Physical Sciences and Mathematics Commons^™

Hematite (U-Th)/He Thermochronometry Detects Asperity Flash Heating During Laboratory Earthquakes, Melissa S. Chapot, Alexis K. Ault, Greg Hirth, Robert G. Mcdermott

Geosciences Faculty Publications

Evidence for coseismic temperature rise that induces dynamic weakening is challenging to directly observe and quantify in natural and experimental fault rocks. Hematite (U-Th)/He (hematite He) thermochronometry may serve as a fault-slip thermometer, sensitive to transient high temperatures associated with earthquakes. We test this hypothesis with hematite deformation experiments at seismic slip rates, using a rotary-shear geometry with an annular ring of silicon carbide (SiC) sliding against a specular hematite slab. Hematite is characterized before and after sliding via textural and hematite He analyses to quantify He loss over variable experimental conditions. Experiments yield slip surfaces localized in an ∼5–30-µm-thick …