新疆阿拉套山花岗岩带的主要特征及形成构造环境

Tectonic Environment and Origin of Granitoids fromAlatao Mountain, Xinjiang, China

阿拉套山花岗岩带产出于巩乃斯板块东北缘，岩带的岩石组合、化学成分、同位素组成表现出由东北向西南的系统变化，随离俯冲带距离的增大，古老地壳物质的贡献愈显著。构造环境判别表明早期花岗闪长岩－二长花岗岩组合产出于岩浆弧环境，与消减作用直接有关，晚期二长花岗岩－碱长花岗岩组合为造山后花岗岩，产出于张性环境，其形成标志着造山作用的结束。

Granitoids in Alatao Mountain are located in the northeastern margin of Gunes microplate.A systematic variation in rock association, major and trace element concentration as well as isotopiccomposition has been observed among these granitoids. As the distance to paleosubduction zone increases, oldcontinental component shows greater contribution in these granitoids. Tectonic discrimination shows that earlygranodiorite-monzogranite association was formed in a magmatic arc environment and directly related to the subduction. Granites of later monzogranite-alkaline feldspar granite association are post-orogenic granites and wereformed in an extension setting. The formation of these post-orogenic granites indicates the end of the orogeny.