Strike-slip faulting on Titan? Modeling shear failure conditions due to pore fluid interactions

Manifestations of strike-slip faulting are well documented on multiple ocean worlds (e.g., Europa, Enceladus, and Ganymede) and strike-slip tectonism may be important not only to the structural development of the surfaces of these satellites, but may also serve as a pathway for the exchange of surface and subsurface materials through shear heating mechanisms. Titan exhibits a complex and dynamic geology with a varied surface morphology developed from fluvial, aeolian, cryovolcanic, and possible tectonic activity. The inferred presence of a porous ice layer saturated with liquid hydrocarbons in Titan's shallow subsurface provides a unique environment for studying zones of frictional weakness, shear heating, and the promotion of cryovolcanism. Models of Titan's shallow subsurface suggest that hydrocarbon-saturated porous ice is underlain by a clathrate-ice mix to depths of ~1 km. Few studies have carefully examined Titan's ability to host shear deformation mechanisms, including considerations for how the presence of near-surface liquid hydrocarbons and the crustal porosity of the ice significantly reduce the resistance to shear failure of strike-slip faults in flexed areas under maximum diurnal tidal stresses. Here, we conduct a sensitivity analysis of Titan's shear failure tendencies, where strong tectonism constraints are limited, but optimal failure conditions may exist due to pore fluid interactions, 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 a suite of oriented fault planes. 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) and for optimally oriented faults, this exploratory model suggests shear failure is achievable under diurnal tidal stresses subject to such pore fluid pressures. The priorities of this work are to develop a physics-based model that provides optimal conditions of shear failure on Titan and places constraints on depths of faulting and ice shell thickness that might support future Dragonfly observations of strike-slip tectonism.