Cenozoic deformation of the Tibetan Plateau:Constraints on emplacement of syn-collisional magma.
青藏高原新生代地壳变形对同碰撞岩浆侵位的制约

Syn-collisional magmatism is an important form of Cenozoic tectonic activity of the Tibetan Plateau,resulted in a variety of magmatic rocks,some of which were originated from the upper mantle.They occurred within the different tectonic elements of the plateau,most of which are very small in size.As how they emplaced into the surface or sub-surface through such thick crust remains as a mystery.Based on deformation analysis of the crust of the plateau,most of Cenozoic intrusive and extrusive rocks are found occurred along the syncline that formed coevally.Such as those occurred along the Chuxiong basin,Lanping-Simao basin and Lao Junshan syncline within the southeastern margin of the plateau,and those occur along the Laguigangri syncline within the southern margin of the plateau,as well as those occur along the Xoh Hil and Qiantang blocks within the northern plateau.A mechanic model is adapted to illustrate the process of emplacement of the magma under control by stress field status of the crust.As it's shown,the lower part of the syncline undergoes tension,by which the magma intrude into the upper crust along extensional fractures,whereas the lower part of the anticline undergoes contraction,which proved the fact that the magma emplace upward into the upper crust.Therefore,the magma is not likely to be found along the anticline.This mechanic model gives a reasonable explanation for the occurrence of emplacement of some small-sized syn-collisional magma through thick crust into the surface or sub-surface.