Multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield

Linking high-resolution U-Pb and40Ar/ 39Ar thermochronometry with pressure-temperature-deformation paths

R. M. Flowers, K. H. Mahan, S. A. Bowring, M. L. Williams, M. S. Pringle, Kip Hodges

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5-2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7-0.8 GPa to 0.4-0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2-0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89-1.88 Ga implies their juxtaposition at 0.7-0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4-0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.

Original languageEnglish (US)
Article numberTC4003
JournalTectonics
Volume25
Issue number4
DOIs
StatePublished - 2006
Externally publishedYes

Fingerprint

Canadian Shield
unroofing
exhumation
lower crust
continental crust
Lakes
shield
crusts
Rocks
lakes
high resolution
histories
rocks
Apatites
temperature
Tectonics
Temperature
Sediments
lake
metamorphism

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield : Linking high-resolution U-Pb and40Ar/ 39Ar thermochronometry with pressure-temperature-deformation paths. / Flowers, R. M.; Mahan, K. H.; Bowring, S. A.; Williams, M. L.; Pringle, M. S.; Hodges, Kip.

In: Tectonics, Vol. 25, No. 4, TC4003, 2006.

Research output: Contribution to journalArticle

@article{d5333fb6a99f4148a544416cd7f0954d,
title = "Multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield: Linking high-resolution U-Pb and40Ar/ 39Ar thermochronometry with pressure-temperature-deformation paths",
abstract = "New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5-2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7-0.8 GPa to 0.4-0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2-0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89-1.88 Ga implies their juxtaposition at 0.7-0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4-0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.",
author = "Flowers, {R. M.} and Mahan, {K. H.} and Bowring, {S. A.} and Williams, {M. L.} and Pringle, {M. S.} and Kip Hodges",
year = "2006",
doi = "10.1029/2005TC001912",
language = "English (US)",
volume = "25",
journal = "Tectonics",
issn = "0278-7407",
publisher = "American Geophysical Union",
number = "4",

}

TY - JOUR

T1 - Multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield

T2 - Linking high-resolution U-Pb and40Ar/ 39Ar thermochronometry with pressure-temperature-deformation paths

AU - Flowers, R. M.

AU - Mahan, K. H.

AU - Bowring, S. A.

AU - Williams, M. L.

AU - Pringle, M. S.

AU - Hodges, Kip

PY - 2006

Y1 - 2006

N2 - New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5-2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7-0.8 GPa to 0.4-0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2-0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89-1.88 Ga implies their juxtaposition at 0.7-0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4-0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.

AB - New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5-2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7-0.8 GPa to 0.4-0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2-0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89-1.88 Ga implies their juxtaposition at 0.7-0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4-0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.

UR - http://www.scopus.com/inward/record.url?scp=33745408422&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33745408422&partnerID=8YFLogxK

U2 - 10.1029/2005TC001912

DO - 10.1029/2005TC001912

M3 - Article

VL - 25

JO - Tectonics

JF - Tectonics

SN - 0278-7407

IS - 4

M1 - TC4003

ER -