Pre-Mesozoic sediments of the Tunguska sedimentary basin complicated by the products of intrusive trap magmatism: Hydrocarbon potential, development issues and their solutions

Abstract

The sedimentary basin examined in this paper is the largest of the three main basins of the Siberian Platform: the Tunguska (S > 1.2 million km2), the Irkutsk (S = 825 thousand km2) and the Pre-Verkhoyansk-Vilyui (according to various estimates, from 280 to 350 thousand km2). Meanwhile, in the Tunguska sedimentary basin area (as of 01.01.2023), only seven hydrocarbon fields have been discovered (quite insignificant in terms of reserves), which is a fairly modest result in comparison to the other two above-mentioned sedimentary basins (much smaller in area) and cannot be explained by the fact that the Tunguska sedimentary basin is poorly studied in terms of oil and gas geology prospecting criteria. Despite the considerable amount of information on the geological structure of the Tunguska sedimentary basin obtained during geological surveying, prospecting and thematic works; special studies devoted to detailed structural and facies analysis and the history of formation of the Permian–Triassic intrusive stratum, all of the above is clearly insufficient. The correlation of the northern and southern types of sections of this stratum is also insufficiently developed, considering the role of facies substitution of the tuffs from the southern part of the Tunguska sedimentary basin by the lavas of its northern territories. Regional studies concerning the identification of magmatic activity centers and determination of the main types of natural mechanisms that initiated the global process of trap magmatism are insufficiently presented. The appearance in recent years of the new data on the little- studied areas of the Putorana Plateau in the north of the sedimentary basin made it possible to create a more comprehensive picture and begin to study the history of the formation of the volcanic strata of the entire sedimentary basin. Thus, despite the relatively poor geological study of the Tunguska sedimentary basin and the presence of traps (reservoir and transgressive intrusions) in the section, the oil and gas prospects of this sedimentary basin can be assessed rather optimistically. Most of the predicted and potential hydrocarbon resources are associated with the Vendian–Lower Cambrian and Riphean complexes.