Characteristic Of Early Jurassic Intrusive Rocks In Jilin Province Xinan-Baoan Region

Xinan-Baoan region,the study area is located in jilin shulan belongs to Mongolia orogenic belt,xiao xing-ZhangGuangCaiLing rock epicontinental plasma arc.In this paper,the early Jurassic intrusive rocks in the study area of the petrology,mineralogy and geochemistry,zircon U-Pb chronology etc.Research has shown that early Jurassic intrusive rocks have high silicon and aluminium rich,rich potassium,iron,magnesium,poor characteristics,belong to peraluminous,high potassium calc-alkaline series rocks,with strong separation and crystallization.Chondrite standardized distribution curve integral to the right,the curve slope is big,the enrichment of light rare earth type,fractionation,obviously in the Eu negative anomaly.Large ion lithophile Rb,U,Th obvious enrichment,Ba,Sr loss is more obvious.The zircon U?Pb isotope age between 172.1-181.6 Ma,emplacement age of early Jurassic.Through the rock formation and tectonic environment and the analysis of the magma source area,showed that after this period granites formed in volcanic arc orogehic environment,mainly for the post-tectonic type A granite type.Is closed extrusion mechanism under the continental crust in the early days,the stress mechanism transformation(by extrusion to stretch),the same collision closed into a stage of back-arc extension rift,lu was affected by the ancient Pacific subduction subduction.The study on subsequent geological survey and prospecting work is of great significance.