The Cenozoic growth of the Qilian Shan in the northeastern Tibetan Plateau: A sedimentary archive from the Jiuxi Basin
The Cenozoic growth of the Qilian Shan in the northeastern Tibetan Plateau: A sedimentary archive from the Jiuxi Basin
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DOI：
10.1002/2015jb012689
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发表时间：
2016-04
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影响因子：
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通讯作者：
Weitao Wang;Peizhen Zhang;J. Pang;C. Garzione;Huiping Zhang;Caicai Liu;D. Zheng;Wenjun Zheng
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文献类型：
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作者：
Weitao Wang;Peizhen Zhang;J. Pang;C. Garzione;Huiping Zhang;Caicai Liu;D. Zheng;Wenjun Zheng
青藏高原盆地的沉积物记录了新生代印度-亚洲碰撞期间形成该地区高地貌的变形和地表隆升过程的时空模式。在这项研究中，对青藏高原最东北部酒西盆地草沟剖面的新地层调查为青藏高原的变形和向北生长提供了年代学约束。磁性地层分析结果表明，所研究的约 1000 m 厚剖面的年龄跨度为约 24.2 Ma 至 2.8 Ma。详细的沉积学和磷灰石裂变径迹 (AFT) 分析表明，碎屑物源、岩相、沉积物积累速率和 AFT 滞后时间的变化发生在 ~13.5–10.5 Ma。我们将这些变化解释为对北祁连山最初抬升的响应。此外，剖面的古地磁偏角结果表明，酒西盆地在~13.5 Ma之前发生了顺时针旋转，随后在13.5~9 Ma期间发生了逆时针旋转。这种旋转方向的逆转可能与阿尔金断裂带最东段的左旋走滑活动直接相关。结合前人研究，我们认为阿尔金断裂带西段的运动可能始于渐新世（>30Ma），而断裂向东端的传播则发生于中新世中晚期。
Sedimentary deposits in Tibetan Basins archive the spatial‐temporal patterns of the deformation and surface uplift processes that created the area's high topography during the Cenozoic India‐Asia collision. In this study, new stratigraphic investigation of the Caogou section from the Jiuxi Basin in the northeasternmost part of Tibetan Plateau provides chronologic constraints on the deformation and northward growth of the plateau. Magnetostratigraphic analysis results suggest that the age of the studied ~1000 m thick section spans from ~24.2 Ma to 2.8 Ma. Detailed sedimentology and apatite fission track (AFT) analyses reveal that variations in the clast provenance, lithofacies, sediment accumulation rates, and AFT lag times occurred at ~13.5–10.5 Ma. We interpret these changes as in response to the initial uplift of the North Qilian Shan. In addition, paleomagnetic declination results from the section indicate a clockwise rotation of the Jiuxi Basin before ~13.5 Ma, which was followed by a subsequent counterclockwise rotation during 13.5–9 Ma. This reversal in rotation direction may be directly related to left‐lateral strike‐slip activity along the easternmost segment of the Altyn Tagh Fault. Combined with previous studies, we suggest that movement on the western part of the Altyn Tagh Fault was probably initiated during the Oligocene (>30 Ma) and that fault propagation to its eastern tip occurred during the middle‐late Miocene.