Geological And Geochemical Features And Genesis Of The Shuangwang Gold Deposit In Taibai County, Shanxi Province

The Shuangwang gold deposit, located in the east of the Fengtai ore concentrationarea of the West Qinling, is a large gold deposit of auriferous albite breccias type. The oredeposit occurs in the weakly metamorphosed upper Devonian Xinghongpu Group,dominated by calcareous siltstone, sericite silty slate and carbonate that comprise flyschoidformation. Gold mineralization is strictly controlled by auriferous breccia bodies. Pyrite isthe most important ore sulfide and the main wall-rock alteration is albitization. Based onthe research of the geological features of the deposit, this paper has systematicallyanalyzed the composition characters of the major elements, the trace elements, the rareearth elements and the stable isotope. The main achievements and conclusions that we gotare as follow:The breccia bodies of Shuangwang gold deposit were formed by the effect ofgas-liquid's hidden exploding. The formation of the breccia bodies has close connectionwith the magatic activities of the Late Triassic, so we classified the breccia to the hiddenexploding breccia. The mineralization of Shuangwang metallogenic belt was controlled byseveral centers of hydrothermal activities which we called hidden exploding centers. Theare four hidden exploding centers in Shuangwang metallogenic belt from the west to theeast, which explored the geological features of strong hydrothermal activities. From thewest to the east, the hidden exploding centers were deeper as we saw from the filedgeological features.The gold mineralization could be divided into two stages, which we called themetasomatism stage before blasting action and the filling stage after blasting action. Theformer stage was mainly by the metasomatism and the latter stage by the filling, themineralization of gold mainly happened in the stage of ankerite-pyrite. The main elements,trace elements and REE elements analysis indicated that Au may had preconcentration inthe formation of Xinghongpu Group and this composed the source bed of gold deposit.Systematic stable isotope analysis results show that the ore-forming fluids of early andmain stages came from mixture fluids and the late mainly came form magmatichydrothermal fluids with little meteoric water. Carbon was mainly derived from the great depth and partly from dissolution of carbonate strata. Sulfur is the mixture sulfur of crustand magma. Lead mainly came from upper crust and mixed little mantle lead.Based on this study, we investigated the genetic type and established the metallogenicmodel of Shuangwang gold deposit. We think that The genetic type of the Shuangwanggold deposit is hidden exploding breccia type gold deposit. The mineralization of theShuangwang gold deposit relates to the post-orogenic environment after the collisionbetween of the North China Plate and the Yangtze Plate in Late Triassic. The early stagemineralization was mainly caused by hydrothermal metasomatism and the main goldmineralization occurred in the hydrothermal filling stage after blasting action.