sgr ms thesis - University of Maine

contrast, conduction is heat transfer through a non-flowing material (Stuwe,
2002). It is important to determine which mode of heat transfer is dominant
because their fundamental differences produce different aureole characteristics
and different timing for peak metamorphism.
Wall rock permeability and the availability of fluids are the two major
factors that determine the degree to which conduction or convection may
dominate in a system. The aureoles of intrusions emplaced at shallow crustal
levels are generally dominated by convection, due to the availability of
substantial fluid volumes and the higher permeability of upper crustal rock
(Johnson et al., 2011). There has been significant work done, especially from
studies in porphyry ore deposits, to determine the probability of hydrothermal
flow as a dominant mechanism for wall rock metamorphism (Cathles, 1977;
Norton and Knight, 1977; Norton and Taylor; 1979; Parmentier and Schedl, 1981;
Johnson and Norton, 1985; Hanson and Barton, 1989; Cook et al., 1997). At
greater depths (below ~8-10km), the role of fluid convection becomes
overshadowed by conduction due to reduced fluid availability and permeability
(Walther, 1990). At these depths, conduction can be a rate controlling factor if
there are no developed fractures that allow direct transfer of magmatic volatiles
into the wall rock (Furlong et al., 1991).
4.2. Contact Metamorphism in the Shatter Zone
Bar Harbor Formation clasts within the Shatter Zone exhibit metamorphic
textures which indicate an increase in thermal influence relative to the intrusive
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