Earth crust of eastern segment of Ukrainian Carpathians in the regional profile RP-5 zone: structure, geodynamics, oil and gas bearing

Abstract

The purpose of the work is to present widely to the scientific community and analyze in detail the structure and oil and gas bearing of the Bukovyna lithosphere (the eastern part of the Carpathian region of Ukraine) based on the unique data on the regional RWМ-CDP profile RP-5 and on the neighboring regional profiles with the involvement of other geological and geophysical data. The methodology includes a detailed comprehensive analysis of the deep structure and oil and gas bearing and oil and gas prospects of the region and its separate zones based on seismic data on the regional profile RP-5 and nearby oil and gas bearing and oil and gas prospective areas with the involvement of a complex of geological and geophysical data. Results. In the zone of the profile RP-5, the occurrence of sedimentary strata and covers of the Folded Carpathians, the Carpathian foredeep and the edge of East-European craton in the earth's crust of Bukovyna was traced in detail, including the different depth tiers of the Carpathian thrusts and folds. The stepwise dipping of the edge of the East-European craton below the Carpathians is revealed here (generally similar to other segments of the Ukrainian Carpathians). The presence here of weakly dislocated autochthonous layers of Mesozoic rocks under the Carpathian thrusts is also established. In these horizons, several bands of folds of the Carpathian extension were discovered, some of them, in particular, the Lopushna fold, are associated with discovered oil and gas deposits. The thickening of the horizons of the lower crust under the axial part of the Bukovyna Folded Carpathians was revealed. In the pre-Carpathian part of the profile, there are 2 deepped ancient "seismofocal" zones of different age of formation and different vergence (researched in detail by S.G. Slonytska using special methods), as well as a number of apophysis-like intrusions. As a result of the comprehensive analysis, the influence of the characteristic features of the local Alpine geodynamic process was traced – the Alpine/Carpathian compression of the lithosphere in the northeast direction orthogonal to the Carpathians and the corresponding thrusts of the allochthon on the previously stepwise dipped here in the southwest direction western edge of the East-European craton as a result of rift-like pre-alpine geodynamic processes. Originality. The peculiarities of the deep structure, geodynamics, seismicity and oil and gas bearing of the Bukovyna lithosphere were determined based on the data of the regional profile RP-5, taking into account new data from oil and gas exploration studies in the subregion and data on various components of the geodynamic process in the whole Carpathian region of Ukraine. The oil and gas prospects of a number of deep folds of autochthonous Mesozoic rocks in the subthrust of the Pokuttya-Bukovyna Carpathians have been predicted and confirmed. Practical significance. The research results make it possible to more clearly justify the directions of oil and gas exploration in the subregion.