青藏高原大同西侧石英二长岩体地球化学及岩石系列

Geochemistry and rock series of quartz monzonite intrusion in west-side of Datong on Qinghai-Xizang Plateau

大同西侧石英二长岩体位于青藏高原西北缘、西昆仑山主峰地带，形成于早古生代。其地质、地球化学研究表明，该岩体岩石组合类型为（石英）二长闪长岩-（石英）二长岩-石英正长岩。岩石主要由斜长石、微斜长石、石英、角闪五、辉石和少量黑云母组成。岩石化学成分富碱、高钾、K2O／Na2O比值大而贫铁，微量元素富集Rb、Sr、Ba等大离子亲石元素和轻稀土元素，属于钾玄岩系列。

Quartz monzonite intrusion in west-side of Datong is situated in the center of the WestKunlun Mts. on the northwestern Qinghai-Xizang Plateau and was intmded in early PaleozoicEra. Geological and geochemical characteristics indicate that rock assemblage type of themassif is (quartz) monzodiorite-(quartz) monzonite-quartz syenite. The rocks consist ofplagioclase, microcline, quartz, hornblende, pyroxene and a bit of biotite. Chemicalcompositions are characterized by alkali-rich, high content of potassium with high value ofK2O/Na2O, LILE-rich, LREE-rich and low content of iron. All above indicate that its rockseries is shoshonite.