San Juan Ridge pluton
San Juan Ridge pluton
Late Jurassic, ~156-162 Ma
Low-K tonalite southeast of Lake Oroville. This pluton has zircon U-Pb ages of ~156-162 Ma (Irwin and Wooden, 2001; Day and Bickford, 2004). The eastern part of the pluton appears to be older than the western part. Interpreted as part of the plutonic component of the Smartville Volcanic complex.