ON ESTABLISHING THE NATURE OF OILAND GAS FIELDS OF THE NEPA-PELEDUY ARCH
To date, the main oil and gas ﬁelds in the Cambrian and Precambrian section of the south Siberian platform are conﬁned to the terrigenous part of the Precambrian sedimentary cover, while in a much more powerful halogen-carbonate (HC) complex of the Vendian-Cambrian and the Lower Cambrian, the little commercial hydrocarbon accumulations were found. Therefore, the prospect of the largest reserve for increasing oil and gas ﬁelds is associated with the carbonate complex. Along with the urgency of identifying the causes of existing imbalance in the development of the ﬁelds, there is a need to assess the realistic prospects of carbonate complex based on the discussion of nature and the mechanism of deposits formation. It is argued that the ﬁelds in the productive formation of the Precambrian terrigenous complex were formed due to sub-vertical ﬂuid ﬂows from sub-fundamental sources under the inﬂuence of fault activations of early northeastern generations, and in the productive carbonate horizons of the Vendian-Cambrian and Lower Cambrian - due to the re-formation of the ﬁelds in terrigenous formations under the inﬂuence of faults of late north-western generation. At the same time, the ﬁeldswere formed in the zones overlapping to faults of earlier generation. This means that in the carbonate reservoirs, it is impossible to achieve the advanced development of deposits, and in determining the order of prospecting the terrigenous horizons should be considered as basic or priority.