晚第四纪以来巴曲河填充-下切及驱动机制  

LATE QUATERNARY DEPOSITION AND INCISION SEQUENCES OF THE BAQU RIVER AND THEIR EXPERIMENTAL IMPLICATION

作　　者：张浩 黄伟亮 项闻 杨虔灝 刘博 ZHANG Hao;HUANG Wei-liang;XIANG Wen;YANG Qian-hao;LIU Bo(College of Geological Engineering and Surveying of Chang′an University(Key Laboratory of Western China Mineral Resources and Geological Engineering),Xi′an 710054,China;Anqing Copper Mine,Tongling Nonferrous Metals Group Holdings Co.,Ltd.,Anqing 246000,China;Nuclear Industry Jinhua Exploration Design Institute Co.,Ltd.,Jinhua 321000,China;Anhui Transport Consulting&Design Institute Co.,Ltd.,Hefei 230088,China)

机构地区：[1]长安大学,地质工程与测绘学院,西部矿产资源与地质工程教育部重点实验室,西安710054 [2]铜陵有色金属集团股份有限公司安庆铜矿,安庆246000 [3]核工业金华勘测设计院有限公司,金华321000 [4]安徽省交通规划设计研究总院股份有限公司,合肥230088

出　　处：《地震地质》2024年第3期570-588,共19页Seismology and Geology

基　　金：国家自然科学基金(42277152,42041006);中央高校基本科研业务专项(300102262910);陕西省科技创新团队项目(2021TD-51);陕西省地学大数据与地质灾害防控三秦学者创新团队项目(2022)共同资助。

摘　　要：晚第四纪以来青藏高原东南缘的构造隆升加剧,导致该区域河流大幅下切并在河谷两侧形成了多层叠置的阶地地貌,这些地貌面是定量化认识高原隆升过程及气候变化的关键。巴曲河巴塘段地处金沙江中游纵谷地带,谷底开阔,河床平缓,钻探及浅层地震勘探揭示河谷内第四纪地层最厚处为108m,且至少经历了2次重要的加积阶段,2次加积事件分别起始于距今318ka和143ka,对应于MIS 10~9及MIS 6~5的冰川消融阶段。河谷内部发育4级河流阶地,其中T1—T3为堆积阶地,T4为基座阶地。结合光释光、^(14)C和宇宙成因核素等年代学方法,确定T1—T3形成于距今1~5ka之间,T4约形成于距今62ka,与古气候资料进行对比后发现,T1—T3的下切时间分别与气候由冷向暖的转换有关。而基于阶地的年代和拔河高度计算,在晚更新世—全新世中期,巴曲河的下切速率为(1.5±0.3)mm/a;全新世中期至今,下切速率增加至(5.5±0.8)mm/a,增强的下切速率与现今的地壳垂向形变速率匹配,表明全新世以来地壳隆升的加剧可能是驱动河流快速下切的主要因素。River terraces are primarily formed by the erosional action of river incision under the influence of vertical movements of the crust or changes in regional erosion base levels,resulting in layered landforms.As products of the long-term evolution of river systems,the formation,development,and evolution of terraces have always been a focal point in Quaternary research.Climate change and tectonic movements play crucial roles in the evolution of river terraces,providing important evidence for studying a region s paleoclimate and tectonic history,while also indicating the geomorphic evolution of rivers.The ages and elevations of river terraces serve as a crucial window for under-standing climate fluctuations and the intensity of tectonic uplift in a specific area.This role cannot be replaced by any other method.Therefore,accurately defining the incision and deposition ages of river terraces is essential for quantitatively reconstructing the development and evolution of rivers,making it a key data point in current research on surface processes and geomorphic evolution.The study area is located at the southeastern margin of the Qinghai-Xizang Plateau,positioned in the main area of the Jinsha River suture zone at the southwestern edge of the Songpan-Ganzi orogenic belt and the eastern part of the Sanjiang orogenic belt.The regional tectonic setting is complex.Since the late Quaternary,the tectonic uplift at the southeastern margin of the Qinghai-Xizang Plateau has intensified,with accelerated plateau uplift in the post-Pleistocene era accompanied by significant tectonic activity.This has led to substantial incision of rivers in the region,forming multiple layers of overlapping terrace landforms on both sides of the river valleys.These landforms are crucial for quantitatively understanding the plateau uplift process and climate change.The Jinsha River is one of the main large rivers in the western parts of Sichuan.The river terraces developed in the Jinsha River valley serve as an important evidence for studying the defor

关 键 词：河流阶地 金沙江下切速率 气候变化 地壳隆升 

分 类 号：P315.2[天文地球—地震学]