CSDMS 2015 annual Meeting - Models meet data, data meet models

Modes of extensional faulting controlled by surface processes

Jean-Arthur Olive

MIT / WHOI Joint Program in Oceanography, United States
Mark Behn WHOI United States
Luca Malatesta Caltech United States

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.

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Of interest for:
  • Terrestrial Working Group
  • Geodynamics Focus Research Group