VOLCANOGENIC LAYERS IN BAZHENOV FORMATION OF THE WESTERN SIBERIAN SEDIMENTARY BASIN

• Main Author: Elena S. Kondrashova
• Format: Article
• Language: Russian
• Published: Tomsk Polytechnic University 2021-03-01
• Series: Известия Томского политехнического университета: Инжиниринг георесурсов
• Subjects: western siberia; the bazhenov formation; mineralogy; petrography; volcanogenic material
• Online Access: http://izvestiya.tpu.ru/archive/article/view/3102/2424

The relevance. The detailed study of the material composition and structural features volcanic horizons identified in the Bazhenov formation sediments will clarify their regional formation patterns and distribution in the territory of the Western Siberian sedimentary basin, as well as new data on volcanism, manifestations in the Upper Jurassic in the territory of the study. The main objective is to determine the features of composition and structure of the abnormally luminescent horizons of the Bazhenov formation, proving their volcanogenic origin, as well as to search for distribution patterns in the study area. Objects: sedimentary rocks, luminescent layers and enclosing rocks of the Bazhenov formation. Methods: X-ray diffractometry, petrographic analysis. Results. In the sediments of the Bazhenov formation in the central and south-eastern part of the Western Siberian basin, the layers with a thickness of 0,2–45 cm with luminescent in ultraviolet light were found. Study of the mineral composition, structural features, structural and textural features of the identified horizons allowed defining the origin of their formation as volcanogenic-pyroclastic. It is assumed that the identified layers were formed as a result of dia- and catagenetic transformation of the volcanoclastic material of tuff sediments in a stagnant sea with a high content of organic matter. In the course of the research two types of volcanogenic horizons were identified. They differ from each other in mineral, petrographic and chemical composition. The 1st horizon is related to the clay type. It is composed mainly of clay minerals (kaolinite and mixed-layer minerals of the illite-smectite series) with admixture of detrital silty material. The 2nd horizon refers to siliceous type, because it is characterized mainly by siliceous (quartz) composition. Each of the identified horizons is isolated in the section and corresponds to its own volcanic event of the Upper Jurassic time.