Caucasus wedge-thrust structures and oil-gas potential

Structural elements with an arched shape in plan occur in the Great and Lesser Caucasus foothills. Their formation is due to the presence of transverse buried rifts, which are overthrust by foreland folds having the form of a wedge in plan. The resulting structures are favourable for the presence of oil and gas accumulations. The Daghestan wedge-nappe (DWN), named by Shatskiy in 1925, is a tectonotype for such structures. The DWN has been thrust over a large rift trough with a transverse orientation to the strike of the Eastern Caucasus folds. Sedimentation and intensive heating through the Mesozoic and Cenozoic resulted in this trough becoming an area of hydrocarbon generation. Wedge-nappe structures are likely to occur widely in all fold belts, such as the Ural and Verhoyansk belts in Russia, the Bulgarian Eastern Balkans and the Suleyman Mountains in Pakistan.