Известия Томского политехнического университета: Инжиниринг георесурсов (Sep 2017)
New data on specific conditions of formation of tournaisian deposits of Kolyvan-Tomsk folded zone
Abstract
The relevance of the research is caused by the necessity to explain the influence of paleoseismicity on catagenetic transformations of terrigenous deposits of tournaisian age, represented by Yarskaya formation in Kolyvan-Tomsk folded zone, due to its petroleum pote ntial. The solution of this issue can affect significantly the assessment of petroleum potential of the deep horizons of the West Siberian plate. The main aim of the research is to determine the features of sedimentation and transformation of tournaisian deposits within the Kolyvan-Tomsk folded zone (near Tomsk) under the influence of dislocations. The methods used in the study: lithological-and-petrographic (particle size distribution, classification of rocks using the chart of V. D. Shvanov, as well as the analysis of authigenic mineral formation), paleontological, lithogeochemical (X-ray diffraction and calculations petrochemical modules on Ya. E. Yudovich and M. P. Katriss). The fluorescent microscopic method was used to study the bituminosity occurrence. The results. The complex approach to the study of tournaisian deposits of the Kolyvan-Tomsk folded zone, represented by Yarskaya formation, allowed the authors to set the specific conditions of their sedimentation and transformation. The deposits of Yarskaya strata were formed in coastal environments. Among the terrigenous deposits the authors determined the signs of seismic dislocations. The signs are indicated by the traces of plastic sludge slumping into thin terrigenous interlayers, sediment displacements, clastic dikes and cross-cut surfaces, leading to disruption of the normal sequence of layers during strata formation. Terrigenous sediments of Yarskaya strata are characterized by frequent interlayering of plastic and relatively fragile rocks which contain the horizons with «stockwork» textures. For the first time in the top of Yarskaya strata of tournaisian age the syngenetic-bituminous mudstones and migration bitumens were established. Bituminization lasted till the paleoseismicity.
