Genesis And Tectonic Setting Of Intrusive Rocks From Baiyinnuoer Lead-zinc Deposit,Inner Mongolia

The Baiyinnuoer Lead-Zinc Deposit is located in the Balinzuoqi,Inner Mongolia Autonomous Region in northern China,and is the largest lead-zinc deposit in northern China.The tectonic location of the deposit is located in the Late Paleozoic orogenic belt in the south of the Greater Xing'an Mountains.The tectonic activity in the area is strong,which creates favorable conditions for the formation of lead-zinc ore bodies.The lead-zinc ore body is located in the Huanggangliang Formation of the Lower Permian with a total deposit resource of 32.74 Mt.The lead-zinc grade is relatively high.The average zinc grade is 5.44%and the average lead grade is 2.02%.On the basis of summarizing the previous research results,this article relies on the project of“Linxi County Yujiawan Lead-Zinc Polymetallic Mine in Inner Mongolia Autonomous Region,Liaoning Chemical Geological Exploration Institute Co.,Ltd.”Use chronology,deposit geochemistry,mineralogy,rock geochemistry and other research methods to carefully study the characteristics of rock,ore macro-and microstructure,rock geochemistry,and trace minerals of ore minerals in the mining area to determine the main magmatic rocks in the mining area Tectonic environment,magma source,metallogenic age,magmatic rock geochemical characteristics,inferred physical and chemical conditions of deposit formation,and then explored its geological significance.The main technical methods include indoor rock ore thin section microscopic identification,intrusive rock lead isotope test,Sr-Nd isotope test,LA-ICP-MS zircon U-Pb dating,etc.The zircon U-Pb chronology results indicate that the ages of granodiorite porphyry,granodiorite and diorite associated with mineralization are 248±1.3 Ma,251±1.8 Ma and 249±1.4 Ma,respectively.Granodiorite and granodiorite porphyry have lower P₂O₅ content?0.13–0.23 wt%?and A/CNK?0.79-1.05?values,and their SiO₂ content and P₂O₅ content are negatively correlated,indicating It has the characteristics of type I granite.The positive?Nd?t?values?±1.3^±1.8?and T_DM2?880-916 Ma?of the Baiyinnuoer intrusive rock indicate that the source area may be crust-mantle mixed magma.The changes in the content of the main elements Rb,Sr and Ba and the negative Nb-Ta-Ti anomalies indicate that during the ascent of magma,differential crystallization may have occurred.Combining regional geology,geochronology,geochemistry and other subject knowledge and isotope data analysis,the mineralization-related intrusive rocks of Baiyinnuoer lead-zinc deposit were formed in the post-collision environment in the late Permian.The early mineralization of Baiyinnuoer lead-zinc deposit?that is,Indosinian mineralization?is likely to be related to the extension of the ancient Asian Ocean after the collision,and early mineralization is the most important mineralization of this deposit.Weak and affected by the subduction of the Mongolian-Okhotsk Ocean.