The Petrogeochemistry Of Intermediate-acidic Intrusive Rocks In Shengge Area And Its Tectonic Significance

By studying on the petrology, petrogeochemistry and the zircon U-Pb chronology about the Shalegongka granitic mass, Huodeshenggou granitic mass, Motelongea granitic mass, Guriwenburigete diorite, Asihuote diorite and Huodeshenggou diorite, we reach the conclusions as follow:1,The Motelongea granitic, Shalegongka granitic mass and Huodeshenggou granitic mass are respectively Monzonite granite, moyite and biotite-granite.They all belong to high-K calc-alkaline granitoid. The A/CNK of Motelongea granitic is<1 and it is metalumlnous. The A/CNK of Shalegongka granitic mass and Huodeshenggou granitic is >1 and they are peralumlnous. The Guriwenburigete diorite, Asihuote diorite and Huodeshenggou diorite are respectively tonalite, quartz diorite and diorite The A/CNK of Guriwenburigete diorite, Asihuote diorite are<1 and they are metalumlnous. The A/CNK of Huodeshenggou diorite is >1 and it is peralumlnous.2,The Zircon LA-ICP-MS dating for the Huodeshenggou granitic mass yields 213.9±5.6Ma (MSDW=2.1) which belongs to the Late Triassic.3,Shalegongka granitic mass, Motelongea granitic mass, Guriwenburigete diorite, Asihuote diorite and Huodeshenggou diorite are allⅠ-type granitites which grew out of southward subduction of oceanic crust and it is corresponding for the subduction of the orogenic period.4,The geochemistry, chronology together with the center acidic volcanic rock of the island arc indicate:the rift appear in 293.5Ma; the ZWL ocean was opened up in318Ma; the subduction of the oceanic crust commenced in 280Ma; collisoinal orogenesis started in 238Ma-213 Ma. After that,it comes into the postorogenic evolution.The ZWL belt experience evolutionary process which is crack-subduction-collision-apotectonic extend, it is an independent orogenic belt.