Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard
The Middle Triassic succession of Svalbard forms a pronounced second-order transgressive–regressive sequence. This is represented by deltaic sediments in western Spitsbergen, grading to deep restricted shelf deposits in central and eastern parts of the archipelago. Nine ichnogenera have been recogni...
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Norwegian Polar Institute
2008
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ftjpolarres:oai:journals.openacademia.net:article/2894 2023-05-15T18:02:42+02:00 Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard Mørk, Atle Bromley, Richard G. 2008-12-01 application/pdf https://polarresearch.net/index.php/polar/article/view/2894 https://doi.org/10.3402/polar.v27i3.6191 eng eng Norwegian Polar Institute https://polarresearch.net/index.php/polar/article/view/2894/6521 https://polarresearch.net/index.php/polar/article/view/2894 doi:10.3402/polar.v27i3.6191 Copyright (c) 2018 Polar Research Polar Research; Vol. 27 No. 3 (2008): Special issue: The Boreal Triassic; 339-359 1751-8369 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2008 ftjpolarres https://doi.org/10.3402/polar.v27i3.6191 2021-11-11T19:13:21Z The Middle Triassic succession of Svalbard forms a pronounced second-order transgressive–regressive sequence. This is represented by deltaic sediments in western Spitsbergen, grading to deep restricted shelf deposits in central and eastern parts of the archipelago. Nine ichnogenera have been recognized, which form three local ichnofacies or trace fossil assemblages: a Thalassinoides assemblage that is dominant in low-energy shelf settings, a Taenidium– Rhizocorallium assemblage that occurs in intermediate-energy deltaic and shelf environments, and a Polykladichnus assemblage that dominates high-energy deltaic environments. These three trace fossil assemblages overlap, both as a result of fluctuations in energy level with time and because of differential preservation of the different tiers. The main control of the distribution of the assemblages is an upwards increase in energy regime during progradation of the deltaic sediments along western Spitsbergen, and a contemporaneous decrease in energy regime more distally. The succession has also experienced fluctuating oxygen levels during deposition, as evidenced by very high organic matter contents and mass mortality of juvenile bivalves. These anoxic periods have been interrupted by periods of bioturbation, with the development of extensive tiered ichnocoenoses. Phosphatization of Thalassinoides fills and subsequent modification of the phosphatic fill by compaction has brought about the formation of phosphate nodules. The typical Thalassinoides framework may be recognized on well-exposed bedding surfaces. The phosphate nodules also occur as conglomeratic lag deposits, commonly occurring at the base of siltstone beds, as a result of episodic heavy storms. Article in Journal/Newspaper Polar Research Svalbard Spitsbergen Polar Research (E-Journal) Svalbard Polar Research 27 3 |
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Polar Research (E-Journal) |
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ftjpolarres |
language |
English |
description |
The Middle Triassic succession of Svalbard forms a pronounced second-order transgressive–regressive sequence. This is represented by deltaic sediments in western Spitsbergen, grading to deep restricted shelf deposits in central and eastern parts of the archipelago. Nine ichnogenera have been recognized, which form three local ichnofacies or trace fossil assemblages: a Thalassinoides assemblage that is dominant in low-energy shelf settings, a Taenidium– Rhizocorallium assemblage that occurs in intermediate-energy deltaic and shelf environments, and a Polykladichnus assemblage that dominates high-energy deltaic environments. These three trace fossil assemblages overlap, both as a result of fluctuations in energy level with time and because of differential preservation of the different tiers. The main control of the distribution of the assemblages is an upwards increase in energy regime during progradation of the deltaic sediments along western Spitsbergen, and a contemporaneous decrease in energy regime more distally. The succession has also experienced fluctuating oxygen levels during deposition, as evidenced by very high organic matter contents and mass mortality of juvenile bivalves. These anoxic periods have been interrupted by periods of bioturbation, with the development of extensive tiered ichnocoenoses. Phosphatization of Thalassinoides fills and subsequent modification of the phosphatic fill by compaction has brought about the formation of phosphate nodules. The typical Thalassinoides framework may be recognized on well-exposed bedding surfaces. The phosphate nodules also occur as conglomeratic lag deposits, commonly occurring at the base of siltstone beds, as a result of episodic heavy storms. |
format |
Article in Journal/Newspaper |
author |
Mørk, Atle Bromley, Richard G. |
spellingShingle |
Mørk, Atle Bromley, Richard G. Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
author_facet |
Mørk, Atle Bromley, Richard G. |
author_sort |
Mørk, Atle |
title |
Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
title_short |
Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
title_full |
Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
title_fullStr |
Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
title_full_unstemmed |
Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard |
title_sort |
ichnology of a marine regressive systems tract: the middle triassic of svalbard |
publisher |
Norwegian Polar Institute |
publishDate |
2008 |
url |
https://polarresearch.net/index.php/polar/article/view/2894 https://doi.org/10.3402/polar.v27i3.6191 |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
Polar Research Svalbard Spitsbergen |
genre_facet |
Polar Research Svalbard Spitsbergen |
op_source |
Polar Research; Vol. 27 No. 3 (2008): Special issue: The Boreal Triassic; 339-359 1751-8369 |
op_relation |
https://polarresearch.net/index.php/polar/article/view/2894/6521 https://polarresearch.net/index.php/polar/article/view/2894 doi:10.3402/polar.v27i3.6191 |
op_rights |
Copyright (c) 2018 Polar Research |
op_doi |
https://doi.org/10.3402/polar.v27i3.6191 |
container_title |
Polar Research |
container_volume |
27 |
container_issue |
3 |
_version_ |
1766173206823043072 |