中国大陆西部地区现今的块体运动

OBSERVATION AND STUDY WITH GPS ON CURRENT BLOCK MOVERMENT IN WESTERN REGION OF CHINA CONTINENT

根据中国地壳运动ＧＰＳ监测网１９９２～１９９６年３次复测结果，分析了我国大陆西部地区现今块体运动的基本特征，结果表明：印度板块向北推挤是我国西部块体褶皱运动和变形的根源；由於内部次级断块的边界条件和受力方式不同，块体边界和内部构造形变亦具有明显的差异。块体运动主要特点表现为：（１）喜马拉雅向南弯曲的弧形边界东西两端，印度板块推挤运动方向不同，导致了弧前方的亚板块和构造块体的运动方向呈扇形散开；（２）青藏高原主体在南北向缩短、东西向延伸的同时存在着明显向东的物质侧向滑移；（３）重要块体分界带和褶皱带两侧运动矢量的比较表明，阿尔金断裂为左旋走滑，天山、祁连山均呈压性；（４）由设置在不同块体的ＧＰＳ测站南北向和东西向运动速率及速率的平均值得到的块体运动速率和方向，呈有规则的变化，其变化规律与地质、地球物理结果具有较好的一致性。

On the basis of the result of 3 repeating surveies (1992, 1994, 1996)for GPS Crustal movement monitoring net in China the analysis of basic characteristics of block movement in the western region of China continent indicates that the northward pushing--compression of the India plate is the origin of the fold and deformation of the western China and that the deformations on the edges and within the region are evidently different because the inner subblocks are constrainted by different boundary conditions and forced styles. The main characteristics of the block movement are as follows. (1 ) The directions of the pushing-- compression of the India Plate at both the eastern and western ends of the southward curved arc boundary of Himalaya are different and it brings about that the moving directions of the subplates and tectonic blocks in front of the arc spread out in a fan shape; (2) The mass of the Qinghai--Xizang plateau is shortening in north--south and extending in east--west,and in the meanwhile there is evidently eastward side strike of some substance ; (3)the comparison between the movement vectors in both side of the division zones and fold zones of important blocks indicates that the Arjin fault is left lateral and the Tianshan and Qilianshan faults are compressive; (4) The movement rate and direction of the block given from north--south and east--west movement rates and their average at the GPS stations on different blocks present regular,and the variation regulation is in good agreement with the geological and geophysical works.