Petrographic composition and material sources of Upper Paleozoic rough-clastic rocks in Western Taimyr

Abstract

Research subject. Gravelites and conglomerates of the Upper Carboniferous and Permian of Western Taimyr. Aim. To reveal features of the petrographic composition of coarse clastic rocks and, on this basis, to clarify the ideas about the composition and position of the feeding province of the western part of the Taimyr sedimentary basin in the Late Paleozoic. Materials and methods. The analysis of materials collected during a layer-by-layer study of sections and microscopic description of 47 large transparent sections with the count of psephitic (more than 2 mm) fragments of quartzites, felsic and basic igneous, metamorphic and sedimentary rocks was performed. The revealed features of the petrographic composition of psephytoliths, in combination with a generalization of previously published geodynamic and paleogeographic reconstructions, were used to refine the model of the geological development of the Taimyr fold-thrust belt and adjacent areas in the Late Paleozoic. Results. It was established that the sections contain polymictic lithoclastic (83%) and petroclastic (15%) psephytoliths, with occasional inclusions of oligomictic essentially quartz varieties (2%). Minor changes in the composition of clasts over time indicate the existence of a single source of clastic material during the entire Late Paleozoic, which formed the sections of Western Taimyr. It was shown that the maturity of psephytolites increases from the southwest to the northwest and northeast. Numerous fragments of phtanites and lydites with remains of radiolarians of the Middle Devonian – early Early Carboniferous were identified, analogs of which are present in the Lemva zone of the Urals and in the basement of Western Siberia. Conclusions. The material forming the coarse clastic rocks of Western Taimyr was transported by the river for 600–1000 km from the folded structures of the “West Siberian land” located in the southwest (in modern coordinates), which formed in the Visean–Serpukhovian ages of the Early Carboniferous during the collision of the East - European, Kazakhstan and Siberian continental blocks.