Petrogenesis And Its Tectonic Significance Of The Late Permian Diorite In Central Jilin Province

The main research object of this paper is the quartz diorite in Toudaogou area and Shuangyang area in central Jilin.On the basis of field geological survey,sampling and indoor sorting of relevant data,detailed petrographic observations of rock mass samples in the study area were completed,zircon LA-ICP-MS U-Pb dating and whole rock geochemical analysis were carried out,The results show that the two types of diorite belonging to the Late Permian are related to the subduction of the paleo-Asian oceanic crust,combined with a large number of predecessors in the western part of Jilin(Suolun-Xila Mulun area),central(Kaiyuan-Changchun area),and eastern(Yanji-Hunchun area)Carboniferous-Triassic(high magnesium)diorite,rock assemblage of intrusive rocks,ophiolite and paleontological fossils have been studied,and the following points have been obtained:1.The LA-ICP-MS U-Pb ages of quartz diorite in Toudaogou area and quartz diorite in Shuangyang area are 250.8±2.50 Ma and 253.1±0.83 Ma,respectively,which belong to the Late Permian.2.The geochemical characteristics of the whole rock show that the quartz diorite in the Shuangyang area is a high-potassium-alkaline type I granite,which is formed by the interaction of the subducted sediments of the Paleo-Asian Ocean plate and the generated water-bearing fluids that replaced the partial melt of the crust;Toudao The quartz diorite in the Gou area is the Sanukiite of the high-magnesium diorite.It is the product of the metasomatism between the melt and fluid produced by the partial melting of the subduction slab of the Paleo-Asian Ocean and the mantle wedge.3.A comparative analysis of the high-magnesium diorite in the study area and its neighboring areas was carried out.It is believed that they are similar to the Sanuki rocks in the high-magnesium diorite/andesite,combined with the Permian-Triassic magmatic age and According to the analysis of attributes,it is believed that the final closing position of the eastern section of the ancient Asian Ocean is the Soron-Xilamulun-Changchun-Yanji area,and the closing method is scissors suture from west to east.