Collaborative Research: Identifying Sediment Sources and Routing of Transcontinental Drainages During Intraplate Deformation

世界上最大的河流通常发源于大陆一侧的山脉，并将沉积物带到大陆另一侧的三角洲。在地质条件不断变化的情况下，使这些寿命长的河流能够维持或重建其航道的因素在很大程度上尚未得到探索。这个项目将研究横贯大陆的河流如何随着时间的变化而变化，以响应河流路径中山脉或盆地的形成。了解河流的反应：它们是否找到了穿过或绕过不断发展的山脉或盆地的途径，以及它们重建先前的路线的速度，对于准确解释其三角洲中的沉积记录至关重要。除了提供对大陆尺度河流的更多了解外，该项目还将为研究生和本科生提供STEM培训，并支持一所大型州立大学和一所小型私立大学的研究基础设施和分析设施。此外，该项目将在一名大学教授的指导下，每年为约30名中学生提供实践STEM培训的机会。研究重点将集中在“原始落基山脉”(ARM)及其相关盆地上，这些盆地主要发育于3.2亿-2.8亿年前的犹他州、科罗拉多州、得克萨斯州和新墨西哥州。这些盆地记录了与大陆尺度河流的分裂和重新融合相关的变化，以响应ARM的演变。该项目将结合传统和尖端方法，包括沉积地层的现场观测、U-Pb辐射测年、Hf同位素分析以及砂岩和火成岩中的锆石和独居石矿物的(U-Th)/He辐射测年，以确定沉积物来自哪里及其随时间变化的方式。此外，还将对火成岩中的锆石矿物进行(U-Th)/He辐射测年，以确定山脉发育的时间。这些数据将随着时间的推移将沉积物来源的变化与山脉和盆地的发展联系起来。将通过开发新的软件来加强这一点，以根据砂岩中矿物的辐射测年来帮助确定沉积物的来源和每个来源的比例。这一裁决反映了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。

The largest rivers in the world often start in mountain ranges on one side of a continent and bring sediment to deltas on the opposite side of the continent. The factors that allow these long-lived rivers to maintain or re-establish their courses in the face of changing geological conditions are largely unexplored. This project will study how transcontinental rivers change with time in response to the formation of mountain ranges or basins in the rivers' pathways. Understanding how rivers respond: whether they find a way through or around the developing mountains or basins, and how quickly they re-establish their prior courses, is critical to accurately interpreting the sedimentary record in their deltas. In addition to providing greater insight into continental-scale rivers, this project will provide STEM training for graduate and undergraduate students and support research infrastructure and analytical facilities at a large state university and a small private university. Further, the project will provide an opportunity for hands-on STEM training for ~30 middle school students per year under the guidance of a university professor. Research will focus on the "Ancestral Rocky Mountains" (ARM) and associated basins, which developed primarily in Utah, Colorado, Texas, and New Mexico 320-280 million years ago. These basins archive changes associated with disruption and reintegration of a continental-scale river in response to ARM evolution. This project will combine traditional and cutting-edge methods including field observations of sedimentary strata, U-Pb radiometric dating, analysis of Hf isotopes, and (U-Th)/He radiometric dating of zircons and monazite minerals in sandstones and igneous rocks to determine where sediment came from and how it changed through time. In addition, (U-Th)/He radiometric dating on zircon minerals in igneous rocks will be used to determine when the mountain ranges developed. These data will link changes in sediment sources to mountain and basin development through time. This will be augmented by development of new software to help determine the sources, and proportion of each source, for sediment based on radiometric dating of minerals in sandstones.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.