First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield
In order to understand the Paleoproterozoic geographic evolution of the Guyana Shield, paleomagnetic and 40Ar/39Ar investigations were carried out on granitoids and volcano-sedimentary rocks from the Oyapok and Camopi rivers (French Guyana–Brazil frontier). Scanning electronic microscope, thermomagn...
Published in: | Precambrian Research |
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HAL CCSD
2001
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Online Access: | https://hal-insu.archives-ouvertes.fr/hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808/document https://hal-insu.archives-ouvertes.fr/hal-00089808/file/Nomade-PrecambrianResearch-2001.pdf https://doi.org/10.1016/S0301-9268(01)00149-8 |
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ftccsdartic:oai:HAL:hal-00089808v1 2023-05-15T16:19:40+02:00 First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield Nomade, Sébastien Chen, Yan Féraud, G. Pouclet, André Théveniaut, Hervé Institut des Sciences de la Terre d'Orléans (ISTO) Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Laboratoire Universitaire d'Astrophysique de Nice (LUAN) Université Nice Sophia Antipolis (. - 2019) (UNS) COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM) 2001 https://hal-insu.archives-ouvertes.fr/hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808/document https://hal-insu.archives-ouvertes.fr/hal-00089808/file/Nomade-PrecambrianResearch-2001.pdf https://doi.org/10.1016/S0301-9268(01)00149-8 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/S0301-9268(01)00149-8 hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808/document https://hal-insu.archives-ouvertes.fr/hal-00089808/file/Nomade-PrecambrianResearch-2001.pdf doi:10.1016/S0301-9268(01)00149-8 info:eu-repo/semantics/OpenAccess ISSN: 0301-9268 Precambrian Research https://hal-insu.archives-ouvertes.fr/hal-00089808 Precambrian Research, Elsevier, 2001, 109, pp.239-256. ⟨10.1016/S0301-9268(01)00149-8⟩ Guyana Shield paleomagnetism 40Ar/39Ar dating Paleoproterozoic [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics info:eu-repo/semantics/article Journal articles 2001 ftccsdartic https://doi.org/10.1016/S0301-9268(01)00149-8 2021-12-12T06:31:19Z In order to understand the Paleoproterozoic geographic evolution of the Guyana Shield, paleomagnetic and 40Ar/39Ar investigations were carried out on granitoids and volcano-sedimentary rocks from the Oyapok and Camopi rivers (French Guyana–Brazil frontier). Scanning electronic microscope, thermomagnetic and isothermomagnetic experiments show that magnetite is the main magnetic remanent carrier in most of the samples. The metavolcano-sedimentary rocks (Paramaca) show a weak magnetization and scattered magnetic directions. Therefore, no reliable magnetic component could be isolated from these samples. Samples taken from tonalite and meta-ultrabasite rocks yield a characteristic magnetic direction, carried by subautomorphous magnetite, that is well defined and distinct from that of the present Earth field and that of nearby Jurassic dikes. A virtual geomagnetic pole (VGP) deduced from this probable primary remanence was calculated, namely pole OYA, λ=28.0°S, φ=346.0°E, N=5, k=31.9 and A95=13.8°. Four 40Ar/39Ar ages, ranging from 2052 to 1973 Ma, were obtained from amphiboles and biotites of tonalite rocks, showing a relatively slow cooling rate of ca 4.8+2.6/−2.1°C Ma−1. The linear extrapolation of this cooling rate to the magnetite unblocking temperature (540 to 580°C) yields a magnetization age of 2036±14 Ma for pole OYA. Pole OYA differs significantly from available paleomagnetic results from Venezuela of the West Guyana Shield dated at 2000±10 Ma. This difference may indicate an important latitudinal movement of the Guyana Shield between 2036 and 2000 Ma with a velocity of 9±7 cm/year. Article in Journal/Newspaper Geomagnetic Pole Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Precambrian Research 109 3-4 239 256 |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
Guyana Shield paleomagnetism 40Ar/39Ar dating Paleoproterozoic [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics |
spellingShingle |
