Composition and character of transformations of the lower silurian carbon-containing rocks at contact with permo-triassic trap complexes on the western part of South Tunguska OGR

Abstract

A detailed petrographic analysis of the Lower Silurian sulfate-carbonate deposits with carbonaceous interlayers from the section of the western part of the South Tungusskaya oil and gas region was carried out in order to establish the patterns of their transformations at contact with the Permian-Triassic sills. The data obtained are compared with temperature measurements on a calcite/dolomite thermometer performed earlier. It is assumed that the non-linearity of the dependence between the amount of heating of sedimentary strata and the power of intrusiv is associated with the heterogeneity of the section in the mineral composition of various layers, their thickness and the amount of organic matter contained in them. Based on this, it is proposed to use the temperature of decomposition of carbonates, taking into account pressure, as the maximum temperature of contact metamorphism, laid down in the physico-chemical justification of the mathematical model. The process proceeds with an increase in the void space due to losses during calcination and the formation of a fracturing system, the scale of development of which has a direct impact on the transformation of rocks, including located far from the intrusion.