Strike-slip tectonism on Titan? Investigating Coulomb failure due to pore fluid interactions on a global scale

Abstract:

Titan displays a dynamic and complex geology with a varied surface morphology developed from aeolian, fluvial, possible cryovolcanic and tectonic activity. The assumed presence of a porous ice layer saturated with liquid hydrocarbons in Titan’s shallow subsurface provides a unique environment for zones of frictional weakness, shear heating, and the promotion of potential cryovolcanism. Unlike other ocean worlds where expressions of strike-slip faulting are well documented (e.g., Europa, Enceladus, and Ganymede), the currently available data for Titan is very limited, although optimal fault failure conditions may exist due to pore fluid interactions. In this study, we examine Titan’s ability to host shear deformation mechanisms while considering the presence of near-surface liquid hydrocarbons and the crustal porosity of the ice, which can significantly reduce the resistance to shear failure of strike-slip faults in flexed areas under maximum diurnal tidal stresses. We conduct a global sensitivity analysis of shear failure tendencies and examine the possibility for strike-slip tectonics guided by Coulomb failure laws and tidal stress mechanisms. Using the SatStress tidal stress model for Titan-appropriate rheology, we compute the diurnal tidal stress tensor and resolve shear and normal stresses onto hypothetical strikes of fault planes from 0º to 360º across the globe. We adopt a coefficient of friction of μf = 0.4 and include the effect of an intermediate hydrostatic pore fluid pressure gradient for Titan. At shallow fault depths (< 1 km), this exploratory model suggests that shear failure is achievable under diurnal tidal stresses subject to such pore fluid pressure, especially in the polar regions. Moreover, we have developed a physics-based model for evaluating optimal conditions of shear failure on Titan, which has the potential to provide constraints on depths of faulting that might support future Dragonfly observations of strike-slip tectonism.