Magma Oxygen Fugacity Of The Wenquan And Taiyangshan Porphyry Deposits In The West Qinling And Its Geological Implications

The Qinling Orogen in central China is a complex collage built through the closure of the northernmost Paleo-Tethys and the suturing of the Yangtze and the North China cratons.The Indosinian granitoids,widely distributed in the West Qinling belt,are closely associated with the porphyry and skarn deposits spatio-temporally.The Wenquan Mo and Taiyangshan Cu deposits are the typical representative of porphyry systems intra-continental environment.The study for magma oxygen fugacity and constrains of mineralization is unclear.In this study,we investigate the lithological and geochemical characteristics of the porphyries and compare their magmatic oxygen fugacity.The Indosinian superimposed orogeny in the West Qinling,including the precollisional(250~235 Ma),syn-collisional(228~215 Ma),and post-collisional(215~185 Ma)magmatism corresponding to the superimposed orogeny.The Wenquan porphyry molybdenum deposit,and Taiyangshan porphyry deposit,located in the West Qinling Orogen,are spatio-temporally and genetically associated with the widely distributed Indosinian granitoids.This composite metallogenic system is associated to the subduction and collision processes of the Paleotethys ocean closure and convergence of North China and South China blocks.The ore-bearing porphyries have higher magmatic oxygen fugacity than the orebarren porphyries.The oxygen fugacities of the porphyies in the Wenquan and Taiyangshan porphyry deposits are relatively high.We therefore proposed that oxidized magmas can be associated with enriched mantle.The high oxygen fugacity melt can extract Mo from the Paleozoic Mo-rich sediments in the Qinling Orogen.The increasing of oxygen fugacity is furthermore beneficial to concentrate Cu and Mo in the residual melt,and favorable for Cu and Mo mineralization.