Physical Sciences and Mathematics Commons^™

U-Pb Studies Of Zircon Cores And Overgrowths, And Monazite: Implications For Age And Petrogenesis Of The Northeastern Idaho Batholith, M. E. Bickford, R. B. Chase, B. K. Nelson, Robert Duncan Shuster, E. C. Arruda

Geography and Geology Faculty Publications

U/Pb isotopic studies of zircons, many containing xenocrystic cores with euhedral overgrowths, and monazite from igneous rocks and metasedimentary inclusions of the northeastern Idaho batholith yield linear arrays on concordia diagrams. We interpret these as mixing lines between an old component (cores) and a young component (overgrowths and zircons without cores). The lower intercept of such arrays with concordia may yield the minimum age of the rocks if the overgrowths and zircons without cores are discordant, or the crystallization age if they are concordant. Monazites yield apparently concordant ages either equal or less than the lower intercept zircon ages. The …