The Big Maria Mountains of SE California preserve evidence of a large-scale fluid flux that accompanied regional metamorphism in late Cretaceous time. Neither magmatism nor radioactive heat sources are adequate to explain the T of metamorphism. Simultaneously crystallizing plutons at different levels within the crust could have contributed to the overall hot fluid flux. A fluid:rock ratio of 17:1 may be calculated given average conditions of 3 kbar, 500oC, an infiltrating fluid of composition XH2O = 1.0, an equilibrium fluid composition of XH2O = 0.97, and 90% wollastonite in the final rock form the reaction quartz + calcite = CO2 + wollastonite. The minimum quantity of fluid of 1.7 rock volume was estimated to pass through the area if the fluid was approximately at granite solidus T at the start. Deep penetrative structures within the crust may have served to channel fluids. -L.C.H.
Additional publication details
Heat transport by fluids during late Cretaceous regional metamorphism in the Big Maria Mountains, southeastern California.