GPS与InSAR揭示喀什坳陷及邻区的垂直运动与构造特征

STUDY ON CRUSTAL DEFORMATION IN KASHI DEPRESSION AND NEIGHBORING REGION OF PAMIR AND TIANSHAN BY GPS AND InSAR

利用喀什地区10年间的GPS点位观测及200多景2003—2007年间的SAR图像,采取层叠InSAR技术获得了喀什坳陷区与南天山及帕米尔块体的现今构造活动的垂直速度场,结果表明:喀什坳陷区的垂直运动具有明显的分界特征,北部以阿图什南翼断层为界,西南以乌泊尔断层为界,东部为塔里木盆地所围限的喀什坳陷区垂直形变表现为下沉,幅度约1 mm/a,而喀什坳陷区的外围为隆升,幅度约为1 mm/a,隆升速度由西往东逐渐减小,表明塔里木盆地基底与南天山及帕米尔高原交界的前缘界线分别为阿图什南翼断层及乌泊尔断层;柯坪推覆构造体内的垂直运动与主要推覆体的构造活动密切相关,即山体褶皱带隆升,谷地沉降,隆升及沉降的速率约为1^-1.5 mm/a;普昌断裂虽然横切柯坪推覆构造体,但横跨该断裂的剖面表明普昌断裂两侧没有明显的垂直形变运动,进一步表明普昌断层作为"类转换断层",其运动以走滑为主。

On the basis of cubic spline function and stack InSAR,we used the GPS data of more than 10 years and over 200 SAR images from 2003 to 2007 to calculate the 3D velocity diagram in the area including Kashi depression and the border region of Pamir and the south Tianshan.There is an obvious boundary feature for the vertical changes in Kashi depression where its north boundary is the south Atushi fault,its sorth-west boundary is the Wupar fault and its east boundary is the Tarim basin.The vertical changes within the interior of Kashi depression is featured by subsidence at 1mm/a,while the peripheral region is featured by uplift at 1mm/a and decreasing from east to west.The front boundary between the basement of Tarim basin,the south Tianshan and the Pamir Plateau are south Autshi fault and Wupar fault.The vertical change of Keping nappe is characteristiced by its tectonics structure.The fold belts uplift and the vally area subside at a rate about 1——1.5 mm/a.Although the Puchang fault crosscuts the Keping nappe,there are not obvious vertical changes in both sides revealed from profiles across the fault.The lateral changes of the shorten rate of Tianshan across Puchang fault from GPS are evident,which indicates that the Puchang fault is a quasi transform fault dominated by strike slip.