The Cordilleran lithosphere of northwestern Canada: nature and state from a geophysical synthesis
Abstract
Various geophysical and geological data indicate that the lithosphere in the northern Canadian Cordillera (NCC) is thin and hot due to its position in a former arc and back arc setting. However, models of the origin and nature of the lithospheric mantle are debated and direct constraints on lithospheric mantle structure are sparse. The deployment of various broadband networks across the region, including the USArray Transportable Array, in combination with remote sensing and potential field methods, now afford an opportunity to study the structure and dynamics of the Cordilleran crust and mantle.
Here we presents the results from a number of recent geophysical studies, most predominantly seismic structural results, which together characterize the NCC lithosphere at different scales. These include receiver functions, teleseismic shear-wave splitting, surface-wave and teleseismic body-wave tomography, gravity anomalies, and Curie depth. These models indicate that: the Moho is flat at ~30-35 km depth; the lithosphere-asthenosphere boundary is located at ~50-60 km; and the Craton lithosphere extends beneath the eastern part of the Cordillera. Toward the south of the NCC, we also identify a dipping structure anchored beneath the Cordillera Deformation Front. From these results we examine three simple end-member tectonic models which potentially explain the observations. These results, combined with geologic evidence, favor models where the lithosphere of the NCC is either exotic or the result of progressive thickening and cooling since the Miocene.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T33C..02S
- Keywords:
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- 1038 Mantle processes;
- GEOCHEMISTRY;
- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS