processes generally nizes that the complex linkages be- to its manifestations in the biosphere occur as transient events and include tween life and planetary processes at and the water column. The R2K Pro- volcanic eruptions and intrusions of mid-ocean ridges can only be under- gramme was conceived to promote an magma at the ridge axis and faulting stood through coordinated studies integrated approach towards the study related to seafloor spreading. that span a broad range of disciplines. of mid-ocean ridges. Emerging from Since 1993, event detection and Thus, Integrated Studies will consist community workshops over the past response efforts have focused on two of multidisciplinary research that is two years, R2K builds directly on the short ridge systems (the Juan de Fuca focused on a small number of pre- scientific and technological successes and Gorda Ridges, northeastern Pa- selected “type” areas that are designed of the RIDGE Programme. The scien- cific Ocean) and have revolutionized to characterize segments of the mid- tific motivation for the R2K Programme our understanding of these active ocean ridge system. The objective of is encapsulated in the phrase “from processes. The field response to Integrated Studies is to develop quan- mantle to microbes” that expresses events detected using the SOSUS ar- titative, whole-system models the inextricable linkages between proc- ray (the Navy’s cabled hydrophone through coordinated and interdisci- esses of planetary renewal in the deep system in the northeastern Pacific plinary experiments. It will be neces- ocean and the origin, evolution and Ocean) has provided fundamental new sary for scientists to understand the sustenance of life in the absence of information about the linkages be- interactions and linkages between the sunlight. R2K is at the beginning of an tween volcanic events at the seafloor, volcanic, tectonic, geochemical and anticipated 12-year programme. the development of hydrothermal biological systems to achieve this The R2K Science Plan aims for a plumes in the ocean above the ridge goal. comprehensive understanding of the crest, hydrothermal circulation and The Integrated Studies theme will relationships among the geological vent biota. initially focus on three sites that were processes of plate spreading at mid- Under the R2K Programme, Time- chosen on the basis of a community ocean ridges and the seafloor and Critical Studies are dedicated to facili- vote and a review by a special R2K sub-surface ecosystems that they tating rapid-response missions that Integrated Site Selection Panel support. Research carried out under can observe, record and sample these ( http://R2K.bio.psu.edu/ this new programme will be structured critical transient phenomena in the ISPANELRPT.htm). These sites will within an integrated, whole-system ocean above the mid-ocean ridge as be centered on a portion of: approach that will encompass a wide well as on the seafloor itself. In the - 9-10°N segment of the East Pacific range of disciplines. Specific geo- initial phases of this element, the pro- Rise; graphic areas will be the focus of de- gramme will be restricted to the north- - The Endeavour Segment of the Juan tailed studies to yield new insights east Pacific where real time detection de Fuca Ridge; into the linkages among the biologi- is possible through the SOSUS array - Either the East or Central Lau Basin cal, chemical and geological processes and where the facilities are available Spreading Center. that are involved in crustal accretion for a rapid response. and subsequent ridge crest processes. Programme Status The R2K Programme will support two Integrated Studies The R2K Programme officially be- main research themes: Time-Critical The Integrated Studies theme of gan October 15, 2001, when the office Studies and Integrated Studies. R2K is intended as a programme of opened at Penn State University. focused, whole system research of Charles Fisher, a professor of biology Time-Critical Studies global mid-ocean ridge processes. at Penn State University is chairing The goal of the Time-Critical Stud- This component addresses the com- the Steering Committee for the pro- ies element is to understand the na- plex, interlinked array of processes gramme with guidance from an Execu- ture, frequency, distribution and that support life at and beneath the tive Committee consisting of Deborah geobiological impacts of magmatic and seafloor as a consequence of the flow Smith from WHOI, James Cowen from Vol. 11(1), 2002 55

National News....

