Mid-Atlantic Ridge Sym- Mexico, Russia, Sweden, Switzer- Quantification of Fluxes Posium in Reykjavik

\ V Jean-Luc CHARLOU vol. 5, no. 2 Fall/Winter 199 6 InterRidge News

Contents InterRidge Update InterRidge Update 1 InterRidge Provisional Calendar....4 InterRidge Phase 2 Projects The InterRidge Office has sus- the United Kingdom, the United SWIR Project tained a high level of activity during States), 2 Associate Members (Nor- Southwest Indian Ridge 15°E-35°E: A Geo- 1996 organising the ODP- way, Portugal) and 11 Corresponding physical Investigation of an Ultra-Slow InterRidge-IAVCEI Workshop in Members (Australia, Canada, Den- Spreading Mid-Ocean Ridge System/ North Falmouth, MA and the FARA- mark, Iceland, India, Italy, Korea, N.R. Grindley et al. 7 InterRidge Mid-Atlantic Ridge Sym- Mexico, Russia, Sweden, Switzer- Quantification of Fluxes posium in Reykjavik. The InterRidge land). Australia has announced its MARFLUX/ATJ Mid-Atlantic Ridge: Hydro- Office edited abstract volumes for intention to upgrade to Associate thermal Fluxes at the Azores Triple Junction/ both meetings. Both meetings were Membership in 1997. H. Bougault et al. 13 well attended and productive (see Arctic Mapping below). Their success was largely due InterRidge and SCOR Arctic Geophysical Data Acquisition from US to the many contributions made by The decision to apply for for- Navy Submarines/ M. Langseth and B. Coakley 18 participants as formal oral presenta- mal SCOR Affiliation was taken at tions and posters and to discussions. the 1996 InterRidge Steering Com- Biological Studies at the Ridge Crest We'd like to take this opportunity to mittee Meeting. InterRidge has been Colonization of Hydrothermal Vents near 9o50"N, East Pacific Rise: A Cruise Report thank the participants of both meet- involved in discussions of SCOR af- from Block Party 1, 2 & 3/ ings for their involvement and for the filiation over the past year and played L.S. Mullineaux et al 19 positive feedback received. In addi- an active part in the initiation of Hot 96 News/ F. Gaill et al. 22 tion, the InterRidge Office continued SCOR Working Group 99 "Linked Report on ROPOS Submersible Operations on overseeing ongoing work on various Mass and Energy Fluxes at Ridge the R/V Thomas G. Thompson Cruise: 12- InterRidge Projects and managed to Crests". Since its formal recognition 27 August 1996/ K. Jumper et al. ...25 produced the Spring/Summer issue by SCOR, InterRidge has closely fol- of InterRidge News on schedule. 4-D Architecture of the Oceanic lowed the progress of WG 99, and Lithosphere several InterRidge representatives On- and Off-axis Submersible Investigations on InterRidge Office Transfer participated in the September 1996 an Highly Magmatic Segment of the Mid- The 1997-1999 term of SCOR WG 99 Symposium at the Atlantic Ridge (21 ^OTf): the TAMMAR InterRidge will be hosted by France. Southampton Oceanographic Centre, Cruise/ P. Gente et al. 27 Mathilde Cannat of CNRS/Univer- UK. International Co-Operative Research sity of Paris 6 has been named as the Geophysical Investigation of Ridge-Hot Spot next InterRidge Chair. The Office InterRidge Projects Interaction at the Galapagos Spreading will be transfered to Paris in January 4-D Architecture of the Oceanic Center/ J J. Dahobeitia et al. 32 1997. Lithosphere A geophysical and geochemical study of the Pacific-Antarctic Ridge south of Udintsev A meeting of the 4-D Archi- FZ: The Pacantarctic cruise with R/V Membership tecture of the Oceanic Lithosphere L 'Atalantel L. Gelietal 36 InterRidge Membership has Project working group (L. Parson, remained constant since the begin- Southampton, Chair) was held in World Ridge Cruise Schedule 39 ning of 1996 with 6 Principal Mem- parallel with the ODP-IR-IAVCEI InterRidge Workshop Summaries bers (France, Germany, Japan, Spain, Workshop