东昆仑早泥盆世碰撞造山的侵入岩证据

The Evidence of Intrusive Rocks about Collision-orogenyduring Early Devonian in Eastern Kunlun Area

东昆仑昆中断裂带及其附近茶德尔塔格西、阿尔格山北、塔鹤托坂日、喀雅克登塔格地区的早泥盆世侵入岩,受昆中断裂长期活动影响,岩石变形强烈,岩体在平面上呈不规则透镜状,沿昆中断裂近东西向分布。岩石地球化学特征属于亚碱性、高钾和低钾钙碱系列,介于偏铝质和过铝质之间;在R1—R2岩石类型分类图中位于闪长岩、英云闪长岩、花岗闪长岩、二长花岗岩区;在微量元素标准化图中,具有Rb、Th、Ba富集,高强场元素Nb、Ta明显亏损的特点;在稀土元素球粒陨石标准化图中,LREE富集,HREE亏损,曲线表现出明显的较为平滑的斜率相似的一组曲线,均属强烈右倾负斜率轻稀土富集型,整体分配模式具有火山弧花岗岩的特征。通过构造环境的综合判断,本文研究的东昆仑早泥盆世侵入岩属于后碰撞造山花岗岩,物质来源,壳幔相互作用的产物,从而确立了加里东晚期东昆仑碰撞造山的构造过程。

The Early Devonian intrusive rocks in central Kunlun fault and its adjacence area in east Kunlun is effected by central Kunlun fault activity, deformed strong, showed irregularly lens- shaped in horizontal plane, distributed approximately west-east direction along the central Kunlun fault. In litho-geochemistry, the intrusive rocks have characteristics of subalkaline, high-K-low-K calc-alkaline,, metaluminous-peraluminous. In R1-R2 diagrams they plot in the areas of black granite, tonalite, granodiorte, and monzogranite . In normalized traces element patterns, they are enriched in Rb,Th,Ba, deeply depleted in HFSE（Nb,Ta）. In chondrite-normalized REE patterns, they are enriched in LREE, depleted in HREE , the curves behave right inclined, and have volcano-arc granitic characters. Based on regional geological data and tectonic setting diagrams of granites, the Early Devonian intrusive rocks studied in this paper are post- collision-orogenic granites, the material resources originated from interaction of crust-mantle. It is concluded that the collision-orogenic movement had taken place in east Kunlun during late Caledonian orogeny.