The Ore Genesis Of Typical Deposits And Metallogenic Prognosis In Qiongheba Fe-Cu Ore Concentrating Area, Xinjiang

The research area is located in the northeast edge of Junggar Basin in Xinjiang province,and the tectonic structure location is the east section of Xiemisitai-Qiongheba island arc beltof Junggar microplate (grade â…¡). It is a part of the famous central Asian metallogenic beltswhich has great prospecting potential of iron mine and copper mine. At present, a certainamount of iron mines and copper mines are found in this area. But generally speaking, thesmall scale and the small quantity is not in direct proportion to the great prospecting potential.To make breakthrough of exploration of ore deposits, we analyze in detail the Baoshan ironand Mengxi copper deposit which is representative in region, set up the prospecting modelaccording to comprehensive information of the iron-copper deposits, and delineate theprospecting target finally.The host strata of Baoshan iron ore is in Beitashan formation of middle Devonian. Thevolcanic rocks of Beitashan fornmation composed of altered tuff, tuff breccia, rhyolitic tuff,crystal tuff, dacite porphyry and volcanic agglomerate.Through the analysis of whole-rockmajor and trace elements, we believe that it is formed in the volcanic island arc environment.oceanic crust subducting to mantle lithosphere area, garnet peridotites and spinel peridotitespartial melted in lithospheric mantle and formed the igneous rock. Skarn rocks as thesurrounding rock develop widely in this mining district.The study of skarn space distribution,mineral composition and major and trace elements shows the skarn is the product of volcanolater period high temperature gas-liquid and volcanics. The lithification of skarn is closelyrelated to the magnetite in hydrothermal stage. Through the comprehensive researches of themorphology of ore body, wall rock, The mineral compositions of the ore and Geochemicalcharacteristics of ore,we think Baoshan iron ore deposit is volcanic type magnetite type. Themineralization stage can be divided into magmatic stage and hydrothermal stage. In magmaticstage, basaltic magma differentiatied in deep magma chamber and formed pulp and richsiderousmagma. When the volcanic eruptted, the magma eruptted to the surface or emplacedlithology contact zone, fault and volcanic apparatus. So we think that iron ore metallogenicepoch and basalt rock of Beitashan group are at the same age, about380Ma. In hydrothermalstage, associated with volcanic intrusive rocks, the gas and liquid during the late volcanic activity or slightly later intruded upward along the fault, extracted the ore-forming materialfrom the surrounding rock by hydrothermal metasomatism, produced the superimposedmineralization.The host strata of Mengxi copper deposit is the middle-late Ordovician Huangcaopogroup which volcanic rocks. He alteration can be divided from the center of plagiograniteporphyry body to the outside just like the following: potlshalterationâ†'sericitizationâ†'propylitization. The ore body distributes in the potlshalteration and the sericitizatio.Thegeochemical characteristics of plagiogranite porphyries in Mengxi copper mine, including themain and trace elements and Sr-Nd-Pb isotope, indicate its crust-mantle mixing origin and theisland arc formation environment. The plagiogranite porphyries yielded a zircon U–Pb age of410±11Ma that represents its diagenetic age. The S and Pb Isotope test results on iron pyriteindicate the constitution of sulphur is stable and the source is single, and the value of34S（-2.1‰～0.3‰）is very close to the value of deep mantle sulfur, which means themetallogenic material comes from mantle. The Pb isotope features indicate the Pb is fromcrust-mantle mixing source area. The porphyry body has the same characteristics andformation age with the ore source area; the ore body is distributed on the Potassium belt andHuangjuan lithificationbelt. Besides, the H-O isotope features also indicates the ore-formingfluid is primitive magmatic water.Metallogenic material mainly derived from magmatichydrothermal fluid which is related with plagiogranite porphyry brought up from the depth. Inaddition, considering the feature that the ore body distributing in the potlshalteration and thesericitization centered around the plagiogranite porphyry and the simultaneity of the orebodyand the rock body formation, the Mengxi deposit is classified as the porphyry copper deposit.On the basis of the study on genesis of mineral deposit and indicator for deposit aboutBaoshan iron mine and Mengxi copper mine, combining the geophysical and geochemicalcharacteristics of the mining area, the collective information prospecting model of iron andcopper deposit is established. The application of the material about research area geology,geophysics and geochemistry together with the established prospecting model and the similaranalogy method, there are11iron mine prospecting target regions,15copper mineprospecting target regions. Then the Eigen value analysis predicts the metallogenetic potentiality of the iron mine and the copper mine. By predicting, there are3A level iron mineprospecting target regions,5B level iron mine prospecting target regions and3C level ironmine prospecting target regions;6A level copper mine prospecting target regions,6B levelcopper mine prospecting target regions and2C level copper mine prospecting target regions.