in North Falmouth. Since FARA-InterRidge MAR Symposium 46 News from Ridge Crest Research Dr. Heather Sloan, Editor. and Related Programmes 48 Dr. Ruth Williams, Assistant Editor Announcements and Notices 53 InterRidge News is published by the InterRidge Office, Department of Geological Sciences, University of Durham, South Road, National Admin. Representatives...66 Durham, DH1 3LE, United Kingdom; National Correspondents 67 tel: 44-191-374-2532, fax: 44-191-374-2510 e-mail: [email protected] InterRidge Steering Committee ....68 http://www.dur.ac.uk/- dglOzzl/ vol. 5, no. 2 1996 13 Quantification of Fluxes Project

MARFLUX/ATJ Mid-Atlantic Ridge: Hydrothermal Fluxes at the Azores Triple Junction

H. Bougault1, C. German , M. Miranda3 and the MARFLUX/ATJ Participants (note 1)

1IFREMER/DRO/GM, BP 70, 29280 Plouzane, France Southampton Oceanography Centre, Empress Dock, Southampton, SO 14 3ZH, UK Centro de Geofisica, Univ. ofLisboa, Rua da Escola Politecnica 58, 1200 Lisboa, Portugal

MARFLUX/ATJ, Mid-Atlan- in 1991. A proposal was written and MARFLUX/ATJ were: tic Ridge: hydrothennal Fluxes at the accepted in 1992. After negotiation, * to group and compile all existing Azores Triple Junction, is a European a formal contract was signed in Nov. data in the area of the ATJ. project to study hydrothermal fluxes 1993 between the partners of the * to document occurrences of physi- at the Mid-Atlantic Ridge (MAR) project and the EC. The contract, a near the Azores Triple Junction document of 75 pages, defines the cal and chemical anomalies in the (ATJ). It was the first project deal- rules and agreements between the EC water column. ing with the study of the ridge sys- and the partners. The various tasks * to map hydrothermal plumes and tem funded by the European Commu- and the "deliverables" are formally determine magmatic and tectonic set- nity (EC). The project, attached to identified. In addition, a consortium tings of potential hydrothermal sites. the EC's MAST 2 (MArine Sciences agreement between the partners is * to provide the scientific community and Technology) programme, started required by the EC. The contract re- with natural laboratories for future in December 1993 and ends formally quires that the project is monitored experiments. in November 1996. closely under the responsibility of the The project has been based co-ordinator of the project and of a around two surface-ship cruises, EC funding steering committee. Six monthly HEAT and ESCAPE. The HEAT EC funding can include sala- progress-reports and annual scientific cruise (C. German PI), conducted in ries, equipment, consumables and and financial reports have to be sub- Aug.-Sept. 1994, was designed to in- travels but the MAST2 programme mitted to the EC. vestigate hydrothermal activity along did not include ship time. Eligibility Funds are provided annually, the MAR between 35°45'N and for EC funding requires a partnership conditional upon acceptance of the 38°40'N in relation to the bathymetry between different laboratories from annual reports. Ship time was funded and morphology of the axis. ES- different countries of the European according to the procedure of the CAPE (M. Miranda PI) was con- Community. In the case of country where a ship time proposal ducted in Oct. 1995 and investigated MARFLUX/ATJ the principal labo- (independent of the EC proposal) was hydrothermal activity at the MAR ratories were in France, the UK, Por- submitted. axis from 38°40'N to 40°N, and tugal and Ireland. Several European within the island archipelago of the scientists responded to a call for a The objectives of MARFLUX/ATJ Azores. manifestation of interest by the EC The principal objectives of The project built on early re-

