Collaborative research: Microscopic fracturing and macroscopic weakening: A novel model for bedrock fracturing by biotite weathering

基岩是如何分解成土壤的？这个问题引起了广泛的兴趣，因为基岩压裂会影响滑坡危害、全球碳循环以及土壤和溪流的营养供应。该项目的主要目标是了解一种常见矿物——黑云母的风化作用是如何导致基岩破裂的。黑云母在风化过程中会膨胀。这将验证一个长期存在的假设，即基岩破裂主要是由黑云母风化造成的。这项工作将通过数值模拟、实地观测和实验室测量相结合来解决这个问题。该项目的核心是开发一种新颖而强大的基岩压裂数值模型。它将用于研究几个基本问题：裂缝的发育如何取决于黑云母的大小、方向和丰度等特征？在什么条件下黑云母风化作用是基岩压裂的主要驱动因素？为了验证模型的预测，将在两个野外地点对黑云母和裂缝特征进行新的测量，其中一个被认为是黑云母风化作用主导岩石断裂的地方（波多黎各的Luquillo临界带天文台），另一个被认为是黑云母风化作用不太重要的地方（加利福尼亚的南内华达山脉临界带天文台）。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。

How does bedrock break down into soil? This question is of wide interest because bedrock fracturing influences landslide hazards, the global carbon cycle, and the supply of nutrients to soils and streams. This project's main goal is to understand how the weathering of a single type of common mineral - biotite, which expands as it weathers - drives bedrock fracturing. This will test a longstanding hypothesis that bedrock fracturing is mainly driven by biotite weathering.This work will tackle this question through a combination of numerical modeling, field observations, and laboratory measurements. At the center of this project is the development of a novel and powerful numerical model for bedrock fracturing. It will be used to investigate several fundamental questions: How does the development of fractures depend on biotite characteristics like size, orientation, and abundance? Under what conditions is biotite weathering the dominant driver of bedrock fracturing? To test the model predictions, new measurements of biotite and fracture characteristics will be conducted at two field sites, one where biotite weathering is thought to dominate rock fracture (the Luquillo Critical Zone Observatory, Puerto Rico), and one where the effects of biotite weathering are expected to be less important (the Southern Sierra Nevada Critical Zone Observatory, California).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.