Paleoenvironment of implementing terrigenous clastic facies of the formation of Mungo-river in the sedimentary basin of Mungo (West Cameroon)

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.