C, O and H isotopic compositions of polymetallic deposits in Lanping Basin, Western Yunnan Province and their geological significance
The characteristics of C, O and H isotopic compositions of polymetallic deposits in the Lanping Basin has been studied. The results show that CO_(2) in ore-forming fluids were derived from thermal decomposition of marine carbonates (or altered marine carbonates) and oxidation and decarbonxylation of sedimentary organic matters; ore-forming fluids were hot brine of basin which derived from paleo-meteoric water by action of water and rocks of basin and basement under some geological conditions, however the ore-forming fluid of Jinding Pb-Zn polymetallic deposit may be mixed with metamorphic fluid. This indicates that ore-forming materials should be derived from crust (basement and strata of basin) and the activity of alkali magma of the Himalayan epoch in peripheral area of basin has made indirect contributions to mineralization of polymetallic deposits in the basin and the sedimentary organic matters had taken part in the mineralization.