Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line
In the western Cameroon, crop out several dyke swarms of Paleozoic–Mesozoic age. These dykes intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Volcanic Line. In the Njimom area, two groups of mafic dykes that crosscut the Neoproterozoic basement rocks have...
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2021
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ftdoajarticles:oai:doaj.org/article:5668cc14520a4652bc805806d294c9e5 2023-05-15T18:21:19+02:00 Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line Noël-Aimée Kouamo Keutchafo Nicole Armelle Wambo Simeni Brillant Kandzi Nforba Agathe Arrissa Noucoucouk Josiane Demlabin Sonmo Depesquidoux Tchato Tchaptchet Jean Pierre Tchouankoue Ciro Cucciniello 2021-12-01T00:00:00Z https://doi.org/10.3390/geosciences12010012 https://doaj.org/article/5668cc14520a4652bc805806d294c9e5 EN eng MDPI AG https://www.mdpi.com/2076-3263/12/1/12 https://doaj.org/toc/2076-3263 doi:10.3390/geosciences12010012 2076-3263 https://doaj.org/article/5668cc14520a4652bc805806d294c9e5 Geosciences, Vol 12, Iss 12, p 12 (2021) mafic dykes mineralogy geochemistry petrogenesis Njimom western Cameroon Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.3390/geosciences12010012 2022-12-30T22:03:03Z In the western Cameroon, crop out several dyke swarms of Paleozoic–Mesozoic age. These dykes intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Volcanic Line. In the Njimom area, two groups of mafic dykes that crosscut the Neoproterozoic basement rocks have been observed. A first group intrudes the mylonites whereas the second group intrudes the granites. The dykes are alkaline basalts and hawaiites. The mineralogical assemblage of both groups of dykes consists of plagioclase, clinopyroxene, altered olivine, and opaque oxides. The dykes that cross-cut the Precambrian mylonitic gneisses show moderate TiO 2 (1.7–2.0 wt.%), low MgO (4.4–7.1 wt.%), and compatible trace element concentrations (e.g., Cr = 70–180 ppm; Ni = 30–110 ppm). The dykes that intrude the granites have TiO 2 contents between 2.3 and 2.5 wt.% and moderate compatible trace element concentrations (e.g., Cr = 260–280 ppm; Ni = 170–230 ppm). MgO varies from 5.9 to 9.2 wt.%. All mafic dykes are enriched in light lanthanide element and show moderate Zr/Nb and high Zr/Y, Nb/Yb, and Ti/V ratios similar to those of average ocean island basalt (OIB)-type magmas. Some dykes that intrude the mylonites show evidence of contamination by continental crust. The composition of the clinopyroxenes of the dykes that intrude the mylonites clearly indicate different and unrelated parental magmas from dykes that intrude the granites. Contents and fractionation of the least and the most incompatible elements suggest low degrees of partial melting (3–5%) of heterogeneous source slightly enriched in incompatible elements in the spinel stability field. The geochemical features of Njimom dykes (in particular the dykes that intrude the granites) are similar to those of Paleozoic and Mesozoic dykes recorded in the southern continental part of the Cameroon Volcanic Line, suggesting multiple reactivations of pre-existing fractures that resulted in the fragmentation of western Gondwana and the opening of the South Atlantic Ocean. Article in Journal/Newspaper South Atlantic Ocean Ocean Island Directory of Open Access Journals: DOAJ Articles Geosciences 12 1 12 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
mafic dykes mineralogy geochemistry petrogenesis Njimom western Cameroon Geology QE1-996.5 |
spellingShingle |
mafic dykes mineralogy geochemistry petrogenesis Njimom western Cameroon Geology QE1-996.5 Noël-Aimée Kouamo Keutchafo Nicole Armelle Wambo Simeni Brillant Kandzi Nforba Agathe Arrissa Noucoucouk Josiane Demlabin Sonmo Depesquidoux Tchato Tchaptchet Jean Pierre Tchouankoue Ciro Cucciniello Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
topic_facet |
