Modeling inherited structures and their effects on strain localization during continental rifting

Continental rifting is a fundamental process of plate tectonics and the Wilson Cycle where weak zones within the continental lithosphere are exploited by both far-field and near-field forces to break-up the continental lithosphere (e.g Molnar et al., 2019). These pre-existing weak-zones are remnants of past tectonic deformation, delineated by shear zones, faults, and/or mobile belts. Reactivation of such inherited structures from previous tectonic phases has been attributed to several continental rift systems, for example, the Rhine graben, Rio Grande rift, Main Ethiopian Rift, Malawi Rift, and the Red Sea. In geodynamic modeling of continental rifts, these weak zones are often approximated by lithospheric thermal perturbation or a weak seed/fault to facilitate strain localization and initiate rifting in response to uniform stretching of the lithosphere. Here, we adopt a different approach building upon models by Salazar-Mora and Sacek (2022) and Peron-Pinvidic et al. (2022) to implement the inherited structures. We start with a geodynamic simulation of continental collision and orogenesis prior to extension but include the effect of temperature-dependent strain healing in the mantle (e.g. Fuchs and Becker, 2021) and time dependent plastic strain healing in the crust (e.g. Olive et al., 2016). We use a 2D geodynamic model ThermoMech (e.g. Xue et al., 2023) coupled to a landscape evolution model FastScape (Yuan et al., 2019), to explore the parameter space in an effort to understand the longevity of weak zones and their implications for rift initiation.

 

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