Conduction model for the thermal evolution of the Cupsuptic aureole, Maine

Two-dimensional and three-dimensional finite difference conduction cooling models incorporating realistic pluton geometries, endothermic metamorphic reactions, and non-linear release of latent heat of magma crystallization were applied to the Cupsuptic pluton in Maine. The excellent agreement between the patterns of maximum temperature isotherms in the model and the spatial locations of the biotite, andalusite, and sillimanite isograds in the Cupsuptic aureole suggest intrusion cooling dominated by conduction. Assuming a discoid shape of the pluton, the agreement between isotherms in the model and isograds in the aureole is favorable with a pluton thickness of 4 km. With an ambient country rock temperature of 350°C, an initial intrusion temperature of 950°C is constrained by geothermometry in the aureole. -Authors