Basement-controlled structure and evolution of the Queen Charlotte Basin, west coast of Canada
1993; Elsevier BV; Volume: 228; Issue: 1-2 Linguagem: Inglês
10.1016/0040-1951(93)90217-8
ISSN1879-3266
Autores Tópico(s)earthquake and tectonic studies
ResumoAbstract Fault-block tectonics, usually associated with intracontinental areas, characterizes the western part of the North America plate immediately adjacent to the Pacific plate. The long-lived, basement-supported mosaic of fault-bounded blocks controlled the evolution of this part of the west coast of Canada since at least the Late Jurassic, manifesting itself strongly in the Tertiary. This conclusion is based on recently collected geological and geophysical data. Gravity and magnetic maps and seismic profiles reveal orthogonal fault networks across the region, in the Tertiary Queen Charlotte sedimentary basin and on its pre-Tertiary rim. The faults were reactivated, and block movements sometimes inverted, in the Cenozoic. Similarity of fault networks across the region suggests inheritance of many structures in the basin from earlier time. Passage of the region over a mantle hot spot in the Miocene may have been a partial cause of renewed block movements. Crosscutting relationships of large faults, and their displacement histories onshore, preclude regional strike-slip faulting in the Tertiary. Tectonic extension within the basin was small, maximum 10%. The previous model of formation of the Queen Charlotte Basin by continental rifting sensu McKenzie (1978) is negated. Evolution of the region was not affected fundamentally by plate interactions at the adjacent continental margin, in particular by the change from subduction to strike-slip regime at 42 Ma. A similar structural style existed in the area before and after that event.
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