The Characteristics Of Pyrite Of Cu-Zn Deposit And Significance Of Mineralization In Huangtupo

In recent years,with the development of China's economy and the need for national defense security,copper as a relatively scarce and important strategic resource has gradually been given due attention.Volcanic massive sulfide(VMS)copper-polymetallic deposit is one of the deposit types providing copper resources.The Volcanogenic Massive Sulfide(VMS)copper-polymetallic deposit is one of deposits that provide copper resources.The study on its mineralization not only has active guidance meaning to the mining practice,but also provide a basis for the prediction of deep resources and further prospecting work of the deposit.The East Tianshan metallogenic belt,Xinjiang,one of the important copper polymetallic metallogenic belts in China,provide a large amount of copper metal resources.The Huangtupo copper-zinc deposit,a medium-sized deposit in the Kalatage area in East Tianshan,occurred in Late Ordovician–Early Silurian marine facies volcano-sedimentary rocks.The orebody occurs as horizontal lens in the middle of Daliugou formation volcanic breccia and tuff.Based on the geological exploration in the field,this paper does detailed research on the mineralogical and geochemical characteristics of pyrite,which is extensively distributed in Huangtupo copper-zinc deposit,and discusses the key scientific issues of the metallogenic epoch,the source of mineralized substances,the feature and evolution of ore-forming fluid and mineralization process.So far,the main achievements include:1.The Huangtupo copper-zinc deposit is composed of the upper massive orebody and the lower reticulated vein orebody.The formation of the deposit has undergone two metallogenic periods: Among them,the first metallogenic period includes hydrothermal exhalative-sedimentary stage and hydrothermal transformation stage,and the second metallogenic stage is the superficial mineralization stage.2.The formation of pyrite in the Huangtupo copper-zinc deposit can be divided into three stages: Pyrite in massive ore bodies mainly consists of fine-grained aggregate pyrite(PyI)and fine-grained subhedral pyrite(PyII)associated with sulphides such as chalcopyrite and sphalerite.Pyrite(PyIII)coexists with chalcopyrite in the stockwork orebody is coarse grained-euhedral crystal,partly ruptured in granules.3.The Re-Os Isotopic Dating of Pyrite in massive ore body yields an age of(425±39)Ma,which dedicates it formed in Middle Silurian.4.All pyrites belong to the slightly deficient type of sulfur,the deposits are formed in a relatively high temperature environment.The upper and lower part of the ore bodies have different formation processes of pyrite;however,they are related to volcanic hydrothermal.The ore-forming fluid is dominated by Cl-rich fluids,mainly from the mixing of mantle-derived magma fluids and seawater.Metallogenic materials were from mantle-derived magma and mixed with some crustal materials.5.The Huangtupo deposit is formed in high temperature and low sulfur fugacity.During the evolution of ore-forming fluid,seawater is added and its reductivity is gradually enhanced.The precipitation of copper and zinc are resulted from the decrease of temperature and the change of forming environment.