U-Th-Pb, Rb-Sr, and Ar-Ar mineral and whole-rock isotopic systematics in a metamorphosed granitic terrane, southeastern California

摘要

Mesozoic structural domes are developed in an older Proterozoic crystalline basement of granitic to granodioritic foliate metaplutonic rocks in the Halloran Hills, southeastern California. Isotopic analyses of whole rocks and mineral separates from these rocks by U-Th-Pb, Rb-Sr, and Ar-Ar techniques yield a complex pattern of discordance that is the result of a fairly simple geologic history. Individual mineral isotopic systems have variably equilibrated with each other in response to Mesozoic regional metamorphism and locally to later heating during Mesozoic batholith emplacement.