新疆阿尔金地区长沙沟一带奥陶纪侵入岩及其演化特征

Evolution Characteristics of Ordovician Intrusive Rock in Changshagou of Altun Region

新疆阿尔金地区长沙沟一带发育的侵入岩岩石类型包括辉石岩、辉长岩、辉绿辉长岩、石英闪长岩和石英二长闪长岩。野外地质特征和LA-ICP-MS锆石U-Pb测年结果显示就位时代均为奥陶纪。其中基性超基性侵入岩具有幔源型特征;中酸性侵入岩显示I型和地S型双重特征,其岩浆主要来源于上地幔,在岩浆上侵过程中同化混染了部分壳源物质,使其具有壳幔混合源的岩浆性质。基性超基性侵入岩形成于超大陆裂解构造环境,系与大陆裂谷或深大断裂有关的深成岩浆作用的产物,中酸性侵入岩是汇聚阶段的产物。

The intrusive rocks in the Changshagou area of Altun of Xinjiang province include py- roxenite, gabhro, 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 intru- sive rocks are resulted in convergence tectonic environment.