Note l: MARFLUX/ATJ participants: M. Aballea4, P. Appriou4, F. Bam'ga9, M. Biscoito8, P. Blondel6, J.-L. Charlou1, A. Cola?o8, D. Coller1I. Costa9, M. Critchley11, L. Dosso3, Y. Fouquet1, P. Jean-Baptiste5, A. Khripounofr, J. Freire Luis7, N. Lourengo7, E. Ludford12, L. Mendes Victor7, A. Marques8, H.D. Needham', D. O'Brien10, H. Ondreas1, L. Parson6, J. Patching10, J. Radford Knoery1, L. Saldanha8 I IFREMER/DRO/GM, BP 70,29280 Plouzane, France 2IFREMER/DRO/EP, BP 70,29280 Plouzane, France 3 GDR GEDO, Ifremer, BP 70,29270 Plouzane France 4 Dpt. Chimie UBO, Av. Le Gorgeu, 29200 Brest, France 5 Lab. Geochim. Isotopique, LMCE Bat. 709,91191, GIF s/Yvette, France 6 SOC, Empress Dock, Southampton, S014 3ZH, UK Centro de Geofisica, Univ. ofLisboa, Rua da Escola Politecnica 58,1200 Lisboa, Portugal IMAR, Lab Maritimo da Guia, Fac. Ciencias, Univ. Lisboa, Estrada do Guincho, 2750 Cascais, Portugal Dpt. Geologia, Fac Ciencias, Univ. Lisboa, Ed. C2 Piso 5 Campo Grande, 1700 Lisboa, Portugal 10 University College Galway, Galway, Ireland II ERA-MAPTEC Ltd, 5 South Leinster St., Dublin 2, Ireland 12Dpt of Geology, Univ. ofBristol, UK A formal co-operation was established with G. Klinkhammer13 and C. Langmuir14. 13 College of Ocean., OSU, Corvallis, OR 97331 -5, USA 14 LDEO, Columbia Univ., Palisades, NY 10964, USA 14 InterRidge News

distance along profile (km) 10 15 20 25

15 20 Manganese MARFLUX/ATJ: HEAT cruise, 1994. MAR: Segment AMAR, Dynamic Hydrocast #7

Figure 1. Hydrothermal plumes along the AMAR segment of the MAR, southwest of the Azores. Vertical cross 3 section of A He, CH4 and Mn (total disolved manganese (Aballea et al., 1995)) along ABCD. Between 1700 m and 2300 m depths, chemical signals are detected everywhere along the segment, with values at least 10 times the seawater background. The three chemical tracers have different chemical properties and consequently do not display identical plume cross sections. All chemical tracers focus on a potential hydrothermal site, the Rainbow site at 27 km near 36°15rN where the transmissometer on TOBI detected a strong signal during the HEAT cruise (German et al., 1996). Note that the Rainbow site is a complex offset. It is an example of the diverse geological settings where hydrothermal discharge takes place along the MAR. vol. 5, no. 2 1996 15 suits of FARA (French American Guen and Lucky Strike vent sites FAMOUS, southern Lucky Strike, Ridge Atlantic project) and has con- (38°N, 37°N), the FAMOUS and south ATJ, (covering a cumulative tinued in co-operation with that pro- AMAR segments (36°-37°N) and the distance of 108 nautical miles along gramme. MARFLUX/ATJ relied in ATJ overlapper at BS^O'N. Simul- the ridge axis) recorded hydrother- particular upon the swath taneously, a transmissometer on mal anomalies along each segment bathymetric data and related geo- TOBI recorded the presence of parti- between AMAR (36°N) to south of physical data collected during the cle-rich hydrothermal plumes. Kurchatov F.Z. (40°N). There was SIGMA cruise (1991) of the FARA Subsequent sampling in- one exception, along the ridge seg- programme (Needham and SIGMA cluded 7 dynamic hydrocast (Note 2) ment located in the area of the triple r Scientific Team, 1991; Detrick et al., deployments (overlapper, southern junction itself between 38°40 N and r 1995; Needham, 1996), and on Lucky Strike, FAMOUS and 39°30 N, where no CH4 or Mn sig- aeromagnetic data collected by the AMAR), yielding more than 250 nal was detected. Hydrothermal University of Lisbon (Freire Luis et seawater samples for shore-based plume signals were found to be very al., 1994; Freire Luis and Miranda, CH4, Mn and He analyses. These strong along southern FAMOUS and 1996). The project also relied upon dynamic hydrocast deployments pro- AMAR. data concerning hydrothermal signals vided an along-axis vertical cross- The two hydrothermal sites detected in the