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Impact of textural patterns on rock weathering rates and size distribution of weathered grains
  • Yoni Israeli,
  • Eyal Salhov,
  • Simon Emmanuel
Yoni Israeli
Hebrew University of Jerusalem, Hebrew University of Jerusalem

Corresponding Author:israeli.yoni@gmail.com

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Eyal Salhov
Hebrew University of Jerusalem, Hebrew University of Jerusalem
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Simon Emmanuel
Hebrew University of Jerusalem, Hebrew University of Jerusalem
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Abstract

Rock texture has a critical influence over the way rocks weather. The most important textural factors affecting weathering are grain size and the presence of cracks and stylolites. These discontinuities operate as planes of mechanical weakness at which chemical weathering is enhanced. However, it is unclear how different rock textures impact weathering rates and the size of weathered grains. Here, we use a cellular automaton numerical model to simulate the weathering of rocks possessing grain boundaries, cracks, and stylolites. We ran simulations of both synthetic patterns as well as natural patterns of cracks, and stylolites. We found that for all patterns, weathering rates increase with the density of discontinuities. When the abundance of discontinuities was lower than ~25%, the synthetic patterns weathering rate followed the order: grid> honeycomb> Voronoi> brick-wall. However, for higher values of discontinuity density, all patterns exhibit similar weathering rates. We also tested the impact of the tortuosity of the pattern on weathering rates, and found rates to decrease with increasing tortuosity. In addition, we show that the rock textural pattern strongly impacts the detached grain size distributions. Rocks with an initial monomodal grain size distribution produce weathered fragments that are normally distributed. In contrast, rocks with an initial log-normal size distribution produce weathered grains that are log-normally distributed. For the natural rock patterns we tested, weathering changed the initial multimodal grain size distributions to lower modality distributions.
02 Mar 2021Published in Earth Surface Processes and Landforms. 10.1002/esp.5093