Redox conditions across the Upper Cambrian in Western Newfoundland, Canada
The lower part of the Martin Point section (~ 110 m - rhythmites) spans the uppermost Shallow Bay and lowermost Green Point formations (uppermost Franconian‒ lowermost Trempealeauan) of the Cow Head Group (western Newfoundland, Canada). It records two post-SPICE events (SPICE – Steptoean Positive Ca...
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ftmemorialuniv:oai:research.library.mun.ca:15986 2023-10-01T03:57:35+02:00 Redox conditions across the Upper Cambrian in Western Newfoundland, Canada Okafor, Miracle-Mary Chisom 2023-02 application/pdf https://research.library.mun.ca/15986/ https://research.library.mun.ca/15986/1/converted.pdf en eng Memorial University of Newfoundland https://research.library.mun.ca/15986/1/converted.pdf Okafor, Miracle-Mary Chisom <https://research.library.mun.ca/view/creator_az/Okafor=3AMiracle-Mary_Chisom=3A=3A.html> (2023) Redox conditions across the Upper Cambrian in Western Newfoundland, Canada. Masters thesis, Memorial University of Newfoundland. thesis_license Thesis NonPeerReviewed 2023 ftmemorialuniv 2023-09-03T06:50:30Z The lower part of the Martin Point section (~ 110 m - rhythmites) spans the uppermost Shallow Bay and lowermost Green Point formations (uppermost Franconian‒ lowermost Trempealeauan) of the Cow Head Group (western Newfoundland, Canada). It records two post-SPICE events (SPICE – Steptoean Positive Carbon Isotope Excursion) marked by negative δ¹³Ccarb excursions (NL1 and NL2) that were also documented in South China. The petrographic and chemical screening of the investigated carbonate samples proves the preservation of at least near-primary geochemical signatures. The proxies of weathering (e.g., Mn, Fe, Al, and ΣREE), bioproductivity (e.g., δ¹³Corg, TOC, P, Ni, Zn, and Cu), and paleoredox (e.g., Cr, Th/U, Ce/Ce*) have been utilized to reconstruct the paleoenvironmental conditions during the post-SPICE events. The TOC, P, Ni, Cu, Cr, ΣREE, Mn, Fe, and U enrichment-factor profiles exhibit a positive pulse at the base of NL2 (upper negative δ¹³Ccarb excursion), followed by a drop. This might have resulted from shoaling organic-rich anoxic waters into an oxygenated shallow environment during transgression, which led to a negative shift in the δ¹³Ccarb and a decrease in TOC contents as well as an increase in the δ¹³Corg. The correlated enrichment in Zn and δ¹⁵Norg values and the Ce/Ce* around unity are consistent with the shoaling scenario. A similar scenario seems to be consistent with NL1 (lower negative δ¹³Ccarb excursion) although the lower resolution of correlated proxy variations makes the interpretations based on a few points and to be therefore taken with caution. The upper part of the Martin Point section spans the upper Martin Point Member (upper Furongian, ~90 m) of the Green Point Formation of the Cow Head Group. It records the HERB event (HERB - Hellnmaria-Red Tops Boundary) marked by a negative δ¹³Ccarb excursion at the base of the Econodontus notchpakensis conodont Zone. The HERB paleoenvironmental proxy enrichment profiles exhibit comparable patterns to those of the post-SPICE, which suggests that the ... Thesis Newfoundland Memorial University of Newfoundland: Research Repository Canada Cow Head ENVELOPE(-57.832,-57.832,49.917,49.917) Shallow Bay ENVELOPE(67.467,67.467,-67.817,-67.817) Green Point ENVELOPE(73.350,73.350,-53.083,-53.083) Martin Point ENVELOPE(-44.683,-44.683,-60.767,-60.767) |
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Open Polar |
collection |
Memorial University of Newfoundland: Research Repository |
op_collection_id |
ftmemorialuniv |
language |
English |
description |
The lower part of the Martin Point section (~ 110 m - rhythmites) spans the uppermost Shallow Bay and lowermost Green Point formations (uppermost Franconian‒ lowermost Trempealeauan) of the Cow Head Group (western Newfoundland, Canada). It records two post-SPICE events (SPICE – Steptoean Positive Carbon Isotope Excursion) marked by negative δ¹³Ccarb excursions (NL1 and NL2) that were also documented in South China. The petrographic and chemical screening of the investigated carbonate samples proves the preservation of at least near-primary geochemical signatures. The proxies of weathering (e.g., Mn, Fe, Al, and ΣREE), bioproductivity (e.g., δ¹³Corg, TOC, P, Ni, Zn, and Cu), and paleoredox (e.g., Cr, Th/U, Ce/Ce*) have been utilized to reconstruct the paleoenvironmental conditions during the post-SPICE events. The TOC, P, Ni, Cu, Cr, ΣREE, Mn, Fe, and U enrichment-factor profiles exhibit a positive pulse at the base of NL2 (upper negative δ¹³Ccarb excursion), followed by a drop. This might have resulted from shoaling organic-rich anoxic waters into an oxygenated shallow environment during transgression, which led to a negative shift in the δ¹³Ccarb and a decrease in TOC contents as well as an increase in the δ¹³Corg. The correlated enrichment in Zn and δ¹⁵Norg values and the Ce/Ce* around unity are consistent with the shoaling scenario. A similar scenario seems to be consistent with NL1 (lower negative δ¹³Ccarb excursion) although the lower resolution of correlated proxy variations makes the interpretations based on a few points and to be therefore taken with caution. The upper part of the Martin Point section spans the upper Martin Point Member (upper Furongian, ~90 m) of the Green Point Formation of the Cow Head Group. It records the HERB event (HERB - Hellnmaria-Red Tops Boundary) marked by a negative δ¹³Ccarb excursion at the base of the Econodontus notchpakensis conodont Zone. The HERB paleoenvironmental proxy enrichment profiles exhibit comparable patterns to those of the post-SPICE, which suggests that the ... |
format |
Thesis |
author |
Okafor, Miracle-Mary Chisom |
spellingShingle |
Okafor, Miracle-Mary Chisom Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
author_facet |
Okafor, Miracle-Mary Chisom |
author_sort |
Okafor, Miracle-Mary Chisom |
title |
Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
title_short |
Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
title_full |
Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
title_fullStr |
Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
title_full_unstemmed |
Redox conditions across the Upper Cambrian in Western Newfoundland, Canada |
title_sort |
redox conditions across the upper cambrian in western newfoundland, canada |
publisher |
Memorial University of Newfoundland |
publishDate |
2023 |
url |
https://research.library.mun.ca/15986/ https://research.library.mun.ca/15986/1/converted.pdf |
long_lat |
ENVELOPE(-57.832,-57.832,49.917,49.917) ENVELOPE(67.467,67.467,-67.817,-67.817) ENVELOPE(73.350,73.350,-53.083,-53.083) ENVELOPE(-44.683,-44.683,-60.767,-60.767) |
geographic |
Canada Cow Head Shallow Bay Green Point Martin Point |
geographic_facet |
Canada Cow Head Shallow Bay Green Point Martin Point |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_relation |
https://research.library.mun.ca/15986/1/converted.pdf Okafor, Miracle-Mary Chisom <https://research.library.mun.ca/view/creator_az/Okafor=3AMiracle-Mary_Chisom=3A=3A.html> (2023) Redox conditions across the Upper Cambrian in Western Newfoundland, Canada. Masters thesis, Memorial University of Newfoundland. |
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thesis_license |
_version_ |
1778529274134790144 |