东昆仑造山带下中三叠统沉积岩地球化学特征

Geochemical Characteristics of Low to Middle Triassic Sedimentary Rocks of Eastern Kunlun Orogenic Belt

东昆仑造山带具有软碰撞、多旋回的特点 ,造山带内的沉积盆地具有多物源和不同的大地构造背景 .东昆仑造山带东段下、中三叠统沉积岩的常量元素组成特征表明 ,母岩大多数为杂砂岩 ,部分为长石砂岩和岩屑砂岩 ,表明该沉积盆地是一个多物源的浊积岩复理石盆地 ,陆源碎屑来自与其毗邻的活动大陆边缘、被动大陆边缘和火山岛弧 .稀土元素的配分模式和特征值表明该沉积盆地的大地构造背景具有活动大陆边缘和大陆岛弧的特征 ,更接近于活动大陆边缘 。

The eastern Kunlun orogenic belt shows characteristics of soft-collision and multi-cycles.The sedimentary basins inside it have multi-sources and different tectonic backgrounds. The constant elements of low to middle Triassic sedimentary rocks of the east part of eastern Kunlun orogenic belt documents that the majority of the source rocks are greywacke and others are felspar sandstones and lithogenic sandstones. This indicates that the sedimentary basin is a multi-sources turbidite flysch basin, of which the terrigenous materials come from the adjacent active continental margins, negative continental margins and volcanic arcs. The distributing model and eigenvalues of trace elements indicate that the sedimentary basin bears backgrounds of active continental margin and continental arc, more close to the active continental margin. These prove that this sedimentary basin is a flysch foreland basin developed in the continental crust.