MINERALOGICAL AND GEOCHEMICAL FEATURES OF LIMESTONES OF THE KATAV FORMATION OF THE AKTASH AREA (YAMANTAU ANTICLINORIUM, SOUTHEN URAL)

Abstract

A mineralogical and geochemical study of limestones of the Katav Formation was carried out, outcrops of which are noted in the Yamantau anticlinorium 8–10 km northwest of Muradymovo settlement on Aktash Area. In the mineralogical composition of limestones, a relatively high content of quartz (4–15 %), presence of small amounts (at the level of 1 %) of dolomite and K-feldspar, variable contents (0.3–1.6 %) of hematite, as well as a constant admixture of chlorite and albite (1–7 %). The presence of hematite in the limestones is considered as possible mineralogical evidence in favor of arid conditions and evaporate sedimentation settings during the Katavian. The contents of F, Cl, V, Cr, Ni, Sr in limestones are below the clarke values, Pb is close to the clarke, Cu, Zn, Zr are 1.5–2 times higher than the clarke. The Clarke values of Co (4 times) and Ba (19 times) are the highest. The established features of the distribution of the halogen elements fluorine and chlorine (extremely low concentrations, their absence of association with calcite, and a high positive correlation with micaceous minerals, which apparently have an epigenetic origin) cannot be considered as evidence of evaporite sedimentation environments in the Katav time.