the University of Hawaii, and David vited speakers, a discussion led by an ment to data management and the Christie from Oregon State Univer- interdisciplinary panel after each talk, rapid dissemination of metadata and sity. In addition to Fisher, the R2K and general poster sessions. Speaker data. Sharing data will maximize tech- programme office has three full time notes and figures, white papers, avail- nology transfer across the programme, staff members. Deborah Hassler is the able data sets, maps, publications, encourage integration of science, co- Ridge 2000 programme coordinator. and bibliographies from the workshop ordination of research, and the con- She is a graduate of the MIT/WHOI can be found at the R2K website. struction and testing of hypotheses. Joint Programme in Oceanography, Implementation plans for each of R2K is a time limited programme, thus and joined the programme following the initial Integrated Study sites were all data collected will be rapidly re- her NSF sponsored Postdoctoral Fel- developed at an open Implementation leased for maximum benefit to all. A lowship at Harvard University with Plan Workshop on April 7-8, 2002 in draft statement regarding this policy Roberta Rudnick. Patty Nordstrom is Albuquerque, NM. These plans iden- is available on the R2K web site for the new programme assistant. Patty tified the geographic focus about comment. has a MS degree in extension educa- which the nested components of each Along with the programme ele- tion and brings a wealth of organiza- Integrated Study will be centered and ments discussed above, R2K is spon- tional, web, and practical experience provided the guidelines for the com- soring a postdoctoral fellowship pro- to the office. Liz Goehring is the edu- ponents that will constitute the set of gramme. The fellowship is intended to cation and outreach coordinator for Integrated Studies necessary at each foster cross-disciplinary fertilization the programme. Liz had 10 years of site. by providing opportunities for indi- experience as a systems engineer with The NSF Programme Announce- viduals to broaden their research ex- IBM, before she obtained a MS de- ment for R2K is available on the NSF pertise as well as to expand the breadth gree in ecology, became involved in and R2K websites and proposals for of ridge science. secondary education outreach activi- funding work at the three Integrated ties and then taught for several years Study sites will be considered begin- Contact Us in the public school system. ning with the August 15, 2002 Ocean Two workshops were conducted Sciences (OCE) target date. The re- in early 2002, one for scientific back- sults of the Community Education and ground and one for planning. These Implementation Plan Workshops are workshops were designed to provide also available on the web site. R2K opportunities for a broad cross-sec- proposals are subject to the normal tion of scientists and engineers to peer-review process and will be re- share information about the Integrated viewed by the regular NSF Ocean To join the mailing list, for timeta- Study sites and to participate in plan- Science Division Panels. Addition- bles, data, upcoming meetings and ning the implementation of the re- ally, the R2K Steering Committee will workshops, contacts and other infor- search programme. perform a relevancy review of all R2K mation about the programme, email us The Community Education Work- proposals. at [email protected], see the shop was held in Long Beach, CA Feb. An important component of the website at http://R2K.bio.psu.edu or 25-27, 2002. Approximately 110 peo- R2K programme is a strong commit- call 814-865-RIDG. ple attended. The primary purpose of this workshop was to provide a forum For more information contact: for community education and the shar- RIDGE Office ing of data among all investigators 208 Mueller Laboratory Tel: + 1 814 865 3365 wishing to write proposals for work at The Pennsylvania State University Fax: + 1 814 865 9131 one of the Integrated Study sites. Each University Park, PA 16802, E-mail: [email protected] day was devoted to one Integrated USA URL: http://R2K.bio.psu.edu Study site and featured several in-

Previous updates from various Nations can be found on the IR web site under the menu "Member Nations" or by going directly to: http://www.intridge.org/act4.html 56 InterRidge News

National News....

MauRidge

By creating the Mauritius Ocea- be beneficial to the Mauritian scien- three foreign scientific cruises ob- nographic Institute (MOI) in January tists in terms of training and experi- tained the approval of the Govern- 2000, Mauritius has expressed its deep- ence in that new area of research. ment of Mauritius to run scientific est interest towards ocean explora- The academic and economic ben- expedition on the part of the CIR fall- tion and research. The idea of setting efit that could be extracted from un- ing in our EEZ. We are presently work- up such an institute was triggered by dertaking ridge research are signifi- ing on bathymetric and magnetic data the fact that the Republic of Mauritius cant to motivate and arouse the en- collected from the area limited by 18° has an EEZ which is 1.9 million km2 thusiasm of Mauritian scientists to be S and 20.6° S along the CIR. and, by the time of its creation, there among those in the front row of such With the above-mentioned inter- was an urgent need to submit a claim scientific activities. est towards ridge research and par- to the United Nation Commission on The increasing interest of the gov- ticularly on the CIR, Mauritius is in the the Limits of the Continental Shelf ernment of the Republic of Mauritius process of forming a national ridge (UNCLCS). towards marine research, particularly research initiative: the Mauritius Ridge The interest of the MOI to under- ridge research, is visible in its action: Research Group. take ridge research was born from the Daniel MARIE fact that part of the Central Indian Mauritius Oceanography Institute Ridge (CIR) falls within the EEZ of the 4th Floor France Centre Republic of Mauritius. Furthermore, Victoria Avenue Tel: + 230 427 4434 ridge research is in its burgeoning Quatre Bornes Fax: + 230 427 4433 stage and joining with the rest of the MAURITIUS Email: [email protected] international community could only

