Tectonic Characteristics and Orogenic Processes of the Inner Mongolia Orogenic Belt in Eastern China, Asia

摘要

Inner Mongolia orogenic belt situated between north China continental block and Mongolia orogenic belt has evolved for a long geological history. Based on the CAAC (continent-arc-arc-conlinent) collision formed at the late Permian-middle Triassic (200-225Ma) which is later than the end of the subduction in this region, a complicated and duplicated tectonic framework developed with the superimposed structures of fold nappes and thrust nappes. The orogenic vergence is toward south and north continental margins from the core of the orogenic belt. respectively. In the orogenic processes, there were two compression events composed of ductile shearing, folding and thrust systems formation and two times extension or erosion consisted of rift-depression and tnetamorphie core complex distributed in different positions in the orogenic belt. The superficial tectonic events illustrate interruptions for every tectonic process, but the evolution of the lower crust-upper mantle beneath the orogenic belt maybe remain a continuity during the orogenic processes. The evolutional processes were controlled by the lithospheric dynamics which was not from the far away subduction or collision such as Dabie Shan in central China or Okhotsk in Far East Asia but derived from the tending towards equilibrium of the lower crust-upper mantle themselves.