| Autor: |
Caesar KH; Department of Geological Sciences, California State University, Fullerton, 800 North State College Boulevard, Fullerton, CA, 92831, USA., Kyle JR; Department of Geological Sciences, University of Texas at Austin, 2275 Speedway Stop C9000, Austin, TX, 78712, USA., Lyons TW; Department of Earth Sciences, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA., Tripati A; Department of Earth, Space and Planetary Sciences, Department of Atmospheric and Oceanic Sciences, Institute of the Environment and Sustainability, University of California, Los Angeles, 595 Charles Young Drive, Los Angeles, CA, 90095, USA., Loyd SJ; Department of Geological Sciences, California State University, Fullerton, 800 North State College Boulevard, Fullerton, CA, 92831, USA. sloyd@fullerton.edu. |
| Abstrakt: |
Major hydrocarbon accumulations occur in traps associated with salt domes. Whereas some of these hydrocarbons remain to be extracted for economic use, significant amounts have degraded in the subsurface, yielding mineral precipitates as byproducts. Salt domes of the Gulf of Mexico Basin typically exhibit extensive deposits of carbonate that form as cap rock atop salt structures. Despite previous efforts to model cap rock formation, the details of subsurface reactions (including the role of microorganisms) remain largely unknown. Here we show that cap rock mineral precipitation occurred via closed-system sulfate reduction, as indicated by new sulfur isotope data. 13 C-depleted carbonate carbon isotope compositions and low clumped isotope-derived carbonate formation temperatures indicate that microbial, sulfate-dependent, anaerobic oxidation of methane (AOM) contributed to carbonate formation. These findings suggest that AOM serves as an unrecognized methane sink that reduces methane emissions in salt dome settings perhaps associated with an extensive, deep subsurface biosphere. |