France

As planned, the Dorsales pro- in agreement with the international French scientists have been very ac- gramme has ended last December, af- context. Canada, Japan and the US tive is this area during the last decade, ter 8 years of existence. The funding have initiated long term observation in the context of European pro- agencies (CNRS and IFREMER) are programmes and are ready to install grammes. Moreover, this site has been not suggesting that the French com- seafloor observatories. selected by InterRidge. The second munity should stop working on mid- Two further workshops (in March target will be the East Pacific Rise at ocean ridges. But they encourage the and April respectively) discussed 13°N. This area will be more inten- community to spend some time think- possible targets. The first target will sively targeted by biological studies, ing about what should be our new be the Mid-Atlantic Ridge south of since the French biologists want to orientations, and to propose a new Azores (MOMAR area). This area has benefit from their record of 20 years of plan for 2003 with focused objec- the advantage of including three major observation. In parallel, some activity tives. In that sense, 2002 is a year of hydrothermal fields (Menez Gwen, will be maintained in the southern transition, during which France re- Lucky Strike and Rainbow) which EPR, which corresponds to the fastest mains a principal member of InterRidge. cover various depths and lithologies. portion of the global ridge system. Several workshops have been or- ganized during the passed six months to discuss these future issues. For more information on the French programme contact: At the first workshop held in Catherine Mével, Roscoff, in October 2001, the French Laboratoire de Geosciences Marines Tel: 33-1-44-27-51-93 community has agreed to concentrate Université Pierre et Marie Curie Fax: 33-1-44-27-39-11 efforts on long term observation and 4 Place Jussieu, Tour 26, 3ème étage E-mail: [email protected] monitoring of active processes at mid- 75252 Paris Cedex 05, FRANCE ocean ridges. This new orientation is Vol. 11(1), 2002 57

National News....

Canada: CanRidge

Canadian ridge scientists and stu- 1990’s. Several very large, hydrother- Ross Chapman of the University of dents will be participating in two field mally active, polymetallic sulphide Victoria. On August 12, Prof. programs in the Northeast Pacific in mounds have been found along a Chapman’s group will be replaced by Summer 2002, both using the ROPOS portion of the ridge that shoals to a new scientific party, led by Prof. Kim remotely-operated submersible. The <2000m. While the area’s notoriously Juniper of the Université du Québec à first (July 12 to August 5, 2002) will be bad weather has hampered extensive Montréal. The Tully will then sail for a collaborative cruise with the NOAA exploration, it is hoped that the larger, the Endeavour Segment of the Juan de VENTS program in which ROPOS will more stable platform offered by the Fuca Ridge for sample collections, be mobilised on the University of Thompson will permit more extensive and the deployment and recovery of Washington research vessel Thomas mapping and sampling of the Explorer long-term faunal colonisation and G. Thompson. Along with NOAA and Ridge fauna and sulphide deposits mineral weathering experiments. Op- University of Washington colleagues, during the 12 days that the vessel will erations at Endeavour Segment will be a Canadian team led by Prof. Steve be on site. mixed with dives at several nearby Scott of the University of Toronto will Upon it’s return to port in Victoria, ODP drill sites, where ROPOS will be first complete work at Axial Volcano British Columbia on August 5, ROPOS used for in situ downloading of data on the Juan de Fuca Ridge, as part of and it’s deep-sea winch will be trans- from instruments in sealed drill holes. the NeMO (New Millenium Observa- ferred from the deck of the Thomas G. One area of particular interest is Mid- tory) program, which began in the Thompson directly to the deck of the dle Valley where it is hoped that in- summer of 1998. The focus of the Canadian vessel John P. Tully. The struments in CORKed holes recorded NeMO program has been the docu- Tully will then set sail for a week of last winter’s major seimic event at mentation of the geological and bio- diving and exploration on a gas hy- Middle Valley. The Tully cruise will logical events that followed a January drate site on the Vancouver Island end in Victoria, British Columbia on 1998 seafloor eruption in the eastern margin with a group headed by Prof. August 22. portion of the Axial caldera. Following the work at Axial Volcano the cruise For more information on CanRidge contact: will move north to Explorer Ridge, a S. Kim Juniper, Canadian InterRidge Correspondent spreading ridge located to the north of GEOTOP the Juan de Fuca Ridge. Hydrothermal Université du Québec à Montréal activity was first discovered on two P.O. Box 8888, Station A Tel: + 1 514 987-3000 ext. 6603 Canadian cruises to Explorer Ridge in Montréal, Québec, H3C 3P8 Fax: + 1 514 987 4647 1984, and portions of the ridge were Canada E-mail: [email protected] revisited with ROPOS in the mid-

