Geological Characteristics And Analysis Of Metallogenic Potential Of Xiangmatang Rock Mass Group In Changning Counnty

Xiangmatang rock mass group,which is exposed in datianba township,Changning county,Yunnan,western Yunnan,is located in the middle lancang river orogenic belt of Sanjiang,where the tectonic evolution is complex,the magmatic activity is intense,and the mineralization is large-scale.Therefore,the investigation on the geological evolution of the study area has very important geological significance for the exploration of the Sanjiang regions.Based on the analysis of geology,petrology,tectonic geology,geochemistry and isotope chronology of Xiangmatang rock mass group in Changning county,this paper makes a comparative analysis of Xiangmatang rock mass group and Lincang granite in the same mining area,and makes a brief analysis of the metallogenic potential of Xiangmatang rock mass group.Xiangmatang granite group is mainly composed of Xiangmatang granodiorite and Chonggang granite.SiO₂ content of Xiangmatang granodiorite was 69.18%⁷4.72%,with an average of 71.08%.The K₂O content was 5.44%⁶.49%in most cases,with an average of 5.49%.The content of total alkali?Na₂O+K₂O?was 5.18%⁸.69%,with an average of 7.78%,and Na₂O<K₂O,which was rich in potassium silicate and low in calcium.The AR index of the sample was 2.02³.33,with an average of 2.97,and it was Alkaline rock.A/CNK value was 1.20¹.47,with an average value of 1.30.It was peraluminous granite.The SiO2-K2O diagram shows that the rocks were mainly potassium basaltic series,and a few were low potassium calc-alkaline series.Comprehensive judgment Xiangmatang granodiorite is potassium basaltic peraluminous granodiorite.Due to the age difference and the distribution position,Chonggang granite was divided into Chonggang 1 and Chonggang 2.The SiO₂ content in Chonggang 1 was 70.18-73.34%,with an average of 71.65%.The content of total alkali?Na₂O+K₂O?was 6.85-8.36%,with an average of 7.40%,and Na₂O<K₂O.The SiO₂ content of Chonggang 2 was 68.20⁷5.78%,with an average of 71.84%.The content of total alkali?Na2O+K2O?was 4.86⁸.08%,with an average of 6.65%,and Na₂O<K₂O.It was rich in silicon potassium and low in calcium.?<3.3,It belongs to calc-alkali series.In combination with the basicity of AR-SiO₂,the rock was composed of calc-basic and alkaline rocks.The Al₂O₃ content was 13.93%¹9.15%,and the average was 15.45%.The value of A/CNK was between 1.21 and2.92,with an average value of 1.54.It was peraluminous granite.The variation map of SiO₂-K₂O shows the series of high kali-calc-potassium basalts,and the Chonggang rock mass was peraluminous granite of high kali-calc-potassium basalts.In the sample of Xiangmatang granodiorite mass group,the microelements of Xiangmatang granodiorite are generally enriched with large ion LILE,Th and Pb,and the elements of high field strength?HFSE?have obvious deficit and obvious negative Eu anomaly.Light rare earth is relative enrichment,while heavy rare earth is relative loss.On the whole,the microelement in Chonggang granite are enriched with LILE,Pb and Th,loss of HFSE and obvious negative Eu anomaly.Light rare earth relative enrichment,heavy rare earth relative loss.Zircon U-Pb dating shows that the zircon U-Pb of the Xiangmatang granodiorite is 211 Ma,formed in the late Triassic.The zircon U-Pb age of Chonggang-1 granite is20.76-32.93Ma,which was formed in the oligocene-miocene.The zircon U-Pb age of the Chonggang-2 granite is 20.9-52.1Ma,which was formed in the Eocene to Miocene.The results of the magmatic origin comprehensive analysis show that Xiangmatang rock mass is S-type granite,which the source area is mainly from the clastic rock source area of poor clayization.The temperature of the Xiangmatang rock mass formation may be about 875?,and the depth of formation is most likely a medium pressure environment,and the pressure formed by the rock mass is a medium pressure environment with a pressure greater than 0.8Gpa.Chonggang rock mass is the S-type granite,which the source area is mainly from the clastic rock source area of poor clayization,temperature of the Chonggang rock mass formation is greater than875?,and the depth of the formation is the low-medium pressure environment,and the rock mass formation pressure is greater than 0.8 Gpa,but is less than 1.2 Gpa.Throug the comparison between Xiangmatang rock mass group and lincang granite related metallogenic rock mass in the same mining area shows that the Xiangmatang rock mass group has a low degree of metallogenic potential after the comparison from the aspects of petrogeochemistry,magmatic evolution degree, oreprospecting mark and age of formation.Throug the comparison between Xiangmatang rock mass group and lincang granite related metallogenic rock mass in the same mining area,it shows that Xiangmatang rock mass group has a low degree of metallogenic potential after the comparison of rock geochemistry,magmatic evolution degree,ore prospecting mark and weathering degree.