University of South Carolina Scholar Commons Faculty Publications Chemistry and Biochemistry, Department of 1988 Hydrothermal Fluids and Petroleum in Surface Sediments of Guaymas Basin, Gulf of California: A Case Study J. M. Gieskes B. R. Simoneit T. Brown Timothy J. Shaw University of South Carolina - Columbia, [email protected] Y. C. Wang See next page for additional authors Follow this and additional works at: https://scholarcommons.sc.edu/chem_facpub Part of the Oceanography Commons, and the Sedimentology Commons Publication Info Published in The Canadian Mineralogist, Volume 26, Issue 3, 1988, pages 589-602. © The aC nadian Mineralogist 1988, Mineralogical Association of Canada Gieskes, J. M., Simoneit, B. R., Brown, T., Shaw, T., Wang, Y. C., & Magenheim, A. (1988). Hydrothermal fluids and petroleum in surface sediments of Guaymas Basin, Gulf of California: a case study. The Canadian Mineralogist, 26(3), 589-602. This Article is brought to you by the Chemistry and Biochemistry, Department of at Scholar Commons. It has been accepted for inclusion in Faculty Publications by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Author(s) J. M. Gieskes, B. R. Simoneit, T. Brown, Timothy J. Shaw, Y. C. Wang, and A. Magenheim This article is available at Scholar Commons: https://scholarcommons.sc.edu/chem_facpub/316 Canadian Mineralogist Vol. 26, pp. 589-602 (1988) HYDROTHERMAL FLUIDS AND PETROLEUM IN SURFACE SEDIMENTS OF GUAYMAS BASIN. GULF OF CALIFORNIA: A CASE STUDY JORIS M. GIESKES Scnpps Institution of Oceanography, Ocean Research Division, A-015, University of California, San Diego, LaJolla, California 92093, U.S.A. BERND R.T. SIMONEIT Petroleum Research Group, College of Oceanography, Oregon State University, Corvallis, Oregon 97331, U.S.A. THOMAS BROWN, TIMOTHY SHAW, YONG-CHEN WANG, ANDREW MAGENHEIM Scnpps Institution ofOceanography, Ocean Research Division, A-015, University ofCalifornia, SanDiego, LaJolla, California 92093, U.S.A. Abstract nusentrc 1981 et 1988. Nous avons porte une attention tome speciale aux courtes carottcs prelevecs dans la couche de Surface sediments in hydrothcrmally active zones of the surface au moyen du submersible DSV ALVIN; les prele- Guaymas Basin, Gulf of California, have been analyzed vements ont die faits dans des regions d'advection verti for the inorganic chemical composition of sediments and cal des fluides d'originc hydrothcrmale, aussi bien dans their interstitial waters, as well as for their organic che des zones a fort ccoulcmcnt advectif que prcs des ecoule- mistry. Analysis of the inorganic constituents ofvent fluids ments diffus a travers Icscpaisscs accumulations de la bac- establishes end-member concentrations of hydrothermal tcric Beggialoa. La composition des caux interstiticlles fluids and also indicates that little change in chemical com montrc que les fluides qui contiennent une composante position has occurred between 1981 and 1988. Special atten hydrothcrmale ainsi que I'cau de mer atteigncnt la surface, tion is given to short surface cores collected with DSV et sont gencralcment munis de sulfurc d'originc peu pro- ALVIN in areas characterized by upward advection of fluids fonde; ce milieu peut done fournir une source d'energie of hydrothermal origin, both in areas of strong advective pour assurer la croissance de bactcries qui catalyscnt l'oxy- flow as well as seepage through large bacterial mats of Beg- dation dc sulfure. Nos etudes sur la composition du petrole giatoa. Interstitial-water compositions suggest that fluids d'originc hydrothcrmale montrem qu'il s'agit d'un condense consisting of hydrothermal and scawater components rise (hydrocarburcs C|-C20 el hydrocarbures polynucleaires to the surface, often carrying a supply of sulfide of shal aromatiques); en grande partic, cettc fraction a migre'avec low origin; this in turn may serve as an energy source for les fluides transported par advection verticale a partir d'une the growth of sulfide-oxidizing bacteria. Studies of the com faible profondcur en dessous de I'interfacc cau-scdiment. position of hydrothermally generated petroleum show that Le petrole des sediments sc trouvc surtout dans les fissu it is a condensate (C|-C2o hydrocarbons and polynuclcar res des fragments a ciment siliceux, et est transforme par aromatic hydrocarbons), and much of this material has biodegradation. Pres de I'event, le petrole est un condense migrated with the upward-advccling fluids from short non allcre, cc qui indiquc que le taux dc migration active depths below the sediment-water interface. The petroleum dans cc milieu surpassc le taux de biodegradation. in the sediments is found mainly in fractures in silica- (Traduit par la Redaction) cemented clasts and it is biodegraded. In the vent/mound, the petroleum is an unaltered condensate, indicating active Mots-clis: accumulations dc Beggialoa, condense, ecoule migration that exceeds biodegradation. mcnt diffus, gaz, golfe dc la Californic, bassin de Guay mas, composition du fluidc hydrothermal, petrole Keywords: Beggialoa mats, condensate, diffuse