Elaboration of Lithofacies Characteristic of Terrigenous Deposits of Devonian in the Platform Area of the Republic of Bashkortostan

Abstract

SUMMARYThe tasks of the research included detailed description of the core with further distinguishing of lithotypes, examination of geological aspects, generation of lithologic and facies maps. In the work the facies model of Devonian terrigenous stratum isformed; the model was obtained based on description of the core of 30 wells, analyses of 423 thin sections and granulometry data of 440 samples. The basis to distinguish lithotypes is layer-by-layer description of rocks according to lithological composition and fraction size as per granulometry, as well as peculiar textural features.In the result of performed analysis of the deposit core of Devonian terrigenous stratum there are 14 lithotypes, which served as a basis for transition to deposition environment and further distinguishing of facies. To specify depositional conditions regional data were used, according to which deposition of sediments in the period of formation of Devonian terrigenous stratum took place in conditions of shallow sea.According to comprehensive study data of the core and geophysical well logging, in the sections of the key-wells relevant facies were distinguished and facies inhomogeneity maps were generated (from the point of view of cyclic structure of horizons).