TECTONIC FRAMEWORK ON THE WESTERN MARGIN OF THE YANGTZE PLATFORM

The study area is located in the junction zone between the Yangtze platform and the SongpanGanzê geosyncline, belonging to the central sector of the Longmen MountainJinping Mountain orogenic belt. This area has undergone four stages of tectonic evolution, i.e.: the formation of the basement, development of the pasive continental margins, folding and mountainmaking and intracontinental mountainmaking. Especially the last two stages gave rise to the present tectonic features. From the viewpoint of the tectonic slabs, the tectonic slabs have been distinguished with the ductile shear zones as the boundaries; thus a tectonic framework of “four zones and five slabs” has been established.