Subduction beneath Laurentia modified the eastern North American cratonic edge

Evidence from P wave and S wave tomography

A. Boyce (Corresponding Author), I. D. Bastow, F. A. Darbyshire, A. G. Ellwood, A. Gilligan, Vadim Levin, W. Menke

Research output: Contribution to journalArticle

14 Citations (Scopus)
4 Downloads (Pure)

Abstract

The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (∼250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ∼300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation. ©2016. The Authors.
Original languageEnglish
Pages (from-to)5013-5030
Number of pages18
JournalJournal of Geophysical Research: Solid Earth
Volume121
Issue number7
Early online date2 Jul 2016
DOIs
Publication statusPublished - Jul 2016

Fingerprint

keels
Laurentia
Tectonics
P waves
tomography
S waves
P-wave
Tomography
S-wave
Archean
Seismic waves
subduction
Proterozoic
tectonics
Earth mantle
cratons
seismic waves
seismic wave
craton
mantle

Keywords

  • Body wave Tomography
  • Cratonic Margins
  • Grenville Orogeny
  • SE Canada

Cite this

Subduction beneath Laurentia modified the eastern North American cratonic edge : Evidence from P wave and S wave tomography. / Boyce, A. (Corresponding Author); Bastow, I. D.; Darbyshire, F. A.; Ellwood, A. G.; Gilligan, A.; Levin, Vadim; Menke, W.

In: Journal of Geophysical Research: Solid Earth, Vol. 121, No. 7, 07.2016, p. 5013-5030.

Research output: Contribution to journalArticle

Boyce, A. ; Bastow, I. D. ; Darbyshire, F. A. ; Ellwood, A. G. ; Gilligan, A. ; Levin, Vadim ; Menke, W. / Subduction beneath Laurentia modified the eastern North American cratonic edge : Evidence from P wave and S wave tomography. In: Journal of Geophysical Research: Solid Earth. 2016 ; Vol. 121, No. 7. pp. 5013-5030.
@article{c60c14abd7e84a81b74aae55e3b082c1,
title = "Subduction beneath Laurentia modified the eastern North American cratonic edge: Evidence from P wave and S wave tomography",
abstract = "The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (∼250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Qu{\'e}bec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ∼300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation. {\circledC}2016. The Authors.",
keywords = "Body wave Tomography, Cratonic Margins, Grenville Orogeny, SE Canada",
author = "A. Boyce and Bastow, {I. D.} and Darbyshire, {F. A.} and Ellwood, {A. G.} and A. Gilligan and Vadim Levin and W. Menke",
note = "Funding Information: NERC Doctoral Training Partnership: Science and Solutions for a Changing Planet and Leverhulme Trust",
year = "2016",
month = "7",
doi = "10.1002/2016JB012838",
language = "English",
volume = "121",
pages = "5013--5030",
journal = "Journal of Geophysical Research: Solid Earth",
issn = "2169-9313",
publisher = "Wiley-Blackwell",
number = "7",

}

TY - JOUR

T1 - Subduction beneath Laurentia modified the eastern North American cratonic edge

T2 - Evidence from P wave and S wave tomography

AU - Boyce, A.

AU - Bastow, I. D.

AU - Darbyshire, F. A.

AU - Ellwood, A. G.

AU - Gilligan, A.

AU - Levin, Vadim

AU - Menke, W.

N1 - Funding Information: NERC Doctoral Training Partnership: Science and Solutions for a Changing Planet and Leverhulme Trust

PY - 2016/7

Y1 - 2016/7

N2 - The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (∼250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ∼300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation. ©2016. The Authors.

AB - The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (∼250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ∼300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation. ©2016. The Authors.

KW - Body wave Tomography

KW - Cratonic Margins

KW - Grenville Orogeny

KW - SE Canada

U2 - 10.1002/2016JB012838

DO - 10.1002/2016JB012838

M3 - Article

VL - 121

SP - 5013

EP - 5030

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 2169-9313

IS - 7

ER -