A molecular-isotopic record of methane hydrate dissociation during the late Quaternary

Author(s): Hinrichs, Kai-Uwe; Hmelo, Laura
Author Affiliation(s): Primary:
Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA, United States
Volume Title: Geological Society of America, 2001 annual meeting
Source: Abstracts with Programs - Geological Society of America, 33(6), p.171; Geological Society of America, 2001 annual meeting, Boston, MA, Nov. 1-10, 2001. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Recently, Kennett et al. reported compelling evidence from carbon isotopic compositions of benthic and planktic foraminifera buried in sediments from ODP Site 893, Santa Barbara Basin, for repeated dissociation events of methane hydrate and subsequent release of methane into the basin (Science 288, 128-133, 2000). More recently, the hypothesis by Kennett and co-workers was supported by the discovery of a biosynthetic product of methane-consuming microorganisms. This compound, the hopanoid diplopterol, has exhibited isotopic compositions of around -60 per mil and occurred only in samples with unusually low carbon isotopic compositions of benthic foraminifera (Hinrichs, G-Cubed, #2000GC000118, 2001). Accordingly, aerobic methanotrophic bacteria oxidized methane that may have formed plumes in bottom waters of the basin. We have extended this work to a stratigraphic investigation of occurrence, distribution, and isotopic composition of biomarker products from methanotrophic microorganisms in relation to the foraminiferal isotopic record. Similarly, molecular products from marine photosynthetic primary producers were examined for their relationship to steep negative isotopic excursions observed in planktonic foraminifera during some interstadials. We will discuss the molecular-isotopic data in relation to the timing and magnitude of methane release and to the associated ecological and environmental response.
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Aliphatic hydrocarbons; Alkanes; C-13/C-12; California; Carbon; Cenozoic; Chemical composition; Continental borderland; East Pacific; Foraminifera; Hydrates; Hydrocarbons; Invertebrata; Isotope ratios; Isotopes; Leg 146; Marine sediments; Methane; Microfossils; North Pacific; Northeast Pacific; ODP Site 893; Ocean Drilling Program; Organic compounds; Pacific Ocean; Protista; Quaternary; Santa Barbara Basin; Sediments; Stable isotopes; United States; Upper Quaternary
Coordinates: N341715 N341715 W1200211 W1200212
Record ID: 2002021813
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