对中国大陆地壳水平变形的初步探索

Preliminary Study on the Horizontal Crustal Deformation in Chinese Mainland

根据全国GPS网 1994年和 1996年两期观测资料的处理结果 ,讨论了中国大陆地区现阶段应变场和应力场。青藏亚板块的西部和东部张应变起主导作用 ,中部压应变占优势 ,主压应变方向为北北东向 ;青藏亚板块东南部东南段云南地区的主压应变方向为北西向 ,压应变和张应变量级相当。新疆亚板块的主压应变方向以北北东向至北东向为主 ,应变量存在差别。华北亚板块的主压应变方向是北东至近东西向为主导 ,局部地段存在差别 ,大部分地区压应变量和张应变量相当。华南亚板块主压应变方向为北北西至北西向 ,与其垂直的另一方向的水平应变量显著变小 ,因此华南亚板块现阶段以压应变占优势。中国大陆地壳的整体主压应变方向为北北东至北东向 ,它反映的是现阶段地壳活动的主应力方向。

In the paper, the current strain field and stress field in Chinese mainland have been discussed based on the processed results of two periods of data observed in 1994 and 1996 in the national GPS network. In the west of Chinese mainland, the principal compressive strain of Qinghai\|Xizang subplate is towards NNE. The western and eastern parts are characterized by extensional strain and the central part by compressive strain. In the southwest, the principal compressive strain in Yunnan Province trends to northwest, and the compressive strain is corresponding to the extensional strain in magnitude. The principal compressive strain of Xinjiang subplate predominates in NNE and NE directions, but the strain magnitudes are different. The principal compressive strain in North China subplate is quite effective in NE and proximate EW directions with difference existing in local segments. However, the compressive strain is corresponding to the extensional strain in magnitude in most areas. The principal compressive strain directions of South China subplate are NNW and NW, and in the direction perpendicular to it, the horizontal strain decreased significantly, and some parts also show and activity of compression. At present, the compressive strain in South China subplate is superior. The integral principal compressive strain in the crust of Chinese mainland trends to NNE and NE. Their principal strain trend is just the principal stress trend of crustal activity in the present stage.