Genesis and Prospecting Potential of Scheelite in the Zhaishang Gold Deposit,Minxian County,Gansu Province

The Zhaishang tungsten gold poly-metal deposit is located in the western part of the Min-Li ore-forming belt, West Qinling.Tungsten ore bodies are occurred as fine veins or stock works, which are developed in the NW-trending broken belt and are mainly composed of scheelite with quartz and rare sulfides, such as pyrite.The tungsten deposit belongs to the quartz vein type in industry.The chronology and geochemistry results of diorite porphyrite dike display that, the diorite porphyrite belong to the S-type granite, they are rich in tungsten element with high fractionation and middle degree oxidation, which were intruded into the wall rocks and provided the matters and fluids for the tungsten mineralization at late Triassic (221Ma).Scheelite mineralogy show that it was derived from the middle temperature, inferior alkali and oxygen magmatic hydrothermal fluid, it formed at the similar age with the syn-chronology dike (about 222Ma), which is consistent with the age of regional magmatism.All these mentioned above indicate that the Zhaishang tungsten deposit belongs to a magmatic hydrothermal deposit, having the intense temporal, spatial and genesis relationship to the diorite porphyrite dike.