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 the Marine Protected Areas programme: http://www.dfo-mpo.gc.ca/oceanscanada/newenglish/htmdocs/mpas/endeavour.htm http://www.pac.dfo-mpo.gc.ca/oceans/mpa/pilots.htm

The Remotely Operated Platform for Ocean Science: http://ropos.com/ 58 InterRidge News

Upcoming Meetings and Workshops

Calendar of MOR Research related events (2002)

More details about all of the following meetings can be found via the Meetings menu on the InterRidge homepage: http://www.intridge.org/info3.html

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 Regime of Ocean Ridges and Dynamics of Hydrothermal Circula tion. 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 information on upcoming international ridge related meetings. We will publish them in IR news and add also post the latest information on the IR website. Vol. 11(1), 2002 59

Upcoming Meetings and Workshops

InterRidge Next Decade Workshop Call 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 opportunity to 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 process is this workshop The aim of this workshop is to establish the goals for InterRidge for the next decade and 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 community are incorporated into its planning and execution. Please take the time now to access the Workshop Web page and register yourself for participation at the workshop. If you cannot make room in your schedule to attend, please submit a summary of what you think InterRidge should try and achieve in the next decade in the form of a white paper (all information about what you might want to include are on the website).

Provisional Agenda June 10th Vision statements from leaders in the fields of spreading axis biology, geology, geophysics and technology. The aim of this session is to set the framework for the workshop and to provide a common 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 of importance and feasibility their visions and aims for the next decade.

June 11th Report session of disciplinary ry working groups. Discussion on the present InterRidge Working Group 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/organisation of 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 finance groups 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

Upcoming Meetings and Workshops

South West Indian Ridge Workshop (SWIR) 17-19 April 2002 Southampton Oceanography Centre, UK http://www.intridge.org/swirwksp.htm 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 proceedings volume in the electronic journal,G-cube: (G3 http://g-cubed.org/).

Mantle Plumes and Metallogeny International Symposium September 4–7, 2002, Petrozavodsk, Russia http://www.intridge.org/plume02.pdf Proposed Symposium topics: General issues of mantle plume evolution Mantle plumes and chemical geodynamics Plumes and rifting, including pre-rift regime Recent and Cenozoic mantle plumes in continental and oceanic lithospheres Mantle plumes in the Phanerozoic and Precambrian Mantle plumes as manifest in geophysical fields and deep structure Numerical modeling of inception and development of mantle plumes Mantle plumes and metallogeny Plumes and biological catastrophes in the Earth’s history

Pre- and post-Symposium field trips will introduce you to unique manifestations of plume magmatism in the Early Proterozoic of Karelia and Devonian magmatism of the Kola Peninsula and to the geological setup of Archean greenstone belts. Vol. 11(1), 2002 61

Upcoming Meetings and Workshops

The Fourth Unmanned Underwater Vehicle Showcase 25-26 September 2002, Southampton Oceanography Centre, UK http://www.uuvs.net/

The Exhibition: the showcase for leading manufacturers of vehicles and subsystems from around the world. The Conference: a leading edge technical programme put together by a committee of industry experts featuring presentations from global leaders in the industry The Demonstrations: see the vehicles and systems in operation in the dockside waters adjacent to SOC.