flow, gas. hydrothermal, composition de l'eau intcrstiticlle, car- Gulf of California, Guaymas Basin, hydrothermal fluid bone organique, hydrocarburcs polynucleaires aroma composition, hydrothermal petroleum, interstitial-water tiques, formation de sulfurcs. composition, organic carbon, polynuclcar aromatic hydrocarbons, sulfide generation. Introduction The hydrothermal system in Guaymas Basin ofthe SOMMAIRE Gulf of California (Fig. 1) is of special interest in the study of hydrothermal ore deposition, especially Les sediments dc surface des zones a manifestations because here newly formed oceanic basement con hydrothcrmalcs dans le bassin dc Guaymas, dans le golfe sists either of sill intrusions in rapidly deposited, de Californic, ont etc analyses afin de determiner la com organic carbon-rich sediments, or of massive intru position chimiquc (fractions inorganique et organiquc) des sediments et dc I'cau intcrstiticlle. L'analysedc la fraction sions at greater depths (Moore 1973, Williams et al. inorganique dc 1'eau des events definil la concentration des 1979, Einsele et al. 1980, Gieskes et al. I982a,b, elements dans Ics fluides hydrothcrmaux avant leur dilu 1988). Hydrothermal interactions involve both the tion, et momrc que tres peu dc changements sonl survc- alteration of basaltic rocks and of sediments, the lat- 589 590 THE CANADIAN MINERALOGIST Fig. 2. Cartoon version of hydrothermal deposit - ALVIN dive 1630. A: diffuse flow, temperature km <206°C; B: yellow bacterial mat; C: yellow bacterial 27*00N ;*• patches or • HVDMTHERml mat, sampled for core 1630-ACI; D: orange bacterial SINTER & MOUNDS mat; E: hydrothermal spires(1-1.5 m tall); F: fault zone (<30cm). Fic. I. Map of study area - note cores 1617-AC 1, 1619- AC2, 1629-AC2, 1630-ACI, and 1984-AC1, all in the Studies of Deep Sea DrillingProject (DSDP) cores southern hydrothermal field. Shaded areas represent obtained from Sites 477, 478, and 481 involved extent of sill complexes (Lonsdale & Becker 1985). interstitial-water chemistry (Gieskes et al. 1982a), solid-phase geochemistry and mineralogy (Kastner 1982, Kelts 1982, Niemitz 1982), and physical proper ter also providing a medium for the thermal genera ties of the sediments (Einsele el al. 1980, Einsele tion of hydrocarbons (Einsele et al. 1980, Kastner 1982).The results led Kastner (1982) and Gieskes el 1982, Simoneil 1983, 1984a,b, 1985a,b, Simoneit & al. (1982b) to conclude that two major hydrother Lonsdale 1982, Kawka & Simoneit 1987, Simoneit mal systems could be distinguished in Guaymas et al. 1984). Basin: 10 20 30 40 SO 60 10 20 30 40 SO $0 0 10 20 30 40 SO 60 Mg(mM) Mg(mM) Mg(mM) 20 30 40 $0 60 10 20 30 40 SO 10 20 30 40 SO 60 Mfl(mM) Mg(mM) Mg(mM) 200 • 9110 • 3 • Fig. 3. Compositional changes versus magnesium concen C 100 trations in hydrothermal vents of southern hydrother S • •• • mal field, Guaymas Basin, 1988. $0 •*^*s,*<. 0 10 20 30 40 SO 60 Mg(mM) HYDROTHERMAL FLUIDS AND PETROLEUM, GUAYMAS BASIN 591 (1) Hydrothermal activity associated with relatively short push cores was obtained in zones of diffuse thin, shallow basaltic sill intrusions in highly porous flow or below Beggialoa bacterial mats. In the sediments. This activity is usually of short duration present study we concentrate on one ALVIN dive and is associated with temperatures <200°C in the area in particular, but discuss the results in a broader vicinity ofthe sills. Decreased porosities indicate that context. expulsion of pore waters accompanies the sill emplacement. Study Area (2) Hydrothermal activity associated with large mag- In August 1985 several dives were made in the matic intrusions at greaterdepths; this activity occurs southern vent field of the southern trough of in a deep-seated, recharging, circulation system. Guaymas Basin (Fig. 1). In particular, core 1630- Hydrothermally altered waters, after reaction with ACI was obtained in an area where hydrothermal underlying basalts, interact with overlying sediments deposits indicated only very recent growth along a and lead to greenschist formation at temperatures of >300°C (Kastner 1982, Kelts 1982). Mass-balance considerations of oxygen isotopes (Kastner 1982) TABLE 1. COMPARISON OF HYDROTHERMAL ENDMEMBER indicated that open-system conditions prevailed dur CONCENTRATIONS OF VENT FLUIDS IN SOUTHERN VENT FIELD ing greenschist formation. This woik Lonsdale & Becker (1985) suggested the presence Campbellera/. (1988) of an additional hydrothermal system in which slow 597-617 610 recharging convection occurs within the sediments Cr<mM> overlying the sills. However, this type of system MgJ* (mM) 0 0 appears to be part ofthe first type described above. S04J"(mM) 0 0 Hydrothermal fluids have been observed to exit Ca2' (mM) 28 27 the sediment column in several ways (Lonsdale & Becker 1985). Fluids emanate from hydrothermal NH4*(mM) IS 13 mounds and chimneys at temperatures up to 3I5°C HjS(mM) 6 6 (Von Damm et al. 1985). They seem to have their K*(mM) 43 47 origin at greater depths, and must have flowed Mn(uM) 140 110 rapidly along fissures and faults in the sedimentary column.