water column section of hydrothermal plumes for already known in the area of inter- 3 (Charlou et al., 1993) and on rock CH4, Mn and He along a cumula- est, namely Lucky Strike (Langmuir sampling (Langmuir et al., 1996; tive distance of 108 nautical miles. et al., in press) and Menez Guen Dosso et al., 1996) between 33 °N and In addition, a total of 22 vertical (Fouquet et al., 1995), are located on 40 °N conducted during the FAZAR ZAPS/CTD profiles were carried out the central topographic highs of seg- cruise (1992, C. Langmuir P.I.). for plume sampling and correlation ments which are characterised by an There has been close co-operation with TOBI plume data. This infor- intense magmatic production. Many between the MARFLUX/ATJ part- mation was used to direct collection hydrothermal plume signals, either ners and North American colleagues of 20 large-volume plume-particle detected through the transmissometer during the FAJRA programme, samples, by in situ filtration, for shore on TOBI or by dynamic hydrocasts, SIGMA and FAZAR (above), Alvin based geochemical/microbiological were found along rift valley walls dives on Lucky Strike hydrothermal analysis. (southern FAMOUS), in transform site (1993, C. Langmuir P.I.), Nautile The principal objective ofES- faults (south of Lucky Strike), at a dives on Lucky Strike and Menez CAPE was to detect hydrothermal ac- segment end (south of FAMOUS) or Guen hydrothermal sites (Diva 1, tivity from 38°40'N (the expected lo- associated with complex off-sets like 1994, Y. Fouquet P.I. and Diva 2, cation of the Triple Junction) to that on AMAR (Fig. 1; Bougault et 1994, D. Desbruyeres P.I.) and dur- 40°20rN (south of Kurchatov F.Z.) al., 1996; German et al., submitted; ing the cruises of MARFLUX/ATJ. and within the Azores domain, German et al., 1996). The plume The objectives of HEAT were Hirondelle Basin (west of San maxima, several hundred meters to characterise the variation in Miguel), West Terceira Basin, West above the inner valley floor, are not tectonism and volcanism and their Graciosa Basin and west of Faial. related to typical neovolcanic ridges relationship to the second-order seg- Seventeen successful vertical CTD- but are associated with tectonics as mentation of the MAR, Se^MCN rosettes were conducted yielding 170 suggested by the bathymetric and (Parson et al., 1995), to locate and seawater samples for Mn, CH4 and side-scan sonar data (Needham and quantify the extent of hydrothermal He analyses. SIGMA Scientific Team, 1991; activity along this section of the neo- Blondel et al., 1996). From previous volcanic ridge axis (Bougault et al., Principal results studies of hydrothermal signals in the 1996; German, 1996), and to inves- TOBI transmissometer data water column along the MAR tigate the geological and geophysi- identified the presence of particle rich (Charlou et al., 1996) and from the cal controls on the nature of hydro- hydrothermal plumes in all of the results of the MARFLUX/ATJ project thermal venting in different south AMAR, AMAR Minor, south- briefly described above, it appears morphotectonic settings (German et ern and central AMAR, southern FA- that hydrothermal activity along the al., 1996). MOUS, north FAMOUS and south- MAR is as common as that along the Initially, 150 nautical miles of em Lucky Strike segments, provid- EPR but develops in more much more an along-axis side-scan sonar survey ing a minimum estimate of perhaps diverse geological settings. Evidence were completed using the SOC deep one vent site per 20 miles along axis. for hydrothermal activity in areas towed instrument, TOBI, 36°-38°N. Thirty vertical hydrocasts and seven where ultramafics are exposed, at the Areas covered included the Menez dynamic hydrocasts, along AMAR, inner comer of an intersection with