mafic dykes mineralogy geochemistry petrogenesis Njimom western Cameroon Geology QE1-996.5 |
description |
In the western Cameroon, crop out several dyke swarms of Paleozoic–Mesozoic age. These dykes intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Volcanic Line. In the Njimom area, two groups of mafic dykes that crosscut the Neoproterozoic basement rocks have been observed. A first group intrudes the mylonites whereas the second group intrudes the granites. The dykes are alkaline basalts and hawaiites. The mineralogical assemblage of both groups of dykes consists of plagioclase, clinopyroxene, altered olivine, and opaque oxides. The dykes that cross-cut the Precambrian mylonitic gneisses show moderate TiO 2 (1.7–2.0 wt.%), low MgO (4.4–7.1 wt.%), and compatible trace element concentrations (e.g., Cr = 70–180 ppm; Ni = 30–110 ppm). The dykes that intrude the granites have TiO 2 contents between 2.3 and 2.5 wt.% and moderate compatible trace element concentrations (e.g., Cr = 260–280 ppm; Ni = 170–230 ppm). MgO varies from 5.9 to 9.2 wt.%. All mafic dykes are enriched in light lanthanide element and show moderate Zr/Nb and high Zr/Y, Nb/Yb, and Ti/V ratios similar to those of average ocean island basalt (OIB)-type magmas. Some dykes that intrude the mylonites show evidence of contamination by continental crust. The composition of the clinopyroxenes of the dykes that intrude the mylonites clearly indicate different and unrelated parental magmas from dykes that intrude the granites. Contents and fractionation of the least and the most incompatible elements suggest low degrees of partial melting (3–5%) of heterogeneous source slightly enriched in incompatible elements in the spinel stability field. The geochemical features of Njimom dykes (in particular the dykes that intrude the granites) are similar to those of Paleozoic and Mesozoic dykes recorded in the southern continental part of the Cameroon Volcanic Line, suggesting multiple reactivations of pre-existing fractures that resulted in the fragmentation of western Gondwana and the opening of the South Atlantic Ocean. |
format |
Article in Journal/Newspaper |
author |
Noël-Aimée Kouamo Keutchafo Nicole Armelle Wambo Simeni Brillant Kandzi Nforba Agathe Arrissa Noucoucouk Josiane Demlabin Sonmo Depesquidoux Tchato Tchaptchet Jean Pierre Tchouankoue Ciro Cucciniello |
author_facet |
Noël-Aimée Kouamo Keutchafo Nicole Armelle Wambo Simeni Brillant Kandzi Nforba Agathe Arrissa Noucoucouk Josiane Demlabin Sonmo Depesquidoux Tchato Tchaptchet Jean Pierre Tchouankoue Ciro Cucciniello |
author_sort |
Noël-Aimée Kouamo Keutchafo |
title |
Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
title_short |
Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
title_full |
Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
title_fullStr |
Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
title_full_unstemmed |
Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line |
title_sort |
petrology of mafic dykes from the njimom area (west-cameroon): a contribution to the characterization of late paleozoic and mesozoic magmatism in the southern continental part of the cameroon volcanic line |
publisher |
MDPI AG |
publishDate |
2021 |
url |
https://doi.org/10.3390/geosciences12010012 https://doaj.org/article/5668cc14520a4652bc805806d294c9e5 |
genre |
South Atlantic Ocean Ocean Island |
genre_facet |
South Atlantic Ocean Ocean Island |
op_source |
Geosciences, Vol 12, Iss 12, p 12 (2021) |
op_relation |
https://www.mdpi.com/2076-3263/12/1/12 https://doaj.org/toc/2076-3263 doi:10.3390/geosciences12010012 2076-3263 https://doaj.org/article/5668cc14520a4652bc805806d294c9e5 |
op_doi |
https://doi.org/10.3390/geosciences12010012 |
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Geosciences |
container_volume |
12 |
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12 |
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1766200520063582208 |