Mechanism of Mass Movement in Submarine Landslide, Along the South Caspian Sea (Iran's Territorial Waters)

The Caspian Sea is located in the central part of the Alpine-Himalayan active mountains belt ,the northern seismic belt running from Black-Sea and bifurcated into two branches; west of the Azerbaijan-Caucasus and across the Caspian Sea in the Kopet-Dagh NW of Iran. World's largest inland body of water, lying to the east of the Caucasus mountains and to the west of the vast steppe of central Asia. The elongated sea sprawls for nearly 1200km from north to south, although its average width is only 320km. It covers an area of ~ 386,400 km2 and its surface lies some 27 meters below sea level. The maximum depth the south (Iran's Territorial), is 1,025 meters below the sea's surface. The drainage basin of the sea covers 3,625 000 km2. The sea contains some 78,200 km3. This paper deals with a discussion of the origin of the Caspian depression and its geologic structure, describes history of changes in geologic sea level, and the different terraces formed by its change. Furthermore, the stratigraphy and structures of the complex of Iran-Azerbaijan at coastal area cover many terraces. Composition of the sediments from the various rivers is strongly affected by climate changes, e.g.; the Volga and Oral (Ural) bring much dissolved carbonate from the superficial soils. The lack of earthquakes within the basin itself indicates that it behaves as a rigid block, though its sedimentary cover is deformed by numerous folds that are developed from rigid basement by overpressured mud. The basin contains a sedimentary sequence almost 20 km thick above a relatively high-velocity basement that is thinner within the basin than on its margins. The basement beneath the basin could be either unusually thick Oceanic Crust or thinned, but relatively high velocity, Continental Crust. The south Caspian Sea is surrounded by active earthquake belts on all sides. In this study we analyze seismic regime and earthquake depth distribution and correlation of seismicity and landslide submarine in the Caspian Sea Region. Well-logs from the south Caspian Sea, offshore Azerbaijan, were interpreted and analyzed in order to clarify the origin, age, and area extent at large-scale (2.500 Km2). Late Pleistocene zone of seafloor deformation and submarine slumping is origin of the Absheron allochton and Iran's territorial waters of south Caspian Sea. These data are uniquely set to evaluate proposed mechanisms for Late- Pleistocene submarine slope failure, and favor a genetic relationship with dissociation of underlying gas hydrates when the sea level was at minimum.

Keywords:

South Caspian Sea , Submarine Landslide , Late-Pleistocene , Sediments , Seismicity ,