The teleseismic signature of fossil subduction: Northwestern Canada

J. P. Mercier, M. G. Bostock, P. Audet, J. B. Gaherty, Edward Garnero, Justin Revenaugh

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Between June 2003 and September 2005, 20 broadband, three-component seismometers were deployed along the MacKenzie-Liard Highway in Canada's Northwest Territories as part of the joint Lithoprobe-IRIS Canada Northwest Experiment (CANOE). These stations traverse a paleo-Proterozoic suture and subduction zone that has been previously documented to mantle depths using seismic reflection profiling. Teleseismic receiver functions computed from ∼250 earthquakes clearly reveal the response of the ancient subduction zone. On the radial component, the suture is evident as a direct conversion from the Moho, the depth of which increases from ∼30 km to ∼50 km over a horizontal distance of ∼70 km before its signature disappears. The structure is still better defined on the transverse component where the Moho appears as the upper boundary of a 10 km thick layer of anisotropy that can be traced from 30 km to at least 90 km depth. The seismic response of this layer is characterized by a frequency dependence that can be modeled by upper and lower boundaries that are discontinuous in material properties and their gradients, respectively. Anisotropy can be characterized by a ±5% variation in shear velocity and hexagonal symmetry with a fast axis that plunges at an oblique angle to the subduction plane. The identification of this structure provides an unambiguous connection between fossil subduction and fine-scale, anisotropic mantle layering. Previous documentation of similar layering below the adjacent Slave province and from a range of Precambrian terranes across the globe provides strong support for the thesis that early cratonic blocks were stabilized through processes of shallow subduction.

Original languageEnglish (US)
Article numberB04308
JournalJournal of Geophysical Research: Solid Earth
Volume113
Issue number4
DOIs
StatePublished - Apr 4 2008

Fingerprint

fossils
Canada
Anisotropy
subduction
Seismographs
signatures
fossil
Moho
subduction zone
Seismic response
anisotropy
Lithoprobe
mantle
Materials properties
Earthquakes
frequency dependence
slave
suture zone
seismograph
seismic response

ASJC Scopus subject areas

  • Atmospheric Science
  • Astronomy and Astrophysics
  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Oceanography

Cite this

The teleseismic signature of fossil subduction : Northwestern Canada. / Mercier, J. P.; Bostock, M. G.; Audet, P.; Gaherty, J. B.; Garnero, Edward; Revenaugh, Justin.

In: Journal of Geophysical Research: Solid Earth, Vol. 113, No. 4, B04308, 04.04.2008.

Research output: Contribution to journalArticle

Mercier, J. P. ; Bostock, M. G. ; Audet, P. ; Gaherty, J. B. ; Garnero, Edward ; Revenaugh, Justin. / The teleseismic signature of fossil subduction : Northwestern Canada. In: Journal of Geophysical Research: Solid Earth. 2008 ; Vol. 113, No. 4.
@article{5126887f30f34befb765c6ca5bfd78f2,
title = "The teleseismic signature of fossil subduction: Northwestern Canada",
abstract = "Between June 2003 and September 2005, 20 broadband, three-component seismometers were deployed along the MacKenzie-Liard Highway in Canada's Northwest Territories as part of the joint Lithoprobe-IRIS Canada Northwest Experiment (CANOE). These stations traverse a paleo-Proterozoic suture and subduction zone that has been previously documented to mantle depths using seismic reflection profiling. Teleseismic receiver functions computed from ∼250 earthquakes clearly reveal the response of the ancient subduction zone. On the radial component, the suture is evident as a direct conversion from the Moho, the depth of which increases from ∼30 km to ∼50 km over a horizontal distance of ∼70 km before its signature disappears. The structure is still better defined on the transverse component where the Moho appears as the upper boundary of a 10 km thick layer of anisotropy that can be traced from 30 km to at least 90 km depth. The seismic response of this layer is characterized by a frequency dependence that can be modeled by upper and lower boundaries that are discontinuous in material properties and their gradients, respectively. Anisotropy can be characterized by a ±5{\%} variation in shear velocity and hexagonal symmetry with a fast axis that plunges at an oblique angle to the subduction plane. The identification of this structure provides an unambiguous connection between fossil subduction and fine-scale, anisotropic mantle layering. Previous documentation of similar layering below the adjacent Slave province and from a range of Precambrian terranes across the globe provides strong support for the thesis that early cratonic blocks were stabilized through processes of shallow subduction.",
author = "Mercier, {J. P.} and Bostock, {M. G.} and P. Audet and Gaherty, {J. B.} and Edward Garnero and Justin Revenaugh",
year = "2008",
month = "4",
day = "4",
doi = "10.1029/2007JB005127",
language = "English (US)",
volume = "113",
journal = "Journal of Geophysical Research: Atmospheres",
issn = "2169-897X",
publisher = "Wiley-Blackwell",
number = "4",

