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Frederick Cook, University of Calgary (Canada)
Don White, Geological Survey of Canada (Canada)
Alan Jones, Dublin Institute for Advanced Studies (Ireland)
David Eaton, University of Calgary (Canada)
Jeremy Hall, Memorial University of Newfoundland (Canada)
Ronald Clowes, University of British Columbia (Canada)
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Analyses and comparisons of data collected during the Lithoprobe and associated projects in Canada lead to the conclusion that the continental geophysical Moho appears to be a deceptively simple feature; it has a variety of signatures at different scales that preclude a single, universally applicable interpretation. While the generally large-scale characteristics of the Moho are well known - it is a relatively abrupt refraction velocity contrast that typically displays a dramatic downward decrease in seismic reflectivity - its origin is perhaps best determined by careful analyses of its structural details, and these are complex and varied.
The available data in Canada, and elsewhere, consistently display variations that can occur over relatively short lateral distances (10's of km or less), as well as a variety of configurations between lower crustal reflections, the Moho, and upper mantle reflections. An implication of the observation of varied and complex lower crust - Moho - upper mantle geometry is that the crust-mantle transition is similarly complex and variable. This in turn leads to the conclusion that, in contrast to the oceanic realm, the continental Moho is neither a simple boundary, nor is it likely to be the same everywhere.
Furthermore, it appears that in a number of areas the geophysical boundary may be superimposed onto older crustal fabric by thermal, metamorphic, and/or mechanical processes with a consequence that old crustal rocks and structures beneath the geophysical Moho may be preserved.
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