RUI: Reconstructing ancient terrestrial landscapes of the southeastern Columbia Basin

随着水、风和火山活动重塑地球表面，地貌在地质时期发生了变化。 在东南部的华盛顿州，今天的景观反映了两个规模难以想象的事件：猛犸喷发和很久以后，冰河时代的特大洪水冲刷和重塑了景观。该项目的重点是这两个事件之间的缺失间隔，并使用古老的土壤来了解这些古老景观形成时的环境。 12名本科生将从事研究的经验，将结合在地球科学中广泛使用的现场和实验室技术，这项研究的目标是描述陆地环境的特点后，哥伦比亚河玄武岩在华盛顿东南部和东北部俄勒冈州，并重建地质过程，塑造了这一地区的景观。 这将通过在哥伦比亚盆地东南部建立一个暴露风化玄武岩接触面和古土壤的现场网络来实现。在每个地点，将对接触区和底层玄武岩的形态进行表征，并将收集样品，用于对微形态特征和大量化学丰度进行实验室分析。 熔岩流暴露在整个地区的不同海拔高度，允许研究降水梯度及其对玄武岩风化的影响，并测量暴露时间或热成岩作用造成的成土作用的差异。 这些分析将提供以下能力：（一）更好地了解喀斯喀特隆起的时间和随后哥伦比亚盆地的干旱化，（二）重建由最近的冰河时代洪水之前的冰川爆发洪水期造成的地貌，以及（三）区分原始土壤风化和埋葬后的过程。 这项研究将增加对太平洋西北部复杂构造的理解，并提供对特大洪水在塑造陆地景观方面的影响的见解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Landscapes change over geological time as water, wind, and volcanic activity reshape Earth’s surface. In southeastern Washington State, today’s landscape reflects two events of unimaginable size: mammoth eruptions of molten lava and much later, Ice Age mega-floods that scoured and reshaped the landscape. This project focuses on the missing interval between these two events and uses ancient soils to learn about the environment when these ancient landscapes formed. Twelve undergraduate students will be engaged in research experiences that will incorporate field and laboratory techniques that are in wide use in the geosciences.The goal of this research is to characterize terrestrial environments following the eruption of the Columbia River Basalts in southeastern Washington and northeastern Oregon, and to reconstruct the geological processes that shaped the landscape in this area. This will be accomplished by creating a network of field sites across the southeastern Columbia Basin that expose weathered basalt contacts and paleosols. At each site the morphology of the contact and underlying basalt will be characterized, and samples will be collected for lab analyses of micromorphological features and bulk chemical abundances. Lava flows are exposed throughout the region at different elevations, allowing for the study of precipitation gradients and their influence on basalt weathering, and to measure differences in pedogenesis caused by exposure time or thermal diagenesis. These analyses will provide the ability to (i) better understand the timing of Cascade uplift and the subsequent aridification of the Columbia Basin, (ii) reconstruct the landforms caused by periods of glacial outburst flooding that predate the most recent Ice Age floods and (iii) distinguish original soil weathering from post-burial processes. This research will increase understanding of the complex tectonics of the Pacific Northwest and provide insights into the impact of megafloods in shaping the terrestrial landscape.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.