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Description
Geologists do not completely understand how magma moves through the crust and what processes aid the emplacement of plutons. Proposed mechanisms for pluton emplacement include releasing bends in strike-slip faults, stoping, assimilation, country rock ductile flow, and volume loss in associated contact metamorphic aureoles. Fluids circulating through wall rocks have the potential to leach elemental mass from them. These fluids are produced by crystallization of magmas and metamorphic reactions in wall rocks and are set in motion by the thermal imbalance between intruded magma and the ambient temperature conditions at a given crustal level. The purpose of this thesis is to present a statistical framework for evaluating mass and volume changes in contact aureoles related to pluton emplacement using the contact metamorphosed argillites in the Shoo Fly Complex as an example. J.A. Grant developed a deterministic approach for assessing mass and volume changes in metasomatically altered rock material. Results derived during this study using the methods of Grant suggest that ~9% of the argillitic mass was transferred out of the contact aureole thus producing an approximate 10% volume loss. However, Grant's method does not consider the statistical problems associated with closed data sets, nor does it consider the uncertainties associated with determining average compositions. Therefore, the probabilistic approach developed by J.J. Ague is preferred. Utilizing techniques suggested by Ague, no statistically significant mass or volume change appears to have occurred during contact metamorphism of argillites of the Shoo Fly Complex. Thus, mass and volume loss in the contact aureole may not have played a crucial role in the emplacement of the Emigrant Gap composite pluton.
