Sulfur cycle in buried evaporites

Research Article| July 01, 1997 Sulfur cycle in buried evaporites R. H. Worden; R. H. Worden 1The School of Geosciences, The Queen's University, Belfast, Northern Ireland BT7 1NN, United Kingdom Search for other works by this author on: GSW Google Scholar P. C. Smalley; P. C. Smalley 2BP Exploration, Exploration Technology Centre, Sunbury Research and Engineering Centre, Chertsey Road, Sunbury on Thames, Middlesex TW16 7LN, United Kingdom Search for other works by this author on: GSW Google Scholar A. E. Fallick A. E. Fallick 3Isotope Geosciences Unit, Scottish University Research Reactor Centre, East Kilbride, Glasgow G75 0QF, United Kingdom Search for other works by this author on: GSW Google Scholar Author and Article Information R. H. Worden 1The School of Geosciences, The Queen's University, Belfast, Northern Ireland BT7 1NN, United Kingdom P. C. Smalley 2BP Exploration, Exploration Technology Centre, Sunbury Research and Engineering Centre, Chertsey Road, Sunbury on Thames, Middlesex TW16 7LN, United Kingdom A. E. Fallick 3Isotope Geosciences Unit, Scottish University Research Reactor Centre, East Kilbride, Glasgow G75 0QF, United Kingdom Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (7): 643–646. https://doi.org/10.1130/0091-7613(1997)025<0643:SCIBE>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation R. H. Worden, P. C. Smalley, A. E. Fallick; Sulfur cycle in buried evaporites. Geology 1997;; 25 (7): 643–646. doi: https://doi.org/10.1130/0091-7613(1997)025<0643:SCIBE>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Sulfur isotopes are potent indicators of the way in which sulfur behaves chemically during diagenesis. We have studied sulfur isotope ratios (34S/32S) from a number of minerals and compounds across the Permian-Triassic boundary in the Khuff Formation, Abu Dhabi. The δ34S in dissolved marine sulfate increased by 10‰ from the Late Permian to the Early Triassic. Despite precipitation of gypsum from Permian and Triassic seawater and its subsequent dehydration to anhydrite at depths greater than about 1000 m, the primary marine stratigraphic sulfur isotope variation has been preserved in anhydrite in the Khuff Formation. A combination of biostratigraphic and absolute age data show that this 10‰ shift occurred over <2 m.y. Gypsum dehydration to anhydrite has not involved significant isotopic fractionation or diagenetic redistribution of material in the subsurface. The sulfur isotope variation across the Permian-Triassic boundary is also present in elemental sulfur and H2S, at depths greater than 4300 m, formed by reaction of anhydrite with hydrocarbons via thermochemical sulfate reduction. This demonstrates that sulfate reduction has not led to isotope fractionation. It also demonstrates that significant mass transfer has not occurred, at least in the vicinity of the Permian-Triassic boundary, even though elemental sulfur and H2S are both fluid phases at depths greater than 4300 m. Thus, despite two major diagenetic processes that converted the sulfur in gypsum into elemental sulfur and H2S by 4300 m burial and the potentially mobile nature of some of the reaction products, the primary differences in sulfur isotopes have been preserved in the rocks and fluids. All reactions occurred in situ; there was no significant sulfur isotope fractionation, and only negligible sulfur was added, subtracted, or moved internally within the system. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.