Repeated pulses of vertical methane flux recorded in glacial sediments from the southeast Bering Sea
Figure S2: Structures of compounds discussed in text: (a) archaeol, (b) di-ai-C15/ai-C15-glycerolether (DAGE-C30), (c) calderarchaeol (acyclic GDGT), (d) crenarchaeol (GDGT with bicyclic and cyclohexa-tricyclic biphytanes), (e) monocyclic GDGT, and (f) biyclic GDGT. (264.3Kb)
Table S1: Stable isotopes measured on Neogloboquadrina pachyderma (sinistral) in HLY02-02-51JPC. (20.59Kb)
Table S2: Stable isotopes measured on Neogloboquadrina pachyderma (sinistral) in HLY02-02-57JPC. (26.48Kb)
Table S7: Total organic carbon, abundance and d13C of archaeol and DAGE-C30 in HLY02-02-51JPC. (574bytes)
Table S8: Total organic carbon, abundance and d13C of archaeol and DAGE-C30 in HLY02-02-57JPC. (448bytes)
Cook, Mea S.
Keigwin, Lloyd D.
MetadataShow full item record
There is controversy over the role of marine methane hydrates in atmospheric methane concentrations and climate change during the last glacial period. In this study of two sediment cores from the southeast Bering Sea (700 m and 1467 m water depth), we identify multiple episodes during the last glacial period of intense methane flux reaching the seafloor. Within the uncertainty of the radiocarbon age model, the episodes are contemporaneous in the two cores and have similar timing and duration as Dansgaard-Oeschger events. The episodes are marked by horizons of sediment containing 13C-depleted authigenic carbonate minerals; 13C-depleted archaeal and bacterial lipids, which resemble those found in ANME-1 type anaerobic methane oxidizing microbial consortia; and changes in the abundance and species distribution of benthic foraminifera. The similar timing and isotopic composition of the authigenic carbonates in the two cores is consistent with a region-wide increase in the upward flux of methane bearing fluids. This study is the first observation outside Santa Barbara Basin of pervasive, repeated methane flux in glacial sediments. However, contrary to the “Clathrate Gun Hypothesis” (Kennett et al., 2003), these coring sites are too deep for methane hydrate destabilization to be the cause, implying that a much larger part of the ocean's sedimentary methane may participate in climate or carbon cycle feedback at millennial timescales. We speculate that pulses of methane in these opal-rich sediments could be caused by the sudden release of overpressure in pore fluids that builds up gradually with silica diagenesis. The release could be triggered by seismic shaking on the Aleutian subduction zone caused by hydrostatic pressure increase associated with sea level rise at the start of interstadials.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 26 (2011): PA2210, doi:10.1029/2010PA001993.
Showing items related by title, author, creator and subject.
Stable isotopic evidence in support of active microbial methane cycling in low-temperature diffuse flow vents at 9°50’N East Pacific Rise Proskurowski, Giora; Lilley, Marvin D.; Olson, Eric J. (2008-01)A unique dataset from paired low- and high-temperature vents at 9°50’N East Pacific Rise provides insight into the microbiological activity in low-temperature diffuse fluids. The stable carbon isotopic composition of CH4 ...
Methane fluxes between terrestrial ecosystems and the atmosphere at northern high latitudes during the past century : a retrospective analysis with a process-based biogeochemistry model Zhuang, Qianlai; Melillo, Jerry M.; Kicklighter, David W.; Prinn, Ronald G.; McGuire, A. David; Steudler, Paul A.; Felzer, Benjamin S.; Hu, Shaomin (American Geophysical Union, 2008-08-18)We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century ...
Scandella, Benjamin P.; Varadharajan, Charuleka; Hemond, Harold F.; Ruppel, Carolyn D.; Juanes, Ruben (American Geophysical Union, 2011-03-26)Methane is a potent greenhouse gas, but its effects on Earth's climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the ...