Stratigraphic and paleobiogeographic affinities between different tectonic units in northwestern China-With a discussion of the tectonic framework of northwestern China

Different new views about the tectonic framework of Northwestern China have been proposed by different disciplines in recent years. According to the comparative analysis of the basement age, Yangtze-type Nanhuaan System (Sinian) and its tillite and Early Paleozoic stratigraphic sequence and paleobiogeographic characteristics, as well as the nature of boundaries between different tectonic units, the present paper deals with the affinity of tectonic units in northwestern China. The tectonic framework of northwestern China is as follows: the Tarim and Yangtze plates belong to a unified large plate once. This large plate and the North China and Siberia plates are three different tectonic domains; Qaidam-Qilian-Alxa as an integrated wedge-shaped block originated from the Tarim-Yangtze plate. This block was displaced on the west along the Altyn Tagh fault and on the east along the western Helanshan margin-Longmenshan fault and wedged into a triangular block during the large-magnitude uplift and northward pushing of the Qinghai-Tibet plateau in the Cenozoic.