Alt, Jeffrey C. et al. (2003): Isotopic composition of gypsum in the Macquarie Island Ophiolite; implications for the sulfur cycle and the subsurface biosphere in oceanic crust
Leg/Site/Hole:
Related Expeditions:
ODP 111
Identifier:
ID:
2003-045540
Type:
georefid
ID:
10.1130/0091-7613(2003)031<0549:ICOGIT>2.0.CO;2
Type:
doi
Creator:
Name:
Alt, Jeffrey C.
Affiliation:
University of Michigan, Department of Geological Sciences, Ann Arbor, MI, United States
Role:
author
Name:
Davidson, Garry J.
Affiliation:
University of Tasmania, Australia
Role:
author
Name:
Teagle, Damon A. H.
Affiliation:
University of Southampton, United Kingdom
Role:
author
Name:
Karson, Jeffrey A.
Affiliation:
Duke University, United States
Role:
author
Identification:
Title:
Isotopic composition of gypsum in the Macquarie Island Ophiolite; implications for the sulfur cycle and the subsurface biosphere in oceanic crust
Year:
2003
Source:
Geology (Boulder)
Publisher:
Geological Society of America (GSA), Boulder, CO, United States
Volume:
31
Issue:
6
Pages:
549-552
Abstract:
The O, S, and Sr isotope compositions were determined for 17 samples of gypsum that replaced anhydrite in the sheeted-dike complex of the Macquarie Island ophiolite. Elevated delta (super 34) S (26.2 ppm-29.0 ppm) and delta (super 18) O values (12.5 ppm-14.4 ppm) of gypsum compared to those of seawater sulfate are the result of microbial sulfate reduction. Low organic carbon contents and little sulfate reduction in sediments, plus a large basaltic Sr component in the gypsum ( (super 87) Sr/ (super 86) Sr = 0.70446-0.70524), indicate that the sulfate source was not pore waters in the overlying sediment. Low delta (super 34) S values of sulfide in basalt lavas are consistent with microbial reduction of seawater sulfate within the volcanic rocks. Tectonic activity at the slow-spreading ridge allowed evolved formation waters to enter hot sheeted-dike complex basement, resulting in heating and precipitation of anhydrite. Results show that microbes can leave geochemical tracers of their activity in oceanic basement and that anhydrite can be preserved in oceanic crust and may be of significance for the oceanic sulfur budget.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:-54.3000 West:158.4800 East:
159.0000 South:-54.4200
Keywords: Isotope geochemistry; Igneous and metamorphic petrology; alkaline earth metals; bacteria; crust; Deep Sea Drilling Project; DSDP Site 504; geochemical cycle; gypsum; hydrothermal conditions; IPOD; isotope ratios; isotopes; Leg 111; Leg 137; Leg 140; Leg 148; Leg 69; Leg 70; Leg 83; Leg 92; Macquarie Island; Macquarie Island Ophiolite; metals; mid-ocean ridges; O-18/O-16; Ocean Drilling Program; ocean floors; oceanic crust; ophiolite; oxygen; S-34/S-32; sea water; Sr-87/Sr-86; stable isotopes; strontium; sulfates; sulfur; West Pacific Ocean Islands;
.