Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls
Analyses of 182 basement cores, when plotted as log U and log Th, show bimodal frequency distributions. Cumulative frequency plots indicate an approximate 35–65% split between the two populations. Histograms of numbers of samples in various rock classes vs. log U fail to explain the bimodal distribu...
Published in: | Canadian Journal of Earth Sciences |
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1979
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crcansciencepubl:10.1139/e79-043 2023-12-17T10:48:21+01:00 Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls Burwash, R. A. 1979 http://dx.doi.org/10.1139/e79-043 http://www.nrcresearchpress.com/doi/pdf/10.1139/e79-043 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 16, issue 3, page 472-483 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1979 crcansciencepubl https://doi.org/10.1139/e79-043 2023-11-19T13:38:50Z Analyses of 182 basement cores, when plotted as log U and log Th, show bimodal frequency distributions. Cumulative frequency plots indicate an approximate 35–65% split between the two populations. Histograms of numbers of samples in various rock classes vs. log U fail to explain the bimodal distribution.A plot of log K vs. log U provides easy visual separation of rocks with varying K/U ratios and U contents. K/U values greater than 3 × 10 4 are ascribed principally to granulite facies metamorphism. K/U values less than 5 × 10 3 represent U-enrichment either in granitic melts or K-metasomatized gneisses. Factor analysis indicates a strong correlation between U, Th. Rb, Pb, and K.The geographic distribution of samples with K/U values greater than 3 × 10 4 can be related to relict Kenoran granulite facies terranes in the subsurface of northeastern Alberta and west central Saskatchewan similar to those mapped on the exposed Shield in northwestern Saskatchewan. These relict granulites could account for most of the samples in the smaller of the two sample populations.The U-enriched rocks are concentrated in three areas: (1) the epizonal, porphyritic granitic plutons of southwestern Saskatchewan, (2) linear quartz monzonite batholiths along the Kasba Lake – Edmonton gravity low, and (3) K-rich gneisses in the Peace River High of northwestern Alberta. In none of these areas is assimilation of large volumes of Aphebian sedimentary rocks indicated. Article in Journal/Newspaper Peace River Canadian Science Publishing (via Crossref) Canada Kasba Lake ENVELOPE(-101.950,-101.950,60.217,60.217) Canadian Journal of Earth Sciences 16 3 472 483 |
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Open Polar |
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Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Burwash, R. A. Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
topic_facet |
General Earth and Planetary Sciences |
description |
Analyses of 182 basement cores, when plotted as log U and log Th, show bimodal frequency distributions. Cumulative frequency plots indicate an approximate 35–65% split between the two populations. Histograms of numbers of samples in various rock classes vs. log U fail to explain the bimodal distribution.A plot of log K vs. log U provides easy visual separation of rocks with varying K/U ratios and U contents. K/U values greater than 3 × 10 4 are ascribed principally to granulite facies metamorphism. K/U values less than 5 × 10 3 represent U-enrichment either in granitic melts or K-metasomatized gneisses. Factor analysis indicates a strong correlation between U, Th. Rb, Pb, and K.The geographic distribution of samples with K/U values greater than 3 × 10 4 can be related to relict Kenoran granulite facies terranes in the subsurface of northeastern Alberta and west central Saskatchewan similar to those mapped on the exposed Shield in northwestern Saskatchewan. These relict granulites could account for most of the samples in the smaller of the two sample populations.The U-enriched rocks are concentrated in three areas: (1) the epizonal, porphyritic granitic plutons of southwestern Saskatchewan, (2) linear quartz monzonite batholiths along the Kasba Lake – Edmonton gravity low, and (3) K-rich gneisses in the Peace River High of northwestern Alberta. In none of these areas is assimilation of large volumes of Aphebian sedimentary rocks indicated. |
format |
Article in Journal/Newspaper |
author |
Burwash, R. A. |
author_facet |
Burwash, R. A. |
author_sort |
Burwash, R. A. |
title |
Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
title_short |
Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
title_full |
Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
title_fullStr |
Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
title_full_unstemmed |
Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls |
title_sort |
uranium and thorium in the precambrian basement of western canada. ii. petrologic and tectonic controls |
publisher |
Canadian Science Publishing |
publishDate |
1979 |
url |
http://dx.doi.org/10.1139/e79-043 http://www.nrcresearchpress.com/doi/pdf/10.1139/e79-043 |
long_lat |
ENVELOPE(-101.950,-101.950,60.217,60.217) |
geographic |
Canada Kasba Lake |
geographic_facet |
Canada Kasba Lake |
genre |
Peace River |
genre_facet |
Peace River |
op_source |
Canadian Journal of Earth Sciences volume 16, issue 3, page 472-483 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e79-043 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
16 |
container_issue |
3 |
container_start_page |
472 |
op_container_end_page |
483 |
_version_ |
1785572487555186688 |