中国地震局赵斌团队取得一项新突破。他在研究GPS速度约束下天山造山带的当代运动学中取得新进展。该项研究成果发表在2024年5月6日出版的《大地测量与地球动力学》上。

据了解，自晚新生代以来，在印度—欧亚板块碰撞的远场作用下，天山造山带恢复活动，可容纳超过200km的地壳缩短。然而，人们对天山山脉的应变分布细节仍不清楚。

该研究团队运用经典的弹性块体模型解释了覆盖整个天山范围的GPS速度新汇编。在前人采用块体建模方法进行研究的基础上，利用地质断层迹线和聚类分析方法，将天山造山带进一步划分为若干块体。除了在天山边界逆冲断层上明显的地壳缩短外，研究反演的逆断层滑动速率显示，在天山造山带内的断裂，如那拉提断裂和伊塞克—库尔湖断层南缘，在调节构造缩短方面起着至关重要的作用。

在72°E-78°E区域，山脉内部的缩短率约为5-7mm/yr。除地壳缩短作用外，走滑运动还发生在山脉内部的断层和前陆褶皱—冲断带的断层上，特别是在天山南缘。这些发现表明，天山山脉的地壳变形比以前认为的更为复杂，塔里木盆地与天山之间的斜向辐合可能导致走滑运动和逆冲运动。

附：英文原文

Title: The present-day kinematics of the Tianshan orogenic belt constrained by GPS velocities

Author: Bin Zhao a

Issue&Volume: 2024/05/06

Abstract: Since the late Cenozoic, the reactivated Tianshan orogenic belt has accommodated crustal shortening exceeding 200 km, primarily due to the far-field effects of the India-Eurasia plate collision. However, the details of the strain partitioning in the Tianshan Mountain range remain elusive. We interpret a new compilation of GPS velocities covering the whole Tianshan range with a classic elastic block model. Compared to previous studies with a block modeling approach, the Tianshan orogenic belt is further subdivided into several blocks based on geological fault traces and a clustering analysis approach. In addition to obvious crustal shortening on the bounding thrust faults of the Tianshan, our inverted fault slip rates also reveal that faults within the Tianshan orogenic belt, such as the Nalati Fault and the southern margin of the Issyk-Kul Lake Fault, which plays a crucial role in accommodating the tectonic crustal shortening. In the 72°E-78°E region, the internal shortening rate within the mountain is approximately 5–7 mm/yr. Besides crustal shortening, strike-slip motion occurs on faults in the interior of the mountain range as well as in the foreland fold-and-thrust belts, especially in the southern margin of the Tianshan. These findings suggest that the crustal deformation in the Tianshan Mountain range is more complex than previously thought, and the oblique convergence between the Tarim Basin and the Tianshan probably results in both strike-slip and thrust motion.

DOI: 10.1016/j.geog.2024.04.004

Source: https://www.sciencedirect.com/science/article/pii/S1674984724000375