| 西藏冈底斯中段南缘曲水地区早中新世隆升剥露历史及控制机制——来自磷灰石(U-Th)/He年代学证据 |
| 投稿时间：2025-09-12 修订日期：2025-12-01 点此下载全文 |
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| 基金项目:国家重点研发计划项目（2022YFC2905001），玉龙铜业技术服务项目（HX2024-42） |
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| 中文摘要:摘要：曲水地区位于拉萨地体南部，冈底斯岩浆弧中段南缘，该地区新生代以来的隆升剥露作用对揭示冈底斯岩浆弧乃至整个青藏高原构造-地貌演化历史具有重要指示意义。本文研究聚焦曲水地区隆升剥露历史，针对曲水地区古-始新世花岗闪长岩高差950.1m的垂直剖面等间距采集9件样品，开展磷灰石(U-Th)/He热年代学定年，获得年龄介于13.7~12.6Ma之间。测年结果和热历史模拟结果显示，曲水地区在19.0~11.5Ma（早中新世）经历了受剥蚀作用控制的快速冷却事件，期间冷却量为299.4℃，冷却速率为40.0℃/Ma，对应的剥露量和剥露速率分别为9.8km和1.3km/Ma；11.5Ma至今，曲水地区进入缓慢冷却阶段，冷却量为11.7℃，冷却速率为1.0℃/Ma，对应的剥露量和剥露速率分别为0.35km和0.03km/Ma。本研究结合区域构造演化资料分析表明，曲水地区早中新世快速剥露活动主要受谢通门-曲水剪切带活动控制。该剪切带通过南向逆冲作用驱动曲水地区地壳缩短增厚，引发地壳均衡调整，进而导致地表强烈剥露；11.5Ma后谢通门-曲水剪切带活动结束，高原内部整体转变为伸展环境，且南部喜马拉雅山脉快速抬升致使曲水地区气候干旱，导致剥露速率降低。 |
| 中文关键词:曲水地区 磷灰石(U-Th)/He 剥露历史 冈底斯 谢通门-曲水剪切带 |
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| Early Miocene Uplift and Exhumation History of the Southern Margin in the Central Gangdese, Quxu Area, Tibet, and Its Governing Mechanisms: Evidence from Apatite (U-Th)/He Thermochronology |
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| Abstract:Abstract: The Quxu area, located in the southern part of the Lhasa Terrane and along the southern margin of the central Gangdese Magmatic Arc, occupies a key position for understanding the tectono–geomorphic evolution of the Gangdese Magmatic Arc and the entire Tibetan Plateau. This study focuses on the uplift and exhumation history of the Quxu area. Nine samples were systematically collected at equal intervals along a 950.1 m vertical profile through Paleocene–Eocene granodiorites. Apatite (U-Th)/He thermochronology yielded AHe ages ranging from 13.7 to 12.6 Ma. Combined thermochronological data and thermal history modeling indicate that the Quxu area underwent a rapid, exhumation-driven cooling event during the Early Miocene (19.0–11.5 Ma). During this interval, the total cooling amounted to 299.4 °C at cooling average rate of 40.0 °C/Ma, corresponding to an exhumation magnitude of 9.8 km and an average exhumation rate of 1.3 km/Ma. Since 11.5 Ma, the area has undergone a phase of slow cooling, characterized by a total cooling of 11.7 °C at a rate of 1.0 °C/Ma, corresponding to an exhumation magnitude of 0.35 km and a rate of 0.03 km/Ma, respectively. Integrated with regional tectonic evolution data, the study suggests that the rapid Early Miocene exhumation in the Quxu area was predominantly controlled by the Xietongmen–Quxu Shear Zone. South-directed thrusting along this zone induced crustal shortening and thickening, subsequently triggering isostatic adjustment and intense surface exhumation. After 11.5 Ma, the exhumation rate in the Quxu area decreased significantly, driven by the cessation of the Xietongmen–Quxu Shear Zone activity, the regional transition to an extensional tectonic regime, and climate aridification induced by the rapid uplift of the southern Himalayas. |
| keywords:Quxu area Apatite (U-Th)/He Exhumation history Gangdese Xietongmen-Quxu shear zone |
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