利用应变场和基线变化率研究新疆南天山地区近期地壳运动特征

Research on the Characteristics of Recent Crustal Movement of the South Tianshan Area in Xinjiang through the Strain Field and the Change Rate of Baseline

利用GPS数据研究南天山地区地壳运动特征,截取了该区域2005～2009年GPS数据,在统一框架下进行解算,并绘制出不同时段的主应变、剪应变以及基线变化速率等图像,研究表明该区域的地壳形变具有自西向东、自南向北减弱的特点,主压应变主要表现为受印度板块向北推挤而形成的近南北向压性应力场。2005～2009年基线变化速率表明,以喀什沿经线南北向为界,其东部区域基本上为压缩区,其西部区域基本上为拉张区,东部的基线缩短平均速率(4.84mm/a)大于西部基线伸长的平均速率(3.06mm/a),以喀什沿纬线东西向为界,其南部区域基线变化平均速率(5.58mm/a)明显高于北部区域基线变化平均速率(3.52mm/a),且伸长、压缩变化速率最大基线均在南部地区,说明南部区域受到塔里木块体和青藏高原挤压比较强烈,表明喀什南部区域地壳运动相对活跃。

In a unified framework,we calculate the selected GPS data in the South Tianshan area of Xinjiang from 2005 to 2009,and illustrate the principal strain,the shear strain,and the change rate of baseline in different periods to study the crustal movement in this area.We find that the crustal deformation in this area is decreasing both from west to east and from south to north,and the principal compressive strain features a compressive stress field in a nearly South-North direction,which results from the northward pushing of the Indian Plate.Taking the longitude line through Kashi City as a boundary,we divide the South Tianshan area into east part and the west part.Then,according to the change rate of the baseline from 2005 to 2009,we find that basically the east part is a compression zone,and the west part is an extension zone.The average shortening rate（4.84 mm/a）of the baseline in the east part is greater than the average lengthening rate（3.06 mm/a）in the west part.Then,we find that the average change rate of the baseline（5.58 mm/a）in the south part is greater than that（3.52 mm/a）in the north part.The maximum shortening rate and the maximum lengthening rate of the baseline happens in the south part,which shows that the south part is fiercely compressed by the Tarim Block and the Qinghai-Tibet Plateau,and the crustal movement in the south of Kashi is relatively active.