吉林省大荒沟-板石沟早前寒武纪基底的岩石单元划分及其地质演化

Division of Lithological Units and Geological Evolution of Early Precambrian Basement in Dahuanggou Banshigou Region, South Jilin Province

根据１５万区域地质调查，将区内的早前寒武纪基底划分为变质上壳岩、中粗粒黑云长英片麻岩、变黑云母钾长花岗岩和变质基性岩四个岩石单元。通过对上述岩石单元岩石类型、地球化学特征、变质变形作用及同位素年代学研究，对其形成时序进行了讨论，由此确定了本区早前寒武纪基底的地质演化轮廓，即在中晚太古时期，本区经历了由玄武安山岩和英安岩双峰式火山建造为主体的上壳岩系的形成阶段，并于２．６Ｇａ遭受角闪岩相变质；随即伴有大规模的ＴＴＧ深成岩浆活动，晚太古末经历绿帘角闪岩相的区域变质作用；至早元古初期，深熔成因的钾质花岗岩侵位，区内已存的早期变质岩石受到该期钾质岩浆的交代改造，并在其成岩之后遭受绿片岩相的区域变质。

The Early Precambrian basement in Dahuanggou banshigou region of South Jilin Province comprises main four lithological units,i.e. metasupracrustal rocks,coarse biotite felsic gneisses, potassium granites and metabasic rocks. An attempt has been made to elucidate the petrography, geochemistry, metamorphism, geochronology and the relation of these rocks in the paper.Based on the results obtained from the research,we present an outline of the evolution of South Jilin Archean terrain.In the Middle Archean supracrustal rocks were formed. Then amphibolite facies metamorphism happened at 2 6Ga,accompainied by ductile shear deformation.Later plutonic TTG intruded.In Late Archean this region underwent epidote amphibolite metamorphism around 2 53Ga,and later there occurred an event of NE directed ductile shear deformation.In Early Proterozoic, potassium granite intruded and then underwent greenschist facies metamorphism at about 2 3Ga. Two events of NW and NE shear deformation also occurred at the later stage of the final regional metamorphism.