Analysis Of Geological And Metallogenic Processes Of The Qunjixi Copper Deposits,Western Tianshan

Qunjixi copper deposit is located in the west of Awulale,within western Tianshan of Xinjiang.The lentoid or veinlike ore bodies are hosted in albitophyre,which intruded into the volcanic rocks of lower Permian Wulang Formation.It can be seen that three kinds of mineralization have occurred successively,the ores show disseminated,vein and net vein structures,ore minerals are mainly consisted of chalcopyrite and chalcopyrite,followed by pyrite and chalcopyrite.Hydrothermal alteration mainly includes potash,carbonation and silicification,all of which are closely related to mineralization.By means of study main elements and trace element geochemistry of the albitophyre in Qunjixi copper deposit,it's found that the rocks are rich in silicon and alkali-rich,high in value of Fe OT/Mg O,rich in Zr,Nb,Ta,Y,Ga,Rb,Th and other high field and strong elements,which are lower Ca O,Mg O,poor Co,Ni,etc.It has obvious negative Eu anomaly and shows the characteristics of A type granite.The features of rock trace elements indicate that the rocks belong to A2 type granite,and demonstrate that albitophyre formed in the extensional extensional environment of Early Permian post collisional stage.The characteristics of major elements in the rock indicate that the magma source is similar to amphibolite and has the participation of crustal materials.In addition,the TZr of the rocks is higher than 900 degrees,indicating that the genesis of the rocks is probably related to the remelting of the new lower crust which caused by lithospheric extension.Through field observation and facieology,it is found that the ore shows multi-stage mineralization characteristics.The precipitation of disseminated metal sulfide is accompanied with the alteration of dispersed potassium feldspar alteration,which may be closely related to the process of post magmatic hydrothermal self metamorphism,and the disseminated mineralization time can be roughly determined according to zircon U-PB Age(301.2±1.8)MA in the porphyry.The 40Ar-39 Ar isotope dating of the vein-shaped altered potassium feldspar associated with mineralization was carried out,and the K-feldspar 40Ar-39 Ar ping Age is(238.0±2.0)Ma.The last stage mineralization is the net vein ore,the Re-Os isotopic dating of pyrite of precipitated in hydrothermal vein body,and the time line age is 192±13Ma,which limits a lower limit for metallogenic epoch.As a whole,the metallogenic time span of Qunjixi copper mine is large,and it is a magmatic hydrothermal-type copper deposit formed in the post collision environment.