[ Paléoenvironnement de mise en place des faciès détritiques terrigènes de la formation du Moungo-fleuve dans le bassin sédimentaire du Moungo (Ouest Cameroun) ]
Volume 13, Issue 2, October 2015, Pages 355–367
Christel Kemteu SOBDJOU1, François Bidzang NDONG2, and Joseph Mvondo ONDOA3
1 Institut de Recherches Géologiques et Minières, BP : 4110 Nlongkak, Yaoundé, Cameroun
2 Institut de Recherches Géologiques et Minières, BP : 4110 Nlongkak, Yaoundé, Cameroon
3 Département des Sciences de la Terre et de l'Univers, Université de Yaoundé 1. BP 812, Yaoundé, Cameroun
Original language: French
Copyright © 2015 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
In a bit to contribute to the study of the sedimentary Formation of the Mungo series, studies on the Mungo river Formation was effectuated in this work. The reconstitution of the paleoenvironment in which the formation was put to place has been done based on six analyses: granulometrical, morphoscopic, heavy mineral, thin section analyses, as well as mineralogical and chemical analyses by x ray diffractometry and fluorescence respectively.
From the granulometrical analyses, plurimodal histograms are indications of multiple sources of sediments. The granulometrical curve show low gradient. The sediments are therefore very poorly to poorly sorted.The morphoscopical analyses reveals the presence of: quartz grains that has not been worn out (53%), having been eroded from proximal source rocks (short transport); sub spherical and shiny quartz grains (44%) having been subjected to an averagely long transportation; spherical and shiny quartz grains (3%) having been subjected to relatively long transportation. The heavy mineral analyses reveal a variety of heavy minerals: pyroxene, rutile, tourmaline, zircon, are indications that part of the sediments came from magmatic source rocks; also, the presence of andalousites is indicative of a metamorphic source rock. The examination of thin sections reveals that the rocks are essentially lithic arkose and litharenites which are respectively less consolidated and averagely consolidated. The x ray diffractometry on a clay facies reveals that it is made up mostly of clay sized particles rather than clay minerals (i.e made up mostly of quartz and hematite with koalinite being the only constitutive clay mineral). A chemical analysis by x ray fluorescence has unraveled the major and trace element contents of the clay facies. The paleoenvironmental context in which the terrigenous detritic facies of the Mungo river Formation was put to place could have been fluvio-deltaic to shallow marine. At a larger scale, the paleoenvironment of deposition of the Mungo series could have been fluviatic to fluvio-deltaic and shallow marine.
Author Keywords: Mungo-river, paleoenvironment, fluvio-deltaic, terrigenous detritic facies.
Volume 13, Issue 2, October 2015, Pages 355–367
Christel Kemteu SOBDJOU1, François Bidzang NDONG2, and Joseph Mvondo ONDOA3
1 Institut de Recherches Géologiques et Minières, BP : 4110 Nlongkak, Yaoundé, Cameroun
2 Institut de Recherches Géologiques et Minières, BP : 4110 Nlongkak, Yaoundé, Cameroon
3 Département des Sciences de la Terre et de l'Univers, Université de Yaoundé 1. BP 812, Yaoundé, Cameroun
Original language: French
Copyright © 2015 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
In a bit to contribute to the study of the sedimentary Formation of the Mungo series, studies on the Mungo river Formation was effectuated in this work. The reconstitution of the paleoenvironment in which the formation was put to place has been done based on six analyses: granulometrical, morphoscopic, heavy mineral, thin section analyses, as well as mineralogical and chemical analyses by x ray diffractometry and fluorescence respectively.
From the granulometrical analyses, plurimodal histograms are indications of multiple sources of sediments. The granulometrical curve show low gradient. The sediments are therefore very poorly to poorly sorted.The morphoscopical analyses reveals the presence of: quartz grains that has not been worn out (53%), having been eroded from proximal source rocks (short transport); sub spherical and shiny quartz grains (44%) having been subjected to an averagely long transportation; spherical and shiny quartz grains (3%) having been subjected to relatively long transportation. The heavy mineral analyses reveal a variety of heavy minerals: pyroxene, rutile, tourmaline, zircon, are indications that part of the sediments came from magmatic source rocks; also, the presence of andalousites is indicative of a metamorphic source rock. The examination of thin sections reveals that the rocks are essentially lithic arkose and litharenites which are respectively less consolidated and averagely consolidated. The x ray diffractometry on a clay facies reveals that it is made up mostly of clay sized particles rather than clay minerals (i.e made up mostly of quartz and hematite with koalinite being the only constitutive clay mineral). A chemical analysis by x ray fluorescence has unraveled the major and trace element contents of the clay facies. The paleoenvironmental context in which the terrigenous detritic facies of the Mungo river Formation was put to place could have been fluvio-deltaic to shallow marine. At a larger scale, the paleoenvironment of deposition of the Mungo series could have been fluviatic to fluvio-deltaic and shallow marine.
Author Keywords: Mungo-river, paleoenvironment, fluvio-deltaic, terrigenous detritic facies.
Abstract: (french)
Cet article est une contribution à l'étude des formations sédimentaires de la série du Moungo au Cameroun. Il s'agit de reconstituer le paléoenvironnement de mise en place de cette formation à partir des analyses granulométrique, morphoscopique, minéraux lourds, lames minces de roches, minéralogique et chimique respectivement par diffractométrie et fluorescence de rayons x.
La granulométrie a montré des histogrammes principalement plurimodaux, suggérant ainsi une multiplicité de sources des sédiments. Les courbes granulométriques obtenues ont présenté une faible pente et un étalement, preuve que les sédiments sont très mal classés, et mal triés.
La morphoscopie a présenté des grains de quartz non usés (53%), érodés des roches mères situées non loin du milieu de dépôt et qui ont subi un court transport (dépôts proximaux) ; des grains de quartz sub-émoussés luisants (44%) qui ont subi un transport moyen ; des grains de quartz émoussés luisants (3%), érodés des roches mères situées loin du milieu de dépôt et qui ont subi un long transport. Les minéraux lourds qui ont été trouvés dans les sédiments sont variés. Le pyroxène, le rutile, la tourmaline et le zircon suggèrent qu'une partie du sédiment provient des roches magmatiques. L'andalousite suggère qu'une partie du sédiment provient des roches métamorphiques. Les lames minces de roches ont présenté une arkose lithique et un litharénite respectivement peu consolidée et moyennement consolidée. Le diffractogramme de rayon x a montré un faciès argileux majoritairement constitué d'argiles granulométriques : le quartz et l'hématite. La kaolinite est la seule argile vraie observée. L'analyse chimique à la fluorescence de rayon x a permis d'identifier les éléments majeurs et traces du faciès argileux. En effet, le paléoenvironnement de mise en place des faciès détritiques terrigènes de la formation du Moungo-fleuve aurait été fluvio-deltaïque à marin restreint.
Author Keywords: Moungo-fleuve, Paléoenvironnement, fluvio-deltaïque, faciès détritiques terrigènes.
How to Cite this Article
Christel Kemteu SOBDJOU, François Bidzang NDONG, and Joseph Mvondo ONDOA, “Paleoenvironment of implementing terrigenous clastic facies of the formation of Mungo-river in the sedimentary basin of Mungo (West Cameroon),” International Journal of Innovation and Applied Studies, vol. 13, no. 2, pp. 355–367, October 2015.
