Tracking the topographic evolution of the Sierra Nevada, California

The Sierra Nevada mountain range in California is a giant granitic batholith created by Triassic-Cretaceous subduction of the Farallon Plate beneath North America. Stretching for ~600 km, the range increases in elevation from north to south where peaks exceed 4,000 m. However, we do not know when or why this variation in elevation evolved. It is thought that it originally had a consistent peak elevation of ~1500 m, but differential tectonic uplift and climate-driven erosion created the more complex landscape seen today. This project will place new constraints on the topographic evolution of the Sierra Nevada by combining aluminium-in-hornblende geobarometry and U-Pb zircon geochronology of Sierran granites with a quantitative geomorphic and geospatial analysis. The aim is to determine how the topography evolved between final Cretaceous emplacement of the batholith and formation of an extensive Eocene erosional surface. The objectives are to determine: (1) Spatiotemporal patterns of crustal exhumation: New U-Pb zircon geochronology and aluminium-in-hornblende barometry analyses of granitic samples will be combined with existing datasets to constrain variations in crustal exhumation across the range. (2) The extent of the relict landscape: This will be done via quantitative topographic analysis and landscape evolution modelling. The mapped landscape will provide a datum to which the emplacement ages and depths will be referenced to determine variations in crustal exhumation. (3) The topographic evolution of the Sierra Nevada: (1) and (2) will be combined to constrain the Cretaceous–Eocene topographic evolution of the Sierra Nevada and place it within a broader tectonic-climatic context.