Fast Liquiñe‐Ofqui Fault Slip Rates and Rapid Uplift Above the Subducted Chile Ridge

Abstract The influence of an oceanic ridge spreading center being subducted on the overlying plate is poorly known. At Chile's Laguna San Rafael, we collected a novel airborne light detection and ranging (lidar)‐derived topographic data set near where an oceanic spreading center, the Chile Ridge, is being subducted under South America. In these data and with corroborative field observations (including fault rocks), we map Quaternary deposits presumably displaced vertically and horizontally along the Liquiñe‐Ofqui Fault Zone's (LOFZ) master fault scarp. Utilizing dated glacier deposits from the well‐researched San Rafael Glacier (among the best studied in Patagonia) with our lidar‐derived offest data (validated in the field) we estimated Holocene horizontal dextral strike slip rates of 13.8 ± 4.9 and 14.1 ± 1.0 mm/yr based on displaced moraine and landslide deposits. The lidar‐derived topographic data set further guided analysis outside of the lidar area, but along strike of the fault, and we document a major vertical fault scarp south of Laguna San Rafael, which have young scarps showing some of Earth's fastest vertical slip rates (∼6 ± 3 mm/yr). Exhumed metamorphic rocks here show long term strike slip displacement and longevity of the LOFZ in Chilean Patagonia. Because the dip slip component is nearly zero 750 km to the north along the LOFZ, the rapid neotectonic surface uplift here is likely controlled and sustained by oblique subduction of the Chile Ridge and associated slab window and contributes to the highest topography in Patagonia (∼4 km).