Figure F8. Chemical map showing relative abundances of (A) Ca, (B) Si, (C) Al, and (D) Mg in a strongly zoned felsic vein with a myrmekitic texture (Sample 176-735B-124R-1, 111-115 cm). The vein margins are marked by sharp changes in Al and are delineated by solid black lines. Very narrow bands of amphibole are present along the vein margins followed inward by zones of sodic plagioclase about 2 mm wide (green bands in [C]). The myrmekitic intergrowths of quartz and plagioclase (Myr) form parallel bands clearly illustrated in (B). The center of the vein is consists chiefly of greenish brown amphibole (Am) separated from the myrmekite by bands of pure plagioclase. Scale bars = 5 mm.

Figure F8. Chemical map showing relative abundances of (A) Ca, (B) Si, (C) Al, and (D) Mg in a strongly zoned felsic vein with a myrmekitic texture (Sample 176-735B-124R-1, 111-115 cm). The vein margins are marked by sharp changes in Al and are delineated by solid black lines. Very narrow bands of amphibole are present along the vein margins followed inward by zones of sodic plagioclase about 2 mm wide (green bands in [C]). The myrmekitic intergrowths of quartz and plagioclase (Myr) form parallel bands clearly illustrated in (B). The center of the vein is consists chiefly of greenish brown amphibole (Am) separated from the myrmekite by bands of pure plagioclase. Scale bars = 5 mm.