Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska
The Lower Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska hosts a high-grade uranium-thorium deposit with past production. The complex is a circular body (~3 km in diameter) which intruded Paleozoic granitoids as well as metasedi...
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2023
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ftdoajarticles:oai:doaj.org/article:26cdd698b7db4fc69d1dd92382744bff 2023-09-26T15:22:22+02:00 Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska Jaroslav Dostal 2023-07-01T00:00:00Z https://doi.org/10.3390/min13081032 https://doaj.org/article/26cdd698b7db4fc69d1dd92382744bff EN eng MDPI AG https://www.mdpi.com/2075-163X/13/8/1032 https://doaj.org/toc/2075-163X doi:10.3390/min13081032 2075-163X https://doaj.org/article/26cdd698b7db4fc69d1dd92382744bff Minerals, Vol 13, Iss 1032, p 1032 (2023) peralkaline granite Alaska uranium thorium rare earth elements deposit Mineralogy QE351-399.2 article 2023 ftdoajarticles https://doi.org/10.3390/min13081032 2023-08-27T00:35:08Z The Lower Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska hosts a high-grade uranium-thorium deposit with past production. The complex is a circular body (~3 km in diameter) which intruded Paleozoic granitoids as well as metasedimentary and metavolcanic rocks of the Alexander Terrane of the North American Cordillera. This shallow seated intrusion, which is composed of fractionated peralkaline granites, is a zoned body with a dominant core of arfvedsonite granite and a rim of aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystallize from the magma. Both arfvedsonite and aegirine granites have overlapping compositions. The rocks have high contents of rare earth elements, Th, U and high field strength elements (Zr, Nb, Hf and Ta) and low contents of Sr, Ba, Eu and Ti, typical of peralkaline granites. The complex hosts structurally controlled rare metal mineralization, which is associated with the late-stage of magma evolution and hydrothermal fluids. Fluorine complexing played a role during the transportation of rare metals in hydrothermal fluids. The U-Th deposit, which occurs at the margin of the aegirine granite zone, includes structurally controlled shear zone-hosted lenses and irregularly shaped pipe-like orebodies. U-Th mineralization is associated with desilicified and albitized granitic rocks and includes mainly uranothorite and uraninite. These minerals mostly form small ovoids in veinlets typically 0.1 to 1 mm wide. The mine produced about 77,000 t of ore at a grade of ~0.76% U 3 O 8 and 3% of ThO 2 . The parent magma of the pluton was likely derived from a metasomatized lithospheric source (mantle or lower crust), which was enriched by subduction related processes during Paleozoic time. Article in Journal/Newspaper Prince of Wales Island Alaska Directory of Open Access Journals: DOAJ Articles Prince of Wales Island ENVELOPE(-99.001,-99.001,72.668,72.668) Minerals 13 8 1032 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
peralkaline granite Alaska uranium thorium rare earth elements deposit Mineralogy QE351-399.2 |
spellingShingle |
peralkaline granite Alaska uranium thorium rare earth elements deposit Mineralogy QE351-399.2 Jaroslav Dostal Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
topic_facet |
peralkaline granite Alaska uranium thorium rare earth elements deposit Mineralogy QE351-399.2 |
description |
The Lower Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska hosts a high-grade uranium-thorium deposit with past production. The complex is a circular body (~3 km in diameter) which intruded Paleozoic granitoids as well as metasedimentary and metavolcanic rocks of the Alexander Terrane of the North American Cordillera. This shallow seated intrusion, which is composed of fractionated peralkaline granites, is a zoned body with a dominant core of arfvedsonite granite and a rim of aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystallize from the magma. Both arfvedsonite and aegirine granites have overlapping compositions. The rocks have high contents of rare earth elements, Th, U and high field strength elements (Zr, Nb, Hf and Ta) and low contents of Sr, Ba, Eu and Ti, typical of peralkaline granites. The complex hosts structurally controlled rare metal mineralization, which is associated with the late-stage of magma evolution and hydrothermal fluids. Fluorine complexing played a role during the transportation of rare metals in hydrothermal fluids. The U-Th deposit, which occurs at the margin of the aegirine granite zone, includes structurally controlled shear zone-hosted lenses and irregularly shaped pipe-like orebodies. U-Th mineralization is associated with desilicified and albitized granitic rocks and includes mainly uranothorite and uraninite. These minerals mostly form small ovoids in veinlets typically 0.1 to 1 mm wide. The mine produced about 77,000 t of ore at a grade of ~0.76% U 3 O 8 and 3% of ThO 2 . The parent magma of the pluton was likely derived from a metasomatized lithospheric source (mantle or lower crust), which was enriched by subduction related processes during Paleozoic time. |
format |
Article in Journal/Newspaper |
author |
Jaroslav Dostal |
author_facet |
Jaroslav Dostal |
author_sort |
Jaroslav Dostal |
title |
Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
title_short |
Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
title_full |
Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
title_fullStr |
Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
title_full_unstemmed |
Jurassic Uranium-Thorium Deposit of Peralkaline Granitic Rocks, Bokan Mountain, Prince of Wales Island, Southeastern Alaska |
title_sort |
jurassic uranium-thorium deposit of peralkaline granitic rocks, bokan mountain, prince of wales island, southeastern alaska |
publisher |
MDPI AG |
publishDate |
2023 |
url |
https://doi.org/10.3390/min13081032 https://doaj.org/article/26cdd698b7db4fc69d1dd92382744bff |
long_lat |
ENVELOPE(-99.001,-99.001,72.668,72.668) |
geographic |
Prince of Wales Island |
geographic_facet |
Prince of Wales Island |
genre |
Prince of Wales Island Alaska |
genre_facet |
Prince of Wales Island Alaska |
op_source |
Minerals, Vol 13, Iss 1032, p 1032 (2023) |
op_relation |
https://www.mdpi.com/2075-163X/13/8/1032 https://doaj.org/toc/2075-163X doi:10.3390/min13081032 2075-163X https://doaj.org/article/26cdd698b7db4fc69d1dd92382744bff |
op_doi |
https://doi.org/10.3390/min13081032 |
container_title |
Minerals |
container_volume |
13 |
container_issue |
8 |
container_start_page |
1032 |
_version_ |
1778148003043868672 |