Carbon and oxygen isotope constraints on mantle fluid involvement in the mineralization of the Huize super-large Pb-Zn deposits, Yunnan Province, China

The Huize super-large Pb - Zn deposits of Yunnan Province, China are characterized by high Pb - Zn grade (Pb + Zn mostly higher than 25-35%) and the abundance of associated useful elements (Ag, Ge, Cd, In, and Ga, etc.). Calcite is the only vein mineral in primary ores in the orefield. This paper analyzes the carbon and oxygen isotopic compositions of 21 calcites and 4 ore-hosting strata (C(1)b). The delta(13)C(PDB) and delta(18)O(SMOW) of calcites are - 2.1-3.5 parts per thousand and 16.7-18.6 parts per thousand, respectively and fall within a narrow range between primary carbonatite and marine carbonate (or C(1)b) in the diagram of delta(13)C(PDB) vs. delta(18)O(SMOW). In combination with other geological and geochemical data, we suggest that the ore-forming fluids represent crustal-mantle fluid mixing. We believe that fluids formed from degassing of magma, accompanying magmatism of the Permian Emeishan basalts, were involved in the mineralization of the Huize super-large Pb-Zn deposits. (C) 2003 Elsevier Science B.V. All rights reserved.