Geochemical Characteristics And Geological Significance Of Metallogenic Rock Mass In Yihetun Tin-polymetallic Deposit,Bairin Left Banner,Inner Mongolia

The southern section of the Greater Xing'an Mountains in eastern China is one of the most important polymetallic metallogenic belts in China.There are many Sn-PbZn-Ag-Cu-Mo polymetallic deposits in the area.There is a close genetic relationship between the mineralization of the deposit and the late Mesozoic magmatism.For a long time,most of the polymetallic deposits in the area are based on the prospecting work of Ag,Pb-Zn,Cu deposits,while the research work on tin polymetallic deposits is relatively thin.The Yihetun rock mass is located in the southern section of the Daxinganling orogenic belt.The Yihetun tin polymetallic deposit is developed in the rock mass,and there are multiple Yunying veins,which has a good prospect of mineralization.At present,the understanding of the rock mass is not perfect.The diagenetic age,genetic type and geodynamic background of the rock mass are still unclear.The main lithologies exposed in the Yihetun rock mass are quartz monzonite porphyry,medium-grained biotite syenite granite and granite porphyry.The LA–ICP–MS zircon U–Pb dating results of the Yihetun rock mass show that the age of the mesogranite biotite syenite granite is 142.1 ± 0.4Ma,the age of the granite porphyry is 132.6 ± 1.8Ma,and the quartz monzonite porphyry The age is 132.9 ± 2.3Ma,the three types of diagenetic diagenesis belong to the Early Cretaceous.In the TAS diagram,samples of medium-grained biotite syenite and granite porphyry fall into the granite area;samples of quartz monzonite porphyry fall into the quartz monzonite area.Granite porphyry and medium-grained biotite syenite granites belong to the high-calciumcalcium-alkaline series,both of which have the characteristics of quasi-alumina-weak peraluminum.The rock belongs to the potassium basalt series,with weak peraluminous characteristics,and its rock genetic type can be classified as type I granite.Quartz porphyry is relatively enriched in elements such as Rb,Sr,Th,U,and Pb,while deficient in elements such as Ba,Nb,Ta,P,and Ti.Light rare earth elements are relatively rich,and the sample has a moderate negative Eu anomaly.The mediumgrained black cloud syenite granite is relatively enriched in elements such as Rb,Th,U,and Pb,while deficient in Ba,Sr,Nb,P,and Ti.Light rare earth elements are enriched,and the sample has a strong negative Eu anomaly.Granite porphyry is relatively rich in elements such as Rb,Th,U,and Pb,while deficient in Ba,Sr,Nb,Ta,P,and Ti.It shows that it is rich in light rare earths and has a strong negative Eu anomaly.By combining the existing research results,it is believed that the Yihetun rock mass experienced a high degree of crystallization differentiation during the evolution of the Nb / Y and Rb / Y + Nb tectonic environment.The samples all fell into the granite area after collision.Combined with the regional structural background,it is speculated that the Yihetun rock mass was formed in the post-orogenic environment of the extensional tectonic system.Compared with the geochemical characteristics of the typical tinpolymetallic deposits in the region,the Yihetun rock bodies have similar high-evolution geochemical characteristics,and the geological-geological-geochemical-geochemical mineralization conditions in the mining area are favorable,and they are found The ore model has a high degree of agreement,favorable metallogenic conditions,and great resource potential.