| 摘要: |
| 新生代以来，印度板块与欧亚大陆碰撞后远程效应不断向北传递，帕米尔地块位于青藏高原西北部，靠近碰撞边界，在这一远程效应的影响下，帕米尔地块发生强烈的南北向地壳缩短，导致其宽度与东侧的青藏高原主体部分形成了鲜明的对比，形成著名的帕米尔构造结。基于前人的研究成果，将帕米尔构造结新生代演化过程归结如下：始新世时，帕米尔构造结开始初步发育，持续的双向俯冲，引起帕米尔高原不断隆升。晚渐新世 — 早中新世，帕米尔构造结西侧主要通过辐射逆冲断裂带吸收地壳变形，东部则是山体弯转、走滑转换断裂共同作用吸收变形，在构造结内部出现片麻质穹窿，构造结轮廓逐步形成。晚中新世，帕米尔构造结不断弯曲，下地壳持续增厚导致高原东北缘出现重力垮塌，扩展体系出现，片麻质穹窿出现在公格尔山和慕士塔格峰。上新世，帕米尔构造结与南天山碰撞，并在南天山和帕米尔两侧形成了平行于山脉走向的褶皱带，此时水汽通道关闭，加剧了塔里木盆地的干旱，并最终导致塔克拉玛干沙漠的出现。 |
| 关键词: 帕米尔构造结 新生代 构造演化 |
| DOI：10.7515/JEE181001 |
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| 基金项目:国家自然科学基金（41702178）；山东省自然科学基金（ZR201702160378）；山东省高校创新基金（J17KA196） |
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| A review of the Cenozoic tectonic evolution of Pamir syntax |
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LIN Xu, CHANG Hong, LI Chang’an, PENG Baofa, WU Quanyuan
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1. College of Resources and Environment and Tourism, Hunan University of Arts and Science, Changde 415000, China
2. Institute of Geography and Environment, Shandong Normal University, Jinan 250358, China
3. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
4. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
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| Abstract: |
| Background, aim, and scope The Pamir Plateau locates in the northwestern margin of the Tibetan Plateau, which has been significantly deformed by the far field effect through the collision between the Indian Plate and Eurasia since the early Cenozoic. The width of the Pamir block is narrower than the Tibetan Plateau, shaping the famous oroclinal bending suggests differences in the deformational history along the strike of the collision zone. To figure out when the Pamir syntax had been formed, it is a key factor to better understand the geological issues on the tectonic evolution of the western margin of the Tibetan Plateau and central Asian, the paleoclimate changing, and the Neo-Tethys retreating etc. since the Cenozoic. Hence, there is necessary to rebuild the evolution process of the Pamir syntax on the basis of the researching results reported from the domestic and overseas. Materials and methods In this study, we summarize the main tectonic events in the Pamir Plateau through the low temperature thermochronology, sedimentology, volcanism, and metamorphism, providing an overview and perspective of the geological meaning of the formation of the Pamir syntax. Especially, the conception of the mountain oroclines are introduced by the main component elements and real studying examples to make more clear the evolution of the Pamir syntax. Results The formation of the Pamir syntax is main ascribed to the northward of the Indian Plate collided with the Eurasia along with the movement of the large scale strike-slip faults, while is prevented by the basement of the Tajik-Tarim Basin to curve. Due to the Indian Plate obliquely subducted under the Eurasia, the structural deformations during continental collision were accommodated by formation of radial thrusting, dextral transfer faulting and gneiss domes along the western and eastern margins and central part, respectively. Discussion In these case, the Pamir block had uplift with high elevation, leading to the Neo-Tethys retreated toward the west parts of the Tarim Basin during the Eocene. The activity of the Main Pamir Thrust occurred in ~20 Ma that indicating of the shape of the Pamir syntax had been gradually formed. The extensional collapse of over-thickened crust and the gneiss domes had appeared in the northeastern margin of Pamir Plateau at late Miocene. The Pamir syntax collided with the southern Tian Shan at Pliocene, leading to the water vapor of the southwest Tarim Basin was closed and the extreme aridity distributed. Conclusions During the Eocene, the Pamir syntax has been taken initial shape due to the intra-continental subduction. The Pamir syntax has been built since late Oligocene — early Miocene. Recommendations and perspectives The evolution of the Pamir syntax remained controversial, such as the low temperature thermochronology data from the bedrock are contrast with the sedimentary records around the Pamir Plateau. Therefore, constructing the evolution processes on the Pamir syntax need to carry out more systematic works. |
| Key words: Pamir syntax Cenozoic tectonic evolution |
