Thermal Anomalies and Fluid Flow in the Continental Crust

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Fluids are involved in nearly all geologic processes, and are ubiquitous in the continental crust to depths of at least 10 to 15 km. As heat is advected by fluid movement, it may lead to distinctive patterns of thermal anomalies which can be interpreted to gain insight into fluid pathways and mechanisms. Field studies of past and present temperatures in the Ouachita Mountains- Arkoma basin area re proposed to gain insight into the mechanisms by which fluid flow occurs in the continental crust and the nature of possible relationships between fluid migrations and orogenesis. The Arkoma basin and Ouachita mountains are of interest because they have been implicated as a source of the hot brines which apparently flooded North America in Late Pennsylvanian-Early Permian time (about 300 +25 Ma), leading to widespread potassic alteration, formation of Mississippi Valley-type (MVT) lead-zinc deposits, and possible resetting of paleomagnetic poles. Mathematical models will also be used to evaluate various hypotheses concerning the mechanisms by which fluid flow takes place in the continental crust. Modeling will include a study of (1) temporal focusing of compaction- or metamorphic-derived fluids, (2) catastrophic release of heat in the crust from free convection an the interaction of free- and forced- convective flow regimes, and (3) the conditions under which free convection is important in tilted geologic media such as may occur in sedimentary basins. Results of the mathematical modeling will be used in conjunction with data collected in field studies to evaluate hypotheses concerning fluid flow in the continental crust, particularly in reference to tectonically-driven fluid migrations.