Cenozoic stage of development of local structures of the Lower Kura Depression and Baku Archipelago related to their oil and gas prospectivity

Abstract

The South Caspian Basin (SCB), including the Lower Kura Depression (LKD), was one of the deep‐sea basins of Tethys before the Late Palaeogene. During the Late Palaeogene, due to the convergence of the Iranian‐Afghan and Anatolian plates with the Eurasian Plate, the SCB was transformed into a marginal sea. By the end of the Miocene, the Arabian Plate converged between Anatolian and Irano‐Afghan, which contributed to fold deformations of north‐eastern orientation in the north‐western part of the Iranian‐Afghan Plate. It led to the development of the western side of SCB and drainage of Kura Depression; since then, the LKD became a western onshore continuation of SCB. A compressive stress regime, established there since the end of the Miocene, directly influenced the structures development process in LKD and Baku Archipelago (BA). Although LKD is located onshore and its eastern edge belongs to SCB west board, together with BA they form a single structural and tectonic zone, which is evidenced by the evolution, spatial orientation of local structures and anticlinal zones. To establish the correlation of the evolution features of LKD and BA, we performed the palaeoanalysis on the basis of reconstructed palaeoprofiles for several LKD and BA structures. From palaeoprofiles, we constructed diagrams of fold growth intensity. The results of the correlation of these diagrams indicate at the consedimentational and continuous character of the development of structures in both zones (except for the buried structures) but featuring different intensity at different intervals of geological time. During the formation time of the Lower Production Series (LPS), both zones were characterized by a relatively rapid growth of the folds. At the time of formation of the Upper Production Series (UPS), Absheron‐Aghjagil structures growth intensity was roughly the same but lower than that of LPS. The most intense growth of folds in both zones occurred in Quaternary time.