Body-wave tomography of western Canada

J. P. Mercier, M. G. Bostock, J. F. Cassidy, K. Dueker, J. B. Gaherty, Edward Garnero, J. Revenaugh, G. Zandt

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

In this study, we have produced P- and S-wave velocity models for western Canada using 23,420 delay times measured on vertical component seismograms, and 15,805 delay times measured on transverse component seismograms, respectively, from a range of permanent and temporary networks. Resolution is best in southwestern British Columbia, and along the CANOE (northwestern Alberta, southern Yukon and Northwest Territories) and BATHOLITHS (northwestern BC) arrays where the station density is the highest, and fair elsewhere. We focus our attention on two distinct features 1) the transition from Phanerozoic to Cratonic mantle in northwestern Canada, and 2) the complex tectonic environment at the northern terminus of the Cascadia subduction zone where the plate boundary changes from convergent to transform. We find that the main transition from Phanerozoic to Cratonic mantle in northwestern Canada occurs at the Cordilleran deformation front and represents a sharp jump in seismic velocity from - 2% to + 2% over a distance of ~ 50 km. In northern Cascadia, we have imaged and characterized the signature of the subducting Juan de Fuca plate and observed evidence of subduction beyond the northern edge of the slab. We also demonstrate that the Anahim hotspot track is underlain by a - 2% low-velocity zone possibly extending to 400 km beneath Nazko cone that appears to be the source of volcanism in this area. Consequently, we associate the source of magmatism in this area to a mantle-scale rather than lithospheric-scale process.

Original languageEnglish (US)
Pages (from-to)480-492
Number of pages13
JournalTectonophysics
Volume475
Issue number3-4
DOIs
StatePublished - Oct 1 2009

Fingerprint

body wave
Canada
tomography
Earth mantle
seismograms
seismogram
mantle
Phanerozoic
Yukon Territory
time lag
Northwest Territories
Juan de Fuca plate
Alberta
British Columbia
low velocity zone
seismic velocity
plate boundary
P waves
low speed
subduction zone

Keywords

  • Anahim volcanic belt
  • Body-wave tomography
  • Cascadia subduction zone
  • Cordillera/craton transition
  • Western Canada

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geophysics

Cite this

Mercier, J. P., Bostock, M. G., Cassidy, J. F., Dueker, K., Gaherty, J. B., Garnero, E., ... Zandt, G. (2009). Body-wave tomography of western Canada. Tectonophysics, 475(3-4), 480-492. https://doi.org/10.1016/j.tecto.2009.05.030

Body-wave tomography of western Canada. / Mercier, J. P.; Bostock, M. G.; Cassidy, J. F.; Dueker, K.; Gaherty, J. B.; Garnero, Edward; Revenaugh, J.; Zandt, G.

In: Tectonophysics, Vol. 475, No. 3-4, 01.10.2009, p. 480-492.

Research output: Contribution to journalArticle

Mercier, JP, Bostock, MG, Cassidy, JF, Dueker, K, Gaherty, JB, Garnero, E, Revenaugh, J & Zandt, G 2009, 'Body-wave tomography of western Canada', Tectonophysics, vol. 475, no. 3-4, pp. 480-492. https://doi.org/10.1016/j.tecto.2009.05.030
Mercier JP, Bostock MG, Cassidy JF, Dueker K, Gaherty JB, Garnero E et al. Body-wave tomography of western Canada. Tectonophysics. 2009 Oct 1;475(3-4):480-492. https://doi.org/10.1016/j.tecto.2009.05.030
Mercier, J. P. ; Bostock, M. G. ; Cassidy, J. F. ; Dueker, K. ; Gaherty, J. B. ; Garnero, Edward ; Revenaugh, J. ; Zandt, G. / Body-wave tomography of western Canada. In: Tectonophysics. 2009 ; Vol. 475, No. 3-4. pp. 480-492.
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