Discussion on the ore-forming fluids,materials sources and genesis of Erdaohe Pb-Zn-Ag deposit,Inner Mongolia
This paper is the result of mineral exploration engineering.[Objective]The Erdaohe silver-lead-zinc deposit is located in the middle section of the Greater Khingan Range.It is a representative large-scale skarn-type deposit discovered in recent years.Studying the origin of this deposit will help guide the exploration of polymetallic deposits in the middle section of the Greater Khingan Range.[Methods]On the basis of field geological survey,this paper made research on the fluid inclusion in the keatite selected at each stage of mineralization,and discussed the ore-forming fluid and material sources in combination with the S and Pb isotopes of ore and the C and O isotopes of calcite.[Results]The research result showed the formation of the deposit throughout the process from the skarn stage to the quarte-sulfide stage and to the quartz carbonate stage.According to the temperature measurement result,the inclusion in keatite was mainly characterized by gas-liquid phase,with the homogenization temperature of 310-435℃at the skarn stage,195-310℃at the quarte-sulfide stage and 148-195℃at the quartz carbonate stage,and the salinity of 11.7%-0.71%NaCleqv at the skarn stage,12.9%-0.35%NaCleqv at the quartz-sulfide stage and 4.18%-0.35%NaCleqv at the quartz-carbonate stage.The C and O isotopes of calcite indicated a water-rock reaction of the deposit,in which atmospheric precipitation was found.The δ34S value of the S isotope of ore was 5.4‰-10.0‰ from a mixture of sulfurs in magma and strata;as per the characteristic parameter of lead isotope,the source of lead was associated with the orogeny-related magmatism,where the lead was mostly from the upper crust,and slightly from the deep source.[Conclusions]Accordingly,the ore-forming fluid and material sources were considered the products of the large-scale magmatism caused by the extension after the closure of Mongolia-Okhotsk for orogeny.