RUI: Fluvial Terraces: A Tool for Integrating Geomorphic Processes, Climatic and Tectonic Events, and Landscape Development

RUI：河流阶地：整合地貌过程、气候和构造事件以及景观开发的工具

• 批准号: 8917116
• 负责人: Dorothy Merritts
• 金额: $ 10.07万
• 依托单位: Franklin and Marshall College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-02-15 至 1992-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8917116&HistoricalAwards=false
• 关键词: RUI; Fluvial; Terraces; Tool; Integrating

This is a geomorphic investigation of fluvial processes in an area in which tectonic activity varies between river basins, and climate varies with time among the basins. Tectonic controls will dominate terrace formation in high uplift rate regions, and climatic controls will gain increasing importance as uplift rate declines. We propose to test this hypothesis on the basis of differences and similarities in the terrace sequences of three moderate size rivers developed in argillaceous sandstone in coastal northern California. Present climatic controls on amount and intensity of precipitation and temperature are very similar for each drainage basin, although these parameters have varied with late Cenozoic climatic perturbations that ultimately drove the rise and fall of eustatic sea level. Base-level processes related to relative rise of the land mass vary by an order of magnitude from the southernmost to the northernmost rivers. Fieldwork in each watershed will consist of continuous surveying and mapping of the longitudinal profiles of erosional terraces, depositional terraces, and the modern channel and floodplain. Seismic refraction studies will quantify depth of fill where not observable. The chronology of terrace formation will be constrained by radiometric dating of organic material from alluvial sediments either resting upon erosional terraces, or within deposits that comprise depositional terraces. This work will allow quantification of the nature and rates of propagation of channel incision and valley in-filling in response to changing climate and long-term tectonism. Comparison of the results for the three rivers, and thus separation of tectonic and climatic controls, should allow: 1) better understanding of the nature of fluvial response to change, 2) interpreting the environmental significance of strath versus fill terraces, and of preserved flights of terraces in general, and 3) integrating an understanding of geomorphic processes with models of landscape evolution.

这是对河流流域的构造活动不同、流域之间的气候随时间变化的地区的河流过程的地貌调查。 构造控制将主导高抬升率地区阶地的形成，而随着抬升率下降，气候控制将变得越来越重要。 我们建议根据加州北部沿海泥质砂岩中发育的三条中等规模河流的阶地序列的差异和相似性来检验这一假设。 目前每个流域对降水量和强度以及温度的气候控制非常相似，尽管这些参数随着新生代晚期的气候扰动而变化，最终驱动了海平面的升降。 从最南端的河流到最北端的河流，与陆地相对上升相关的基准面过程存在一个数量级的差异。 每个流域的实地工作将包括对侵蚀阶地、沉积阶地以及现代河道和洪泛区纵向剖面的连续测量和绘图。 地震折射研究将量化不可观测的填充深度。 阶地形成的年代将受到来自冲积沉积物的有机物质的放射性测年的限制，这些沉积物要么位于侵蚀阶地上，要么位于构成沉积阶地的沉积物内。 这项工作将能够量化河道切割和山谷填充的性质和传播速度，以应对气候变化和长期构造作用。 对这三条河流的结果进行比较，从而将构造和气候控制分开，应该可以：1）更好地了解河流对变化的响应的性质，2）解释地层与填土阶地以及保留的飞行的环境意义梯田的一般情况，3）将对地貌过程的理解与景观演化模型相结合。