青海中部昆南增生杂岩带变形分期及构造过程

A discussion on the deformation phases and tectonic process of the Southern Kunlun accretionary complex belt,in central Qinghai

昆南增生杂岩带是加里东期—印支期南部特提斯大洋岩石圈板块由南向北长期俯冲的产物,是东昆仑造山带的重要组成部分。在昆南雪水河—驼路沟一带对昆南增生杂岩带进行了近NNW向构造剖面测制,通过详细的野外接触关系、露头地质体组成、变形-变质特征观察以及室内显微构造分析,将雪水河—驼路沟一带昆南构造混杂岩带划分为9个构造岩片。对比各构造岩片内变形特征,初步建立了昆南增生杂岩带的相对构造变形序列,识别出4期变形作用。结合区域构造演化资料,对昆南增生杂岩带的4期变形的构造背景及过程进行了讨论,试图建立其构造演化模式,认为在青藏高原快速隆升阶段,东昆南增生杂岩带中原生构造面理被改造重置。

The Southern Kunlun accretionary complex belt, which was formed in the process of the long-term northward subduction of the Tethys oceanic lithosphere plate during Caledonian-Indosinian period, played an important role in the eastern Kunlun orogenic belt. Based on the structural profile survey in Xueshnihe area, the authors investigated in detail contact relationship, material composi- tion, and deformational-metamorphic characteristics of the outcrops in combination with the study of the microstructure under micro- scope and, as a result, recognized nine different tectonic massifs. On the basis of a comparative study of the structural deformation of each massif, the relative deformation sequence of the South Kuniun accretionary complex was tentatively established, and a 4-phase de- formation was recognized. In combination with the regional tectonic evolution, the authors discussed the tectonic setting and the pro- cess of the deformation phases, and tried to establish an evolution model. It is held that the tectonic foliation experienced reformation and superimposition during the plateau uplift in east Kunlun accretionary complex. This study is significant for understanding the tectonic process of the Kunlun orogenic belt.