Petrogenesis of Archean PGM-bearing chromitites and associated ultramafic-mafic-anorthositic rocks from the Guelb el Azib layered complex (West African craton, Mauritania)
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 a...
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ftunivbruxelles:oai:dipot.ulb.ac.be:2013/168630 2023-05-15T16:29:59+02:00 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 2013-01 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/168630 https://dipot.ulb.ac.be/dspace/bitstream/2013/168630/1/Elsevier_152260.pdf en eng uri/info:doi/10.1016/j.precamres.2012.10.005 uri/info:pii/S0301926812002550 uri/info:scp/84875085438 https://dipot.ulb.ac.be/dspace/bitstream/2013/168630/1/Elsevier_152260.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/168630 1 full-text file(s): info:eu-repo/semantics/restrictedAccess Precambrian research, 224 Géologie Pétrologie Géochimie Anorthosite Archean tholeiite Granulites Layered complex Mafic-ultramafic rocks info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2013 ftunivbruxelles 2022-06-12T20:36:31Z 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. © 2012 Elsevier B.V. SCOPUS: ar.j info:eu-repo/semantics/published Article in Journal/Newspaper Greenland DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Greenland |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Géologie Pétrologie Géochimie Anorthosite Archean tholeiite Granulites Layered complex Mafic-ultramafic rocks |
spellingShingle |
Géologie Pétrologie Géochimie Anorthosite Archean tholeiite Granulites Layered complex Mafic-ultramafic rocks 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 |
Géologie Pétrologie Géochimie Anorthosite Archean tholeiite Granulites Layered complex Mafic-ultramafic rocks |
description |
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. © 2012 Elsevier B.V. SCOPUS: ar.j info:eu-repo/semantics/published |
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) |
publishDate |
2013 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/168630 https://dipot.ulb.ac.be/dspace/bitstream/2013/168630/1/Elsevier_152260.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Precambrian research, 224 |
op_relation |
uri/info:doi/10.1016/j.precamres.2012.10.005 uri/info:pii/S0301926812002550 uri/info:scp/84875085438 https://dipot.ulb.ac.be/dspace/bitstream/2013/168630/1/Elsevier_152260.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/168630 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/restrictedAccess |
_version_ |
1766019695820931072 |