Genesis Of Qiaoxiahala Iron-Copper(Gold)Deposit,Xinjiang Province NW China

Qiaoxiahala iron-copper deposit is a medium-sized iron-based multi-metal deposit located in northern part of Xingjiang province.Through the petrography observation of the polished section and thin section of rock and ore samples collected from of Qiaoxiahala iron-copper(gold)deposits,major and trace element testing analysis of rocks and ore and magnetite and garnet electron probe analysis,summarizes the geological and geochemical characteristics of Qiaoxiahala deposit,skarn genesis,a ore-forming materials sources,ore-controlling factors and genesis mechanism.This study suggests:1.Skarn of Qiaoxiahala iron-copper deposit was formatted by Hercynian intrusive replacing calcareous rocks of Beitashan format.Garnet of Qiaoxiahala deposit are mainly grossular-andradite series,whose end-member is similar to world-famous skarn iron deposits.2.Magnetite discrimination diagram(Ti02-A1203 and Ca+Al+Mn Vs.Ti+V)show the skarn genesis of Qiaoxiahal iron-copper(gold)deposit.In retrograde metamorphism Fe will release from skarn minerals,under appropriate environment,magnetite occur precipitate.Mineralization types of Qiaoxiahala iron-copper deposit is skarn-type.Formation of iron ore bodies are earlier than the copper ore bodies,they format in different skarn mineralization period.3.Andradite,hedenbergite and other iron-bearing minerals occur epidotization and replaced by epidote in retrograde stage,in these process Fe was released.Magnetite precipitated under appropriate conditions,and then format iron ore body.4.Andradite and other minerals released Cu from the lattice in retrograde stage,due to changing of redox environment and physical chemical condition in Quartz-sulfide stage,as well as albitization,chalcopyrite precipitate,forming copper body.5.There is no superimposed and re-enrich relationship between iron ore body and copper ore body,the different mineralization attributed to the different stages of the skarn mineralization.