Sedimentation conditions and clast transport during the formation of sedimentary paleobasins in the north of Irkutsk Oblast and river network formation

Abstract

Background. Changes in the composition of clastic material reflect changes in both the paleogeographic environment and clast transport paths. In turn, this indicates changes in the conditions of regional development. The research relevance is determined by multidirectionality of Earth sciences, such as paleogeography, neotectonics, stratigraphy, hydrology, relief formation, etc.Aim. To establish the genesis of river valleys and bench complexes in the northern areas of the Irkutsk Oblast.Materials and methods. The clastic material of the Upper Paleozoic-Mesozoic sedimentary deposits in the northern areas of the Irkutsk Oblast was studied. The work is aimed at reconstructing the contours of sedimentary paleobasins of the Carboniferous, Permian, and Jurassic ages and the conditions of sedimentary strata formation. The results of site investigation and drilling works carried out in the 1960s and 1970s were interpreted from the standpoint of modern information.Results. The nature of river network formation and clast transport processes was determined. The direction and sources of clast transport were identified, along with the conditions of re-deposition of clastic material at different stages of the geological development of the area under study.Conclusions. The modern river network in the northern areas of the Irkutsk Oblast is based on the valleys formed under the action of catastrophic glacial water discharge flows.