Funds were provided to interpret and analyze a large (640 km²), industry-quality, 3-D multichannel seismic reflection dataset (@ 3 s) and well-logs from the petroliferous South Caspian basin, offshore Azerbaijan, in order to clarify the origin, age, and areal extent of a large-scale (> 2,500 km²) late-Pleistocene zone of seafloor deformation and submarine slumping, the Absheron Allochthon. These data are uniquely set to evaluate proposed mechanisms for late-Pleistocene large-scale submarine slope failure, and favor a genetic relationship with dissociation of underlying gas hydrates when the sea level was at a minimum. Previous analysis of two regional seismic reflection profiles from the study area documented the occurrence of gas hydrates concealed beneath the seafloor (~300 m) in water depths of 400-650 m. Historic sea level changes in the Caspian basin have exceeded 3 m over the last century, and were significantly amplified in comparison to global sea level changes during the Pleistocene time. Since the inland Caspian Sea is affected by sea level fluctuations at much shorter time scales and much larger amplitudes than the world’s oceans, the premise is that climate-induced changes in sea level were responsible for large scale slope failure and seabed deformation through massive dissociation of buried gas hydrates during the sea level lowstands in the late-Pleistocene. This region may become a natural laboratory to study the relationships among the gas hydrate dissociation and seafloor deformation, and may be further used as a proxy for similar processes in the world’s oceans.

Personnel
Camelia C. Knapp

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