Thermal Evolution of Coastal California with Application to Hydrocarbon Maturation

Coastal California has evolved through a series of plate tectonic interactions that significantly affected the geologic, thermal, and hydrocarbon maturation histories of the area. Numerical solutions for steady-state heat transfer are used to estimate temperature suppression resulting from plate subduction along coastal California, and to model thermal refraction within the Pismo basin. Numerical solutions for time-dependent heat transfer estimate the thermal effect of the passage of the Mendocino triple junction with consequent upwelling of asthenosphere. Thermal solutions vary for different areas along coastal California depending on the magnitude of the temperature suppression due to subduction, the geometry of the space into which the asthenosphere upwells, the time since passage of the triple junction, and the specific depositional history of each basin. Paleotemperatures are calculated for the Pismo basin, predicting that the basal 300 m of source rocks have generated hydrocarbons.