Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies
International audience The Upper Cambrian at the Martin Point section (∼110 m-thick) in western Newfoundland is a part of the Cow Head Group and partially spans the coeval Tuckers Cove and the Martin Point members of the Shallow Bay and Green Point formations, respectively. These units comprise alte...
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Online Access: | https://brgm.hal.science/hal-04582104 https://brgm.hal.science/hal-04582104/document https://brgm.hal.science/hal-04582104/file/Gonz%C3%A1lez%20Robacio%20et%20al.%20-%202024%20-%20Paleoenvironmental%20variations%20during%20the%20Late%20Camb.pdf https://doi.org/10.1016/j.marpetgeo.2024.106817 |
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ftbrgm:oai:HAL:hal-04582104v1 2024-09-15T18:20:03+00:00 Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies González Robacio, Luisa Azmy, Karem Guéguen, Bleuenn Claret, Francis Memorial University of Newfoundland = Université Memorial de Terre-Neuve St. John's, Canada (MUN) Observatoire des Sciences de l'Univers de Rennes (OSUR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Bureau de Recherches Géologiques et Minières (BRGM) This project was supported by funding (to Karem Azmy) from MITACS and the Petroleum Exploration Enhancement Program (PEEP), NL, Canada. 2024-07 https://brgm.hal.science/hal-04582104 https://brgm.hal.science/hal-04582104/document https://brgm.hal.science/hal-04582104/file/Gonz%C3%A1lez%20Robacio%20et%20al.%20-%202024%20-%20Paleoenvironmental%20variations%20during%20the%20Late%20Camb.pdf https://doi.org/10.1016/j.marpetgeo.2024.106817 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.marpetgeo.2024.106817 hal-04582104 https://brgm.hal.science/hal-04582104 https://brgm.hal.science/hal-04582104/document https://brgm.hal.science/hal-04582104/file/Gonz%C3%A1lez%20Robacio%20et%20al.%20-%202024%20-%20Paleoenvironmental%20variations%20during%20the%20Late%20Camb.pdf doi:10.1016/j.marpetgeo.2024.106817 ISSN: 0264-8172 Marine and Petroleum Geology https://brgm.hal.science/hal-04582104 Marine and Petroleum Geology, 2024, 165, pp.106817. ⟨10.1016/j.marpetgeo.2024.106817⟩ Upper Cambrian paleoenvironment I/(Ca+Mg) ratiosZn-isotopes Eastern laurentia Martin point (Western Newfoundland Canada) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2024 ftbrgm https://doi.org/10.1016/j.marpetgeo.2024.106817 2024-07-25T23:34:53Z International audience The Upper Cambrian at the Martin Point section (∼110 m-thick) in western Newfoundland is a part of the Cow Head Group and partially spans the coeval Tuckers Cove and the Martin Point members of the Shallow Bay and Green Point formations, respectively. These units comprise alternating shale, minor conglomerate beds, and limestone rhythmites of a toe-of-slope apron. Earlier studies of the C-isotope profile, based on the lime mudstone interbeds, documented global negative δ13Ccarb shifts (from old to young: NL1, NL2, HERB) correlated with the lowermost Proconodontus posterocostatus, Proconodontus muelleri and base of Eoconodontus notchpeakensis conodont zones, respectively (post-Steptoean Positive Carbon Isotope Excursion NL1 and NL2 and Hellnmaria-Red Tops Boundary-HERB). Samples were extracted from the most preserved spots of micritic to near-micritic grain size (≤4 μm−10 μm). Fabric retention confirms petrographic preservation and insignificant correlations (R2 ≤ 0.1) of diagenetic proxies (e.g., Sr) with their environmental counterparts support the preservation of at least near-primary geochemical signatures. The paleoenvironmental proxies (TOC, Zn, P, Cu, Al/Ti, Mn, Fe, V, Mo) support dominant dysoxic conditions. The δ66Zn values (0.09–0.73 ‰ JMC Lyon) and (I/(Ca + Mg)) ratios (0.02–0.48 μmol/mol) vary consistently throughout the studied events. The minor decreases in δ66Zn values seem to denote inhibition of bioproductivity in a dysoxic water column, consistent with warm and humid climate during general transgressive settings and shoaling of organic-rich water into the shallow environment. The low I/(Ca + Mg) ratios (<0.5 μmol/mol) reinforce this interpretation, suggesting general dysoxic settings throughout the entire section. Article in Journal/Newspaper Newfoundland BRGM: HAL (Bureau de Recherches Géologiques et Minières) Marine and Petroleum Geology 165 106817 |
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BRGM: HAL (Bureau de Recherches Géologiques et Minières) |
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ftbrgm |
language |
English |
topic |
