Abstract:

For the purposes of extracting genesis and prospecting information of the Erdaokan Ag-Pb-Zn deposit, a detailed investigation on chemical compositions,trace elements, rare earth element, as well as S-Pb isotopes of the pyrite related to mineralization.Genetic typomorphic characteristics of the pyrite, such as S/Fe, Au/Ag, Co/Ni, Fe/(S+As), Fe/(S+As), Co-Ni-As, etc., suggest that this deposit belongs to the intermediate to epithermal volcanic hydrothermal deposit, with the pyrite from the middle-superficial part of the prospecting orebody. The LREE are relatively more enrichment than The HREE. Eu negative anomalies are weak but Ce anomalies are not significant. Relative enrichment high field strength element(HFSE)such as Th,U,P,Hf and Yb. Loss large ion lithophile element(LILE) such as Rb, K and Sr.Ratios of Y/Ho reveal that the pyrite in the oreforming fluid closely related to the crust and mantle. The Zr/Hf and Nb/Ta values indicate that the ore-forming fluid is in a stable environment. However, there may be foreign hydrothermal substances mixed in the ore-forming process. Sulfur isotope values are concentrated in +2.3‰ to +8.6‰, it indicates that the source of ore-forming material is deep. Ratios of ²⁰⁶Pb/²⁰⁴Pb (18.007-18.034), ²⁰⁷Pb/²⁰⁴Pb (15.501-15.522), and ²⁰⁸Pb/²⁰⁴Pb (37.704-37.755), for the pyrites suggest that the ore-forming materials were sourced mainly from the mantle materials mixing with minor crustal materials.Based on the geochemical characteristics and typical deposit characteristics of this area, the Erdaokan Ag-Pb-Zn deposit is considered to be an epithermal hydrothermal silver deposit,which has been denuded to the middle and shallow part at present, and still has certain prospecting potential in the deep part.

Key words: pyrite, typomorphic characteristics, stable isotope, genesis of deposit, Erdaokan Ag-Pb-Zn deposit, Duobaoshan region of Heilongjiang Province