3-DIMENSIONAL COLLISIONAL STRUCTURE OF THE TRANS-HUDSON OROGEN, CANADA

The three-dimensional structure of the eastern Trans-Hudson Orogen (TH O), part of a Paleoproterozoic continent-continent collision zone in c entral North America, is revealed through a network of LITHOPROBE seis mic reflection profiles. The seismic images are interpreted to delinea te a series of stacked thrust sheets essentially confined to the crust . E-W profiles show strong, E-dipping reflections extending throughout the crust while N-S profiles record events outlining antiformal and s ynformal structures. This allows the identification of decollements th at may have localized along pre-existing structures (e.g. possible bas in-bounding extensional faults) and at major rheological boundaries (e .g. basement-cover contact, upper-middle crust transition). The presen t topographic surface displays oblique crustal sections with 10-15 km of structural relief, generated during post-collisional, intracontinen tal transpression of THO as a result of crustal-scale folding and faul ting.