Evolution Characteristics of Ordovician Intrusive Rock in Changshagou of Altun Region

The intrusive rocks in the Changshagou area of Altun of Xinjiang province include pyroxenite, gabbro, diabase gabbro, quartz diorite and quartz monzodiorite. Both field geological characteristics and LA-ICP-MS zircon U-Pb dating show that the rocks formed in Ordovician. Basic-ultrabasic intrusive rock has the characteristics of mantle source type; intermediate-acidic intrusive rocks show dual characteristics of type I and type S, with its magma coming mainly from the upper mantle. Assimilation by blending in part of the crust-source material in the process of magma invasion endows the rock with the nature of crust-mantle mixed source magma. Formed in continental cracking tectonic environment, the basic-ultrabasic intrusive rocks are the product of plutonic magmatism related to deep fault and continental rift, while the intermediate-acid intrusive rocks are resulted in convergence tectonic environment.