MOMAR II Workshop 15-17 June 2002, Horta (Azores, Portugal) Towards planning of seafloor observatory programs for the MAR region For the latest information go to: http://www.intridge.org/

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 space b) 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 data e) establish links with existing national and international observatory-related projects: data and connector standards, transfer of technology f) discuss and evaluate management proposals of study sites, and aspects related with scientific interpretation and dissemination for the general public g) discuss and evaluate possibilities and strategies for funding of the observatory. 62 InterRidge News

Upcoming Meetings and Workshops

1st InterRidge Theoretical Institute (IRTI) Thermal Regime of Ocean Ridges and Dynamics of Hydrothermal Circulation 9-13 September 2002, University of Pavia, Italy

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

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, and modeling studies of hydrothermal circulation and their implications for thermal evolution of the oceanic lithosphere. (2) To identify key scientific issues that could be addressed in coming years and discuss a general plan for more focused international collaboration in this important research field. (3) To educate a broad spectrum of international researchers, post-docs, and graduate students on the state-of-the-art research approaches, especially experimental and theoretical modeling capabilities.

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

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

The short-course will be held in the historic lecture theatre of the University of Pavia, situated approximately 30miles/50km south of Milano. The field course will be to the northern Apennine 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 and about 30 attendees for the workshop. Because space is likely to be limited, those interested in participating, either to the short-course and field excursion or for the full duration of the whole IRTI, should register their interests with Agnieszka Adamczewska at ([email protected] tokyo.ac.jp).

We look forward to seeing you in Italy! Chris German ([email protected]) & Jian Lin ([email protected]) Vol. 11(1), 2002 63

