sgr ms thesis - University of Maine

elatively thin aureole surrounding an igneous intrusion. There are significant
changes in metamorphic grade through the aureole, and in many cases it is
possible to track the entire prograde metamorphic gradient within a single rock
unit (Kerrick, 1991). The highest grade metamorphic facies is found adjacent to
the intrusive contact and peak metamorphic temperature decreases outward.
The effect pressure has on contact metamorphism is dependent on the depth of
the intruding heat source (Furlong et al., 1991). At shallow depths, temperature is
the driving force of metamorphism and the contact aureole is typically well
contrasted to the host material, which may be unmetamorphosed. For deep
pluton aureoles, it is more difficult to distinguish the aureole from the already
regionally metamorphosed rocks (Kerrick, 1991). The size of the aureole
correlates positively to the size of the intrusion, therefore it directly relates to the
heat source reserve (Kerrick, 1991).
4.1.1. Conductive, Convective, and Advective Heat Transfer
Heat transfer from pluton to wall rock can be dominantly driven by
conduction and by convection and/or advection. The rate of conductive heat
transfer is a function of the thermal diffusivity of the wall rock, while convective
and advective heating rate is a function of the velocity of a flowing body, such as
groundwater or magmatic flow (Turcotte and Schubert, 1982). Convection is a
buoyancy driven process caused by the heating of a mobile fluid, and implies a
circulating flow path of fluids driven by a heat source. Advection applies to an
open system where fluids are permanently driven off by the heat source. In
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