Geological Characteristics And Metallogenic Conditions Of Mopanshan Copper Deposit In Beishan,Gansu Province

The Beishan metallogenic belt of the East Tianshan is located in the middle section of Tianshan –Xingmeng copper polymetallic metallogenic province,which is the south-middle part of Pal-Asian metallogenic megaprovince in Central Asia.Recently,as the discoveries of the Tuwu,Yandong and other porphyry copper deposits,the studies of copper deposits in this area have attracted much attention in academic circles.The Mopanshan Copper Mine is a newly discovered deposit in the Beishan metallogenic belt with a low degree of research.In order to understand the metallogenic mechanism of this deposit further,the detailed field survey and microscopic observation have been carried out,while the Isotope dating and geochemical analysis have been used in this dissertation.Combined with the previous research results,the Mopanshan copper deposit have been analyzed and discussed from the aspects of metallogenic era,tectonic background and metallogenic conditions.And then,some suggestions for further prospecting direction have been provided.The main understandings obtained in this dissertation are:1.Currently,the Mopanshan Copper Mine has been discovered nine copper ore bodies.The main body of the ore body is produced in the contact zone of K-feldspar granite and granodiorite.The ore body shape is mainly “vein” and "Lenticular".2.The Mopanshan copper deposit belongs to post-magmatic hydrothermal deposit.The mineralization is mainly veined and impregnated types.This deposit was formed by Hydrothermal period and epigenetic period,The hydrothermal period can be further divided three stages of fluorite,quartz-molybdenite-chalcopyrite-magnetite,quartz-sericite-chalcopyrite-bronite-pyrite,quartz-calcite-galena-sphalerite.3.The intrusive rocks exposed in the mining area are mainly K-feldspar granite and granodiorite,the ore-forming rock mass is K-feldspar granite.The zircon U–Pb isotope analysis indicated that the feldspar age of the K-feldspar granite is 423.2 ± 1.4Ma,which is the Late Silurian;the diagenetic age of the granodiorite is 429.5 ± 1.9Ma,which belongs to the Middle Silurian.4.Comparing the petrological and geochemical characteristics of the ore-formingsurrounding rocks of the Mopanshan copper deposit and the Huitongshan copper deposit,it is considered that the mineralization of both is related to K-feldspar granite,which belongs to the high potassium calcium and alkaline series.The ore-forming surrounding rock is controlled by the northwest and northeast faults.5.The high polarization anomaly shows that the deep and southern parts of the Mopanshan mining area have better prospecting prospect.