Geological structure and faunistic characteristics of the Mansurovo unique locality of early triassic tetrapods and ichnofossils, Orenburg Region

The geological features of the Mansurovo unique locality of the remains of tetrapods and ichnofossils, Orenburg Region (Gostevskaya Formation, Lower Olenekian Substage, Ustmylian Horizon) are considered. A layer-by-layer description cross-section of 16 ditchs and their correlation with the section construction along the line of ditchs are provided. The Mansurovo section, based on biostratigraphic (Wetlugasaurus malachovi grouping of the Wetlugasaurus Fauna) and lithologic-facies data, correlates with the middle part of the stratotype section of the Gostevskaya Formation (Buzuluk Depression of the East European Platform). The geological features of the locality indicate a heterogeneous structure of the identified four geological units of channel-floodplain genesis within the study area, which correspond to alternating sedimentation cycles. The genesis of deposits was clarified using structural-textural analysis and microlithological analysis of rocks in thin sections. The faunistic complex of tetrapods and macroflora, as well as unique complex of ichnofossils were also characterized. Based on the data of lithological-facial analysis, a sedimentation model of the genesis of the locality is presented, showing the uneven nature of sedimentation pattern due to the wandering of river branches and their periodic drying out in a hot and arid climate during the Early Olenekian. Taking into account paleontological data, taphonomy was analyzed, indicating the burial process in the river setting in strong current condition and the possible death of Temnospondyli in subaquatic conditions.