Carbon isotopic evidence for methane hydrate instability during quaternary interstadials

Large (about 5 per mil) millennial-scale benthic foraminiferal carbon isotopic oscillations in the Santa Barbara Basin during the last 60,000 years reflect widespread shoaling of sedimentary methane gradients and increased outgassing from gas hydrate dissociation during interstadials. Furthermore, several large, brief, negative excursions (up to -6 per mil) coinciding with smaller shifts (up to -3 per mil) in depth-stratified planktonic foraminiferal species indicate massive releases of methane from basin sediments. Gas hydrate stability was modulated by intermediate-water temperature changes induced by switches in thermohaline circulation. These oscillations were likely widespread along the California margin and elsewhere, affecting gas hydrate instability and contributing to millennial-scale atmospheric methane oscillations.

[1]  M. Maslin,et al.  Sea-level –and gas-hydrate–controlled catastrophic sediment failures of the Amazon Fan , 1998 .

[2]  J. Kennett,et al.  A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin , 1995, Nature.

[3]  G. Dickens,et al.  Methane hydrate stability in seawater , 1994 .

[4]  J. Jouzel,et al.  Evidence for general instability of past climate from a 250-kyr ice-core record , 1993, Nature.

[5]  G. Dickens,et al.  The Source and Fate of Massive Carbon Input During the Latest Paleocene Thermal Maximum. , 1999, Science.

[6]  M. Salgado-Labouriau,et al.  A dry climatic event during the late Quaternary of tropical Brazil , 1998 .

[7]  J. Severinghaus,et al.  Timing of abrupt climate change at the end of the Younger Dryas interval from thermally fractionated gases in polar ice , 1998, Nature.

[8]  R. M. Owen,et al.  Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene , 1995 .

[9]  Walter S Borowski,et al.  Increased continental-margin slumping frequency during sea-level lowstands above gas hydrate–bearing sediments , 1996 .

[10]  G. Klinkhammer,et al.  Porewater cadmium geochemistry and the porewater cadmium:δ13C relationship , 1991 .

[11]  T. Stocker,et al.  Atmospheric CO2 concentration and millennial-scale climate change during the last glacial period , 1998, Nature.

[12]  R. Rezak.  Deep-Sea Carbonates , 1974 .

[13]  R. Cicerone,et al.  Biogeochemical aspects of atmospheric methane , 1988 .

[14]  E. Nisbet.  The end of the ice age , 1990 .

[15]  D. Raynaud,et al.  Ice-core record of atmospheric methane changes: relevance to climatic changes and possible gas hydrate sources , 1998, Geological Society, London, Special Publications.

[16]  J. Kennett,et al.  Brief interstadial events in the Santa Barbara basin, NE Pacific, during the past 60 kyr , 1996, Nature.

[17]  C. Lorius,et al.  Ice-core record of atmospheric methane over the past 160,000 years , 1990, Nature.

[18]  Euan G. Nisbet,et al.  Giant submarine landslides , 1998, Nature.

[19]  I. Duijnstee,et al.  Benthic foraminifers: proxies or problems?: A review of paleocological concepts , 1999 .

[20]  R. Kayen,et al.  Pleistocene slope instability of gas hydrate‐laden sediment on the Beaufort sea margin , 1991 .

[21]  J. Kennett,et al.  Dansgaard-Oeschger Cycles and the California Current System: Planktonic foraminiferal response to rapid climate change in Santa Barbara Basin, Ocean Drilling Program Hole 893A , 2000 .

[22]  M. Field,et al.  Gas hydrates on the northern California continental margin , 1985 .

[23]  I. Fung,et al.  Potential distribution of methane hydrates in the world's oceans , 1994 .

[24]  K. Kvenvolden.  Methane hydrate — A major reservoir of carbon in the shallow geosphere? , 1988 .

[25]  S. Emerson,et al.  The relationship between pore water carbon isotopic composition and bottom water oxygen concentration , 1988 .

[26]  G. Wefer,et al.  Clues to ancient methane release , 1994, Nature.

[27]  James P. Kennett,et al.  Biotic response to late Quaternary rapid climate switches in Santa Barbara Basin: Ecological and evolutionary implications , 1999 .

[28]  M. Kashgarian,et al.  Ventilation changes in the northeast Pacific during the Last Deglaciation , 1996 .

