Bear Valley intrusive suite
Bear Valley intrusive suite
Cretaceous, ~92-113 Ma
Occurs in southwestern Sierra Nevada and Tehachapi Mountains. Suite generally occurs west of Proto-Kern Canyon fault. Medium-size pluton (tonalite of Hoffman Canyon), part of suite, occurs east of fault in southeastern Sierra Nevada, west of Jawbone Canyon fault. Chiefly tonalite, gabbro, granodiorite, and associated mafic and ultramafic rocks, mafic gneiss, and granulite. Zircon U-Pb age ~92-113 Ma (Saleeby and others, 2007, 2008; Chapman, 2012); hornblende K-Ar and Ar-Ar ages of ~85-88 Ma (Ross, 1983; Saleeby and others, 2007); zircon U-Th/He age of ~84 Ma and biotite Rb-Sr age of 85 Ma (Saleeby and others, 2007); biotite K-Ar and Ar-Ar ages of ~75-87 Ma (Evernden and Kistler, 1970; Ross, 1983; Saleeby and others, 2007). Major plutons: mafic gneiss and amphibolite of Jawbone Canyon, biotite-hornblende-bearing tonalite of Bear Valley Springs, hypersthene-bearing tonalite of Bison Peak, gabbro of Tunis Creek (norite and hornblende gabbro, commonly recrystallized), tonalite of Mount Adelaide, granodiorite of Poso Flat, granodiorite of Pine Flat, tonalite of Dunlap Meadow, granodiorite of Hatchet Peak, tonalite of Hoffman Canyon, granodiorite of Hershey Ranch, tonalite of Walt Klein Ranch, tonalite of Fountain Springs, tonalite of Carvin-Bower Ranch, granodiorite of Peppermint Meadow, granodiorite of Deer Creek, gabbro of Live Oak, tonalite of Zumwalt Ranch, along with unnamed mafic and ultramafic plutonic rocks, amphibolite, gneiss, and granulite. Equivalent to parts of the Domelands, Needles, Bear Valley, and Kern River intrusive suites of Nadin and Saleeby (2008). Suite interpreted as forming in a deep level of the middle Cretaceous Sierra Nevada batholith during mixing of mantle-derived magma and old metasedimentary continental rocks (Saleeby and others, 2008).