The role of bedrock erodibility in the topography and landscape evolution of the Appalachian Mountains

基岩侵蚀性在阿巴拉契亚山脉地形和景观演化中的作用

• 批准号: 2333215
• 负责人: James Spotila
• 金额: $ 34.22万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2333215&HistoricalAwards=false
• 关键词: role; bedrock; erodibility; topography; landscape

Mountains linger on the continents long after they are built by tectonic motions. During their erosional decay, these diminishing mountains are subject to modification by changing conditions, including climate, basin dynamics, and renewed tectonics, resulting in complex signals. Another factor that controls the evolution of these landscapes is the material properties of the eroding bedrock, which change through time as rocks are exhumed. Correlations exist between topography and rock type in many ancient mountain ranges, including in the Appalachian Mountains, the type locality of this phenomenon. In sedimentary rocks of the Appalachians, the role of bedrock properties is at least qualitatively clear, but in metamorphic rocks the relationships are murkier. The purpose of this investigation is to determine the degree to which metamorphic rocks of the high Blue Ridge control the landscape and to quantify specifically what makes them durable. This will contribute to understanding of the origin of the Appalachian landscape, as well as to the processes that control erodibility along ancient passive margins. This project also supports a program for developing and adding a field experience as a required element for eighth grade Earth Science classes in a rural Appalachian middle school (~350 students/year), where currently no field trips are included in the curriculum. The specific goals of this project are to measure bedrock properties of complex metamorphic rock of the Virginia and North Carolina Blue Ridge, including rock strength (e.g., point-load testing), discontinuities (e.g., fracture scanlines), mineralogy, and sensitivity to chemical and physical surface processes via laboratory testing (freezing/thawing, heating/cooling, microwave acid digestion, and slake testing). A large data collection effort (~150 locations, 500 samples) will fill a major data gap for the material properties of complex Blue Ridge rock types. Samples will be acquired from both natural and anthropogenic exposures and will be compared to relative topographic position (i.e., ridges and peaks vs. valley bottoms) as well as a host of other geomorphic metrics. Data will be synthesized to test the degree to which bedrock controls topography and ultimately be integrated into a model of what controls long-term erodibility in this setting.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.

山脉在构造运动形成后很长一段时间仍在大陆上徘徊。在侵蚀衰退期间，这些逐渐缩小的山脉会受到气候、盆地动力学和更新构造等条件变化的影响，从而产生复杂的信号。控制这些景观演变的另一个因素是侵蚀基岩的材料特性，随着岩石被挖掘出来，这些特性会随着时间的推移而变化。许多古代山脉的地形和岩石类型之间存在相关性，包括这种现象的典型地点阿巴拉契亚山脉。在阿巴拉契亚山脉的沉积岩中，基岩性质的作用至少在定性上是明确的，但在变质岩中，这种关系就比较模糊了。这项调查的目的是确定高蓝岭的变质岩控制景观的程度，并具体量化是什么使它们持久。这将有助于了解阿巴拉契亚景观的起源，以及控制侵蚀的过程，沿沿着古老的被动边缘。该项目还支持开发和添加实地经验作为阿巴拉契亚农村中学（约350名学生/年）八年级地球科学课程的必要元素的计划，目前课程中不包括实地考察。 该项目的具体目标是测量弗吉尼亚州和北卡罗来纳州蓝岭复杂变质岩的基岩性质，包括岩石强度（例如，点负载测试），不连续性（例如，裂缝扫描线）、矿物学以及通过实验室测试（冷冻/解冻、加热/冷却、微波酸消化和熟化测试）对化学和物理表面过程的敏感性。大量的数据收集工作（约150个地点，500个样本）将填补复杂蓝岭岩石类型材料特性的主要数据空白。将从自然和人为暴露中获取样本，并将其与相对地形位置（即，山脊和山峰与谷底）以及许多其他地貌指标。数据将被综合，以测试基岩控制地形的程度，并最终被整合到一个模型中，什么控制长期的可蚀性在此setting.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。