THE DEEP STRUCTURE OF THE NEPA-PELEDUY ARCH OF THE NEPA-BOTUOBA ANTECLISE IN THE DEVELOPMENT OF B.A. SOKOLOV'S HYPOTHESIS

Abstract

The studies were conducted in the territory of the Nepa-Peleduy arch (NPA) of the Nepa-Botuoba anteclise (NBA), which is strategically important for the Russian Federation as it contains large and unique hydrocarbon fields, including those essential for the ESPO oil pipeline and the presently under-construction Power of Siberia gas pipeline. Because the hydrocarbon potential of the sedimentary cover is largely exhausted, the aim is now to increase the regional stocks. Verifying the hypothesis of the Corresponding Member of the Russian Academy of Sciences B.A. Sokolov, stating that the allochthonous block of the crystalline basement, overlapping the aulacogen Riphean sediments, lies at the base of the NPA, would open the possibility of increasing the hydrocarbon reserves in the ‘subbasement’ formations. It would also clarify the controversial nature of the NPA deposits, which have no sediments with a high organic carbon content. In this study, we present a Hilbert transform of a time section of the common midpoint method (CDP) from a fragment of the Batholith-1 geotraverse passing through the Katanga saddle, the NPA and the Pre-Patom trough, as well as geophysical materials and well data from the same profile. Supporting B.A. Sokolov’s hypothesis, we confirm the existence of a relict crystalline terrane crosscut by the wells at the base of the NPA and forming the roof of the underlying lower Vendian and Riphean sediment units. Our data clearly document the position of the western side of the inverted paleorift, the thickness of the terrane and the physical characteristics of the underlying sediments. These results are justifying hydrocarbon exploration of the ‘subbasement’ sediments.