Constraints on the Formation of the Bitterroot Lobe of the Idaho Batholith, Idahoand Montana, from U-Pb Zircon Geochronology and Feldspar Pb Isotopic Data

摘要

Zircons from Cretaceous and Tertiary plutonic rocks of the west-central portionof the Bitterroot lobe of the Idaho batholith contain abundant inherited cores that make precise U-Pb age determination difficult. Zircons from a tonalite emplaced along the western periphery of the batholith yield an almost concordant