Shaver Intrusive Suite
Shaver Intrusive Suite
middle Cretaceous, ~99-114 Ma
Occurs along western slopes of central Sierra Nevada, across San Joaquin River. Extends northward into area west of Sonora Pass, including several isolated small plutons. Chiefly granodiorite and granite. Zircon U-Pb ages from this unit range from ~99-114 Ma (Stern and others, 1981; Chen and Moore, 1982; Saleeby and others, 1990; Tobisch and others, 1993; Lackey and others, 2012; Ardill and others, 2018). This unit has also yielded hornblende K-Ar and Ar-Ar ages of ~86-92 Ma and biotite K-Ar and Ar-Ar ages of ~83-91 Ma (Kistler and others, 1965; Tobisch and others, 1993), along with sphene fission track ages of ~83-88 Ma and apatite fission track ages of ~79-95 Ma (Naeser and Dodge, 1969). Major plutons: Dinkey Creek Granodiorite, granodiorite of McKinley Grove, granodiorite of the Pick and Shovel Mine area, granite of Ordinance Creek, the southernmost body of the granite of Shuteye Peak, granites of Dinkey Dome, Short Hair Creek, Sheepthief Creek, lower Bear Creek, and Mushroom Rock. May include granodiorites of Whisky Ridge and Stevenson Creek. This unit differs from the formally accepted definition of Bateman (1992) in age and extent based on the subsequent work cited above. We do not include the ~116 Ma date of the Tombstone Creek pluton (Chen and Moore, 1982) because it is from a locality near two others with much younger dates (~99-102 Ma; Chen and Moore, 1982; Saleeby, 1990). We suspect the ~116 Ma age may be affected by the proximity of the locality to adjacent older wall rock.