Geological Characteristics And Genesis Of The Jinshan Gold Deposit, Xinjiang, China

The Jinshan gold deposit is a large epithermal deposit in west Tianshan Moutain, China. It is hosted in lower Dahalajunshan Formation of Early Carboniferous. The ore bodies are stratiform-like, and have a transitional relation with the wall rocks. The ores have brecciated structure, disseminated structure and net-vein-like structure. The ore minerals mainly includes pyrite, then native gold and native silver which contains gold. The gangue mineral is mainly composed of quartz, secondly of barite, dickite, sericite. The wall rock alteration in the mining area mainly includes silicification, pytitization, .The main ore forming has three stages, the original sedimentary enrichment stage, the epithermal stage and the supergene leaching enrichment stage. The epithermal stage has four phases, the surface-like chalcedony-pyrite phase, the quartz-vein-pyrite-arsenopyrite phase,the realgar-orpiment-stibnite phase and the carbonate-quartz phase. The ore-forming fluid is mainly composed of magmatic water, with part of meteoric water mixed in. During the evolution, the character of fluid went through a big change, from acid in the beginning to neutral at last. Researches on isotope composition are reported in this paper. It is shown that t theδ34S values of the sulfide vary from -12.7‰to 17.4‰, it has not a tower distributional effects, the results indicate that it not only related to metallogenic physicochemical conditions.but also have multiple sources. The ores from the deposit show relatively significant variations in Pb isotopic composition. There exists obvious linear distribution for ores in the Pb diagrams. Ore lead from the gold deposit should belong to the crust-mantle mixed Pb. Mineralization should take place in an open system, and the deep seated materials seem to have been involved in mineralization. Carbon origin in this deposit is mainly from acidic magmatic hydrothermal and The dissolution of marine carbonate. The enrichment of Au is close to As, Sb, Hg, Pb, Ni, showing that the realgar orpiment-stibnite phase could be the most important phase in all the ore-forming phases.The ore bodies are controlled by stratum, Faults, unconformity and Hydrothermal breccia, of which the most important is faults.