利用活断层资料模拟中国大陆及其邻区晚第四纪地壳变形场

LATE QUATERNARY CRUSTAL DEFORMATION FIELD IN CHINA'S CONTINENT AND ITS ADJACENT REGIONS INFERRED FROM ACTIVE FAULT DATA

活动构造是现今大陆地壳变形的重要反映。文中对发育于中国大陆及其邻区的活断层资料进行了系统的收集和分析整理 ,并结合活断层定量研究对主要活断层做出了较为粗略的分类。在此基础上 ,借助改进的Haines方法 (即双三次样条函数 ) ,根据中国大陆及其邻区的主要活断层资料 ,推算得出将地壳变形看作连续变形情况下的中国大陆现今地壳变形的应变率场和速度场模型。模型与现今GPS观测结果可以较好地吻合。文中还针对模型计算结果对中国大陆各区的运动矢量变化特征进行了分析 ,并通过与GPS观测结果的比较 。

Active tectonics is the important manifestation of the present crustal deformation. The data of the major active faults in China and its adjacent regions were collected and sorted according to their scale and significance. Furthermore, the faults were classified roughly on the basis of available quantitative data of active faults. Based on these data, the strain rate field of the crustal deformation and the distribution of horizontal velocity field in China's continent were modeled by using Haines' method. The results of modeling were obtained on the assumption that the crustal deformation in China's continent is continuous deformation. The results of the modeling accord very well with those obtained from GPS observation. In addition, the variation of motion vectors in every block of China's continent was analyzed on the basis of the modeling result. The effects of the secondary faults on the crustal deformation in this region were estimated quantitatively by comparing with the results of GPS observation. From the afore-mentioned results, some important conclusions can be drawn as follows: (1) crustal deformations are mostly absorbed by the major faults, and only about 10% of the deformation is absorbed by the secondary faults; (2) crustal deformation in west China is much stronger than that in east China. The geodynamics of crustal deformation in east and west China is quite different. The collision between the Indian and Eurasian plates is the dominating cause of crustal deformation in west China; (3) crustal deformation in China is characterized as block movement. The active block boundaries and the major faults are the place where the velocity vector changes significantly; (4) a small-angle clockwise rotation of the deformation vector occurs in South China, which is the result of the combined action of the Philippines and Pacific plates.