Guyana Shield paleomagnetism 40Ar/39Ar dating Paleoproterozoic [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics Nomade, Sébastien Chen, Yan Féraud, G. Pouclet, André Théveniaut, Hervé First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
topic_facet |
Guyana Shield paleomagnetism 40Ar/39Ar dating Paleoproterozoic [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics |
description |
In order to understand the Paleoproterozoic geographic evolution of the Guyana Shield, paleomagnetic and 40Ar/39Ar investigations were carried out on granitoids and volcano-sedimentary rocks from the Oyapok and Camopi rivers (French Guyana–Brazil frontier). Scanning electronic microscope, thermomagnetic and isothermomagnetic experiments show that magnetite is the main magnetic remanent carrier in most of the samples. The metavolcano-sedimentary rocks (Paramaca) show a weak magnetization and scattered magnetic directions. Therefore, no reliable magnetic component could be isolated from these samples. Samples taken from tonalite and meta-ultrabasite rocks yield a characteristic magnetic direction, carried by subautomorphous magnetite, that is well defined and distinct from that of the present Earth field and that of nearby Jurassic dikes. A virtual geomagnetic pole (VGP) deduced from this probable primary remanence was calculated, namely pole OYA, λ=28.0°S, φ=346.0°E, N=5, k=31.9 and A95=13.8°. Four 40Ar/39Ar ages, ranging from 2052 to 1973 Ma, were obtained from amphiboles and biotites of tonalite rocks, showing a relatively slow cooling rate of ca 4.8+2.6/−2.1°C Ma−1. The linear extrapolation of this cooling rate to the magnetite unblocking temperature (540 to 580°C) yields a magnetization age of 2036±14 Ma for pole OYA. Pole OYA differs significantly from available paleomagnetic results from Venezuela of the West Guyana Shield dated at 2000±10 Ma. This difference may indicate an important latitudinal movement of the Guyana Shield between 2036 and 2000 Ma with a velocity of 9±7 cm/year. |
author2 |
Institut des Sciences de la Terre d'Orléans (ISTO) Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Laboratoire Universitaire d'Astrophysique de Nice (LUAN) Université Nice Sophia Antipolis (. - 2019) (UNS) COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM) |
format |
Article in Journal/Newspaper |
author |
Nomade, Sébastien Chen, Yan Féraud, G. Pouclet, André Théveniaut, Hervé |
author_facet |
Nomade, Sébastien Chen, Yan Féraud, G. Pouclet, André Théveniaut, Hervé |
author_sort |
Nomade, Sébastien |
title |
First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
title_short |
First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
title_full |
First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
title_fullStr |
First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
title_full_unstemmed |
First paleomagnetic and 40Ar/39Ar study of Paleoproterozoic rocks from the French Guyana (Camopi and Oyapok rivers), northeastern Guyana Shield |
title_sort |
first paleomagnetic and 40ar/39ar study of paleoproterozoic rocks from the french guyana (camopi and oyapok rivers), northeastern guyana shield |
publisher |
HAL CCSD |
publishDate |
2001 |
url |
https://hal-insu.archives-ouvertes.fr/hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808/document https://hal-insu.archives-ouvertes.fr/hal-00089808/file/Nomade-PrecambrianResearch-2001.pdf https://doi.org/10.1016/S0301-9268(01)00149-8 |
genre |
Geomagnetic Pole |
genre_facet |
Geomagnetic Pole |
op_source |
ISSN: 0301-9268 Precambrian Research https://hal-insu.archives-ouvertes.fr/hal-00089808 Precambrian Research, Elsevier, 2001, 109, pp.239-256. ⟨10.1016/S0301-9268(01)00149-8⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/S0301-9268(01)00149-8 hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808 https://hal-insu.archives-ouvertes.fr/hal-00089808/document https://hal-insu.archives-ouvertes.fr/hal-00089808/file/Nomade-PrecambrianResearch-2001.pdf doi:10.1016/S0301-9268(01)00149-8 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1016/S0301-9268(01)00149-8 |
container_title |
Precambrian Research |
container_volume |
109 |
container_issue |
3-4 |
container_start_page |
239 |
op_container_end_page |
256 |
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1766006080982220800 |