Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield
New U-Pb geochronology for an extensive exposure of high-pressure granulites in the East Lake Athabasca region of the western Canadian shield is consistent with a history characterized by 2.55 Ga stabilization of cratonic lithosphere, 650 million years of lower crustal residence and cratonic stabili...
Published in: | Contributions to Mineralogy and Petrology |
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Online Access: | http://hdl.handle.net/1885/33423 https://doi.org/10.1007/s00410-008-0301-5 https://openresearch-repository.anu.edu.au/bitstream/1885/33423/5/Flowers_etal_Stabiliz_ISW_2008.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/33423/7/01_Flowers_Stabilization_and_reactivation_2008.pdf.jpg |
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/33423 2024-01-14T10:08:29+01:00 Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield Flowers, R M Bowring, Samuel A Mahan, K H Williams, M L Williams, Ian http://hdl.handle.net/1885/33423 https://doi.org/10.1007/s00410-008-0301-5 https://openresearch-repository.anu.edu.au/bitstream/1885/33423/5/Flowers_etal_Stabiliz_ISW_2008.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/33423/7/01_Flowers_Stabilization_and_reactivation_2008.pdf.jpg unknown Springer 0010-7999 http://hdl.handle.net/1885/33423 doi:10.1007/s00410-008-0301-5 https://openresearch-repository.anu.edu.au/bitstream/1885/33423/5/Flowers_etal_Stabiliz_ISW_2008.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/33423/7/01_Flowers_Stabilization_and_reactivation_2008.pdf.jpg Contributions to Mineralogy and Petrology Keywords: asthenosphere cathodoluminescence craton exhumation granulite facies high pressure ion microprobe recrystallization thermochronology uranium-lead dating zircon Alberta Athabasca Canada Canadian Shield North America Journal article ftanucanberra https://doi.org/10.1007/s00410-008-0301-5 2023-12-15T09:36:25Z New U-Pb geochronology for an extensive exposure of high-pressure granulites in the East Lake Athabasca region of the western Canadian shield is consistent with a history characterized by 2.55 Ga stabilization of cratonic lithosphere, 650 million years of lower crustal residence and cratonic stability, and 1.9 Ga reactivation of the craton during lithospheric attenuation and asthenospheric upwelling. High precision single-grain and fragment zircon data define distinctive discordia arrays between 2.55 and 1.9 Ga. U-Pb ion microprobe spot analyses yield a similar range of U-Pb dates with no obvious correlation between date and cathodoluminescence zonation. We attribute the complex U-Pb zircon systematics to growth of the primary populations during a 2.55 Ga high-pressure granulite facies event (∼1.3 GPa, 850°C) recorded by the dominant mineral assemblage of the mafic granulite gneisses, with subsequent zircon recrystallization and minor secondary zircon growth during a second high-pressure granulite facies event (1.0 GPa, ∼800°C) at 1.9 Ga. The occurrence of two discrete granulite facies metamorphic events in the lower crust, separated by an interval of 650 million years that included isobaric cooling for at least some of this time, suggests that the rocks resided at lower crustal depths until 1.9 Ga. We infer that this phase of lower crustal residence and little tectonic activity is coincident with an extended period of cratonic stability. Detailed structural and thermochronological datasets indicate that multistage unroofing of the lower crustal rocks occurred in the following 200 million years. Extended lower crustal residence would logically be the history inferred for lower crust in most cratonic regions, but the unusual aspect of the history in the East Lake Athabasca region is the subsequent lithospheric reactivation that initiated transport of the lower crust to the surface. We suggest that a weakened strength profile related to the 1.9 Ga heating left the lithosphere susceptible to far-field tectonic ... Article in Journal/Newspaper Lake Athabasca Australian National University: ANU Digital Collections Canada East Lake ENVELOPE(-100.456,-100.456,58.219,58.219) Contributions to Mineralogy and Petrology 156 4 529 549 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: asthenosphere cathodoluminescence craton exhumation granulite facies high pressure ion microprobe recrystallization thermochronology uranium-lead dating zircon Alberta Athabasca Canada Canadian Shield North America |
