Figure F6. A. 40Ar/39Ar age spectrum and (39Ar)K/(37Ar)Ca plot for Core 180-1117-alt. The separate contained highly altered plagioclase grains. The white spectrum is corrected assuming an atmospheric (40Ar/36Ar)i = 295.5, the black spectrum is corrected using (40Ar/36Ar)i = 392.3 ± 8.7 from the isochron plot. B. Isochron plot for Core 180-1117-alt plagioclase step heat experiment. MSWD = mean squared weighted deviates.

Figure F6. A. ⁴⁰Ar/³⁹Ar age spectrum and (³⁹Ar)_K/(³⁷Ar)_Ca plot for Core 180-1117-alt. The separate contained highly altered plagioclase grains. The white spectrum is corrected assuming an atmospheric (⁴⁰Ar/³⁶Ar)_i = 295.5, the black spectrum is corrected using (⁴⁰Ar/³⁶Ar)_i = 392.3 ± 8.7 from the isochron plot. B. Isochron plot for Core 180-1117-alt plagioclase step heat experiment. MSWD = mean squared weighted deviates.