A NEW MECHANISM OF THE FORMATION OF CARBONATE MANGANESE ORES: EVIDENCE FROM δ13C AND δ18O DATA ON THE SOUTH FAIZULIN DEPOSIT, SOUTHERN URALS

Abstract

New type of forming process for the carbonate Mn ores is suggested that envisages a participation of methane in formation of rhodochrosite. The latter are characterized by wide variations of δ13C values over the (-51.4)-(-20.4)% range. In this case, the values of δ18O vary from 15.5 to 18.7%. Such isotope composition is nontypical for carbonates of earth crust abundant groups. On this sign, the studied rhodochrosites may be considered as the anomalous minerals. The isotope composition data enable to assume that methane (ethane, propane) is the basic or even single source of C in rhodochrosite.