Stanislaus River intrusive suite
Stanislaus River intrusive suite
Late Jurassic, ~151 and ~162-166 Ma
Occurs east of the western metamorphic belt in the central Sierra Nevada. Chiefly tonalite and granite. Major plutons: foliated tonalite of Granite Creek and unfoliated granite of Woods Creek. This unit has zircon U-Pb ages of ~151 Ma from the granite of Woods Creek and ~162-166 Ma from the foliated tonalite of Granite Creek (Stern and others, 1981). Intense schistosity and local lineation in the tonalite of Granite Creek is continuous with schistosity and lineation in adjacent metamorphic rocks. Unit intrudes across the Calaveras-Shoo Fly thrust. Stern and others (1981) combine this unit with the Standard and Cobb Creek plutons (part of our Don Pedro intrusive suite, unit Gdp) as their Jawbone granitoid sequence, but we retain a separate unit because of the more felsic composition of the plutons and the presence of younger unfoliated granite.