The metamorphic core complexes of the Basin and Range Province record a long and complex geologic history that includes contraction and crustal shortening followed by extensional deformation and thinning. Many studies using a wide range of methods have attempted to uncover how regional extensional collapse of the crust initiated. Previous work on high temperature processes has documented older, Cretaceous to Eocene (~70 – 34 Ma) deformation, whereas studies of shallower crust (using low temperature thermochronology and basin analysis) highlight more recent, Miocene (~15 Ma) processes. In order to address a gap in the thermochronologic record across the Ruby Mountains – East Humboldt Range – Wood Hills metamorphic core complex in northeastern Nevada, we use zircon and apatite (U-Th)/He thermochronology within a well-understood structural framework from samples in the Wood Hills to document the cooling and exhumational history of the shallower parts of the core complex.
New zircon and apatite (U-Th)/He dates from the Wood Hills record late Eocene to late Miocene cooling through a zircon He closure temperature of ~150 - 180 °C and an apatite He closure temperature of ~60 - 70 °C. These results are consistent with previous studies using 40Ar/39Ar and (U-Th)/He thermochronology that suggest that cooling related to extensional exhumation in the Wood Hills occurred during at least two cooling events: one at ~40 Ma and another beginning at ~20 Ma. Furthermore, apatite dates obtained from the northern Wood Hills suggest an exhumational cooling event continued until ~10 Ma, similar to apatite (U-Th)/He dates from throughout the complex. Date-eU correlations coupled with thermal modeling aids to support a multi-step exhumation path in the Wood Hills that has also been largely documented in other parts of the metamorphic core complex
