西昆仑山构造特征与演化

TECTONIC FEATURES AND EVOLUTION OF THE WESTERN KUNLUN MOUNTAIN REGION

西昆仑山位于青藏高原西北缘,新疆的南部。该区存在两条不同时期的重要构造带,即麻扎—康西瓦—木孜塔格和库地—苏巴什构造带。昆仑山被这两条构造带分成了三部分:北带、中带和南带。南带从构造意义讲已不属昆仑山区范围,中带是两期岛弧的叠加,北带是在被动大陆边缘基础上叠加了岛弧到弧后的发展产物。因此,昆仑山区是一个复合地体,经历了多期变形与岩浆活动,沉积类型也较多。

Several geological investigations have been carried on the Qinghai-Xizang Plateau since 1960, and a tectonic framework has been establi'ched. But the division of tectonic unit in the Kunlun-Karakorum Mts region situated northwest of Qinghai-Xizang Plateau and south of Xinjiang did not be yet clear. Having taken part in many Geotra verses: the Kashi-Hongqilapu, Yecheng-Shiquanhe, Mazha-Qiaogeli Peak, Yutian-Kliya Pass and Ruojiang-Mangyan-Muzhitage Peak in 1987-1988, the author gives here a preliminary suggestion on the division of tectonic unit and geological evolution of the middle-western segment of the Kunlun Mountains.Two important tectonic zones of different geologic periods in the Kunlun Mts region were recognized during our expedition. They are Mazha-Kangxiwa-Muzhitage zone which is previously the fourth suture zone, and Kudi-Subashi tectonic zone which is newly found as an important earlier suture zone. The Kunlun Mountains are separated by these two major zones into three belts: the northern, middle and southern belts.Tectonically, the southern belt does not belong to the Kunlun Mts region, it may be connected with the Hoh Xili-Bayan Har region to east. The middle belt is a superposition zone of two-phase arcs, i.e. a Permian-Triassic arc has superposed on an early Paleozoic arc. Plu-tonites are widely distributed in the superposition zone. The northern belt is a passive continental margin from Sinian to early Paleozoic, and superposed by a Permian-Triassic arc or back-arc. Thus, the Kunlun Mts region tectonically is a composite terrane. It was experierced several phases of deformation and magmatism, and the sediments are also complicated. Then a discussion is also made on the tectonic evolution of the Kunlun Mts since the Sinian period.