Dynamic Compressive Strength and Fragmentation in Felsic Crystalline Rocks

Rae, Auriol S. P. and Kenkmann, Thomas and Padmanabha, Vivek and Poelchau, Michael H. and Schäfer, Frank (2020) Dynamic Compressive Strength and Fragmentation in Felsic Crystalline Rocks. Journal of Geophysical Research: Planets. ISSN 2169-9097 DOI https://doi.org/10.1029/2020JE006561

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Brittle deformation in rocks depends upon loading rate; with increasing rates, typically greater than ~102 s‐1, rocks become significantly stronger and undergo increasingly severe fragmentation. Dynamic conditions required for rate‐dependent brittle failure may be reached during impact events, seismogenic rupture, and landslides. Material characteristics and fragment characterization of specific geomaterials from dynamic loading are only approximately known. Here we determine the characteristic strain rate for dynamic behavior in felsic crystalline rocks, including anisotropy, and describe the resulting fragments. Regardless of the type of felsic crystalline rock or anisotropy, the characteristic strain rate is the same within uncertainties for all tested materials, with an average value of 229 ± 81 s‐1. Despite the lack of variation of the critical strain rate with lithology, we find that the degree of fragmentation as a function of strain rate varies depending on material. Scaled or not, the fragmentation results are inconsistent with current theoretical models of fragmentation. Additionally, we demonstrate that conditions during impact cratering, where the impactor diameter is less than ~100 m, are analogous to the experiments carried out here, and therefore that dynamic strengthening and compressive fragmentation should be considered as important processes during impact cratering.

Item Type: Article
Uncontrolled Keywords: NILAREP; IA76
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
07 - Gold Open Access
Journal or Publication Title: Journal of Geophysical Research: Planets
Identification Number: https://doi.org/10.1029/2020JE006561
Depositing User: Sarah Humbert
Date Deposited: 09 Oct 2020 17:23
Last Modified: 09 Oct 2020 17:23
URI: http://eprints.esc.cam.ac.uk/id/eprint/4888

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