Quantifying long-term aeolian abrasion rates on hard rock surfaces

在干旱地区，在地球和其他星球上，风吹来的沙子侵蚀和重塑了地貌。在人类的时间尺度上，这种侵蚀可以是无限小的，所以不清楚需要多长时间才能形成这些景观。该项目将使用最近在地球化学测量方面的两项进展来测量南加州通风设施的侵蚀率，这些通风设施是在暴风雨期间被喷沙侵蚀的巨石。在这些测量的基础上，该项目将调查过去气候变化是否产生了不同的通风设备侵蚀率。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以上高度。几个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的已知侵蚀速率相匹配。最后，这个项目将创建所有10个研究的呼吸器的3-D数字模型，并将它们免费提供给世界各地的教育工作者，并附带一个教学模块。这些巨石很罕见，很难接近，因此创建照片逼真的教育模型极大地增加了对这些迷人的地质特征的了解。还将免费向感兴趣的教室提供有限的3-D打印手持模型，并将在网上张贴打印说明。该项目的目标是利用光学刺激发光(OSL)和宇宙起源的原位10Be和14C方法的最新进展，量化通风设备表面风沙磨损率的空间和时间演变。利率将从几毫米到几十厘米的长度和从十年到几千年的时间尺度来衡量。该项目涉及五个主要研究任务：(1)在加利福尼亚州南部的两个地点进行实地考察；(2)原位宇宙成因14C-10Be暴露年龄和侵蚀率分析(每个通风口1对14C-10Be样品，共计10个)；(3)通风口(每个通风口10个OSL深度剖面，总计100个)和人工侵蚀岩石柱体(每个岩性3个剥蚀率和10个岩性，总计30个)的OSL深度剖面侵蚀率分析；(4)使用运动结构摄影测量法从现场拍摄的10个通风口的照片生成数字3-D模型；以及(5)在会议和同行评议的期刊文章中介绍结果。项目结果将首次证明，发光测量可以在毫米尺度上准确恢复坚硬岩石的侵蚀速率。该奖项反映了NSF的法定使命，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，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.