Figure 9: Hornblende and biotite composition.
a) Mg/(Mg+Fe) for biotite and hornblende in ECS are similar. SMR and ECS have different Mg/ (Mg+Fe) ratios.
b) For biotite with hornblende overgrowth and isolated biotite grains, biotite with hornblende overgrowths has higher Mg/(Mg+Fe) ratios.
(BB, BAT and SMR are minerals from Banco Bonito Lava Flow, Battleship Rock Tuff, and South Mountain Rhyolite, BAT-(Hb) and BB-(Hb) are biotite with hornblende overgrowth)..

figure 9