Indian Valley pluton
Indian Valley pluton
Late Jurassic, ~150-155 Ma
A small, composite body of metagabbro and biotite-hornblende tonalite east of Lake Oroville. This pluton has zircon U-Pb ages of ~152 Ma (Day and Bickford, 2004) and ~155 Ma (Langenheim and others, 2025). Day and Bickford (2004) also report a zircon U-Pb age of ~150 Ma for a tonalite dike that cuts foliation in the Clipper Gap Formation (unit YACG) just east of the pluton, which they relate to the pluton. The pluton has also yielded a hornblende K-Ar age of ~143 Ma (Bohlke and McKee, 1984).