Hill, T. M. and Kennett, J. P. (2003): Methane hydrate and Quaternary climate change; evidence from sediment records and modern methane seeps

Leg/Site/Hole:
ODP 146
ODP 146 893
Identifier:
2007-002312
georefid

Creator:
Hill, T. M.
University of California at Santa Barbara, Department of Geological Sciences, Santa Barbara, CA, United States
author

Kennett, J. P.
author

Identification:
Methane hydrate and Quaternary climate change; evidence from sediment records and modern methane seeps
2003
In: Anonymous, XVI INQUA congress; Shaping the Earth; a Quaternary perspective; programs with abstracts
[International Union for Quaternary Research], International
16
130
Methane hydrates have been implicated as a possible forcing mechanism for rapid climate change during the late Quaternary. Releases from the hydrate reservoir are recorded as carbon isotopic spikes in marine sediment records and may represent a significant perturbation of the global carbon cycle. While the role of methane hydrates in rapid climate change is controversial, aspects of this hypothesis are currently being tested using high-resolution sediment records and studies at modern methane seep environments. Carbon isotopic (delta 13C) spikes previously recorded in Santa Barbara Basin (ODP Site 893) have been interpreted as evidence of massive local gas hydrate destabilization. Further studies of stadial/interstadial transitions ODP Site 893 at ultra-high resolution have uncovered additional delta 13C excursions. These delta 13C spikes occur immediately following bottom water warming associated with the onset of interstadials. These spikes occur in both benthic and planktonic foraminifera, and are very brief, lasting only decades. The observed delta 13C spikes are similar in magnitude to those observed in foraminifera from modern methane seeps (Santa Barbara Basin and Hydrate Ridge, Oregon). Benthic foraminifera living at modern methane seeps record negative delta 13C values (to -10ppm). In addition, certain foraminiferal species are well adapted to the high-organic, low-oxygen methane seep environment. Because these trends are recorded in live foraminifera, concern about authigenic carbonate altering the delta 13C signature is negated. Ongoing research is comparing the relative response of surface and intermediate waters during abrupt climatic warming. Intermediate waters are important because they reside at the critical depth of potential instability of the methane hydrate reservoir in the late Quaternary. In Santa Barbara Basin, delta 18O changes record inferred intermediate water warmings of 2-3 degrees C during stadial to interstadial transitions. These records also indicate that during stadial/interstadial transitions and the deglacial episode, intermediate water warming either preceded or may have been synchronous with surface water warming. This research continues to test and lend supportive evidence to the hypothesis that the methane hydrate reservoir may have played a crucial role in late Quaternary climate change.
English
Coverage:Geographic coordinates:
North:34.1715
West:-120.0212East: -120.0211
South:34.1715

Quaternary geology; aliphatic hydrocarbons; alkanes; C-13/C-12; carbon; Cenozoic; climate change; East Pacific; gas hydrates; gas seeps; Hydrate Ridge; hydrocarbons; isotope ratios; isotopes; Leg 146; marine sediments; methane; North Pacific; Northeast Pacific; Ocean Drilling Program; ODP Site 893; Oregon; organic compounds; Pacific Ocean; paleoclimatology; Quaternary; Santa Barbara Basin; sediments; stable isotopes; United States;

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