Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania)
International audience The Archean Guelb el Azib layered complex (GAC) in the West African craton of Mauritania is composed of an association of serpentinites, chromitites, amphibolites and anorthosites with few fine-grained amphibolite dykes. The complex forms tectonic slices in 2.9–3.5 Ga TTG gnei...
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ftunivangershal:oai:HAL:hal-01764070v1 2023-11-12T04:18:01+01:00 Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) Berger, Julien Diot, Hervé Lo, Khalidou Ohnenstetter, Daniel Femenias, Olivier Pivin, Marjorie Demaiffe, Daniel Bernard, Alain Charlier, Bernard Fonds National de la Recherche Scientifique Bruxelles (FNRS) Université libre de Bruxelles (ULB) Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG) Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST) Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université de Nouakchott Al-Aasriya (UNA) Centre de Recherches Pétrographiques et Géochimiques (CRPG) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) IAMGOLD Corporation-West Africa Department of Earth, Atmospheric and Planetary Sciences MIT, Cambridge (EAPS) Massachusetts Institute of Technology (MIT) 2013-01 https://hal.univ-lorraine.fr/hal-01764070 https://doi.org/10.1016/j.precamres.2012.10.005 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.precamres.2012.10.005 hal-01764070 https://hal.univ-lorraine.fr/hal-01764070 doi:10.1016/j.precamres.2012.10.005 ISSN: 0301-9268 Precambrian Research https://hal.univ-lorraine.fr/hal-01764070 Precambrian Research, 2013, 224, pp.612 - 628. ⟨10.1016/j.precamres.2012.10.005⟩ Anorthosite Layered complex Archean tholeiite Granulites Mafic–ultramafic rocks [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2013 ftunivangershal https://doi.org/10.1016/j.precamres.2012.10.005 2023-10-25T16:19:28Z International audience The Archean Guelb el Azib layered complex (GAC) in the West African craton of Mauritania is composed of an association of serpentinites, chromitites, amphibolites and anorthosites with few fine-grained amphibolite dykes. The complex forms tectonic slices in 2.9–3.5 Ga TTG gneiss terrains in close association with supracrustal rocks (BIFs, impure marbles, amphibolites). It was affected by a main granulite-facies grade metamorphism (up to 900 °C at 5–6 kbar) with subsequent retrogression in amphibolite and greenschist facies conditions.The preserved igneous macrostructures, the mineral compositions and the nature of relic magmatic assemblages have been used to constrain the composition of the parental melts and the conditions of crystallization. According to petrological observations and to comparison with experimental data, the formation of the complex can be explained by fractionation of a slightly hydrous high-alumina basaltic melt at low pressure. The early fractionation of olivine and the absence of massive clinopyroxene fractionation before plagioclase saturation led to crystallization of highly calcic plagioclase with Fe-, Al-rich but Cr-poor chromite from a hydrous tholeiitic parental magma, similar to worldwide Archean tholeiites.The complex shares many similarities with Archean anorthosite layered complexes, possibly formed in a supra-subduction zone environment according to results obtained on similar 2.9–3.0 Ga complexes from Greenland and India (namely Fiskenaesset and Sittampundi). Three phases of PGE mineralization affected the GAC chromitites: (i) igneous crystallization of laurite; (ii) formation of late magmatic IPGE sulpho-arsenides (irarsite–hollingworthite) and (iii) hydrothermal Pt–Pd mineralization represented by sperrylite and rustenburgite. Article in Journal/Newspaper Greenland Portail des publications scientifiques de l’Université d’Angers (HAL) Greenland Precambrian Research 224 612 628 |
institution |
Open Polar |
collection |
Portail des publications scientifiques de l’Université d’Angers (HAL) |
op_collection_id |
ftunivangershal |
language |
English |
topic |
Anorthosite Layered complex Archean tholeiite Granulites Mafic–ultramafic rocks [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Anorthosite Layered complex Archean tholeiite Granulites Mafic–ultramafic rocks [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Berger, Julien Diot, Hervé Lo, Khalidou Ohnenstetter, Daniel Femenias, Olivier Pivin, Marjorie Demaiffe, Daniel Bernard, Alain Charlier, Bernard Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
