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Formation and suppression of strike-slip fault systems

Ivy S. Curren, & Peter Bird

Under Review 2014, SCEC Contribution #1898

Transform faults are a defining feature of plate tectonics, yet many regions on land where shearing is the primary deformation mechanism are almost completely lacking or have underdeveloped strike-slip fault systems. Regions that exhibit rapid toroidal (shearing) flow as indicated by GPS velocities, focal mechanisms, and/or neotectonic models but lack pervasive strike-slip faulting tend to possess common features that predate shearing, such as: (1) extensive fracturing perpendicular or sub-perpendicular to the shear plane (e.g., South Iceland Seismic Zone), and/or (2) regional cover of flood basalts or andesites containing columnar joints (e.g., Brothers Fault Zone, Oregon). We present a new plane-stress finite-strain analog model created to investigate the evolution of primary deformation zones (PDZs) in pure strike-slip systems where crustal heterogeneities exist prior to shear initiation. Experimental results indicate that preexisting structures have a marked influence on the geometry of such systems (in comparison to systems with originally pristine surfaces) and that more than twice as much net offset is required for throughgoing strike-slip faulting to occur. Fault zone development observed in these experiments provides new insight for kinematic interpretations of structural data from similar fault systems on Earth, Venus and other terrestrial bodies.

Curren, I. S., & Bird, P. (2014). Formation and suppression of strike-slip fault systems. Pure and Applied Geophysics, (under review).