西昆仑北缘出露的中元古代火山—沉积岩系可分为两大系列,一是北带的巨厚逆向演化的双峰式火山岩,其上部为复理石、磨拉石,火山岩的岩石地球化学特征表明,从早到晚岩石的碱度逐渐降低,从碱性、钙碱性向拉斑系列演化,代表了一个伸展构造背景下火山岩演化序列,火山—沉积岩系 The Mesoproterozoic volcanic-sedimentary rocks exposed in the northern margin of the western Kunlun Mountains can be divided into two major series: the bimodal volcanic rocks of the gigantic and inversely evolving breezes in the northern belt, the upper part of which are flyschings, molasses and rocks of volcanic rocks Geochemical characteristics show that the alkalinity of the rock gradually decreases from early to late and evolves from basic to calcareous series, representing a sequence of volcanic rocks under the extensional tectonic setting. The volcanic-sedimentary rocks