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Steep crustal-scale faults, having their origins in the Late Archean and Early Proterozoic and trending NE-SW, which define the fundamental block lithospheric structure of the North American craton, are seen from geological and geophysical evidence to continue far into the interior of the Late Proterozoic-Phanerozoic Canadian Cordilleran mobile megabelt. This suggests that variously reworked ex-cratonic basement blocks underlie much of the Cordillera. The western edge of the modern craton is probably near the Rocky Mountain-Omineca belt boundary; the Rocky Mountain fold-and-thrust belt on the east side of the Cordillera is evidently rootless and overlies the undisturbed cratonic basement. Phanerozoic differences between the Cordilleran tectonic belts, resulting from a long, dissimilar, multi-cycle history of waxing and waning orogenesis apparent from the rock record, lie chiefly in the degree of indigenous tectonic remobilization and reworking of the ancient crust.
Sommario
Governing principles in regional tectonic evolution.- Rock units in regional tectonic analysis.- Conceptual fundamentals of regional tectonic analysis on continents.- View of the cordilleran mobile megabelts evolution from the craton.- Omineca orogenic belt as tectonotype of the Eastern Cordilleran miogeosyncline.- Broad look at geodynamial mechanisms of crustal restructuring in the Cordilleran orogens and median massifs.- Lessons from Cordilleran geology for the methodology of regional tectonic analysis of mobile megabelts.- Practical utility of rock evidence and geophysical studies in restoring regional tectonic history in mobile megabelts.