Upper Cambrian paleoenvironment I/(Ca+Mg) ratiosZn-isotopes Eastern laurentia Martin point (Western Newfoundland Canada) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Upper Cambrian paleoenvironment I/(Ca+Mg) ratiosZn-isotopes Eastern laurentia Martin point (Western Newfoundland Canada) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences González Robacio, Luisa Azmy, Karem Guéguen, Bleuenn Claret, Francis Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
topic_facet |
Upper Cambrian paleoenvironment I/(Ca+Mg) ratiosZn-isotopes Eastern laurentia Martin point (Western Newfoundland Canada) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience The Upper Cambrian at the Martin Point section (∼110 m-thick) in western Newfoundland is a part of the Cow Head Group and partially spans the coeval Tuckers Cove and the Martin Point members of the Shallow Bay and Green Point formations, respectively. These units comprise alternating shale, minor conglomerate beds, and limestone rhythmites of a toe-of-slope apron. Earlier studies of the C-isotope profile, based on the lime mudstone interbeds, documented global negative δ13Ccarb shifts (from old to young: NL1, NL2, HERB) correlated with the lowermost Proconodontus posterocostatus, Proconodontus muelleri and base of Eoconodontus notchpeakensis conodont zones, respectively (post-Steptoean Positive Carbon Isotope Excursion NL1 and NL2 and Hellnmaria-Red Tops Boundary-HERB). Samples were extracted from the most preserved spots of micritic to near-micritic grain size (≤4 μm−10 μm). Fabric retention confirms petrographic preservation and insignificant correlations (R2 ≤ 0.1) of diagenetic proxies (e.g., Sr) with their environmental counterparts support the preservation of at least near-primary geochemical signatures. The paleoenvironmental proxies (TOC, Zn, P, Cu, Al/Ti, Mn, Fe, V, Mo) support dominant dysoxic conditions. The δ66Zn values (0.09–0.73 ‰ JMC Lyon) and (I/(Ca + Mg)) ratios (0.02–0.48 μmol/mol) vary consistently throughout the studied events. The minor decreases in δ66Zn values seem to denote inhibition of bioproductivity in a dysoxic water column, consistent with warm and humid climate during general transgressive settings and shoaling of organic-rich water into the shallow environment. The low I/(Ca + Mg) ratios (<0.5 μmol/mol) reinforce this interpretation, suggesting general dysoxic settings throughout the entire section. |
author2 |
Memorial University of Newfoundland = Université Memorial de Terre-Neuve St. John's, Canada (MUN) Observatoire des Sciences de l'Univers de Rennes (OSUR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Bureau de Recherches Géologiques et Minières (BRGM) This project was supported by funding (to Karem Azmy) from MITACS and the Petroleum Exploration Enhancement Program (PEEP), NL, Canada. |
format |
Article in Journal/Newspaper |
author |
González Robacio, Luisa Azmy, Karem Guéguen, Bleuenn Claret, Francis |
author_facet |
González Robacio, Luisa Azmy, Karem Guéguen, Bleuenn Claret, Francis |
author_sort |
González Robacio, Luisa |
title |
Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
title_short |
Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
title_full |
Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
title_fullStr |
Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
title_full_unstemmed |
Paleoenvironmental variations during the Late Cambrian: Implications from Zn isotopes, I/(Ca+Mg) ratios, and other elemental proxies |
title_sort |
paleoenvironmental variations during the late cambrian: implications from zn isotopes, i/(ca+mg) ratios, and other elemental proxies |
publisher |
HAL CCSD |
publishDate |
2024 |
url |
https://brgm.hal.science/hal-04582104 https://brgm.hal.science/hal-04582104/document https://brgm.hal.science/hal-04582104/file/Gonz%C3%A1lez%20Robacio%20et%20al.%20-%202024%20-%20Paleoenvironmental%20variations%20during%20the%20Late%20Camb.pdf https://doi.org/10.1016/j.marpetgeo.2024.106817 |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_source |
ISSN: 0264-8172 Marine and Petroleum Geology https://brgm.hal.science/hal-04582104 Marine and Petroleum Geology, 2024, 165, pp.106817. ⟨10.1016/j.marpetgeo.2024.106817⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.marpetgeo.2024.106817 hal-04582104 https://brgm.hal.science/hal-04582104 https://brgm.hal.science/hal-04582104/document https://brgm.hal.science/hal-04582104/file/Gonz%C3%A1lez%20Robacio%20et%20al.%20-%202024%20-%20Paleoenvironmental%20variations%20during%20the%20Late%20Camb.pdf doi:10.1016/j.marpetgeo.2024.106817 |
op_doi |
https://doi.org/10.1016/j.marpetgeo.2024.106817 |
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Marine and Petroleum Geology |
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165 |
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106817 |
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1810458411958009856 |