[29]  J. Pandolfi,et al.  Reconciliation of late Quaternary sea levels derived from coral terraces at Huon Peninsula with deep sea oxygen isotope records , 1996 .

[30]  M. Sarnthein,et al.  Benthic foraminiferal δ13C and accumulation rates of organic carbon: Uvigerina Peregrina group and Cibicidoides Wuellerstorfi , 1986 .

[31]  A. Yayanos,et al.  The Distribution of Methane in the Upper Waters of the Southern California Bight , 1992 .

[32]  J. Kennett,et al.  CLIMATICALLY RELATED MILLENNIAL-SCALE FLUCTUATIONS IN STRENGTH OF CALIFORNIA MARGIN OXYGEN-MINIMUM ZONE DURING THE PAST 60 K.Y , 1999 .

[33]  P. Lonsdale.  A Transform Continental Margin Rich in Hydrocarbons, Gulf of California , 1985 .

[34]  R. Barnes,et al.  Methane production and consumption in anoxic marine sediments , 1976 .

[35]  W. Berger,et al.  Deep-sea carbonates: Reading the carbon-isotope signal , 1986 .

[36]  B. Haq.  Natural gas hydrates: searching for the long-term climatic and slope-stability records , 1998, Geological Society, London, Special Publications.

[37]  Franklin M. Orr,et al.  Deep-ocean field test of methane hydrate formation from a remotely operated vehicle , 1997 .

[38]  J. Jouzel,et al.  Irregular glacial interstadials recorded in a new Greenland ice core , 1992, Nature.

[39]  M. Field,et al.  Subsurface gas offshore of northern California and its link to submarine geomorphology , 1999 .

[40]  C. Winant,et al.  Characteristic patterns of the circulation in the Santa Barbara Channel , 1998 .

[41]  L. Keigwin,et al.  The influence of microhabitats on the carbon isotopic composition of deep‐sea benthic foraminifera , 1990 .

[42]  K. Kvenvolden.  Methane hydrates and global climate , 1988 .

[43]  A. Mix,et al.  Environmental control of living symbiotic and asymbiotic foraminifera of the California Current , 1995 .

[44]  A. Mix,et al.  Deep-dwelling planktonic foraminifera of the northeastern Pacific Ocean reveal environmental control of oxygen and carbon isotopic disequilibria , 1996 .

[45]  J. Bernhard,et al.  Benthic foraminiferal proxy to estimate dysoxic bottom-water oxygen concentrations; Santa Barbara Basin, U.S. Pacific continental margin , 1997 .

[46]  Gerald R. Dickens,et al.  Direct measurement of in situ methane quantities in a large gas-hydrate reservoir , 1997, Nature.

[47]  W. Dillon,et al.  Is the extent of glaciation limited by marine gas-hydrates , 1991 .

[48]  D. Kosiur,et al.  Methane production in Santa Barbara basin sediments , 1979 .

[49]  H. Behling,et al.  Environmental history of the Colombian savannas of the Llanos Orientales since the Last Glacial Maximum from lake records El Pinal and Carimagua , 1999 .

[50]  J. Brooks,et al.  Gas hydrate that breaches the sea floor on the continental slope of the Gulf of Mexico , 1994 .

[51]  E. Nisbet.  Sources of atmospheric CH4 in early postglacial time , 1992 .

[52]  J. Brooks,et al.  Observations of gas hydrates in marine sediments, offshore northern California , 1991 .

[53]  E. Brook,et al.  Rapid Variations in Atmospheric Methane Concentration During the Past 110,000 Years , 1996, Science.

[54]  Neil H. Kenyon,et al.  Evidence for long-term instability in the Storegga Slide region off western Norway , 1996 .

[55]  R. Rothwell,et al.  Low-sea-level emplacement of a very large Late Pleistocene ‘megaturbidite’ in the western Mediterranean Sea , 1998, Nature.

[56]  Keith A. Kvenvolden,et al.  A review of the geochemistry of methane in natural gas hydrate , 1995 .

[57]  J. Kennett,et al.  Latest Quaternary North Pacific surface-water responses imply atmosphere-driven climate instability , 1999 .

[58]  W. Borowski,et al.  Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate , 1996 .

[59]  J. Hansen,et al.  The ice-core record: climate sensitivity and future greenhouse warming , 1990, Nature.

[60]  M. Ledru,et al.  Vegetation dynamics in southern and central Brazil during the last 10 , 1998 .