2025/04/01 by Alexia Rojas, Emily H. G. Cooperdock, Florian Hofmann +1
paper · doi:10.1029/2024tc008727
Abstract The San Andreas Fault (SAF) zone is a prototypical continental transform fault system used to understand the rates and timing of plate‐boundary‐scale deformation. Extensive studies of the SAF document internal complexities, including how transpressive uplift occurs and varies spatially in strike‐slip systems. We utilize geochronology and low‐temperature thermochronology to re‐evaluate a plutonic piercing point and to identify heterogeneities in exhumation along the SAF restraining bend, known as the “Big Bend.” The Triassic K‐feldspar megaporphyritic monzogranite piercing point at Liebre Mountain and Mill Creek represents ∼160 km of right‐lateral fault motion. Here we present new zircon U‐Pb, bulk rock geochemistry, apatite and zircon (U‐Th)/He, and apatite fission track chronometry on a high‐resolution fault‐perpendicular sample transect from 0.25 to 4 km away from the SAF. Our results, coupled with inverse thermal history modeling, confirm that the Liebre Mountain and Mill Creek bodies broadly share a thermal history until the initiation of SAF‐related separation at ∼5 Ma. Age relationships along fault‐perpendicular transects reveal asymmetrical uplift recorded in the lowest temperature chronometers (