spellingShingle |
Keywords: asthenosphere cathodoluminescence craton exhumation granulite facies high pressure ion microprobe recrystallization thermochronology uranium-lead dating zircon Alberta Athabasca Canada Canadian Shield North America Flowers, R M Bowring, Samuel A Mahan, K H Williams, M L Williams, Ian Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
topic_facet |
Keywords: asthenosphere cathodoluminescence craton exhumation granulite facies high pressure ion microprobe recrystallization thermochronology uranium-lead dating zircon Alberta Athabasca Canada Canadian Shield North America |
description |
New U-Pb geochronology for an extensive exposure of high-pressure granulites in the East Lake Athabasca region of the western Canadian shield is consistent with a history characterized by 2.55 Ga stabilization of cratonic lithosphere, 650 million years of lower crustal residence and cratonic stability, and 1.9 Ga reactivation of the craton during lithospheric attenuation and asthenospheric upwelling. High precision single-grain and fragment zircon data define distinctive discordia arrays between 2.55 and 1.9 Ga. U-Pb ion microprobe spot analyses yield a similar range of U-Pb dates with no obvious correlation between date and cathodoluminescence zonation. We attribute the complex U-Pb zircon systematics to growth of the primary populations during a 2.55 Ga high-pressure granulite facies event (∼1.3 GPa, 850°C) recorded by the dominant mineral assemblage of the mafic granulite gneisses, with subsequent zircon recrystallization and minor secondary zircon growth during a second high-pressure granulite facies event (1.0 GPa, ∼800°C) at 1.9 Ga. The occurrence of two discrete granulite facies metamorphic events in the lower crust, separated by an interval of 650 million years that included isobaric cooling for at least some of this time, suggests that the rocks resided at lower crustal depths until 1.9 Ga. We infer that this phase of lower crustal residence and little tectonic activity is coincident with an extended period of cratonic stability. Detailed structural and thermochronological datasets indicate that multistage unroofing of the lower crustal rocks occurred in the following 200 million years. Extended lower crustal residence would logically be the history inferred for lower crust in most cratonic regions, but the unusual aspect of the history in the East Lake Athabasca region is the subsequent lithospheric reactivation that initiated transport of the lower crust to the surface. We suggest that a weakened strength profile related to the 1.9 Ga heating left the lithosphere susceptible to far-field tectonic ... |
format |
Article in Journal/Newspaper |
author |
Flowers, R M Bowring, Samuel A Mahan, K H Williams, M L Williams, Ian |
author_facet |
Flowers, R M Bowring, Samuel A Mahan, K H Williams, M L Williams, Ian |
author_sort |
Flowers, R M |
title |
Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
title_short |
Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
title_full |
Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
title_fullStr |
Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
title_full_unstemmed |
Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield |
title_sort |
stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western canadian shield |
publisher |
Springer |
url |
http://hdl.handle.net/1885/33423 https://doi.org/10.1007/s00410-008-0301-5 https://openresearch-repository.anu.edu.au/bitstream/1885/33423/5/Flowers_etal_Stabiliz_ISW_2008.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/33423/7/01_Flowers_Stabilization_and_reactivation_2008.pdf.jpg |
long_lat |
ENVELOPE(-100.456,-100.456,58.219,58.219) |
geographic |
Canada East Lake |
geographic_facet |
Canada East Lake |
genre |
Lake Athabasca |
genre_facet |
Lake Athabasca |
op_source |
Contributions to Mineralogy and Petrology |
op_relation |
0010-7999 http://hdl.handle.net/1885/33423 doi:10.1007/s00410-008-0301-5 https://openresearch-repository.anu.edu.au/bitstream/1885/33423/5/Flowers_etal_Stabiliz_ISW_2008.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/33423/7/01_Flowers_Stabilization_and_reactivation_2008.pdf.jpg |
op_doi |
https://doi.org/10.1007/s00410-008-0301-5 |
container_title |
Contributions to Mineralogy and Petrology |
container_volume |
156 |
container_issue |
4 |
container_start_page |
529 |
op_container_end_page |
549 |
_version_ |
1788062904878104576 |