Tectonic evolution of core zones of orogenic belts - Canadian cordillera and Grenville province

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Funds are requested to support field-based research on the tectonic evolution of mid-crustal rocks in core zones of collisional mountain belts, and related costs for U-Pb geochronology (age and thermal history) laboratory studies and graduate student support.  Research is collaborative and includes a significant contribution to the training and mentoring of students in geology, geochronology, research program design, communication of results and professional development.  Research constrains: i) the geometry, timing and role of distributed strain, and ductile thrust and extensional shear zone systems, in the mid-crust; ii) the relationships between melting in rocks, granite production and deformation; iii) the significance of Lithoprobe geophysical data by direct correlation with rocks at the surface; and iv) reasons for the complexities of geochronology data used to date geological events. The aim is to characterize how the mid-crust responded to and facilitated mountain building and collapse, what processes were operative, and how core-zone deformation relates to the rest of the orogen.  Cordilleran research is particularly fruitful because the chosen field areas are very well exposed, and we utilize and build on a superb geological and geophysical framework.  The results are important in understanding the evolution of the mountain belt itself, and for interpretation of Lithoprobe geophysical data.  We are making progress on more sophisticated "process-oriented" problems in: i) geochronology, with implications for how age data are generally interpreted, and ii) structural geology and tectonics, with implications for understanding mountain belts and older Precambrian geologic provinces.  The anticipated outcomes of this research are reinterpretation of the significance and timing of structures and thermal history in rocks, revised geometric and tectonic models for the Canadian Cordilleran and western Grenville, refined understanding of the construction and collapse of mountain belts and mentoring students.  The research results are of interest to geologists and geochronologists working on tectonic problems worldwide, Cordilleran and Grenville geologists, field mappers in regional geological surveys and mineral exploration geologists.