Gamaleegrad Intermediate Intrusive Rock and Its Geotectonic Significance in the Taxkorgan Region of Western Kunlun Orogenic Belt,Xinjiang

Gamaleegrad intermediate intrusive rock, located at the southwestern margin of the Tarim Block and the northeast edge of Karakoram continental margin, is composed of calc-alkaline monzogranite series and alkaline granite series, which were formed between late Cambrian and early Ordovician.Based on geochemical analysis, the main elements and trace elements of Gamaleegrad intrusive rock have been studied in detail, as well as the tectonic setting of the intrusive sequence and geodynamic model between plates around the intrusive sequence have been discussed.The results show that the Gamaleegrad intermediate intrusive rock is a combination of monzogranite-granite (MG-G), which is mixed with sub-neutral granitic magma (high Sr, Zr and low Rb) that experienced the crustal remelting in the evolutionary process of intrusive sequence.It mainly belongs to I-type granites, which was formed in continental backarc extensional basin under the condition of subduction collision.Based on physical environment and tectonic setting in the course of magmatic evolution, it is speculated that the formation of these intrusive rock is closely related to subduction collision of Kuda oceanic crust towards Tarim ancient block, indicating the disappearance of Kuda Ocean and the formation of back-arc spreading granite.Meanwhile, it means that the continent-continent collision had taken place between Tarim ancient block and Qaidam ancient block, indicating that both of them were finally converged into Rodinia supercontinent.