试论新疆东准噶尔早古生代岩石圈板块构造演化

EARLY PALEOZOIC EVOLUTION OF LITHOSPHERE PLATE,EAST JUNGGAR, XINJIANG

本文根据近年对新疆东准噶尔地层古生物、蛇绿岩和岛弧型岩浆岩等的野外调查和室内综合研究,系统阐述了该区早古生代期间岩石圈板块构造演化的前奥陶纪板内、奥陶纪至中志留世洋盆和晚志留世陆表海3个构造阶段,并把该区奥陶纪至中志留世的大地构造单元分为阿尔泰被动陆缘区、扎河坝北塔山缝合带(前身为东准噶尔洋盆)和准噶尔地块北部活动陆缘区(包括索尔巴斯他乌-纸房岛弧和库布苏弧后盆地),对各构造单元的特征及演化做了比较详细的论述。同时,对东准噶尔早古生代的大地构造背景及与邻区的关系亦进行了探讨。

Based on the research into the strata, paleontology, ophiolites, and magmatic activities of island arc-type, Early Paleozoic evolution of the lithosphere plate of East Junggar, Xinjiang, China, is divided into three tectonic stages, i. e. Preordovician within-plate, the Ordovician to the Middle Silurian ocean and the Late Silurian epicontinental sea.During the development of the ocean which separated the north Altai margin of the Siberian with the south Junggar block which was part of the mid-Asia paleoplate before the Ordovician, the oceanic crust was subducted southwards under the Junggar block along the line from Zhaheba to Beitashan. In the northern margin of the block Sorbastau-Zhifang island arc and Kubusu back-arc basin were developed. The closure of the ocean in the end of the Middle Silurian led to collision of the Altai passive margin with the Sorbastau-Zhifang island arc. During the Late Silurian on epicontinental sea occurred in the area. The sediments and Tuvaella fossils contained in the upper Silurian implies that the Junggar block had been part of the Siberian.