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

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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.