Study On Tungsten-molybdenum Mineralization In Qingyang Area, Anhui Province

Based on the general knowledge of the regional geology, typical Qingyang-Jiuhuashan complex pluton and Gaojiabang, Baizhangyan which are in the northern of the pluton were chosen for studying in this paper. The field investigation and drill-core samples observation have been carried out in this paper, as well as rock geochemical analysis, LA-ICP-MS zircon isotope dating, molybdenite Re-Os dating and EMPA methods, in order to discuss the formation process of Qingyang-Jiuhuashan complex pluton and explain the mechanism of tungsten-molybdenum deposits. The main results are as follows:The zircon LA-ICP MS U-Pb dating shows 4 stages of Qingyang-Jiuhuashan complex pluton:Stage Ⅰ granodiorite(143.3±1.0Ma), Stage Ⅱ monzogranite(137.6± 1.5Ma), StageⅢ moyite(131.3±1.2Ma) and StageⅣfine grained porphyritic granite (132.0±2.0Ma). The ages of granodiorite and fine grained granodiorite-porphyry in Gaojiabang ore district are 144.9±1.2Ma and 145±2Ma. The ore-bearing intrusions in Gaojiabang and Baizhangy are the products in the process of evolution of Qingyang-Jiuhuashan complex pluton, which are corresponding to Stage Ⅰ and Stage Ⅳ of, respectively.Studying on main and trace elements of whole rocks and EMPA of rock-form minerals show that:Qingyang-Jiuhuashan complex pluton and the ore-bearing intrusions in W-Mo deposits are from the mixture of crust and mantle, from the same initial magma chamber, with high calc-alkaline and metaluminous to peraluminous characters.EMPA analysis shows that:Pyroxenes in skarns of Gaojiabang deposit belong to Di-Hd series, and garnets belong to Gro-And series. Their composition are very differences with Baizhangyang deposit, indicating components of garnet and pyroxene in W-Mo skarns do not have special properties. The components of garnet zones and garnet-pyroxene mineral pair indicate that the ore-forming environment is changing.Molybdenite Re-Os isotope dating shows a mineralization age of 146.1±4.8Ma. Combined with the existing data, there were two stages of W-Mo mineralization during Yanshanian in south Anhui Province:146-136Ma and 134-128Ma.Discuss the contribution of formation, structure and magmatic rocks to the mineralization, respectively, to establish a deposit metallogenic model, put forward the prospecting marks.This work enhances the understanding of the W-Mo metallogenic regularity in south Anhui Province, and can guide the exploration of new tungsten molybdenum polymetallic deposits in this areas.