Modes of extensional faulting controlled by surface processes

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Extensional tectonics
Normal faults
Surface processes
Continental rift
We investigate the feedbacks between surface processes and tectonics in an extensional setting by coupling a 2-D geodynamical model with a landscape evolution law. Focusing on the evolution of a single normal fault, we show that surface processes significantly enhance the amount of horizontal extension a fault can accommodate before being abandoned in favor of a new fault. In simulations with very slow erosion rates, a 15 km thick brittle layer extends via a succession of crosscutting short-lived faults (heave < 5 km). By contrast, when erosion rates are comparable to the regional extension velocity, deformation is accommodated on long-lived faults (heave >10 km). Using simple scaling arguments, we quantify the effect of surface mass removal on the force balance acting on a growing normal fault. This leads us to propose that the major range-bounding normal faults observed in many continental rifts owe their large offsets to erosional and depositional processes.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 6725–6733, doi:10.1002/2014GL061507.
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Geophysical Research Letters 41 (2014): 6725–6733
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