Geochemistry And Metallogenic Model Of The Qixiashan Lead-zinc Polymetallic Deposit, Jiangsu

Researchers previously have done many geological researches in Qixiashan lead-zinc polymetallic deposit and made abundant achievements. But the metallogenic conditions and the source for metallogenic matter and genesis are understood differently. In this article, based on the works previously, we study the characteristics of geology and geochemistry, in addition to the geological setting, we discuss the ore-controlling factors, the source for metallogenic matter, fluid property and so on. we also emphasize on studying Magmatism effect of mineralization, enhance realization in genesis of the deposit. Main conclusions as following:(1) The Qixiashan lead-zinc polymetallic deposit lies on The Yanjing Fracture Zone of the Middle and Lower Yangtze River, at the edge of the sedimentary basin of The Paleozoic era. The deposit is obviously stratabound and controlled by rock lithology, longitudinal faults, Unconformities, palaeokarst structural belt and covered intrusion.(2) The structure of ore has the syngenetic and epigeneetic features, which indicates that the deposits are hydrothermal superimposed transformation products.(3) It seems that the rock body dose not exist in the Mine Area, but the isotope geochemistry show great mantle information. The fact proves that there is covered intrusion in deep mine. Sulfur and lead isotope geochemistry indicated that the material source maybe derived from the pluton and sinian system. Carbon, hydrogen and oxygen isotope show that the fluid inclusion is complex with the mixture of granitic water, initial water, meteoric water and organic-water.(4) The trace elements characteristics also show that the ore-forming materials come from different geological body. material source maybe mostly derived from the pluton. While the other material source is derived from the source bed of sinian system rather than from host volcanic rocks.(5) Violent movement of the fault blocks occurs in Yanshan extensional tectonic events, which cause large-scaled magmatism and provide the condition for meteoric water penetrating into the deep crust and extracting the ore-forming materials. The postmagmatic hydrotherm mixed with the subaqueous ore-bearing hot brine upwell along deep fracture and enter structural traps, then joins shallow brine with rich organic matter and sulfur. large minerals precipitation occurs on geochemical reduction barriers.Consequently the ore deposits can be considered to be largely postmagmatic hydrothermal, multiple source, long-distance, stratabound ore deposit through integrated researches of Ore-controlling Factors and the discussion of mine evolution processes.