Grain-size-evolution controls on lithospheric weakening during continental rifting
نویسندگان
چکیده
Abstract Variation in the effective strength of lithosphere allows for active plate tectonics and is permitted by different deformation mechanisms operating crust upper mantle. The dominant are debated, but geodynamic models often employ grain-size-independent or evaluate a single grain size. However, observations from nature rock experiments suggest transition to grain-size-dependent due reduction size can cause lithospheric weakening. Here, we two-dimensional thermo-mechanical numerical model mantle investigate grain-size evolution continental rift setting, on basis recent growth law polycrystalline olivine. We find that average olivine greater asthenospheric (centimetre-scale grains) than at crust–mantle boundary (millimetre-scale grains). This distribution could result dislocation creep being mechanism along lithospheric-scale shear zones, sizes localized causes diffusion as mechanism, causing weakening facilitating initiation rifting.
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ژورنال
عنوان ژورنال: Nature Geoscience
سال: 2022
ISSN: ['1752-0894', '1752-0908']
DOI: https://doi.org/10.1038/s41561-022-00964-9