Note 2 A dynamic hydrocast is composed of four modules attached at different depths to a cable towed behind the ship. Each module contains 10 "proportional" bottles and an electronic controller to monitor the operation (recording depth, bottle filling). A proportional bottle consists of a cylinder and a piston. The proportional bottle is filled up by a pump / propeller system. According to this principle, each sample of seawater is collected "proportion- ally" along the distance covered by the bottle and represents an "average" sample over this distance. When a bottle is filled up, the system goes on to fill the next one. As a result, one obtains a sample array (four lines parallel to the bottom, 10 samples per line) along a vertical cross-section of the plume. 16 InterRidge News a fracture zone as well as on the walls Biscoito, 1996). The chemistry of Ridge: Acoustic classification of the rift valley well away from frac- large-volume plume-particle sam- of TOBI side-scan imagery from ture zones, was described in the area ples, obtained by in situ filtration, is 27°N-30°N and 36°N-38°N, of 15 °N on the MAR (Bougault et al., being studied along with detection Journal of Conference Abstracts, 1993; Charlou and Donval, 1993). and description of their microbial 1, 759-758, 1996. The recent discovery of a hydrother- community structure (O'Brien et al., Bougault, H., J.-L. Charlou, Y. mal site developing on the wall of the 1996). Fouquet, H.D. Needham, N. rift valley at 14 °4 5 "N on the MAR, a Based on the results obtained Vaslet, P. Appriou, P. Jean- site where ultramafic rocks are ex- during the FARA and MARFLUX/ Baptiste, P.A. Rona, L. Dmitri ev posed (Krasnov et al., 1995), is an ATJ projects in the area of the Azores, and S. Silantiev, Fast and slow illustration of the large differences in further studies will be conducted in spreading ridges: structure and hydrothermal activity existing be- 1997-98 under the AMORES project hydrothermal activity, tween the MAR and the EPR. The funded by the MAST 3 EC. Its aims ultramafic topographic highs, major result ofMARFLUX/ATJ is to are: and CH4 output, Journal of Geo- confirm and describe the various geo- • to discover new expressions of physical Research, 98, 9643- logical settings where hydrothermal Ocean/Lithosphere exchanges from 9651, 1993. activity takes place. the different signals recorded in the Bougault, H., J. Radford Knoery, J.- In addition to the principal water column corresponding to dif- L. Charlou, H.D. Needham, P. objective of the project, to detect and ferent geological settings of the MAR Appriou, M. Aballea, P. Jean locate hydrothermal activity in the • to study volcanic and/or tectonic Baptiste, C.R. German, M. area of the ATJ and to tie the sites to controls on hydrothermal discharges, Miranda and C.H. Langmuir, MARFLUX/ATJ. Hydrothermal seafloor (side-scan) images, in particular related to transform activity along the Mid-Atlantic MARFLUX/ATJ was funded for the faults and complex offsets study of several aspects of hydrother- Ridge axis, in the area of the • to study the influence of the Azores mal exchanges, and complementary Azores Triple Junction. Mn, studies were undertaken in the course Hot Spot (gradient in depth and in CH4, He plumes from dynamic of the project. The distribution of hy- chemical properties of the ocean hydrocasts, Journal of Confer- drogen sulfide, a short life hydrother- crust) on physico-chemical properties ence Abstracts, 1, 761-762, mal tracer in sea water, was studied of hydrothermal exchanges from 1996. Menez Guen at 38°N to AMAR at around the Lucky Strike and Menez Charlou, J.-L., H. Bougault, J.