Coupling Relationship Between Copper Enrichment And Brine On The Earth's Surface Kuqa Evaporite Basin,Xinjiang

The sandstone-type mineralization is the second largest in copper ore sorts in terms of quantity and reserves,Compared with porphyry-type copper deposits.The strata with gigantic thickness had been developed from tens of meters to several meters.in the Kuqa Evaporite Basin in Xinjiang From Paleogene to Neogene.In recent years,in the process of finding potassium in the Kuqa Basin,Many copper mineralization spots were found in Neogene strata based on field geological survey,Green copper minerals coexist with gypsum,halite,glauberite and other salt minerals.Copper mineralization spots are mainly distributed in the Kelasu structural anticline belt in the northern part of the basin and the Qiulitage structural anticline belt in the southern part.It is basically located on the two wings of the anticline axis,distributed along the two major faulted structural belts in a nearly east-west direction,closely adjacent to the salt dome.During the author's field geological survey,there are three main types of copper mineralization: sandstone type,limestone type,and mudstone type.Kangcun group of Pliocene is a main ore bed,and the other is Jidike group of Miocene.The main lithology related to mineralization is the grayish white(gravel bearing)medium coarse sandstone and the grayish green mudstone.Indoor analyzing the samples by slice analysis,SEM,XRD,copper isotope analysis,chemistry analysis of brine samples,field brine mixing simulation experiment and other means,so we can find out the relationship among copper enrichment,brine and salt-type minerals.The main copper minerals are paratacamite,native copper,azurite,covellite,chalcocite,chalcopyrite.The paratacamite is the most widely distributed and common copper mineral in the study area.The precipitation of Paratacamite in copper mineralized gypsum veins is controlled by the crystallization sequence ofy salt minerals,the crystallization sequence is first gypsum,then glauberite,then paratacamite,and finally rock salt.For the first time,reducing brine was found the deep in the earth,and copper bearing brine was found in the Kizil copper mineralization spot in the north of the basin.Through mixing experiments of two different types of brines carried in the field,it was found that the mixing of the two did not cause the precipitation of copper element.The copper isotope analysis data show that the copper source of the basin is probably related to the large-scale volcanic activity and granite intrusion accompanied by the early Tianshan orogeny.