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Active crustal deformation in the Tian Shan region, central Asia
Tectonophysics ( IF 2.7 ) Pub Date : 2021-04-22 , DOI: 10.1016/j.tecto.2021.228868
Yuhang Li , Mian Liu , Ming Hao , Liangyu Zhu , Duxin Cui , Qingliang Wang

The Tian Shan mountain ranges in central Asia are one of the largest and most active intracontinental orogenic belts in the world. Its Cenozoic reactivation and deformation manifest the far-field impact of the Indian-Eurasian continental collision. How the collision-induced crustal shortening is accomondated in the Tian Shan region, however, remains debated. Some of the shortening is clearly accommodated by the piedmont fold-and-thrust belts; but the role of deformation in the interior of the orogen, and the overall pattern of crustal deformation in the Tian Shan region, differs in previous studies. We have used NeoKinema, a kinematic finite-element computer code, to analyze the long-term average rates of strain and its partitioning in the Tian Shan region. The model is constrained by updated kinematic data sets, including fault traces, geological fault slip rates, GPS site velocities, principal stress directions, and kinematic boundary conditions. Our results indicate that, in addition to shortening in the piedmont fold-and-thrust belts, significant shortening and strike-slip faulting have occurred in the interior of the Tian Shan orogen. The intra-orogen strain is concentrated north of the Nalati Fault, around the intramontane basins. The overall pattern of crustal deformation in the Tian Shan region is pure shear shortening, facilitated by NEE-trending sinistral and NW-NWW trending dextral strike-slip faults that cut across the mountain ranges. We also calculated the long-term potential of seismicity in the region and compared it with eartrhquake records.



中文翻译:

中亚天山地区活跃的地壳变形

中亚的天山山脉是世界上最大,最活跃的陆内造山带之一。它的新生代活动和变形反映了印度-欧亚大陆碰撞的远场影响。然而,在天山地区如何伴随着碰撞引起的地壳缩短仍然存在争议。山麓的褶皱和冲断带显然可以减轻一些起伏;但是变形在造山带内部的作用以及天山地区地壳变形的总体模式在以前的研究中是不同的。我们已经使用运动学有限元计算机代码NeoKinema分析了天山地区的长期平均应变率及其划分。该模型受更新的运动学数据集(包括故障轨迹,地质断层滑移率,GPS站点速度,主应力方向和运动学边界条件。我们的结果表明,除了山前褶皱冲断带缩短外,天山造山带内部还发生了明显的缩短和走滑断层。造山带内应变集中在纳拉特断层以北,在山内盆地周围。天山地区地壳形变的整体模式是纯剪切缩短,这是由跨越山脉的NEE向左旋和NW-NWW向右旋走滑断裂所推动的。我们还计算了该地区地震活动的长期潜力,并将其与地震记录进行了比较。我们的结果表明,除了山前褶皱冲断带缩短外,天山造山带内部还发生了明显的缩短和走滑断层。造山带内应变集中在纳拉特断层以北,在山内盆地周围。天山地区地壳形变的整体模式是纯剪切缩短,这是由跨越山脉的NEE向左旋和NW-NWW向右旋走滑断裂所推动的。我们还计算了该地区地震活动的长期潜力,并将其与地震记录进行了比较。我们的结果表明,除了山前褶皱冲断带缩短外,天山造山带内部还发生了明显的缩短和走滑断层。造山带内应变集中在纳拉特断层以北,在山内盆地周围。天山地区地壳形变的整体模式是纯剪切缩短,这是由跨越山脉的NEE向左旋和NW-NWW向右旋走滑断裂所推动的。我们还计算了该地区地震活动的长期潜力,并将其与地震记录进行了比较。造山带内应变集中在纳拉特断层以北,在山内盆地周围。天山地区地壳形变的整体模式是纯剪切缩短,这是由跨越山脉的NEE向左旋和NW-NWW向右旋走滑断裂所推动的。我们还计算了该地区地震活动的长期潜力,并将其与地震记录进行了比较。造山带内应变集中在纳拉特断层以北,在山内盆地周围。天山地区地壳形变的整体模式是纯剪切缩短,这是由跨越山脉的NEE向左旋和NW-NWW向右旋走滑断裂所推动的。我们还计算了该地区地震活动的长期潜力,并将其与地震记录进行了比较。

更新日期:2021-04-22
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