through the Yellowstone hydrothermal system than Cl, F,
or S (TABLE 1). In contrast, basaltic magmas generally contain
lower concentrations of dissolved Cl and F, and their
composition and origin at mantle pressures permit them to
contain 10 to 30 times more dissolved CO2 (and S) than a
mid-crustal rhyolite (Lowenstern 2001 and references
therein). Also, thermal considerations dictate that the volume
of basaltic magma parental to the rhyolite (or those
basaltic intrusions inducing crustal melting) will be at least
three to five times greater than that of any derivative silicic
magma (White et al. 2006). Thus, basaltic intrusions could
contain 50 to 100 times more available CO2 than the silicic
magmas themselves. The basaltic input means that magma
continues to accumulate and sustains the overlying silicic
magma reservoir (FIG. 3).