Geological Characteristics And The Mineralization Process From Huangshaping W-Mo Polymetallic Deposit In Hunan Province

Huangshaping polymetallic deposit is an important skarn W-Mo deposit which is located in the southwest part of Guiyang,Hunan Province.We have done a systematic research on the characteristics of geology,petrography,geochemistry and mineralogy,with a focus on the mineralization process.The followings are major achievements obtained in this dissertation.1.The Huangshaping granite porphyry belongs to sub-alkaline series.The whole rock trace elements result shows little enrichment in LREE,with obvious Eu negative anomalies.The REE is strongly fractionated and the REE patterns are inclined from LREE to HREE.Characteristic of trace elements is rich in high field strength elements of U,Pb and Th.The Huangshaping granites belong to A-type granites and the source is crust.The forming environment is locally extending-thinning and non-orogenic which caused the remelting of crust.The granite porphyry is dated at 160.7±1.1Ma which indicates the Late Jurassic.Compared to the Re-Os isochron method of molybdenite(153.8±4.8Ma),we can conclude that the mineralization of W,Mo and the diagenesis of Huangshaping granite porphy almostly occurred at the same time.2.According to the output state of skarn,mineral assemblage,petrographic characteristics and sulfides' type and component.The metallogenic periods can be divided into skarn period and quartz-sulfide period.The skarn period includes skarn stage and retrograde alteration stage;The early sulfide stage and late sulfide stage make up the quartz-sulfide period.3.The skarn minerals are mainly garnet,pyroxene,vesuvianite,amphibole,epidote,chlorite.The garnets are andradite-grossularite series and vary from grossularite to andradite.The andradites commonly have zonal structure which can record the evolutionary process of physicochemical conditions.The andradite and grossularite both contain Sn,but the content of Sn in the former is higher than the latter.The pyroxenes are mainly diopside-hedenbergite series,the content of Fe and Mn has a rising trend from the internal contact zone to the external contact zone.The amphiboles in this deposit can be classified into ferro-edenite and ferropargasite which belong to calcic amphiboles.Metallic minerals mainly include scheelite,magnetite,molybdenite,bismuthinite,cassiterite,sphalerite and galena.4.Mineralogical characteristics suggest that the property of fluid changed with two redox fluctuations at least.The ratio of Mn/Fe in pyroxenes reflects the mineralization zoning of W(Sn)-Mo-Bi?Fe?Zn-Pb in Huangshaping polymetallic deposit.