The Role of Climate and Erosion in Shaping Strike-Slip Fault Landscapes: Insights from the Extreme Hyperarid Atacama Desert

Abstract

In oblique subduction margins, crustal-scale strike-slip faults can drive surface deformation, river and hillslope reorganization, and localized exhumation at bends and fault terminations. Yet their contribution to long-term landscape evolution is difficult to resolve where climate-controlled erosion rates are low and deformation is long-lived. The Coastal Cordillera of Northern Chile, within the Atacama Desert, provides an ideal natural laboratory to address this challenge, allowing evaluation of upper-plate structural and topographic development in a long-lived oblique subduction zone under extreme aridity. To resolve the contributions of climate and tectonics to Earth’s surface evolution across geophysical to geological timescales, this dissertation couples remote sensing, synthetic and field data, and geodetic, geomorphological, and thermal modeling. In Chapter 1, I assess the topographic response to slow strike-slip faulting under hyperarid conditions along the Salar Grande Fault, at the northern termination of the Atacama Fault System. By comparing geodetic and geomorphological fault-slip-rate estimates, I argue that the Salar Grande Fault slips at rates <1 mm/yr, providing the tectonic conditions for slow slip to leave a topographic signature in upstream ridgelines perpendicular to the fault. These findings suggest that, despite hyperarid conditions, more erosionally efficient humid intervals must allow the landscape to keep pace with active strike-slip faulting and imprint tectonic disequilibrium on channels and ridges. In Chapter 2, I explore the geomorphic processes that drive disequilibrium in such a hyperarid landscape. Simulating synthetic landscapes with oscillatory dry and humid periods, I find that climate variability and fault-slip rate control sediment aggradation and channel morphology along strike-slip faults. Hillslope-derived sediment provides additional time for rivers to respond and adapt to tectonic perturbations, revealing mechanisms that help explain the observations from Chapter 1. In Chapter 3, inspired by the importance of sediment in altering landscape response times, I test whether sediment transport and alluvial cover modify divide mobility in strike-slip fault models. These experiments show that sediment transport changes the geomorphic expression of strike-slip faulting and modifies upstream ridgelines perpendicular to the fault, but does not overturn the first-order control of bedrock erodibility, diffusion and slip rate on upstream adjustment. This result suggests that sediment influences how disequilibrium is expressed in channels and relief structure, even when it does not fundamentally shift landscapes between dynamic and stable divide-mobility regimes. Finally, in Chapter 4, I take the contributions of strike-slip faults to a longer timescale perspective and argue that the Salar Grande Fault contributed to Oligocene exhumation along the Coastal Cordillera. Using low-temperature thermochronology and thermal modeling, I reconstruct a cooling history of the Coastal Range from the Jurassic to the Late Cenozoic. These findings show that long-lived strike-slip fault systems can generate measurable vertical displacements and forearc topography even under extremely low erosion rates, highlighting both the challenges and diagnostic value of thermochronology in hyperarid, slowly eroding environments. Together, these chapters show that strike-slip faults in hyperarid environments leave detectable but limited records of deformation across timescales. Climate determines when rivers can respond, sediment alters how that response is expressed in the topography, and long-lived fault geometry controls where advection and exhumation is localized. This dissertation demonstrates that even in settings where erosion is limited for millions of years, the coupled effects of fault slip, transient climate, sediment transport, and exhumation can preserve a measurable record of upper-plate deformation and geomorphic adjustment.