InterRidge National Correspondents

Australia India Philippines Dr. Trevor Falloon Dr. Sridhar D. Iyer Dr. Graciano P. Yumul, Jr. Geology Department E-mail: [email protected] National Institute of Geological Sciences University of Tasmania and University of the Philippines GPO Box 252C, Hobart Dr. K.A. Kamesh Raju Diliman, Quezon City, 1101, Philippines Tasmania 7001, Australia E-mail: [email protected] E-mail: [email protected] E-mail: [email protected] National Institute of Oceanography Portugal Austria H.O. Dona Paula Prof. Fernando Barriga Dr. Monika Bright Goa 403 004, India Departamento de Geologia Marine Biol., Institute for Ecology Facul. de Ciencias and Conservation Biology Italy Universidade de Lisboa University of Vienna, Althanstr. 14, Prof. Enrico Bonatti Edificio C2, Piso 5, Campo Grande A-1090 Vienna , Austria Instituto di Geologia Marina C.N.R., PT 1700 Lisboa, Portugal E-mail: [email protected] Universita di Bologna, E-mail: [email protected] Brazil Via P. Gobetti 101, I-40129 Bologna, Italy Russia Dr. Suzanna Sichel E-mail: [email protected] Dr. Sergei A. Silantyev Dept. de Geologia - Lagemar UFF and Vernadsky Inst. of Geochemistry Av. Litorânea s/nº 4° andar Dr. Paola Tartarotti Russian Academy of Sciences CEP: 24210-340 Dipartimento di Geologia, Paleontologia 19, Kosygina Street Gragoatá Niterói RJ Brazil e Geofisica, Universita di Padova, Moscow 117975, Russia E-mail: [email protected] Via Giotto 1, 1-35137 Padova, Italy E-mail: [email protected] Canada E-mail: [email protected] SOPAC Dr. Kim Juniper Japan Dr. Russell Howorth GEOTOP SOPAC, Prof. Nobuhiro Isezaki Universite du Québec à Montréal Private Mail Bag, Department of Earth Sciences, P.O. Box 8888, succursale Centre Ville, Suva, Fiji Faculty of Science, Chiba University, Montréal, Québec, H3C 3P8, Canada E-mail: [email protected] E-mail: [email protected] Yayoi-cho 1-33, Inage-ku, Chiba-shi, and Chiba 260, Japan South Africa Dr. Kathryn M. Gillis E-mail: [email protected] Dr. Anton P. le Roex School of Earth and Ocean Sciences Korea Department of Geological Sciences University of Cape Town University of Victoria, MS 4015 Dr. Sang-Mook Lee Rondebosch 7700, South Africa Victoria, BC V8W 2Y2, Canada Marine Geology and Geophysics Division E-mail: [email protected] E-mail: [email protected] KORDI, Ansan, P.O. Box 29 China Seoul 425-600, Korea Spain Dr. Wang Zhihong E-mail: [email protected] Dr. Juan José Dañobeitia Laboratory of Lithosphere Tectonic Inst. Jaime Almera de Ciencias de la Evolution Mauritius Tierra, CSIC Institute of Geology and Geophysics Dr. Daniel P. E. Marie C/Lluis Sole i Sabaris s/n Chinese Academy of Sciences Mauritius Oceanography Institute 08028 Barcelona, Spain Beijing 100029, P.R. China 4th Floor, France Centre E-mail: [email protected] E-mail: [email protected] Victoria Avenue, Quatre Bornes, Mauritius E-mail: [email protected] Sweden Denmark Dr. Nils Holm Dr. John Hopper Mexico Dept. of Geology and Geochemistry Danish Lithosphere Centre Dr. J. Eduardo Aguayo-Camargo University of Stockholm Oester Voldgade 10, Kobenhavn Inst. de Ciencias del Mar y Limnologia S-106 91 Stockholm, Sweden DK-1350, Denmark U. Nacional Autonoma de Mexico E-mail: [email protected] E-mail: [email protected] Apartado Postal 70-305 Switzerland Mexico City, 04510, Mexico France Dr. Gretchen Früh-Green E-mail: [email protected] Dr. Catherine Mével Department of Earth Sciences Laboratoire de Geosciences Marines Morocco ETH-Z, Sonneggstr. 5 IPGP - Université Pierre et Marie Curie Prof. Jamal Auajjar CH-8092 Zurich, Switzerland Case 110, 4 place Jussieu, Universite Mohammed V E-mail: [email protected] 75252 Paris cedex 05, France Agdal Ecole Mahammadia des Ingenieurs United Kingdom E-mail: [email protected] Depat. de Genie Mineral, Avenue Ibn Sina, Dr. Chris German Germany BP 765, Agdal, Rabat 10 000, Morocco Challenger Division for Seafloor Processes Dr. Colin Devey E-mail: [email protected] Southampton Oceanography Centre Fachbereich 5 Geowissenschaften New Zealand European Way, Empress Dock Southampton, SO14 3ZH, UK Universität Bremen Dr. Ian Wright Postfach 330440 E-mail: [email protected] Nat. Inst. of Water and Atmospheric D-28334 Bremen, Germany Research, P.O. Box 14-901 USA E-mail: [email protected] Wellington 3, New Zealand Dr. Charles Fisher, RIDGE Chair Iceland E-mail: [email protected] RIDGE Office Dr. Karl Gronvold Norway Department of Biology, Nordic Volcanological Institute Prof. Rolf Pedersen Pennsylvania State University, University of Iceland Institute of Solid Earth Physics 208 Mueller Laboratory, Grensasvegur 50 University of Bergen University Park PA 16802, USA IS 108 Reykjavik, Iceland Allegt. 41, 5007 Bergen, Norway E-mail: [email protected] E-mail: [email protected] E-mail: [email protected] 64 InterRidge News

