NEW PROGRESS AND NEW RECOGNITION IN THE TECTONIC STUDY OF THE QINLING-DABA MOUNTAINS AND THEIR ADJACENT AREAS

The paper mainly discusses the new progress and new recognition in the tsctonic study of the Qinling-Daba Mountains and their adjacent areas. （1） From many aspects, the paper demonstrates that there was no real ancient ocean in the study region but a polyphase rift sea trough and that the Yangtze and North China continental blocks belong to the same lithospheric plate. （2） A new tectonic （metallogenic） area division of the region has been made; of these areas, the most important Paleo-Qinling rift-accretion belt and others were formed in the Proterozoic and Early Paleozoic respectively. （3） Different intraplate subduction-collision zones were formed in different geological stages within the Qinling tectonic belt, of which the Shangdan fracture zone is only a late Caledonian collision zone, while the Lixian-Mayanhe-Shanyang fracture zone is a collision zone formed during the last event of collision （in the Early-Middle Triassic） of the Yangtze and North China continental blocks. Therefore, the Qinling belt is a superposed orogenic belt formed by ifntraplate polycyclic rifting-accretion-coalescence and collision.