Fluids produced during the heating of metamorphic rocks impact a broad array of geologic processes, including the evolution of the atmosphere and its greenhouse gas content; the formation of ore deposits; the transport of heat; the generation of magmas and volcanic activity; and the production of faults and seismicity. Proper understanding of these and other fluid-driven processes, however, requires a regional-scale understanding of fluid circulation patterns through the crust at depths in excess of 15 km below the surface during mountain-building events. Barrovian-style metamorphism is the most common type recognized worldwide and, as such, is a basic model for understanding metamorphic processes as well as the geochemical and geophysical impacts of fluids comprising water, carbon dioxide, dissolved solutes, and other constituents. The proposed work focuses on the Barrovian type locality of Scotland, and will use the elemental and isotopic mass transfer recorded in the rocks together with numerical models constrained by field- and laboratory-based initial and boundary conditions to test hypotheses of fluid flow, heat transport, and magma formation during metamorphism. Three field areas spanning the crustal depth range of ~15 to ~35 km will be examined, with a particular focus on the Highland Boundary Fault. This crustal-scale structure extends ~250 km across Scotland and is clearly a fundamental control on the spatial distribution of metamorphic rock types in the Barrovian sequence. Nonetheless, despite over a century of study, its role in the geochemical and tectonic evolution of earth's crust during the global-scale, Caledonian-Appalachian mountain building episode remains controversial and poorly resolved.
Human resources will be developed because field- and laboratory-based Ph.D. graduate student as well as undergraduate B.S. thesis research is critical to the project. PI Ague is leading a complete renovation of the rock and mineral section of the Yale Peabody Museum, and this will allow integration of new research results into Earth science displays viewed by over 150,000 visitors annually. A large fraction of these visitors are schoolchildren, many of whom live in the urban centers of New Haven, Bridgeport, and other Connecticut cities. The exhibition would be the only one of its kind in Connecticut or Rhode Island and, as such, serve as a critical regional scientific and educational resource for the Museum's diverse audiences. A series of books and accompanying CDs/DVDs on Earth Science for K-6 grade students and an interactive web site will be produced to coincide with the exhibition; the project will support production of one of the books.
