Figure 5. Cooling curves for the Bear Island domain of the Mather Gorge Formation and for the Sykesville Formation. Filled circle represents 40Ar/39Ar amphibole cooling age; open star, Rb-Sr muscovite cooling ages; open triangle, 40Ar/39Ar muscovite cooling age; filled triangle, 40Ar/39Ar biotite cooling age; filled hexagon, U-Pb zircon growth age; ZFT, zircon fission- track cooling ages; MGF, Mather Gorge Formation. Open rectangles denote error bars. All U-Pb zircon age data are on the Sykesville Formation cooling curve. Modified from Kunk and others (in press). |