Oxic and anoxic regions of subseafloor sediment

Author(s): D'Hondt, Steven; Pockalny, Robert A.; Spivack, Arthur J.; Inagaki, Fumio; Murray, Richard W.; Adhikari, Rishi Ram; Gribsholt, Britta; Kallmeyer, Jens; McKinley, Claire Cecilia; Morono, Yuki; Roy, Hans; Sauvage, Justine; Ziebis, Wiebke
Author Affiliation(s): Primary:
University of Rhode Island, Narragansett, RI, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Boston University, United States
University of Bremen, Germany
Viden Djurs, Denmark
Helmholtz Centre Potsdam, Germany
Texas A&M University-College Station, United States
Aarhus University, Denmark
University of Southern California, United States
Volume Title: AGU 2015 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2015; American Geophysical Union 2015 fall meeting, San Francisco, CA, Dec. 14-18, 2015. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Dissolved oxygen content defines two broad categories of subseafloor sediment. In areas with high rates of microbial respiration, most of the sediment column is anoxic and active anaerobic microbial communities are present for hundreds of meters or more below the seafloor. In these regions, O2 and aerobic communities penetrate only millimeters to centimeters into the sediment from the sediment-water interface. In some areas of active fluid flow through the underlying basalt, O2 may also penetrate meters upward into the sediment from the basalt. In areas with low sedimentary respiration, O2 and aerobic communities penetrate tens of meters downward from the seafloor and may persist throughout the entire sediment column. IODP Expedition 329 showed that microbial cells and aerobic respiration persist through the entire sediment sequence (to depths of at least 75 meters below seafloor) in the South Pacific Gyre. Extrapolating from these results and a global relationship of O2 penetration depth to sedimentation rate and sediment thickness, we suggest that oxygen and aerobic communities occur throughout the entire sediment sequence in 15-44% of the Pacific and 9-37% of the global seafloor. Subduction of sediment from largely anoxic regions and subduction of sediment and basalt from fully oxic regions are respectively sources of reduced and oxidized material to the mantle. The balance between oxic and anoxic regions has presumably changed considerably throughout Earth history. Regions with largely anoxic sediment and regions with fully oxic sediment present fundamentally different opportunities for understanding of (i) paleoceanographic history and (ii) the nature of microbial life under extreme energy limitations.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Cores; East Pacific; Expedition 329; Integrated Ocean Drilling Program; Marine sediments; Pacific Ocean; Sediments; South Pacific; Southeast Pacific
Coordinates: S455800 S235100 W1230900 W1660000
Record ID: 2016060117
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