topic_facet |
Anorthosite Layered complex Archean tholeiite Granulites Mafic–ultramafic rocks [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience The Archean Guelb el Azib layered complex (GAC) in the West African craton of Mauritania is composed of an association of serpentinites, chromitites, amphibolites and anorthosites with few fine-grained amphibolite dykes. The complex forms tectonic slices in 2.9–3.5 Ga TTG gneiss terrains in close association with supracrustal rocks (BIFs, impure marbles, amphibolites). It was affected by a main granulite-facies grade metamorphism (up to 900 °C at 5–6 kbar) with subsequent retrogression in amphibolite and greenschist facies conditions.The preserved igneous macrostructures, the mineral compositions and the nature of relic magmatic assemblages have been used to constrain the composition of the parental melts and the conditions of crystallization. According to petrological observations and to comparison with experimental data, the formation of the complex can be explained by fractionation of a slightly hydrous high-alumina basaltic melt at low pressure. The early fractionation of olivine and the absence of massive clinopyroxene fractionation before plagioclase saturation led to crystallization of highly calcic plagioclase with Fe-, Al-rich but Cr-poor chromite from a hydrous tholeiitic parental magma, similar to worldwide Archean tholeiites.The complex shares many similarities with Archean anorthosite layered complexes, possibly formed in a supra-subduction zone environment according to results obtained on similar 2.9–3.0 Ga complexes from Greenland and India (namely Fiskenaesset and Sittampundi). Three phases of PGE mineralization affected the GAC chromitites: (i) igneous crystallization of laurite; (ii) formation of late magmatic IPGE sulpho-arsenides (irarsite–hollingworthite) and (iii) hydrothermal Pt–Pd mineralization represented by sperrylite and rustenburgite. |
author2 |
Fonds National de la Recherche Scientifique Bruxelles (FNRS) Université libre de Bruxelles (ULB) Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG) Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST) Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université de Nouakchott Al-Aasriya (UNA) Centre de Recherches Pétrographiques et Géochimiques (CRPG) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) IAMGOLD Corporation-West Africa Department of Earth, Atmospheric and Planetary Sciences MIT, Cambridge (EAPS) Massachusetts Institute of Technology (MIT) |
format |
Article in Journal/Newspaper |
author |
Berger, Julien Diot, Hervé Lo, Khalidou Ohnenstetter, Daniel Femenias, Olivier Pivin, Marjorie Demaiffe, Daniel Bernard, Alain Charlier, Bernard |
author_facet |
Berger, Julien Diot, Hervé Lo, Khalidou Ohnenstetter, Daniel Femenias, Olivier Pivin, Marjorie Demaiffe, Daniel Bernard, Alain Charlier, Bernard |
author_sort |
Berger, Julien |
title |
Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
title_short |
Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
title_full |
Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
title_fullStr |
Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
title_full_unstemmed |
Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania) |
title_sort |
petrogenesis of archean pgm-bearing chromitites and associated ultramafic–mafic–anorthositic rocks from the guelb el azib layered complex (west african craton, mauritania) |
publisher |
HAL CCSD |
publishDate |
2013 |
url |
https://hal.univ-lorraine.fr/hal-01764070 https://doi.org/10.1016/j.precamres.2012.10.005 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
ISSN: 0301-9268 Precambrian Research https://hal.univ-lorraine.fr/hal-01764070 Precambrian Research, 2013, 224, pp.612 - 628. ⟨10.1016/j.precamres.2012.10.005⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.precamres.2012.10.005 hal-01764070 https://hal.univ-lorraine.fr/hal-01764070 doi:10.1016/j.precamres.2012.10.005 |
op_doi |
https://doi.org/10.1016/j.precamres.2012.10.005 |
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Precambrian Research |
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224 |
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