Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon
Mesozoic convergence of the Wrangellia composite terrane with the western margin of North America resulted in the collapse of intervening flysch basins. One of these basins, the Jurassic-Cretaceous Gravina-Nuzotin belt, comprises from south to north, the Gravina sequence and Gravina belt in southeas...
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ftdoajarticles:oai:doaj.org/article:6fa68674a4e748318c49c269c4877f5a 2023-05-15T18:48:45+02:00 Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon Grant W Lowey 2021-08-01T00:00:00Z https://doi.org/10.3934/geosci.2021022 https://doaj.org/article/6fa68674a4e748318c49c269c4877f5a EN eng AIMS Press https://www.aimspress.com/article/doi/10.3934/geosci.2021022?viewType=HTML https://doaj.org/toc/2471-2132 doi:10.3934/geosci.2021022 2471-2132 https://doaj.org/article/6fa68674a4e748318c49c269c4877f5a AIMS Geosciences, Vol 7, Iss 3, Pp 355-389 (2021) tectonic setting flysch basin north american cordillera gravina-nutzotin belt dezadeash formation subgreenschist facies Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.3934/geosci.2021022 2022-12-31T10:37:03Z Mesozoic convergence of the Wrangellia composite terrane with the western margin of North America resulted in the collapse of intervening flysch basins. One of these basins, the Jurassic-Cretaceous Gravina-Nuzotin belt, comprises from south to north, the Gravina sequence and Gravina belt in southeastern Alaska, the Dezadeash Formation in Yukon, and the Nutzotin Mountains sequence in eastern Alaska. Previous work shows that the Gravina sequence and Gravina belt were underthrust > 20 km beneath the margin of North America in mid-Cretaceous time, culminating in amphibolite facies metamorphism. This tectonometamorphic scenario was subsequently applied to the entire Gravina-Nutzotin belt, despite any detailed studies pertaining to the tectonometamorphic evolution of the Dezadeash Formation. The present analysis of the Dezadeash Formation reveals that metamorphic mineral assemblages in sandstone and tuff document subgreenschist, high temperature zeolite facies metamorphism; Kübler indices of illite and Árkai indices of chlorite in mudstone record diagenetic to high anchizone metapelitic conditions; and the color of organic matter (i.e., the Thermal Alteration Index of palynomorphs and the Conodont Alteration Index) and pyrolysis of organic matter in mudstone and hemipelagite beds document thermal maturation at catagenesis to mesogenesis stages. Collectively, the mineralogic and organic thermal indicators in the Dezadeash Formation suggest that strata experienced maximum pressure-temperature conditions of 2.5 ± 0.5 kbar and 250 ± 25 ℃ in the Early Cretaceous. The inferred tectonometamorphic evolution of the Dezadeash Formation does not support the northern part of the Gravina-Nutzotin belt being underthrust > 20 km beneath the western margin of North America in mid-Cretaceous time, thus contrasting sharply with the Gravina sequence and Gravina belt in the southern part of the Gravina-Nutzotin belt. The diverse tectonometamorphic histories recorded by the southern and northern parts of the Gravina-Nutzotin belt ... Article in Journal/Newspaper Alaska Yukon Directory of Open Access Journals: DOAJ Articles Dezadeash ENVELOPE(-137.059,-137.059,60.372,60.372) Jura ENVELOPE(13.501,13.501,68.062,68.062) Nutzotin Mountains ENVELOPE(-140.921,-140.921,61.999,61.999) Yukon AIMS Geosciences 7 3 355 389 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
tectonic setting flysch basin north american cordillera gravina-nutzotin belt dezadeash formation subgreenschist facies Geology QE1-996.5 |
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tectonic setting flysch basin north american cordillera gravina-nutzotin belt dezadeash formation subgreenschist facies Geology QE1-996.5 Grant W Lowey Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
topic_facet |
tectonic setting flysch basin north american cordillera gravina-nutzotin belt dezadeash formation subgreenschist facies Geology QE1-996.5 |
description |
Mesozoic convergence of the Wrangellia composite terrane with the western margin of North America resulted in the collapse of intervening flysch basins. One of these basins, the Jurassic-Cretaceous Gravina-Nuzotin belt, comprises from south to north, the Gravina sequence and Gravina belt in southeastern Alaska, the Dezadeash Formation in Yukon, and the Nutzotin Mountains sequence in eastern Alaska. Previous work shows that the Gravina sequence and Gravina belt were underthrust > 20 km beneath the margin of North America in mid-Cretaceous time, culminating in amphibolite facies metamorphism. This tectonometamorphic scenario was subsequently applied to the entire Gravina-Nutzotin belt, despite any detailed studies pertaining to the tectonometamorphic evolution of the Dezadeash Formation. The present analysis of the Dezadeash Formation reveals that metamorphic mineral assemblages in sandstone and tuff document subgreenschist, high temperature zeolite facies metamorphism; Kübler indices of illite and Árkai indices of chlorite in mudstone record diagenetic to high anchizone metapelitic conditions; and the color of organic matter (i.e., the Thermal Alteration Index of palynomorphs and the Conodont Alteration Index) and pyrolysis of organic matter in mudstone and hemipelagite beds document thermal maturation at catagenesis to mesogenesis stages. Collectively, the mineralogic and organic thermal indicators in the Dezadeash Formation suggest that strata experienced maximum pressure-temperature conditions of 2.5 ± 0.5 kbar and 250 ± 25 ℃ in the Early Cretaceous. The inferred tectonometamorphic evolution of the Dezadeash Formation does not support the northern part of the Gravina-Nutzotin belt being underthrust > 20 km beneath the western margin of North America in mid-Cretaceous time, thus contrasting sharply with the Gravina sequence and Gravina belt in the southern part of the Gravina-Nutzotin belt. The diverse tectonometamorphic histories recorded by the southern and northern parts of the Gravina-Nutzotin belt ... |
format |
Article in Journal/Newspaper |
author |
Grant W Lowey |
author_facet |
Grant W Lowey |
author_sort |
Grant W Lowey |
title |
Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
title_short |
Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
title_full |
Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
title_fullStr |
Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
title_full_unstemmed |
Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon |
title_sort |
very low-grade metamorphism of the dezadeash formation (jura-cretaceous): constraints on the tectonometamorphic history of the dezadeash flysch basin and implications regarding the tectonic evolution of the northern cordillera of alaska and yukon |
publisher |
AIMS Press |
publishDate |
2021 |
url |
https://doi.org/10.3934/geosci.2021022 https://doaj.org/article/6fa68674a4e748318c49c269c4877f5a |
long_lat |
ENVELOPE(-137.059,-137.059,60.372,60.372) ENVELOPE(13.501,13.501,68.062,68.062) ENVELOPE(-140.921,-140.921,61.999,61.999) |
geographic |
Dezadeash Jura Nutzotin Mountains Yukon |
geographic_facet |
Dezadeash Jura Nutzotin Mountains Yukon |
genre |
Alaska Yukon |
genre_facet |
Alaska Yukon |
op_source |
AIMS Geosciences, Vol 7, Iss 3, Pp 355-389 (2021) |
op_relation |
https://www.aimspress.com/article/doi/10.3934/geosci.2021022?viewType=HTML https://doaj.org/toc/2471-2132 doi:10.3934/geosci.2021022 2471-2132 https://doaj.org/article/6fa68674a4e748318c49c269c4877f5a |
op_doi |
https://doi.org/10.3934/geosci.2021022 |
container_title |
AIMS Geosciences |
container_volume |
7 |
container_issue |
3 |
container_start_page |
355 |
op_container_end_page |
389 |
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1766242011693711360 |