Evidence for underthrusting beneath the Queen Charlotte Margin, British Columbia, from teleseismic receiver function analysis
A. M. M. Bustin,
R. D. Hyndman,
H. Kao,
J. F. Cassidy,
Corresponding Author
A. M. M. Bustin
School of Earth and Ocean Sciences, University of Victoria, PO Box 3055 , Victoria BC V8W 3P6 , Canada. E-mail: [email protected]
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Now at: Earth and Ocean Sciences, University of British Columbia, 6339 Stores Rd, Vancouver BC V6T 1Z4, Canada.Search for more papers by this authorR. D. Hyndman
School of Earth and Ocean Sciences, University of Victoria, PO Box 3055 , Victoria BC V8W 3P6 , Canada. E-mail: [email protected]
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorH. Kao
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorJ. F. Cassidy
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorA. M. M. Bustin,
R. D. Hyndman,
H. Kao,
J. F. Cassidy,
Corresponding Author
A. M. M. Bustin
School of Earth and Ocean Sciences, University of Victoria, PO Box 3055 , Victoria BC V8W 3P6 , Canada. E-mail: [email protected]
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Now at: Earth and Ocean Sciences, University of British Columbia, 6339 Stores Rd, Vancouver BC V6T 1Z4, Canada.Search for more papers by this authorR. D. Hyndman
School of Earth and Ocean Sciences, University of Victoria, PO Box 3055 , Victoria BC V8W 3P6 , Canada. E-mail: [email protected]
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorH. Kao
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorJ. F. Cassidy
Pacific Geoscience Centre, Geological Survey of Canada, PO Box 6000 , Sidney BC V8L 4B2 , Canada
Search for more papers by this authorSUMMARY
The Queen Charlotte Fault zone is the transpressive boundary between the North America and Pacific Plates along the northwestern margin of British Columbia. Two models have been suggested for the accommodation of the ∼20 mm yr−1 of convergence along the fault boundary: (1) underthrusting; (2) internal crustal deformation. Strong evidence supporting an underthrusting model is provided by a detailed teleseismic receiver function analysis that defines the underthrusting slab. Forward and inverse modelling techniques were applied to receiver function data calculated at two permanent and four temporary seismic stations within the Queen Charlotte Islands. The modelling reveals a ∼10 km thick low-velocity zone dipping eastward at 28° interpreted to be underthrusting oceanic crust. The oceanic crust is located beneath a thin (28 km) eastward thickening (10°) continental crust.
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