藏东南老君山地区河流侵蚀和拉分断陷导致的岩石剥露历史的对比

项目名称： 藏东南老君山地区河流侵蚀和拉分断陷导致的岩石剥露历史的对比

项目编号： No.41203044

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 地球化学

项目作者： 沈晓明

作者单位： 中国地震局地壳应力研究所

项目金额： 25万元

中文摘要： 定量分析不同内外动力主导的岩石剥露历史的差异，对深入理解不同动力过程在地貌演化中的作用，提高低温热年代学数据解释的准确性，更好的约束造山带构造活动和地貌演化具有重要意义。以河流侵蚀为主的外动力和断裂走滑-拉分断陷为主的内动力是控制青藏高原东南缘岩石剥露的重要地质作用。本项目拟以老君山地区典型河流侵蚀地貌和拉分断陷地貌为研究对象，对两种地貌进行详细的野外调查和比对；设定3条剥露过程单一(或河流侵蚀或拉分断陷)、不同高程处可采集到磷灰石样品的剖面；以磷灰石(U-Th)/He和裂变径迹定年为手段，揭示老君山地区河流下切和拉分断陷两种不同动力过程造成的岩石剥露历史，包括时间、速率、期次和幅度；深入剖析不同剥露方式之间的异同及原因。在两种不同剥露历史相互制约的基础上，分析研究区断裂活动历史和河流地貌演化，并探讨控制青藏高原东南缘地壳变形和地貌演化的可能地球动力学机制。

中文关键词： (U-Th)/He；渐新世-早中新世；河流下切；地壳抬升；

英文摘要： Quantitative analysis of internal agency- and external agency-driven exhumation history are crucial for an improved understanding the role of different dynamic processes in landscape evolution, enhancing the accuracy of data interpretation of low temperature thermochronology, and thus better constraining the tectonic activities and landscape evolution of orogenic belt. River incision (external agency) and pull-aparting (internal agency) are the main driving forces that control the exhumation of southeastern Tibetan Plateau. In order to decipher these two forces-driven exhumation history, we will aim at the Laojun Mountain area (>2400m relief in 50km2) to carry out detailed geological investigation and geomorphic comparison, and then design 3 traverses for apatite sample collection (1 across the Jinsha river gorge and 2 across the Weixi-Qiaohou and Longpan-Qiaohou strike-slip faults, respectively). Apatite (U-Th)/He and fission track techniques will be conducted to reconstruct the distinct exhumation history around the Laojun Mountain, including timing, rate, episode and amplitude. Further analysis and interpretation for these data will be made to reveal the differences between the river incision and fault-related exhumation processes. On the basis of mutual dating constraint of the two distinct exhumation, we wi

英文关键词： (U-Th)/He dating；Oligocene to Early Miocene；river incision；surface uplift；