Research Article

Subcritical Phase Separation and Occurrence of Deep-Seated Brines at the NW Caldera Vent Field, Brothers Volcano: Evidence from Fluid Inclusions in Hydrothermal Precipitates

Figure 5

Fluid inclusion salinities () and entrapment temperatures () in comparison with vent fluid salinities and temperatures. (a) Histogram of and for all inclusions. The results are color coded according to inclusion types. Type IIa inclusions are shown in red, and Type IIb inclusions shown in blue. (b) for Type IIb inclusions. (c) Salinities in vent fluid samples [33, 47, 48]. (d) Histogram of for all inclusions. (e) Histogram of for Type IIb inclusions. (f) Temperatures of vent fluid samples [33, 47, 48]. Note: the vertical blue line denotes seawater salinity (). The red-shaded area marks the boiling temperatures at seafloor pressure (from the base of caldera floor at 1850 mbsl to the uppermost part of the caldera rim at 1300 mbsl). The black horizontal lines give the range (thin lines) and the (thick lines) of and of two barite samples investigated in the fluid inclusion study by de Ronde et al. [6].