-P. 36°N Guen hydrothermal sites (Radford Donval, H. Pelle, C. Langmuir Knoery et al., 1996). The explosive • to study the behavior of chemical and F.S. Team, Seawater CH4 versus effusive character of eruption and biological species both around concentration over the Mid-At- phases were studied as a function of hydrothermal sites and in plumes lantic Ridge from the Hayes F.Z. depth on the 38°20'N and Menez • to study the various aspects of hy- to the Azores Triple Junction, Guen segments (Ondreas et al., drothermal biological communities Eos Trans., AGU, 74, 380, 1996). Hydrothermal deposits • to establish natural laboratories to 1993. formed in different geological set- study the time variation of hydrother- Charlou, J.-L., H. Bougault, Y. tings of the MAR (i.e. different mal sites. Fouquet, J.-P. Donval, E. depths; Fouquet et al., 1996), slab Douville, J. Radford Knoery, M. formation at Lucky Strike, alteration References Aballea, H.D. Needham, P. of sulfides and comparison with an- Aballea, M., J. Radford-Knoery, H. Jean-Baptiste, P.A. Rona, C.H. cient fossil deposits (Barriga, 1996; Bougault, J.Y. Landure, H. Langmuir and C.R. German, Costa et al., 1995) have been stud- Pelle, P. Appriou, M. Laur and Methane degassing, hydrother- ied. Significant current velocities C.R. German, Preliminary re- mal activity and have been recorded at Luclcy Strike. sults from the MARPLUX/ATJ serpentinization between the Using dynamic hydrocast He data program. Characterisation of Fifteen-Twenty Fracture Zone and current velocity measured on the hydrothermal plumes using area and the Azores Triple Junc- bottom, 3He flux at the segment scale manganese samples collected tion area (Mid-Atlantic Ridge), has been compared to the He flux at with dynamical hydrocasts, Journal of Conference Abstracts, the scale of the North Atlantic (Jean EUG Strasbourg, Terra Ab- 1, 771-772, 1996. Baptiste et al., 1996). Larvae col- stracts, 7, 205, 1995. Charlou, J.-L. and J.-P. Donval, Hy- lected in sediment traps deployed Barriga, F.J.A.S., Seafloor mineral drothermal methane venting over a period of one year at Lucky deposits: The ancient examples, from 12°N to 26°N along the Strike enabled study and dicussion of Journal of Conference Abstracts, Mid-Atlantic Ridge, Journal of the recruitment periodicity ofbivalves 1, 754-755, 1996. Geophysical Research, 98, (Comtet et al., 1996). Differences in Blondel, P., L.M. Parson, B.J. Murton 9625-9642, 1993. the fish fauna at Lucky Strike (1700 and C.R. German, Comtet, T., D. Desbruyeres, A. m) and Menez Guen (800 m) have Hydrothermalism and surface Khripounoff and A., been described (Saldanha and geology along the Mid-Atlantic Vangriesheim, Mussel popula- vol 5, no. 2 1996 17

tion structure and recruitment Elastic thickness of the on the Mid-Atlantic Ridge, on two hydrothermal areas on lithosphere at the Azores Pla- Earth and Planetary Science the Mid-Atlantic Ridge: Lucky teau deduced from gravity data, Letters, in press. Strike (37° 17TsT, 1700 m) and Journal of Conference Abstracts, Langmuir, C.H., J. Reynolds, H. Menez Guen (37°50'N, 850 m), 1, 818-819, 1996. Bougault, T. Plank, L. Dosso, D. Journal of Conference Abstracts, German, C.R., Hydrothermal activ- Desonie, E. Gier and Y. Niu, A 1, 777-778, 1996. ity along the Mid-Atlantic petrological traverse along the Costa, I., F.J.A.S. Barriga and Y. Ridge: Tectonic vs. volcanic Mid-Atlantic Ridge across the Fouquet, Alteration processes controls ?, Journal of Confer- Azores hot spot, Journal of Con- associated with active hydro- ence Abstracts, 1, 794, 1996. ference Abstracts, 1, 813-814, thermal sites: The Lucky Strike German, C.R., G.P. Klinkhammer 1996. and Menez Guen examples and M.D. Rudnicki, The Rain- Needham, H.D., Some features of the (37o20"N and 37°50'N, Mid-At- bow hydrothermal plume, North America - Africa plate lantic Ridge), Memorias n°4, 36°15'N, Mid-Atlantic Ridge, boundary, Journal of Conference Universidade do Porto - Geophysical Research Letters, Abstracts, 1, 834-835, 1996. Faculdade