论文摘要
印度-欧亚板块的持续碰撞导致了青藏高原的抬升,形成了区域上连续分布的高海拔,低起伏地貌面。在青藏高原东缘,该地貌面被大型河流所切割,形成高原面和深切河谷共存的地貌特征并。青藏高原东缘的这些河流还呈现出奇特的几何特征。前人的研究表明这些河流曾发生过袭夺。本文笔者以流经青藏高原东缘的长江的两条支流大渡河与安宁河为研究对象,开展大渡河的下切历史研究,探讨大渡河与安宁河之间潜在的河流袭夺及其对区域地形演化的影响,重塑青藏高原东缘的抬升历史。论文主要取得了以下成果与认识:通过基岩磷灰石(U-Th)/He(AHe)和锆石(U-Th)/He(ZHe)定年,揭示了大渡河晚中新世的下切作用。该下切开始的时间与青藏高原东部其他地区的剥露同时发生,表明区域构造隆升引发了河流下切。通过对大渡河和安宁河现今河沙和安宁河上新世昔格达组沉积物的碎屑锆石U-Pb定年,发现昔格达组沉积物具有与现代大渡河相似的碎屑锆石U-Pb年龄分布,这表明在昔格达组沉积期间大渡河与安宁河之间是相互连通的,这种连通性后来被截断在此基础上,基于对比区域断层运动历史对比,本文推测大渡河和安宁河之间的河流袭夺与大凉山断层的活动有关。大渡河流域地形指标空间分布特征(包括测量曲线测量积分(HI),河流长度梯度(SLK),地形坡度和地形起伏)的研究发现,它们与构造抬升速率的时-空变化或者河流袭夺导致的地貌的重新活化有关,进一步支持了大渡河和安宁河之间存在河流袭夺。结果表明大渡河流盆地隆升速率的加速开始在10Ma,并且自此隆升速率逐渐从0.1mm/yr增加到现今的2.1mm/yr。总结上述研究结果,本文认为自晚中新世(10 Ma)以来,青藏高原东缘的隆升引发了大渡河的快速下蚀。然而,区域构造抬升之后的局部断层活动导致的河流袭夺也影响区域地貌的发育,形成瞬时地貌。
论文目录
AcknowledgementsAbstract中文摘要Chapter 1 Introduction 1.1 Reviews on the previous studies on the eastern Tibetan plateau margin 1.2 Motivation and aims 1.3 Research contents 1.4 Thesis structureChapter 2 Geological and geomorphic settings of the eastern Tibetan plateau 2.1 Geological setting 2.2 Geomorphic settingChapter 3 River incision in the eastern Tibetan plateau 3.1 Introduction 3.2 Geological background 3.3 (U-Th)/He thermochronometry 3.4 Sample collection 3.5 Analytical method 3.5.1 Apatite sample preparation and analytical techniques 3.5.2 Zircon sample preparation and analytical techniques 3.6 Thermochronometric ages 3.7 Thermal history modeling of low-temperature thermochronometric data 3.8 SummaryChapter 4 Provenance analysis by detrital U-Pb dating of zircon in the Dadu and Anning Rivers 4.1 Introduction 4.2 Zircon U-Pb methodology 4.3 Sampling description 4.4 Analytical method 4.4.1 Detrital zircon U-Pb results 4.5 SummaryChapter 5 Controls on the landscape development of the Dadu River drainage basin, eastern Tibetanplateau 5.1 Introduction 5.2 Topographic analysis 5.2.1 Hypsometric curve and hypsometric integral (HI) 5.2.2 Normalized stream-length gradient (SLK) 5.2.3 Local relief and slope 5.2.4 Channel steepness 5.3 SummaryChapter 6 Inversion uplift history of the Dadu River drainage basin 6.1 Introduction 6.2 Theoretical background 6.3 Results 6.3.1 Constraints of m/n 6.3.2 Constraints of erodibility coefficient 6.3.3 Inversion of uplift history 6.4 Independent constraints 6.4.1 Constraints from long-term exhumation history 6.4.2 Constraints from short-term erosion rates 6.4.3 Constraints from geodesy 6.5 SummaryChapter.7 Discussion 7.1 Implication of the Tibetan plateau uplift 7.2 Dadu River incision process 7.3 Triggers for Dadu River incision in the late Miocene 7.4 Uplift history of the Dadu River drainage basin 7.5 Comparison between topographic metrics and erosion rates and cause for patterns oftopographic metrics 7.6 Capture between the Dadu and Anning Rivers8. ConclusionReferences附件Suhail Ahmed Hakro
文章来源
类型: 博士论文
作者: Suhail Ahmed
导师: Hanlin Chen,Rong Yang
关键词: 青藏高原东部,大渡河,安宁河,昔格达组,低温热年代学,河流袭夺,线性反演
来源: 浙江大学
年度: 2019
分类: 基础科学
专业: 自然地理学和测绘学,地质学
单位: 浙江大学
分类号: P931;P542
DOI: 10.27461/d.cnki.gzjdx.2019.000565
总页数: 127
文件大小: 13006K
下载量: 443
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标签:青藏高原东部论文; 大渡河论文; 安宁河论文; 昔格达组论文; 低温热年代学论文; 河流袭夺论文; 线性反演论文;