}

TY - JOUR

T1 - The teleseismic signature of fossil subduction

T2 - Northwestern Canada

AU - Mercier, J. P.

AU - Bostock, M. G.

AU - Audet, P.

AU - Gaherty, J. B.

AU - Garnero, Edward

AU - Revenaugh, Justin

PY - 2008/4/4

Y1 - 2008/4/4

N2 - Between June 2003 and September 2005, 20 broadband, three-component seismometers were deployed along the MacKenzie-Liard Highway in Canada's Northwest Territories as part of the joint Lithoprobe-IRIS Canada Northwest Experiment (CANOE). These stations traverse a paleo-Proterozoic suture and subduction zone that has been previously documented to mantle depths using seismic reflection profiling. Teleseismic receiver functions computed from ∼250 earthquakes clearly reveal the response of the ancient subduction zone. On the radial component, the suture is evident as a direct conversion from the Moho, the depth of which increases from ∼30 km to ∼50 km over a horizontal distance of ∼70 km before its signature disappears. The structure is still better defined on the transverse component where the Moho appears as the upper boundary of a 10 km thick layer of anisotropy that can be traced from 30 km to at least 90 km depth. The seismic response of this layer is characterized by a frequency dependence that can be modeled by upper and lower boundaries that are discontinuous in material properties and their gradients, respectively. Anisotropy can be characterized by a ±5% variation in shear velocity and hexagonal symmetry with a fast axis that plunges at an oblique angle to the subduction plane. The identification of this structure provides an unambiguous connection between fossil subduction and fine-scale, anisotropic mantle layering. Previous documentation of similar layering below the adjacent Slave province and from a range of Precambrian terranes across the globe provides strong support for the thesis that early cratonic blocks were stabilized through processes of shallow subduction.

AB - Between June 2003 and September 2005, 20 broadband, three-component seismometers were deployed along the MacKenzie-Liard Highway in Canada's Northwest Territories as part of the joint Lithoprobe-IRIS Canada Northwest Experiment (CANOE). These stations traverse a paleo-Proterozoic suture and subduction zone that has been previously documented to mantle depths using seismic reflection profiling. Teleseismic receiver functions computed from ∼250 earthquakes clearly reveal the response of the ancient subduction zone. On the radial component, the suture is evident as a direct conversion from the Moho, the depth of which increases from ∼30 km to ∼50 km over a horizontal distance of ∼70 km before its signature disappears. The structure is still better defined on the transverse component where the Moho appears as the upper boundary of a 10 km thick layer of anisotropy that can be traced from 30 km to at least 90 km depth. The seismic response of this layer is characterized by a frequency dependence that can be modeled by upper and lower boundaries that are discontinuous in material properties and their gradients, respectively. Anisotropy can be characterized by a ±5% variation in shear velocity and hexagonal symmetry with a fast axis that plunges at an oblique angle to the subduction plane. The identification of this structure provides an unambiguous connection between fossil subduction and fine-scale, anisotropic mantle layering. Previous documentation of similar layering below the adjacent Slave province and from a range of Precambrian terranes across the globe provides strong support for the thesis that early cratonic blocks were stabilized through processes of shallow subduction.

UR - http://www.scopus.com/inward/record.url?scp=45149110430&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=45149110430&partnerID=8YFLogxK

U2 - 10.1029/2007JB005127

DO - 10.1029/2007JB005127

M3 - Article

AN - SCOPUS:45149110430

VL - 113

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

SN - 2169-897X

IS - 4

M1 - B04308

ER -