Deciphering the Thermal History of the Great Valley Forearc Basin at Del Puerto Canyon, California

This study seeks to reconstruct the thermal evolution of the Great Valley Forearc (GVF) basin, California exposed in outcrop along its western margin. Despite the basin’s abundant petroleum systems within the Central Valley, the thermal history of the western outcrop belt remains less understood. The GVF is saturated with syn- and post-depositional normal and thrust faults, as well as slip-strike displacement from the San Andreas fault system following cessation of deposition. We combine field mapping with geochronology and low-temperature thermochronology to reconstruct the thermal history of the GVF basin adjacent to major, previously mapped faults. At Del Puerto Canyon, the Tesla–Ortigalita Fault (TOF), a thrust fault with right-lateral slip, has been previously interpreted as active from the Miocene to the present and may be responsible for exhuming parts of the GVF basin. Analysis of zircons using U-Pb geochronology sampled from Del Puerto Canyon within the GVF demonstrates that the Jurassic–Cretaceous Knoxville Formation was present during the slip along the TOF, constraining fault activity back to the Cretaceous at this location. Apatite and zircons (U-Th)/He results show thermal resetting of apatites, yielding dates of 55–10 Ma, while zircons show minimal resetting, with dates ranging from 106–63 Ma, coinciding with depositional ages. Ongoing thermal-history modeling seeks to constrain maximum burial temperatures and initiation of cooling. At present, the TOF has sections of near-vertical movement exhuming parts of the basin. Continued efforts seek to understand the structural complexity of the basin to further interpret and understand the thermal history of the basin.