Crustal evolution of Palaeozoic in Beishan area, Gansu and Inner Mongolia, China

The AnZ ancient continent was been splited from the Early Cambrian in Beishan area bounded by Gansu and Inner Mongolia, China. The oceanic basin was finally been closed to form a new unified continent in the end of Carboniferous, went through two periods of plate tectonic system and two times of main underthrust-collision orogeny. The first period of plate tectonic system occured in Early Palaeozoic(O₂~S₃), Kazakhstan plate and Tarim plate were firstly divided along Hongliuhe-Niujuanzi-Xichangjing. The oceanic crust underthrusted from south to north in Late Ordovicain-Silura in and the oceanic basin was been closed to forma unified continent again in the end of Silurain. The second one took place in the middle period of Late Palaeozoic(C),Kazakhstan plate and Tarim plate were secondly divided,following the formation of Hong shishan-Baiheshan-Pengbo shan seconddary ocean. The plate tectonic frame had been concluded in the end of Carboniferous,and a new unified continent had been formed. After this,Beishan area got into intracontinental evolution,and appea red a series of spreading mechanismin Carboniferous-Permian,such as intracontinental rifts,chasmic trough,faulted basins,and so on.