Metallogenic Environment And Discussion On Genetic Type Of GongPoQuan Copper Deposit,in BeiShan Area,GanSu Province

Gongpoquan copper deposit is very popular all through the ages because of its specialgeological features of tectonic position and complex geological characteristics. After years ofresearches and explorations, there are a number of valuable research results and data havebeen accumulated.But in the field of metallogenic environment and its genetic type of oredeposit,some important scientific problems are still existed,waiting to be solved. This paperregards the two year’s work of field investigation as the dominant, combining with laboratoryresearch in rock and ore microscope observation and research as well as the major elements,the rare earth elements(REES) and the trace elements test analysis, to research and discuss themetallogenic environment and ore genesis type of Gongpoquan copper deposit. Majorachievements have been made in the following points:1. Through the field investigation, there are three ductile shear belts in the mining areahave been identified,whose distribution of the directions are NEE、NWW and NNW. Studiesshow that, they are the ore metallogenic structures of Gongpoquan copper deposit, and havehad controlled the ore bodys’ morphology and layer occurrence as well.2. The three ductile shear belts in the mining area are correspondingly divided into threestages, each stage tectonic activities are accompanied by magma activity and mineralization.Characteristics of the mineralization of the first and second periods of tectonic activity arebasically the same, mainly forming fine grained disseminated ore.While the thied periods oftectonic activity form group of massive and stockwork ore. It is because of the superpositionof multi-stage mineralization resulting in the formation of a massive rich copper ore.3. By the researches of the major elements, the REES and the trace elements of thebasic-ultrabasic rocks in the mining area, combing with the tectonic pattern and magmatitecharacteristics， comprehensive research shows that these basic-ultrabasic rocks areophiolite,which formed in the back-arc basin tectonic setting of abatement belt.ThereforeGongpoquan copper deposit’s formation is related to the back-arc basin tectonic setting.4. There are some porphyry which can be called (ultra) small rocks,they are usuallyexposed with a small scale like the little rock branches or rock pulses in the mining area.Someof the (ultra) small rocks have the phenomenon of the development of mineralization. There isno clear dependencies between the spatial distribution of the ore body and porphyry.5. Through the comparative study of typical deposits at home and abroad, Gongpoquancopper deposit has big differences compared with the typical deposits, mainly in ore bodymorphology、occurrence, ore controlling mechanism, wall rock alteration types and their spatial distribution，Ore texture and structure. Combining with the fact that the ductile shearbelts controlls ore and three times of mineralization, from the contributions of magmatite tomineralization，Gongpoquan copper deposit is the type of superimposed deposit which iscontrolled by the ductile shear belts and the magmatism.While in this respect of the dominantore-controlling factors,it is the type of ductile shear zone copper deposit.