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TitleTranspression between two warm mafic plates: the Queen Charlotte Fault revisited
AuthorRohr, K M M; Scheidhauer, M; Trehu, A M
SourceJournal of Geophysical Research vol. 105, no. B4, 2000 p. 8147-8172, https://doi.org/10.1029/1999jb900403
Year2000
Alt SeriesGeological Survey of Canada, Contribution Series 1999079
PublisherWiley-Blackwell
Documentserial
Lang.English
Mediapaper; on-line; digital
File formathtml; pdf
ProvinceBritish Columbia; Offshore region
NTS102; 103
Lat/Long WENS-134.0000 -128.0000 56.0000 50.0000
Subjectsgeophysics; tectonics; plate margins; faults, transform; deformation; oceanic crust; subduction; seismic reflection surveys; faulting; Mohorovicic discontinuity; isostasy; faults, strike-slip; gravity anomalies; plate motions
Illustrationslocation maps; geological sketch maps; cross-sections, stratigraphic; seismic reflection profiles; tables; graphs
Released2000 04 10
AbstractThe Queen Charlotte Fault is a transpressive transform plate boundary between the Pacific and North American plates offshore western Canada. Previous models for the accommodation of transpression include internal deformation of both plates adjacent to the plate boundary or oblique subduction of the oceanic plate; the latter has been the preferred model. Both plates are warm and mafic and have similar mechanical structures. New multichannel seismic reflection data show a near-vertical Queen Charlotte Fault down to the first water bottom multiple, significant subsidence east of the Queen Charlotte Fault, a large melange where the fault is in a compressive left step, and faulting which involves oceanic basement. Gravity modeling of profiles indicates that Moho varies fairly smoothly across the plate boundary. Isostatic anomalies indicate that the Pacific plate is flexed downward adjacent to the Queen Charlotte Fault. Upward flexure of North America along with crust thickened relative to crust in the adjacent basin creates topography known as the Queen Charlotte Islands. Combined with other regional studies, these observations suggest that the plate boundary is a vertical strike-slip fault and that transpression is taken up within each plate.
GEOSCAN ID210568