Geological Characteristics And Tectonic Significance Of Early Permian Gabbro In Alax You Qi,Inner Mongolia

The study area is located in the western part of the Inner Mongolia Autonomous Region,belonging to the northern part of the northern part of the North China Alxa plots.This paper is from the west to the east along the Ejin Chongji-Sarah-The early Permian gabbro is the object of study.By studying and studying predecessors' data,the petrology,petrochemistry and chronology are studied on the basis of field observation to discuss its formation and tectonic surroundings.The main body of the Early Permian gabbro is dark gray-gray-green,fine-grained structure,block-like structure,and weakly pheromone-like structure.The main types of rocks include: olive gabbro,gabbro,gabbro,diorite and quartz diorite.The geochemical characteristics of the rocks show that the Early Permian gabbro is mainly granite and calc-alkaline rocks.Light,heavy rare earth within the degree of fractionation are low,but light rare earth fractionation slightly better than heavy rare earth.?Eu is 0.63 ~ 1.00,mostly less than 1,is not obvious negative europium anomalies.?Ce is 0.93 ~ 0.99,cerium anomaly is not obvious;rare earth distribution curve for the right,is a light rare earth enrichment type.The total shows Th,La,Nd,Zr enrichment,K,Sr,P,Ti loss.Part of the rock shows the characteristics of high magnesium diorite,should belong to the product of oceanic subduction.The weighted mean age of the Early Permian gabbro was 300.8±1.1Ma?264.72± 0.93 Ma?274.6± 1.1 Ma?269.3± 1.6 Ma using the LA-ICP-MS zircon U-Pb dating method.Its age is between the Middle Perme and the Early Permian.Combined with the contact between the geological body,this set of rock emplacement era as early Permian.According to the geological data,it is found that the formation of the Early Permian gabbro is related to the subduction,which is mainly formed in the tectonic setting of the paleoceanic plateau to the southern margin of the North China block.