青藏高原东南缘弧形旋扭活动构造体系及其动力学特征与机制

在系统总结前人成果资料基础上,结合最新的遥感解译与地表调查资料发现,青藏高原东南缘地壳最新的顺时针旋转运动主要受控于由川滇外弧带和滇西内弧带构成的双弧型川滇弧形旋扭活动构造体系。进一步的综合分析认为,该构造体系的弧形旋扭运动学变形模式的动力学机制及其内部块体变形的差异性与不均匀性,主要是该区边界力的作用方式、先存地质结构和现今的地壳与岩石圈结构、岩石圈物质组成及其物理性质、深部的热状态、重力势能等多种因素共同作用的结果。其中,印度板块与扬子地块之间的右旋剪切和青藏高原内部物质向东南的不均匀挤出共同产生的力偶作用和岩石圈性质与结构,可能是造成该区围绕东喜马拉雅构造结整体发生顺时针旋转运动和旋扭叠加伸展变形最重要的因素。

The arc rotational-shear active tectonic system on the southeastern margin of Tibetan Plateau and its dynamic characteristics and mechanism

On the basis of previous data on active faults in combination with information of active faults on the southeast margin of the Tibetan Plateau obtained by the authors based on remote sensing and ground survey, the authors hold that the main active fault zones constitute a large convex for the east arc-shaped tectonic system called Sichuan-Yunnan arc-shaped rotational-shear active tectonic system. The related factors mainly include the boundary forces between different blocks, the existing structural features and crustal structure, lithospheric material composition and its physical properties and deep thermal state, as well as gravitational potential energy between different lithospheric blocks. Among these factors, lithosphere structure and physical properties boundary force as well as the boundary forces resulting from right lateral shear between India plate and Yangtze plate and the eastward extrusion of the Tibetan Plateau might have been the most important factors that controlled and affected clockwise rotation of Sichuan-Yunnan blocks and produced shear and extension deformation around the EHS.