Slate Creek Complex
Slate Creek Complex
Early Jurassic and Late Triassic, ~193-209 Ma
Tectonostratigraphic stack of mafic volcanic rocks, mafic to intermediate plutonic rocks, and serpentinite-matrix mélange. Felsic tuff from this unit has yielded a zircon U-Pb age of ~193 Ma (Saleeby and others, 1989b), whereas tonalite from this unit has zircon U-Pb ages of ~207 and ~209 Ma (Edelman and others, 1989).  Hornblende K-Ar ages of ~148 Ma and ~162 Ma (Hietanen, 1981) and a hornblende Ar-Ar age of ~171 Ma (Fagan and others, 2001) are probably metamorphic ages (Edelman and others, 1989). The formally accepted age of this unit is Early Jurassic, but the radiometric ages of the diorite member (unit YSSCd) extend the age of this unit into Late Triassic. Locally divided into: