NATURE OF THE QIANGTANG BASIN AND ITS TECTONIC EVOLUTION

The Qiangtang Basin is a huge sedimentary basin which is situated between the Banggonghu Lake-Nujiang River suture zone and the Xijinwulan-Jinshajiang River suture zone.Its formation and evolution was controlled by the dynamics of the Tethys tectonic belt.An analysis of the sedimentary sequence and of the essential mineral components,chemical components and trace elements of the clastic rocks as well as the chemical components of igneous rocks in the Qiangtang Basin show that the basin resulted from a superimposition of different types of tectonic basins in different periods i.e.a craton riftbasin in the Late Paleozoic,a foreland basin in the Mesozoic and an intermountain graben basin in the Cenozoic.