Quantifying long-term aeolian abrasion rates on hard rock surfaces

在干旱地区，在地球和其他行星上，风沙侵蚀和重塑景观。在人类的时间尺度上，这种侵蚀可以是不可估量的小，所以不清楚形成这些景观需要多长时间。该项目将使用地球化学测量的两项最新进展来测量南加州通风岩的侵蚀速率，这些岩石在风暴期间被喷砂侵蚀。基于这些测量，该项目将调查过去的气候变化是否产生了不同的通风侵蚀率。这些测量还将测试风沙的侵蚀是否取决于岩石类型或地表高度。几块参考岩石将以已知的速度进行人工侵蚀，然后进行测量，以测试基于地球化学测量的预测侵蚀速率是否与实际已知的侵蚀速率相匹配。最后，该项目将创建所有10个研究过的通气事实的3-D数字模型，并附带一个教学模块，免费提供给各地的教育工作者。这些巨石是罕见的，难以接近，所以创建逼真的教育模型大大增加了访问这些迷人的地质特征。有限的3d打印手持式模型也将免费提供给感兴趣的教室，打印说明将在网上发布。该项目的目标是利用光学激发发光（OSL）和宇宙成因（原位10Be和14C）方法的最新进展，量化通风设备表面风成磨损率的时空演变。速率的测量长度从几毫米到几十厘米不等，时间尺度从十年到千年不等。该项目包括五个主要研究任务：(1)在南加州的两个地点进行实地考察；(2)原位宇宙成因14C-10Be暴露年龄和侵蚀速率分析（每个ventifact 1对14C-10Be样品，共10个）；(3)通风口（每个通风口10条OSL深度剖面，共100条）和人工侵蚀岩柱（每个岩性3条，10个岩性共30条）的OSL深度剖面侵蚀速率分析；(4)使用动态结构摄影测量法从10个ventifacts的现场照片生成数字3d模型，并使用3d打印的手持教育模型以及附带的教育视频；(5)在会议和同行评议的期刊文章中展示结果。项目结果将首次证明，发光测量可以精确地恢复毫米尺度上的硬岩侵蚀速率。测量的速率将对现有但未经经验测试的磨损机制进行基准测试。该奖项反映了美国国家科学基金会的法定使命，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。

In arid regions, on Earth and on other planets, wind-blown sand erodes and reshapes landscapes. On human timescales, this erosion can be immeasurably small, so it is unclear how long it takes to form these landscapes. This project will use two recent advances in geochemical measurements to measure erosion rates on southern Californian ventifacts, boulders which are eroded by sand blasting during windstorms. Based on these measurements, this project will investigate whether a past shift in climate produced different ventifact erosion rates. These measurements will also test whether erosion by wind-blown sand depends on rock type or height above the ground surface. Several reference rocks will be manually eroded at a known rate and then measured to test whether the predicted erosion rates based on geochemical measurements match the actual, known erosion rates. Finally, this project will create 3-D digital models of all ten studied ventifacts and make them freely available to educators everywhere with an accompanying teaching module. These boulders are rare and difficult to access, so creating photorealistic educational models dramatically increases access to these fascinating geological features. A limited supply of 3-D printed, handheld models will also be provided at no cost to interested classrooms and printing instructions will be posted online.The project goal is to quantify the spatial and temporal evolution of aeolian abrasion rates across the surface of ventifacts using recent advances in optically stimulated luminescence (OSL) and cosmogenic, in situ 10Be and 14C methods. Rates will be measured on lengths ranging from several mm to tens of cm and timescales from decadal to multi-millennial. This project involves five major research tasks: (1) field campaign to two sites in southern California; (2) in situ cosmogenic 14C-10Be exposure age and erosion rate analysis (1 paired 14C-10Be sample per ventifact, totaling 10); (3) OSL depth profile erosion rate analysis of ventifacts (10 OSL depth profiles per ventifact, totaling 100) and manually eroded rock cylinders (3 erosion rates per lithology and 10 lithologies, totaling 30); (4) generation of digital 3-D models from field photographs of 10 ventifacts using structure-from-motion photogrammetry and handheld educational models from 3-D printing along with an accompanying educational video; and (5) presentation of results at conferences and in peer-reviewed journal articles. Project results will demonstrate, for the first time, that luminescence measurements can accurately recover hard rock erosion rates on a mm-scale. Measured rates will benchmark existing but empirically untested abrasion mechanisms.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.