Outer forearc uplift and exhumation during high-flux magmatism: Evidence from detrital zircon geochemistry of the Nacimiento forearc basin, California, USA

Abstract

Abstract We present new coupled detrital zircon trace-element and U–Pb age data from Valanginian–Santonian strata of the Nacimiento forearc basin (California, USA) to enhance provenance discrimination and investigate the evolution of the late Mesozoic California margin. Our data document at least five different Jurassic–earliest Cretaceous zircon populations with variable U/Yb ratios, and zircon that displays systematically increasing U/Yb from 130 to 80 Ma. Based on the presence of a distinctive population of geochemically primitive, 168–157 Ma low-U/Yb zircon that is found in Albian–Lower Cenomanian strata but not in older Valanginian strata, we infer a period of uplift and Albian–early Cenomanian erosion of forearc basement (the Coast Range ophiolite) that was coincident with increasing Cordilleran arc magmatic flux.