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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

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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 on 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 numerical model to simulate weathering of rocks possessing grain boundaries, cracks, and stylolites. We ran simulations with either synthetic or natural patterns of discontinuities. We found that for all patterns, weathering rates increase with discontinuity density. When the density was <~25%, the weathering rate of synthetic patterns followed the order: grid >honeycomb >Voronoi >brick-wall. For higher values, all weathering rates were similar. We also found that weathering rates decreased as the tortuosity of the pattern increased. Moreover, we show that textural patterns strongly impact the size distributions of detached grains. 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 patterns, weathering produced lower modality distributions.
02 Mar 2021Published in Earth Surface Processes and Landforms. 10.1002/esp.5093