HR: 0830h
AN: OS51B-0862    [PDF]
TI: Large-scale Submarine Landslide of the South Caspian Sea: Possible Evidence for Generation by Gas Hydrate Dissociation During Sea Level Lowstand
AU: * Knapp, C C
EM: camelia@geol.sc.edu
AF: Dept. Geological Sciences University of South Carolina, 701 Sumter St., Columbia, SC 29208 United States
AU: Knapp, J H
EM: knapp@geol.sc.edu
AF: Dept. Geological Sciences University of South Carolina, 701 Sumter St., Columbia, SC 29208 United States
AU: Mitchell, C
EM: acatch_22@hotmail.com
AF: Dept. Geological Sciences University of South Carolina, 701 Sumter St., Columbia, SC 29208 United States
AB: Massive slope failure in the South Caspian basin, identified on industry multichannel seismic reflection data, shows a close spatial relationship with buried gas hydrates in the continental slope in the deepwater of Azerbaijan. Covering a region in excess of 200 sq. km, the Absheron Allochthon is characterized by a highly faulted and disrupted stratigraphic sequence ~200-300 m in thickness, with extensive normal faulting updip and a clearly recognizable toe thrust along the downdip extent. Pleistocene strata below the allochthon appear unaffected by this shallow deformation, while seafloor expression of this deformation suggests one of two possibilities for the age of the Absheron Allochthon: (1) Late Pleistocene movement, followed by relatively minimal deposition in Recent time, or (2) Recent (and ongoing?) development of the allochthon. Basin bathymetry suggests the former model is plausible, since rising sea-level has apparently displaced deltaic depocenters laterally by hundreds of kilometers. Historic sea level changes in the Caspian basin have exceeded 3 m over the last century, and were significantly amplified in comparison with global sea level changes during Pleistocene time. Since the inland Caspian Sea has been affected by sea level fluctuations at much shorter time scales and much larger amplitudes than the world's oceans, climate-induced changes in Caspian Sea level may have been responsible for large scale slope failure and seabed deformation through massive dissociation of buried gas hydrates during the sea level falls at the end of Pleistocene. Due to the historic large-scale variations of sea level of the landlocked Caspian Sea, this region represents a natural laboratory to study the relationships among the gas hydrate dissociation and seafloor deformation, and can be used as a proxy for similar processes in the world's oceans.
DE: 1615 Biogeochemical processes (4805)
DE: 1800 HYDROLOGY
DE: 3022 Marine sediments--processes and transport
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting