Geometry and Kinematic Evolution of the Hotan-Tiklik Segment of the Western Kunlun Thrust Belt: Constrained by Structural Analyses and Apatite Fission Track Thermochronology
Geometry and Kinematic Evolution of the Hotan-Tiklik Segment of the Western Kunlun Thrust Belt: Constrained by Structural Analyses and Apatite Fission Track Thermochronology
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DOI：
10.1086/689187
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发表时间：
2017-01
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影响因子：
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通讯作者：
Xiaogan Cheng;Hanlin Chen;Xiubin Lin;Lei Wu;J. Gong
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作者：
Xiaogan Cheng;Hanlin Chen;Xiubin Lin;Lei Wu;J. Gong
西昆仑冲断带是北部稳定的塔里木盆地和南部强烈变形的新生代青藏高原的分界线。由于其重要的构造位置，了解其构造演化应具有重要意义的传播变形从西藏到其邻近地区的印度-欧亚会聚。本文根据西昆仑冲断带和田-提克里克段的野外调查和地震反射剖面资料，提出了新的构造分析。研究结果表明，该构造剖面穿越两大逆冲带，即南部腹地的提克里克逆冲带和北部前陆的和田逆冲带。其中，和田冲断带是薄皮的，其变形特征是断层弯曲褶皱和断层沿沿着层滑动，而提克里克冲断带涉及基底，其变形由目前陡倾的提克里克断层驱动。磷灰石裂变径迹热年代学结合生长地层和平衡剖面的研究结果表明，和田-提克里克段经历了两个阶段的变形：（1）提克里克逆冲断层的发育是在晚渐新世-早中新世，中晚中新世以来又有一次;（2）和田逆冲断层的活动是中新世中晚以来逆冲断层向盆地扩展的结果。平衡横截面，结合磷灰石裂变径迹结果，表明，Hotan-Tiklik段贡献了总缩短幅度超过约。34 ± 6公里。在此，CA。4 ± 2和ca.和田背斜和和田拆离断层分别吸收了23 ± 1 km的缩短量，这两个缩短量都与拆离层有关。这表明拆离层在青藏高原西部向塔里木盆地的变形传播过程中起了重要作用。
The western Kunlun thrust belt defines the boundary between the stable Tarim Basin in the north and the intensely deformed Cenozoic Tibetan Plateau in the south. Because of its important tectonic position, understanding its tectonic evolution should have important implications for propagation of deformation from Tibet to its neighboring cratonal regions during India-Eurasia convergence. We here present new structural analyses based on field investigations and seismic reflection profiles across the Hotan-Tiklik segment of the western Kunlun thrust belt. The results indicate that the structural section crosses two major thrust zones: the Tiklik zone in the hinterland to the south and the Hotan zone in the foreland to the north. Within these, the Hotan thrust zone is thin skinned, with its deformation characterized by fault-bend folding and fault slipping along detachment layers, whereas the Tiklik thrust zone involves basement, with its deformation driven by the currently steeply dipping Tiklik fault. Results from apatite fission track thermochronology in combination with growth strata and balanced cross section indicate that the Hotan-Tiklik segment underwent two-stage deformation: (1) development of the Tiklik thrust during the late Oligocene–early Miocene and again since the mid- to late Miocene and (2) activity of the Hotan thrust since the mid- to late Miocene as a result of basinward propagation of thrusting. The balanced cross section, combined with the apatite fission track results, suggests that the Hotan-Tiklik segment contributes a total shortening magnitude of more than ca. 34 ± 6 km. Within this, ca. 4 ± 2 and ca. 23 ± 1 km of the shortenings were absorbed by the Hotan anticline and the Hotan detachment fault, respectively, both of which were related to detachment layers. This suggests that detachment layers played an efficient role in propagating deformation from the western Tibetan Plateau into the Tarim Basin.