Abstract
According to Ferry (e.g., 1987), metamorphosed pelitic and carbonate rocks from southcentral Maine record mineral equilibrium with a water-rich fluid; yet, the prograde reactions liberated a CO2-rich fluid. This implies a large and pervasive H2O influx during the initial stageso f metamorphism. Fluid inclusions from twelve quartz segregationso f variable metamorphic grade record a complex fluid history. Most of the first-generation fluid inclusions are CO2-rich and have densities appropriate to the peak metamorphic conditions. These inclusions may contain the fluid released from prograde decarbonation reactions. In general, composition of the fluid inclusions changes with grade, reflecting limited circulation of the locally derived fluids in fracture networks. In one quartz segregation, the fluid-inclusion composition does vary with rock type in an outcrop. A later influx of H2O is recordedb y a late generationo f fluid inclusions and is associatedw ith hydrothermal alteration ofgranitic stocks. The late-stage fluids may have triggered retrograde reactions that resulted in the N2, N2-CO2, and CH4 observed in later generations of fluid inclusions.
