CAREER: Tectonically dead but geomorphologically alive: Investigating the role of hard rocks as triggers of widespread, long-term landscape change in continent interiors

尽管在人类看来，流域及其所在的河流网络似乎是静止的，但它们逐渐和/或突然地改变了形态，在数千年到数百万年的时间尺度上增长、缩小，甚至消失。一个多世纪以来，河网重组一直是大陆内部令人费解的主要景观。当远离任何活跃的地质断层时，人们几乎不知道是什么触发了它们，它们启动的频率有多高，或者它们的演化速度有多快。在这个项目中，首席研究员将评估这样一种假说，即河流出口附近的抗阻岩石触发并调节了大陆内陆广泛的河网重组。由于人类社会依赖水发展和繁荣，限制河流过去、现在和未来分布的潜在调控因素，对于了解地球表面和地下水资源的可用性和可持续性是至关重要的。通过这个项目的发现，首席调查员将创建一个身临其境的、协作的教学计划，以培训不同的本科生和研究生群体，掌握与环境高度相关的主题和技术。这项工作将促进科学知识在美国、巴西的高等教育以及纽约大都会地区的合作高中中的整合。尽管处于构造死寂的环境中，但大陆内陆的景观充斥着排水网络重组和持续的地形变化的证据。目前，还没有统一的机制系统地解释这些景观中流域分水岭迁移和河流夺取事件的空间分布、大小、方式和时间。这项研究项目将把(I)排水分水岭迁移速率和(Ii)河流捕获事件的频率-震级与下游长达数百公里的岩性变化联系起来。首席研究员的研究小组将(I)使用宇宙成因核素限制巴西东南部构造死亡的巴拉那盆地东部大型相邻流域之间的流域面积交换率，(Ii)将这些交换率直接与盆地对岩石性质(即岩石腐蚀性、抗拉强度和抗压强度)的差异联系起来，以及(Iii)利用LandLab库将经验证据与景观演变的数值模拟相结合。利用这一综合的野外+实验室+数值模拟三位一体的方法，研究结果将系统地解释大陆内部的排水重组速度，而不受外部的、难以约束的触发因素的影响。Τ项目还将通过可获得的、脚手架式的定量地貌学培训机会，在科学发现和本科教育之间建立一扇无缝的大门。这些活动将激励并增强参与的、代表不足的学生群体应对环境挑战的能力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Though seemingly static to humans, watersheds – and the river networks they host – gradually and/or abruptly change configuration, growing, shrinking, and even disappearing over timescales of thousands to millions of years. River network reorganizations have remained enigmatic staples of landscapes in the interiors of continents for over a century. When far from any active geologic faults, little is known about what triggers them, how frequently they initiate, or how fast they evolve. In this project, the principal investigator will evaluate the hypothesis that resistant rocks near the outlets of rivers trigger and regulate the widespread river network reorganization in continent interiors. As human societies depend on water to develop and thrive, constraining the underlying regulators of past, current, and future distributions of rivers is fundamental to understanding the availability and sustainability of water resources on the Earth’s surface and subsurface. Through this project’s discoveries, the principal investigator will create an immersive, collaborative teaching initiative to train a diverse group of undergraduate and graduate students in topics and techniques of high environmental relevance. The work will foster the integration of scientific knowledge in higher education in the US, Brazil, and in collaborating high schools of the New York Metro area.Despite being in tectonically dead settings, landscapes in continent interiors are rife with evidence of drainage network reorganization and ongoing topographic change. Currently, no unifying mechanism systematically explains the spatial distribution, magnitudes, modes, and timing of drainage divide migration and river capture events in those landscapes. This research project will mechanistically link (i) rates of drainage divide migration and (ii) frequency-magnitudes of river capture events to lithologic changes of up to hundreds of kilometers downstream. The principal investigator’s research group will (i) constrain drainage area exchange rates between large neighboring drainage basins of the tectonically dead eastern Paraná Basin in southeast Brazil using cosmogenic nuclides, (ii) directly link those rates to basin-pair differences in rock properties (i.e. rock erodibilities, tensile, and compressive strengths), and (iii) integrate the empirical evidence with numerical modeling of landscape evolution using the Landlab library. Using this integrated Field + Laboratory + Numerical Modeling triad, the research results will systematically explain rates of drainage reorganization in continent interiors independent of external, hard-to-constrain triggers. Τhe project will also create a seamless doorway between scientific discovery and undergraduate education through accessible, scaffolded training opportunities in Quantitative Geomorphology. The activities will inspire and empower the participating, underrepresented student populations to tackle environmental challenges.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.