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Abstract: Seismic Stratigraphy of the South Caspian Sea

Professor Pervis Mamedov, Dr. Davud Babaev

Identifying, characterizing, and correlating unconformities is one of the major tools of seismic stratigraphy. Unconformities are common in the sediments deposited in basins associated with active tectonic belts. Unconformities within the sediments of the South Caspian basin reflect major geological events within the evolution of the Greater Caucasus, Lesser Caucasus, and Elburz tectonic belts of the Alpine orogeny.

The Tertiary sedimentary section of the South Caspian is characterized by rapid deposition of a thick section of sands and shales, with a maximum of over 20,000 meters. Within this sedimentary fill we recognize two major regional unconformities separating macro sequences. The lower unconformity establishes in some areas the top Cretaceous surface and in other areas the top Paleocene-Eocene surface. The upper unconformity is time transgressive and establishes the lower boundary of the Pliocene-Quaternary macro sequence in those areas where the South Caspian basin has undergone recent down-warping.

Identification and characterization of the major, basin-wide unconformities is important to relate the timing of major structural and stratigraphic events from one area to another. Within this same framework, identifying and characterizing smaller unconformities and hiatuses is an essential tool for lithologic prediction, especially in deep water and away from existing well control.

The isolation of the South Caspian basin from the Tethys open marine environment during the Neogene has given rise to rapid fluctuation in the sea level of the Caspian Sea. These fluctuations are controlled by the tectonic events in the adjoining mountain belts and changes in water input from the Volga-Ural, paleo-Ozboy-Amu Darya river systems.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France