ARE THERMAL DOMES HEATED BY CO2-RICH FLUIDS FROM THE MANTLE

A large part of the fluid present in the thermal dome at Naxos, Greece, during the main stage of metamorphism was CO2-rich and of deep-seated origin. Samples of this pervasive fluid were trapped in fluid inclusions, which are particularly abundant in syn-metamorphic quartz segregations. These quartz segregations are considered to represent the main passageways of the escaping fluids. Mass-balance calculations based on δ13C values of fluids and rocks indicate that most fluid/rock mass ratios are between 0.06 and 0.8. The heat added to the metamorphic system by the cooling of these fluids may have been the prime cause of metamorphism and updoming. © 1979.