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The separate layer of rhizoid limestone from Urzhumian red succession of Tetyushi Volga region was studied to clarify its depositional features. Field description, optical microscopy, bulk geochemistry, stable isotopes of carbon and oxygen analysis, scanning electron microscopy (SEM) were used. The limestone under study has a thickness of about 1 m, is penetrated by a network of thin root channels (rhizoid limestone), the upper part of the rhizoid limestone is overlain by thin-laminated leafy limestone (3-5 cm) (l...

Here we focused on the massive, non-pedogenic, loess-like siltstones, which are common within the fluvio-lacustrine Middle Permian red sediments of Kazan Volga region, to refine their depositional settings. Sedimentological, mineralogical and geochemical methods including field description, grain size analysis, optical microscopy, bulk geochemistry and X-ray diffraction, were used. Siltstone facies from the Urzhumian red beds of this region are represented by two types: laminated and massive, the last one is commo...

Paleosol profiles from the reference section of the Urzhumian stage of Middle Permian in the Cheremushka Ravine, the Kazan Volga region, were studied in order to detail the paleogeographic and palaeoclimatic conditions. Field and laboratory methods, including grain size analysis, optical microscopy, X-ray fluorescence of siliciclastics, X-ray diffraction of clayey component, were used. Urzhumian succession of 70 m thick is represented by red-bed fluvial-lacustrine deposits with predominance of mudstones. The upper...