Cyclic 100-ka (glacial-interglacial) migration of subseafloor redox zonation on the Peruvian shelf

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doi: 10.1073/pnas.1305981110
Author(s): Contreras, Sergio; Meister, Patrick; Liu, Bo; Prieto-Mollar, Xavier; Hinrichs, Kai-Uwe; Khalili, Arzhang; Ferdelman, Timothy G.; Kuypers, Marcel M. M.; Jorgensen, Bo Barker
Author Affiliation(s): Primary:
Max Planck Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
Other:
University of Bremen, Germany
Volume Title: Proceedings of the National Academy of Sciences of the United States of America
Source: Proceedings of the National Academy of Sciences of the United States of America, 110(45), p.18098-18103. Publisher: National Academy of Sciences, Washington, DC, United States. ISSN: 0027-8424 CODEN: PNASA6
Note: In English. 46 refs.; illus., incl. 1 table, chart
Summary: The coupling of subseafloor microbial life to oceanographic and atmospheric conditions is poorly understood. We examined diagenetic imprints and lipid biomarkers of past subseafloor microbial activity to evaluate its response to glacial-interglacial cycles in a sedimentary section drilled on the Peruvian shelf (Ocean Drilling Program Leg 201, Site 1229). Multiple and distinct layers of diagenetic barite and dolomite, i.e., minerals that typically form at the sulfate-methane transition (SMT), occur at much shallower burial depth than the present SMT around 30 meters below seafloor. These shallow layers co-occur with peaks of 13C-depleted archaeol, a molecular fossil of anaerobic methane-oxidizing Archaea. Present-day, non-steady state distributions of dissolved sulfate also suggest that the SMT is highly sensitive to variations in organic carbon flux to the surface shelf sediments that may lead to shoaling of the SMT. Reaction-transport modeling substantiates our hypothesis that shallow SMTs occur in response to cyclic sediment deposition with a high organic carbon flux during interglacials and a low organic carbon flux during glacial stages. Long diffusion distances expectedly dampen the response of deeply buried microbial communities to changes in sediment deposition and other oceanographic drivers over relatively short geological time scales, e.g., glacial-interglacial periods. However, our study demonstrates how dynamically sediment biogeochemistry of the Peru Margin has responded to glacial-interglacial change and how these changes are now preserved in the geological record. Such changes in subsurface biogeochemical zonation need to be taken into account to assess the role of the subseafloor biosphere in global element and redox cycling
Year of Publication: 2013
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Aliphatic hydrocarbons; Alkaline earth metals; Alkanes; Aluminum; Archaea; Archaeol; Ba/Al; Barite; Barium; Biochemistry; Biogenic processes; Biomarkers; Biosphere; C-13; C-13/C-12; Ca/Al; Calcium; Carbon; Carbonates; Cenozoic; Cyclic processes; Depth; Diagenesis; Dolomite; East Pacific; Eh; Equatorial Pacific; Geochemical cycle; Glacial environment; Holocene; Hydrocarbons; Interglacial environment; Isotope ratios; Isotopes; Leg 201; Lipids; Marine environment; Marine sediments; Metals; Methane; Microorganisms; Middle Pleistocene; ODP Site 1229; Ocean Drilling Program; Organic compounds; Oxidation; Pacific Ocean; Peru; Pleistocene; Pore water; Quaternary; Reactive transport; Sediments; Shelf environment; South America; South Pacific; Southeast Pacific; Stable isotopes; Sulfate-methane transition; Sulfates; Transport; Upper Pleistocene; Upwelling
Coordinates: S105900 S105900 W0775800 W0775800
Record ID: 2014033416
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