Study of Shear Zones and Associated Intrusions, Coastal Orogen, British Columbia and Alaska

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Mid to deep levels of continental crust are exposed in the collisional orogen of the Coast Crystalline Complex of South- eastern Alaska and adjacent British Columbia. Crustal thicken- ing and metamorphisms as well as later uplift were accomplished by movement of crustal blocks along regional shear zones and accompanied by emplacement of tabular bodies of intrusive igneous rocks. This project aims to determine the timing of shear zone formation relative to metamorphism and igneous intrusion. The deformation mechanisms, amount of shear strain, sense of displacement and the P and T of the deformation will be obtained by a combination of detailed field and microstructural studies, fluid inclusion and isotopic studies. Results will evaluate the role of fluids, magma and hydrothermal, in shear zone initiation, movement and closure and will be of considerable utility in understanding crustal evolution in orogenic zones generally.