| The Hardaban deposit is a large-scale lead-zinc deposit discovered in recent years,which is located in the Sayram Massif lead-zinc metallogenic belt,West Tianshan.This paper focuses on the sulfide structure,trace elements,isotope composition and the mineralization mechanism of the Hardaban lead-zinc deposit,studied sulfide detailed structure and the in-situ trace element and isotope,expound the composition and variation of trace elements in sulfides of every stage and the source of ore-forming materials.Combining the geological characteristics of the deposit and previous research,.This paper explain the metallogenic process of the Hardaban lead-zinc deposit and determine the type of the deposit.The Hardaban lead-zinc ore body are mainly hosted by the upper subgroup of the Hardaban group?Chhrb?,Mesoproterozoic Great Wall system.The host rocks are dolomite,dolomite-limestone,carbonaceous microcrystalline limestone and fine-grained limestone.The mineral combination of the Hardaban lead-zinc deposit is relatively simple.The ore are consist of sphalerite,galena,pyrite and a small amount of chalcopyrite,magnetite,and the gangue mineral are mainly dolomite,calcite and a small amount of barite.The sphalerite can be divided into two types according to the paragenetic relationship with galena.The color of sphalerite can be changed from dark brown to light yellow.Sphalerite has a lower Cd content and a higher Zn/Cd ratio,reflecting that the sphalerite was formed in a medium-temperature environment.According to the content of FeS in sphalerite formed with pyrite and magnetite,the formation temperature of sphalerite in this deposit is estimated to be 250-260?and 150-175?.The pyrite in this deposit has various structures.According to LA-ICP-MS analysis result,pyrite can be divided into three phase:Py1 is rich in Sb,Se,Tl,Ba,Mn,Pb,Bi,As,Cu,Ag,Sn and other metallogenic elements and low-temperature elements,Co/Ni ratio is mostly less than 1,with characteristics of sedimentary genesis;Py2formed during diagenesis basically,contains no mineral inclusions.Compared with Py1and Py3,Py2 has significantly higher Co and As,and the content of other trace elements is very low;Py3 has high content of metal elements,such as Zn,Sb,Pb,As.The Co/Ni ratios of Py3 are greater than 1,with characteristics of hydrothermal origin.The?34S value of sphalerite in the Hardaban lead-zinc deposit is 8.4‰18.3‰?average is 15.0‰?.The?34S value reflects that the reduced sulfur in the metallogenic stage is mainly from seawater sulfate through thermochemical reduction reaction.The?34S value of pyrite?Py1?formed during the deposition period is 3.98.1‰,reflecting the reduced sulfur comes from the magmatic hydrothermal fluid;The sphalerite Rb-Sr isochron age is 432±45Ma,indicate deposit mineralize in early Paleozoic.Compared Hardaban lead-zinc deposit with the typical SEDEX-type lead-zinc deposits at inland and abroad,found unlike the typical SEDEX lead-zinc deposit,the sedimentary exhalative processes of the Hardaban lead-zinc deposit only provides an ore source layer for the formation of the deposit.The main metallogenic process is the hydrothermal metasomatization process.The ore-forming material comes from the cyclic extraction from the deep ore source layer by hydrothermal fluid.Combined with the geological characteristics,the formation age and the source of ore-forming materials,speculated that the Hardaban lead-zinc deposit is a SEDEX-hydrothermal metasomatic type deposit. |
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