Collaborative Research: ACCRETE: An Integrated Study of Continental Growth at a Convergent-to-Transpressive Plate Margin

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9219002 Diebold This project involves a pilot seismic profile designed to improve understanding of processes of continental growth associated with terrane accretion in the Coast orogen of southeast Alaska and British Columbia. The seismic data will provide constraints pertaining to models for the role of thick-skinned thrusting, metamorphism and magmatism in the formation of continental lithosphere. They will also constrain models on how subduction and translation were accommodated during a major shift in relative plate motions from head-on (mid Cretaceous) to transcurrent (Eocene), and how this rearrangement affected crustal development. The seismic results will guide design of subsequent research proposals on these problems. The seismic profiling will use an acoustic source array deployed from a marine research ship that crosses the Coast orogen along a 130 km long fjord, and densely spaced (3-5 km) 3-component seismic recorders placed along the shore to record offsets from 0 to 200 km. The ship will also deploy a 4 km long hydrophone streamer for simultaneous MCS (multi-channel seismic) profiling. This unique experiment combines proven marine seismic techniques with the new capability of the seismic recorders to determine mid to lower crustal structure and physical properties of an area of known continental accretion. ***