南天山-帕米尔现代地壳形变特征与应变场分布
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摘要
利用1998—2011年南天山地区近90个GPS测站观测资料,获取了南天山-帕米尔地区的现今地壳运动速度场、水平应变场以及区域内主要断层的活动速率。GPS运动速率表明:1)研究区主要表现为南北向缩短挤压的运动趋势,并呈现出顺时针旋转的特征;2)最大主压应变分布自西向东递减,应变场的空间分布受区域构造的影响,与构造走向正交;3)剪应变高值区与中强地震存在密切关系,剪应变最大值集中分布在南天山西段与柯坪断裂北部地区。
An accurate crustal deformation field was derived from repeat surveys of almost 90 GPS stations carried out from 1998 to 2011 in southern Tianshan-Pamir region and present velocity field related to stable Euro-Asia plate and the distribution of crustal horizontal strain field were obtained as well.We studied the active velocity along the main faults in the region and the following results are achived.1)The crustal shortening from south to north is the main movement trend in the southern Tianshan-Pamir region.The movement of whole area shows the characteristics of clockwise rotation.2)The amplitude of maximum principle compressive strain decreases from west to east in the southern Tianshan-Pamir region.The regional tectonics controls the space distribution of the strain field.It shows the features that the principal stress direction basically is orthogonal to the direction of the tectonic trend in the region.3)There are close relation between the area of high shear strain and strong earthquakes.The maximum shear strain rate field concentrates mainly in the west of southern Tianshan,and the north area of Kalpin fault.
An accurate crustal deformation field was derived from repeat surveys of almost 90 GPS stations carried out from 1998 to 2011 in southern Tianshan-Pamir region and present velocity field related to stable Euro-Asia plate and the distribution of crustal horizontal strain field were obtained as well.We studied the active velocity along the main faults in the region and the following results are achived.1)The crustal shortening from south to north is the main movement trend in the southern Tianshan-Pamir region.The movement of whole area shows the characteristics of clockwise rotation.2)The amplitude of maximum principle compressive strain decreases from west to east in the southern Tianshan-Pamir region.The regional tectonics controls the space distribution of the strain field.It shows the features that the principal stress direction basically is orthogonal to the direction of the tectonic trend in the region.3)There are close relation between the area of high shear strain and strong earthquakes.The maximum shear strain rate field concentrates mainly in the west of southern Tianshan,and the north area of Kalpin fault.
引文
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10冉勇康,等.西南天山柯坪推覆构造东段晚第四纪变形样式与缩短速率[J].地震地质,2006,28(2):179-193.(Ran Yongkang,et al.Deformation pattern and shorteningrates in the east part of Kalpin thrust system in southwestTianshan durirng late Quaternary[J].Seismology and Geol-ogy,2006,28(2):179-193)
11黄立人,等.构造地块的相对运动与应变[J].地壳形变与地震,1999,(2):17-26.(Huang Liren,et al.Relativemovement and strain of tectonic block[J].Crustal Deforma-tion and Earthquake,1999,(2):17-26)
2沈军,等.2003年2月24日新疆巴楚-伽师6.8级地震发震构造[J].地震地质,2006,28(2):205-212.(ShenJun,et al.The seismogenic tectonics of the Ms 6.8 Bachu-Jiashi,Xinjiang earthquake in Feb.24,2003[J].Seismolo-gy and Geology,2006,28(2):205-212)
3曲国胜,等,造山带弧形构造——西昆仑-帕米尔弧及其预测[J].地质科学,1996,3l(4):313-326.(Qu Guosh-eng,et al.Arc tectonics in orogenic belts[J].Scientia Geo-logica Sinica,1996,31(4):313-326)
4 Burtman V S and Molnar P.Geological and geophysical evi-dence for deep subduction of continental crust beneath thePamir[J].Geol Soc Am Spec.,1993,281:1-76.
5宋扬,等,帕米尔弧东段逆冲推覆构造特征[J].现代地质,2011,25(1):15-21.(Song Yang,et al.Characteris-tics of overthrust in the eastern Pamir structural arc,westernTibetan Plateau[J].Geoscience,2011,25(1):15-21)
6 Zheng Hongbo,et al.Pliocene uplift of the northern TibetanPlateau[J].Geology,2000,28(8):715-718.
7 Yang Shaomin,et al.The deformation pattern and fault ratein the Tianshan Mountains inferred from GPS observations2008[J].Science in China Series D:Earth Science,2008,51(8):1 064-1 080.
8何文渊,等.塔里木盆地柯坪断隆断裂构造分析[J].中国地质,2002,29(1):37-43.(He Wenyuan,et al.Analysisof structures in the Kalpin fault uplift tarim basin[J].Chi-nese Geology,2002,29(1):37-43)
9曲国胜,等.柯坪塔格推覆构造几何学、运动学及其构造演化[J].地学前缘,2003,10(增刊):142-152.(Qu Guosheng,et al.Geometry,kinematics andtectonic evolution of Kepingtage thrust system[J].EarthScience Frontiers,2003,10(Supp):142-152)
10冉勇康,等.西南天山柯坪推覆构造东段晚第四纪变形样式与缩短速率[J].地震地质,2006,28(2):179-193.(Ran Yongkang,et al.Deformation pattern and shorteningrates in the east part of Kalpin thrust system in southwestTianshan durirng late Quaternary[J].Seismology and Geol-ogy,2006,28(2):179-193)
11黄立人,等.构造地块的相对运动与应变[J].地壳形变与地震,1999,(2):17-26.(Huang Liren,et al.Relativemovement and strain of tectonic block[J].Crustal Deforma-tion and Earthquake,1999,(2):17-26)
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