The Discussion Of Characteristics And Tectonic Settings Of Indosinian Hypabyssal Granitoids In ZeKu Region,Qinghai

The West Qinling orogenic belt is an important place of the central mainland Orogen which cross the west and east of our country.In this time,the study area is located in the intersections of Qilian,the west Qinling and the East Kunlun orogenic belt.And it belongs to Zeku County of Huangnan Tibetan Autonomous Prefecture.In long geological history process,the study area has experienced the complicated tectonic evolution,magmatic evolution and so on.Compared with the study area,the granite in other areas of West qinling has been researched more than once.Especially the Indosinian granite,such as the"Five golden flowers"granite plutions in Longnan city,Tianshui City in Gansu province,Wenquan rock mass in Wushan County of Gansu provice and granite in Gonghe Basin of Qinghai province.The dissertation research of the granite in Ze Ku Country Qinghai province utilizing Petrology,petrography,Rock geochemical,U-Pb isotope dating and other ways.By with the relevant data,come to the conclusion that the ganites arranged on North east,south west.It exposed less and output in the form of dike and other form.The relationship with Triassic strata is Intrusive contact.The main types of rock is gabbro,diorite,granodiorite and granite porphyry.lithology transit from neutral to acidic.Granitoid of areaterritory research have Following features:SiO₂ ranged from53.34%to 76.70%,Na₂O+K₂O ranged from 3.23%-11.03%,Rich in aluminium,K₂0/Na₂O ranged from more than 1 to less than 1.A/CNK ranged from 0.67 to 3.37.Gabbro,diorite and granodiorite are High-K calc-alkaline and belong I-type granites.Porphyry belonging to high Peraluminous S-type granites.the REE contents of Ⅰ and S granites are not high.LREE are Enriched and HREE are loss.Eu ranged from 0.75 to0.8.Ⅰ-type granites contain high Ta、La、Nd、Hf、Sm、Lu.And low Th、U、Ba、K、P、Ti.S-type granites are abundant in Rb、Th、U、Ta、La and short of Nb、Ba、K、Nb、Sr、P、Ti.According to the research,there are two granitoids types in Ze Ku.And Ⅰ-type granites formed Earlier than S-type granites.Ⅰ-type granites were formed under the thickened crust during the early post-collision period.S-type granites were formed under the crustal extension environment after delamination.granites in Ze Ku were formed in Tectonic setting of Animaqing oceanic crust pitchdown,which Infers Animaqing ocean basin closing time is Late Middle Triassic.