InterRidge Steering Committee

Dr. Kensaku Tamaki Dr. Jérôme Dyment Dr. Masataka Kinoshita InterRidge Chair CNRS UMR 6538 Deep Sea Research Department Ocean Research Institute, Institut Univ. Europeen de la Mer JAMSTEC, 2-15 Natsushima University of Tokyo Universite de Bretagne Occidentale Yokosuka, 237-0061, Japan 1-15-1 Minamidai, Nakano, 1 Place Nicolas Copernic Tel: +81 468 67 9323 Tokyo 164-8639, Japan 29280 Plouzane, France Fax: +81 468 67-9315 Tel: + 81 3 5351 6443 Tel : + 33 2 9849 8720 Fax: + 81 3 5351 6445 Fax : + 33 2 9849 8760 E-mail: [email protected] E-mail: [email protected] E-mail : [email protected] Dr. Jian Lin, ad hoc Prof. Fernando Barriga Dr. Javier Escartín, ad hoc Department of Geology & Geophysics Departamento de Geologia Laboratoire de Geosciences Marines Woods Hole Oceanographic Institution Facul. de Ciencias IPGP - Université Pierre et Marie Curie Woods Hole, MA 02543-1541, USA Universidade de Lisboa Case 89, 4 place Jussieu, Tel: + 1 508 289 2576 Edificio C2, Piso 5, Campo Grande 75252 Paris cedex 05, France Fax: + 1 508 457 2187 PT 1700 Lisboa, Portugal Tel: + 33 1 4427 4601 E-mail: [email protected] Tel: +351 1 750 0066 Fax: + 33 1 4427 3911 Fax: +351 1 759 9380 E-mail: [email protected] Dr. Sang-Mook Lee E-mail: [email protected] Deep-Sea Resources Research Center Dr. Charles Fisher KORDI, Ansan, P.O. Box 29 Dr. Phillippe Blondel, ad hoc Department of Biology, Seoul 425-600, Republic of Korea Tel: +82 31 400 6363 Department of Physics Pennsylvania State University, Fax: +82 31 418 8772 University of Bath 208 Mueller Laboratory, Email: [email protected] Bath BA2 7AY, UK University Park PA 16802, USA Tel: + 44 1225 826 826 Tel: +1 814 865 3365 Dr. Catherine Mével Fax: + 44 1225 826 110 Fax: +1 814 865 9131 IPGP - Université Pierre et Marie Curie E-mail: [email protected] E-mail: [email protected] Case 110, 4 place Jussieu, Prof. Enrico Bonatti Dr. Françoise Gaill, ad hoc 75252 Paris cedex 05, France Tel: + 33 1 4427 5193 Instituto di Geologia Marina C.N.R. Laboratoire de Biologie Marine Fax: + 33 1 4427 3911 Universita di Bologna CNRS UPR 7622 E-mail: [email protected] Via P. Gobetti 101 Université Pierre et Marie Curie I-40129 Bologna, Italy (Paris 6), 7 Quai Saint-Bernard Dr. Abhay Mudholkar Tel: + 39 51 639 8935 F-75252 Paris Cédex 05, France National Institute of Oceanography Fax: + 39 51 639 8939 Tel: + 33 1 44 27 30 63 Dona Paula, GOA 403 004, India E-mail: [email protected] Fax: + 33 1 44 27 52 50 E-mail: [email protected] Tel: + 91-832 221-322 ex 4322 Fax: + 91-832-223-340 Dr. Dave M. Christie E-mail: [email protected] COAS, Oregon State University Prof. Toshitaka Gamo 104 Oceanography Adm. Building Division of Earth and Planetary Prof. Rolf Pedersen Corvallis, OR 97331-5503, USA Sciences Graduate School of Science Tel: + 1 541 737 5205 Hokkaido University Institute of Solid Earth Physics Fax: + 1 541 737 2064 N10 W8 University of Bergen, Allegaten 41, E-mail: [email protected] Sapporo, 060-0810, Japan N-5007 Bergen, Norway Tel: +81 11 706 2725 Tel: + 47 5558 3517 Prof. Paul R. Dando Fax: +81 11 746 0394 Fax: + 47 5558 9416 E-mail: [email protected] School of Ocean Sciences E-mail: [email protected] University of Wales-Bangor, Menai Bridge Dr. Christopher R. German, ad hoc Dr. Ricardo Santos, ad hoc Anglesey, LL59 5EY, UK Challenger Div. for Seafloor Processes University of the Azores Tel: + 44 1248 382 904 Southampton Oceanography Centre Dept. of Oceanography and Fisheries Fax: + 44 1248 382 620 Southampton, SO14 3ZH, UK PT- 9901-862 Horta (Azores), Portugal E-mail: [email protected] Tel: + 44 1703 596 542 tel: +351 292 292 944 Fax: + 44 1703 596 554 fax: +351 292 292 659 Dr. Colin W. Devey E-mail: [email protected] e-mail: [email protected] Fachbereich 5 Geowissenschaften Universität Bremen Dr. Kim Juniper Dr. Spahr C. Webb, ad hoc Postfach 330440 GEOTOP Lamont Doherty Earth Observatory, D-28334 Bremen, Germany Université du Québec à Montréal Columbia University Tel: + 49 421 218 9205 P.O. Box 8888, Station A New York 10964, USA Fax: + 49 421 218 9460 Montréal, Québec, H3C 3P8, Canada Tel: + 1 845-365-8439 E-mail: [email protected] Tel: + 1 514 987 3000 ext. 6603 Fax: + 1 845-365-8150 Fax: + 1 514 987 4647 E-mail: [email protected] E-mail: [email protected]