Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T.
Near Pilot Lake, the east boundary of the Fort Smith – Great Slave Lake radiometric high coincides with the contact of a well-foliated, porphyroblastic microcline–plagioclase–quartz-garnet–biotite gneiss 1 (Pilot Lake Gneiss) with a hybrid assemblage of quartzite, mica schist, garnet–cordierite gnei...
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Canadian Science Publishing
1981
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crcansciencepubl:10.1139/e81-081 2023-12-17T10:30:38+01:00 Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. Burwash, R. A. Cape, D. F. 1981 http://dx.doi.org/10.1139/e81-081 http://www.nrcresearchpress.com/doi/pdf/10.1139/e81-081 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 18, issue 5, page 842-851 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1981 crcansciencepubl https://doi.org/10.1139/e81-081 2023-11-19T13:39:08Z Near Pilot Lake, the east boundary of the Fort Smith – Great Slave Lake radiometric high coincides with the contact of a well-foliated, porphyroblastic microcline–plagioclase–quartz-garnet–biotite gneiss 1 (Pilot Lake Gneiss) with a hybrid assemblage of quartzite, mica schist, garnet–cordierite gneiss, and minor amphibolite (Variable Paragneiss). Anomalously high concentrations of uranium and thorium are associated with mafic-rich, lenticular bodies with a mineral assemblage biotite + monazite + zircon + ilmenite + hematite ± apatite ± plagioclase ± quartz. The mafic pods occur within both the Variable Paragneiss and the Pilot Lake Gneiss. Corundum and spinel occur in the mafic lenses and sillimanite, kyanite, and hypersthene in other inclusions in the Pilot Lake Gneiss.The ilmenite–magnetite–monazite–zircon–apatite assemblage is interpreted as a "black sand" concentration in a clastic sedimentary sequence subsequently metamorphosed by a regional granulite facies event. A granitic pluton intruded during the same orogenic cycle assimilated the clastic metasedimentary rocks containing black sand interlayers, becoming enriched in thorium from the monazite. A second metamorphic event at lower P–T conditions, accompanied by strong cataclasis, developed the texture of the Pilot Lake Gneiss as now observed. Shearing within the gneiss locally concentrated hematite + quartz + uranium.Regional tectonic extrapolations suggest that the pyroxene granulite event was Kenoran and the later amphibolite event Hudsonian. Article in Journal/Newspaper Great Slave Lake Canadian Science Publishing (via Crossref) Great Slave Lake ENVELOPE(-114.001,-114.001,61.500,61.500) Fort Smith ENVELOPE(-111.889,-111.889,60.004,60.004) Pilot Lake ENVELOPE(-111.001,-111.001,60.284,60.284) Canadian Journal of Earth Sciences 18 5 842 851 |
institution |
Open Polar |
collection |
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. Cape, D. F. Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
topic_facet |
General Earth and Planetary Sciences |
description |
Near Pilot Lake, the east boundary of the Fort Smith – Great Slave Lake radiometric high coincides with the contact of a well-foliated, porphyroblastic microcline–plagioclase–quartz-garnet–biotite gneiss 1 (Pilot Lake Gneiss) with a hybrid assemblage of quartzite, mica schist, garnet–cordierite gneiss, and minor amphibolite (Variable Paragneiss). Anomalously high concentrations of uranium and thorium are associated with mafic-rich, lenticular bodies with a mineral assemblage biotite + monazite + zircon + ilmenite + hematite ± apatite ± plagioclase ± quartz. The mafic pods occur within both the Variable Paragneiss and the Pilot Lake Gneiss. Corundum and spinel occur in the mafic lenses and sillimanite, kyanite, and hypersthene in other inclusions in the Pilot Lake Gneiss.The ilmenite–magnetite–monazite–zircon–apatite assemblage is interpreted as a "black sand" concentration in a clastic sedimentary sequence subsequently metamorphosed by a regional granulite facies event. A granitic pluton intruded during the same orogenic cycle assimilated the clastic metasedimentary rocks containing black sand interlayers, becoming enriched in thorium from the monazite. A second metamorphic event at lower P–T conditions, accompanied by strong cataclasis, developed the texture of the Pilot Lake Gneiss as now observed. Shearing within the gneiss locally concentrated hematite + quartz + uranium.Regional tectonic extrapolations suggest that the pyroxene granulite event was Kenoran and the later amphibolite event Hudsonian. |
format |
Article in Journal/Newspaper |
author |
Burwash, R. A. Cape, D. F. |
author_facet |
Burwash, R. A. Cape, D. F. |
author_sort |
Burwash, R. A. |
title |
Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
title_short |
Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
title_full |
Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
title_fullStr |
Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
title_full_unstemmed |
Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T. |
title_sort |
petrology of the fort smith - great slave lake radiometric high near pilot lake, n.w.t. |
publisher |
Canadian Science Publishing |
publishDate |
1981 |
url |
http://dx.doi.org/10.1139/e81-081 http://www.nrcresearchpress.com/doi/pdf/10.1139/e81-081 |
long_lat |
ENVELOPE(-114.001,-114.001,61.500,61.500) ENVELOPE(-111.889,-111.889,60.004,60.004) ENVELOPE(-111.001,-111.001,60.284,60.284) |
geographic |
Great Slave Lake Fort Smith Pilot Lake |
geographic_facet |
Great Slave Lake Fort Smith Pilot Lake |
genre |
Great Slave Lake |
genre_facet |
Great Slave Lake |
op_source |
Canadian Journal of Earth Sciences volume 18, issue 5, page 842-851 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e81-081 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
18 |
container_issue |
5 |
container_start_page |
842 |
op_container_end_page |
851 |
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1785583630399045632 |