de Ciencias, Museu submitted. Needham, H.D. and SIGMA Scien- e Laboratorio de Geologico, German, C.R., L.M. Parson and tific Team, The crest of the Mid- 979-983, 1995. HEAT Scientific Team, Hydro- Atlantic Ridge between 40° and Detrick, R.S., H.D. Needham and V. thermal exploration near the 15°N: Very broad swath map- Renard, Gravity anomalies and Azores Triple Junction: tectonic ping with the EM 12 echo crustal thickness variations control of venting at slow- sounding system, EOS Trans., along the Mid-Atlantic Ridge spreading ridges?, Earth and AGU ,72, 470, 1991. between 33°N and 40°N, Jour- Planetary Science Letters, 138, O'Brien, D., D. Eardley, M. Carton nal of Geophysical Research, 93-104, 1996. and J. Patching, Bacteriology of 100 (B3), 3767-3787, 1995. Jean-Baptiste, P., J.C. Dutay, A. hydrothermal plumes from the Dosso, L., O. Bonnier, C. Bollinger, Dapoigny, P. Allard, H. Mid-Atlantic Ridge, Journal of H. Bougault, J. Etoubleau and Bougault, J.-L. Charlou, Y. Conference Abstracts, 1, 838, C.H. Langmuir, Geochemical Fouquet, J. Radford Knoery, A. 1996. structure of the Mid-Atlantic Vangriesheim, H.D. Needham Ondreas, H., Y. Fouquet, I. Costa, N. Ridge between 10° and 41°N, and P. Rona, Hydrothermal Ac- Louren^o, M. Tivey and G. Journal of Conference Abstracts, tivity on the Mid-Atlantic Ridge AufEret, Volcanic and morpho- I, 784, 1996. from 15°Nto 65°N: Helium iso- logical features at the Mid-At- Fouquet, Y., P. Murphy, M.K. Tivey, tope distribution and constraints lantic Ridge axis south of the K. Heniy, F. Barriga, I. Costa, on hydrothermal fluxes, Journal Azores (37° - 39°N): A study P. Cambon, H. Bougault, C. of Conference Abstracts, 1, 803, at the submersible scale, Jour- Langmuir, D. Prieur, P. Rona, S. 1996. nal of Conference Abstracts, 1, Krasnov and I. Poroshina, Com- Krasnov, S.G., G.A. Cherkashev, T.V. 839-840, 1996. parison of sulfide mineralization Stepanova, B.N. Batuyev, A.G. Parson, L.M., D.W. Coller, C.R. Ger- related to slow spreading ridges Krotov, B.V. Malin, M.N. man, H.D. Needham and H.S. with high magmatic budget Maslov, V.F. Markov, I.M. Party, Inter-relationship be- (Lucky Strike and Menez Guen) Poroshina, M.S. Samovarov, tween volcanism and tectonism and low magmatic budget (15°N A.M. Ashadze, L.I. Lazareva at the MAR, 38-36°N, EUG Area), Journal of Conference and I.K. Yermolayev, Detailed Strasbourg, Terra Abstracts, 7, Abstracts, 1, 789-790, 1996. geological studies of hydrother- 148, 1995. Fouquet, Y., H. Ondreas, J.-L. mal fields in the North Atlan- Radford Knoery, J., J.-L. Charlou, M. Charlou, J.-P. Donval, J. tic, in Hydrothermal Vents and Aballea, J.-P. Donval and Y. Radford-Knoery, I. Costa, N. Processes, edited by L.M. Par- Fouquet, Near seafloor distribu- Lourengo and M.K. Tivey, At- son, C.L. Walker and D.R. tion of hydrothermal tracers lantic lava lakes and hot vents, Dixon, pp. 43-64, The Geologi- (sulfide, methane, manganese) Nature, 377, 201, 1995. cal Society, London, 1995. in Lucky Strike and Menez Freire Luis, J., J.M. Miranda, A. Langmuir, C., S. Humphris, D. Gwen segments, Journal of Con- Galdeano, P. Patriat, J.C. Fornari, C. Van Dover, K. Von ference Abstracts, 1, 808,1996. Rossignol and L.A. Mendes Vic- Damm, M.K. Tivey, D. Saldanha, L. and M. Biscoito, On the tor, The Azores Triple Junction Colodner, J.-L. Charlou, D. fish fauna from the Lucky Strike evolution since 10 Ma from an Desonie, C. Wilson, Y. Fouquet, and Menez Gwen hydrothermal aeromagnetic survey of the Mid- G. Klinkhammer and H. vent fields (Mid-Atlantic Atlantic Ridge, Earth and Plan- Bougault, Description and sig- Ridge), Journal of Conference etary Science Letters, 125,439- nificance of hydrothermal vents Abstracts, 1, 853, 1996. 459, 1994. near a mantle hot spot: The Freire Luis, J. and J.M.A. Miranda, Lucky Strike vent field at 37°N