Spirit Mountain batholith (SMB)
The SMB is a ca.10 x 20 km granitic pluton offering kilometers of largely uninterrupted exposure (Fig. 2). The pluton was emplaced in the northern Colorado River extensional corridor over a period of ~2 My (ca. 17.5–15.3 Ma) (Claiborne et al ., 2006, 2010, Walker Jr et al ., 2007). Post-emplacement tilting 45º W resulted in a cross-sectional window of the SMB exposed at the surface today (Faulds et al. , 1992, Haapala et al. , 2005, Howardet al. , 1994) (Fig. 2).