GREAT JURASSIC THRUST NAPPES IN THE BEISHAN MOUNTAINS-GOBI AREA OF CHINA AND SOUTHERN MONGOLIA AND THEIR KINEMATIC ANALYSIS

摘要

Thrust nappes have been recognized for over a century. Almost without exception the examples discovered so far occurred during convergence of lithospheric plates, and the collision of thick crustal blocks. Two enormous Mesozoic thrust-nappes with displacement over 120-180 km were recently discovered within the Late Palaeozoic - Indosinian orogenic belt in the Beishan Mountains of China and the South Gobi (Sino-Mongolk boundary) area. The thrust nappes occurred long after the main orogenic processes in the area and are interpreted to be a post-Hercynian-Indosinian event and an expression of a great intracontinental deformation. There are few reports of this type of feature in the geological literature. It is therefore necessary to analysis in some detail their kinematic characteristics and to discuss the problem of possible during force responsible for such features.