Geological Characteristics And Metallogenesis Of The Shiwuliqiao Gold Deposit In Tahe, Heilongjiang Province

The Shiwuliqiao gold deposit, located in the Au(Cu-Mo) mineralization belt in Heilongjiang, the northeastern tip of Da Hinggan Mountains volcanic belt.The orebodies shape are regular in veins, besides there are some shrinkages, expand and pinch-out. It can be divided into four mineralization stages approximately: First is veinning pyrite-quartz stage; The second is disseminated pyrite ± chalcopyrite-quartz stage; The third is sulphides-quartz stage; The last one is less sulphide-carbonate salt phase. The sulphides–quartz are main mineralization stage.The study shows andesite host rocks and mineralization in rhyolite porphyry formed late age were 125.85 ± 0.56 Ma, 115.80 ± 0.45 Ma, to define time of the deposit formation between 125.85 ±0.56 Ma ~ 115.80 ± 0.45 Ma by LA-ICP-MS zircon U-Pb dating.The mining area mainly exposed intermediate and acid volcanic rocks. The andesite host rocks are calc-alkaline, and having the characteristics that high-K calc-alkaline basalts transition to shoshonite. Mine rock(ore) REE model is LREE enrichment rightist partition, and have weak or very weak negative Eu anomaly; LILE enriched in Rb, Th, U, K, etc., depleted in high field strong elements of Nb, Ta, P, Ti and the like. Th / Hf-Ta / Hf tectonic discrimination diagrams, combined with the same period of Da Hinggan Mountains regional tectonic evolution background, that the deposit formed in extensional environment.Two types of fluid inclusions have been distinguished in the early and main mineralization, in the Shiwuliqiao gold deposit, include liquid-rich and gas-rich fluid inclusions. The early stage fluid is immiscible fluid, the homogenization temperatures vary from 283 ℃ to 394 ℃, salinities vary from 2.56wt% to 7.99 wt% Na Cl eqv; In the main stage, the homogenization temperatures vary from 251 ℃ to 298 ℃, salinities vary from 2.56 wt% to 5.09 wt% Na Cl eqv. H-O isotope indicates that the ore-forming fluid is the mixed water of magmatic water and meteoric water. The S isotope suggests the oreforming material coming from thermal granitic magma fluid. Primary halo trace element studies have shown that the ore-forming material were from the andesite.The Shiwuliqiao gold deposit is a shallow epithermal deposit in volcanic rocks.