Mineral composition and formation conditions of Lower and Upper Kazanian boundary beds in stratotype section of Prikazansk Region
Mineral composition of the boundary beds of Lower and Upper Kazanian in «Ust’-Trekhglavy» Section was studied by X-ray diffraction, ICP spectroscopy and optical microscopy. The Lower Kazanian fosilliferous biomicrite dolomites are established to have undergone less diagenetic transformation than the Upper Kazanian micrite dolomites. The supposed dolomite-formation mechanisms are reconstructed: the Lower Kazanian beds were possibly formed in the course of sea basin shallowing, and the Upper Kazanian ones were formed in sabkha environment.