Abstract:

DonggouJinlongshan gold deposit located in flysch folded thrust belt brachyanticline in southern Qinling orogen is considered to be a typical Carlin type gold deposit and its metallogenic epoch yet to be determined. The regional tectonic system analysis showed that the brachyanticline is a dome structure which was formed by the superposition of east west closed dome and north east broad top anticline; the mineralization was mainly controlled by the late north east brittle structure and eastwest heterolithic facies unconformity interface. The geochemistry result of regional exploration shows that the anomalies of Au, As, and Sb register better, and that the anomalies distribute along northeast in beaded presentation and register obviously with the dome structure and the annular structure of remote sensing interpretation. The 40Ar/39Ar plateau age of sericite is 142.34±0.83 Ma, and the isochron age is 141.6±2.8 Ma, which shows that the mineralization happened in the early stage of the Late Mesozoic. The formation of pyrite has the characteristics of three periods; the auriferous pyrite has a symbiotic relationship with arsenopyrite and stibnite. Combining with regional date that the mineralization has a relationship with deep buried rock, and the deposit type is a remote epithermal deposit which is related to the deep hydrothermal fluid after the magmatic stage; the mineralization occurred in the squeezeextended transition period at 141142 Ma in the early Late Mesozoic; it suggests that the decompression and warming environment at the squeeze extended transition period is the most favorable metallogenic geodynamic background.

Key words: DonggouJinlongshan, gold deposit, dome structure, Ar Ar age, the ore forming fluid, epithermal deposit