The Poachie region at the south edge of the Colorado Plateau transition zone in western Arizona is underlain by early and middle Proterozoic plutonic rocks locally separated by screens of amphibolite-facies early Proterozoic metamorphic rocks and is in the eastern part of the Mojave crustal province, as shown by 35 Pb-isotope analyses of rocks and feldspars. Previously published mapping, 10 U-Pb zircon ages, 55 rock analyses, and other studies in the larger region of the transition zone lead to interpretation of the history and origin of the Proterozoic crust.
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USGS Numbered Series
Geology, geochronology, geochemistry, and Pb-isotopic compositions of Proterozoic rocks, Poachie region, west-central Arizona; a study of the east boundary of Proterozoic Mojave crustal province