HR: 1340h
AN: GC43A-0953    [Abstracts]
TI: Climate Clues From the Caspian Sea: Gas Hydrates and Seafloor Deformation
AU: * Amos, C C
EM: camos@geol.sc.edu
AF: Dept. of Geological Sciences, University of South Carolina, 701 Sumter Street, EWS 617, Columbia, SC 29208, United States
AU: Knapp, C C
EM: camelia@geol.sc.edu
AF: Dept. of Geological Sciences, University of South Carolina, 701 Sumter Street, EWS 617, Columbia, SC 29208, United States
AU: Knapp, J H
EM: knapp@geol.sc.edu
AF: Dept. of Geological Sciences, University of South Carolina, 701 Sumter Street, EWS 617, Columbia, SC 29208, United States
AB: The presence of buried gas hydrates in the South Caspian Sea has been interpreted using 2-D seismic reflection data. Evidence for buried gas hydrates consists of a shallow (300-500 m below seafloor) comparatively high velocity zone approximately parallel to the seafloor bounded by a positive-polarity reflector at the top and a high- amplitude negative-polarity reflector at the base. The position of gas hydrates fall within the stability field predicted for the South Caspian Basin. New industry quality 3-D seismic data are being used to determine the relationship between the presence of gas hydrates and an approximately 2,500 km2 late-Pleistocene zone of seafloor deformation and submarine slumping in the South Caspian Sea, named the Absheron Allochthon. Well-logs from the South Caspian Sea offshore Azerbaijan are being correlated with the 3-D seismic data to determine the age and origin of the Absheron Allochthon. The history of sea level changes in the Caspian Sea in the past ~700 ka emphasizes a major ~100 m drop in sea level during the latest deglaciation (late Pleistocene). Preliminary results show that the Absheron Allochthon may have formed through catastrophic failure of the western South Caspian continental slope as a result of dissociation of underlying buried gas hydrates. If this proves to be true, then repeated, remarkably rapid global warming events in the Caspian Sea during the late Quaternary were likely due to rapid marine gas hydrate (clathrate) dissociation rather than exhalation from wetlands.
DE: 3004 Gas and hydrate systems
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting