Deep structure, tectonics, evolution and hydrocarbon potential of the north-western shelf of the Black Sea along 31°20’E

Abstract

A density modeling of the north-western shelf of the Black Sea along 31°20’ E was carried out. According to its results, a complex block structure of the area is determined, which is closely connected with the history of its development. Signs of Baikal tectonic activation of the southern edge of the pre-Riphean Eastern European platform, as well as the adjacent part of the Scythian plate have been revealed. Areas formed during the Hercynian and Cimmerian epochs of tectogenesis have been identified within the Scythian plate. At the base of the Karkinit Trough, two areas of reduced crust resulting from riftogenesis with varying degrees of intensity of basification have been established. Two ancient volcanos of ryolite composition were found on the basement surface on the northern slope of the Kalamit swell. It is highly probable that the Gamburtsev uplift is an eastern extension of the Gubkin swell. According to the structure and value of the calculated densities, it is established that the Gamburtsev uplift is a «blind» mud volcano, which was formed during the second stage of the late Cimmerian cycle and was active throughout the Cretaceous period. A detailed analysis of the deep structure and fault tectonics of the local structures of the sedimentary cover in the intersection of the profile and the area of gas seeps was carried out. It was found that the Flangova, Partizanska and Hamburtseva structures are more promising for hydrocarbon accumulation. The hydrocarbon potential of the Ushakov structure (H-41) is questionable, because structurally and tectonically it is analogous to the Delphin structure, which was deemed unproductive based on drilling results. The area of gas seeps was found to be confined to a mantle fault, which separates two blocks with distinctly different structures and Meso-Cenozoic evolution of the Earth’s crust. It is proposed to conduct a detailed seismic survey in this area in order to identify local structures in the sedimentary cover, promising for hydrocarbons.