Many research studies have been done in the Mungo-River valley, they were mostly concerning the genesis and stratification of outcrops, but not really their petrology (description and classification). According to those reasons, this article is going to increase the petrology’s understanding of Mungo-River’s cretaceous outcrops, in Douala sub-basin. So, the studies have been done on Moundeck village’s outcrops and near the railway bridge on the Mungo-River. In fact, the studies were concerning the description of eight outcrops; the classification of their facies and the interpretation of their genesis. The description of outcrops has showed that they are constituted of positive and negative sequences. The thin sections have permitted to classify the facies described as litharenites and lithic arkoses, which are friable rocks. The genesis of Mungo-River’s outcrops could be understood according to two approaches. On the one hand, the sedimentary structures such as intercrossed and oblique stratifications observed on outcrops signify that, the sedimentation had been taken place in a fluvio-deltaic environment. On the other hand, the positive and negative sequences delimited on described outcrops, testify the influence of sedimentary cycles (transgression and regression) within the depositing environment.

This article examines the results of chemical data of the granitoids of the Ngovayang massif at the Northwestern border of the Congo craton in South Cameroon. The aim is to identify the sources and geotectonic framework of emplacement of these formations. It is a contribution to the understanding of the geodynamic context of the Ngovayang massif in the Nyong unit. 24 samples were analyzed by XRF and ICP/MS and are constituted of orthogneiss, charnockitic gneiss, migmatites and metagranites. This study brings out the progressive variation of the nature of the gneissic basement of this massif. Orthogneisses are the principal rocks and are characterized by an enrichment in Na as opposed to an impoverishment in K. This confirms their enrichment in plagioclase and their impoverishment in alkaline feldspar, K/Na ratios < 0.5. Trace element contents are also characteristics, marked by an enrichment in light rare earths (Laavg=10.48ppm) and impoverishment in heavy rare earths (Ybavg=0.63ppm). Their spectra are much fractionated ((La/Yb)N=15.86) without any significant anomaly in Eu but a negative anomaly in Ti and Nb. These results confirm its belonging to granitoids of the TTG type of trondhjemitic affinity. The migmatites have a granodioritic composition and are calco-alkaline. They have low Y content and are comparable with the CA2 type of pluton. They originate from the melting of a source containing garnet in melting residues, similar to those generating TTGs. The migmatitic gneisses seem to be the product of sediments. Charnockitic gneisses have two different trends; the firsts are of granodioritic composition and the procedure of their emplacement is that of differentiation similar to that of TTGs. The seconds have a tonalitic composition and formed by the partial melting of a source containing no garnet and eventually no hornblende. No matter the domain, the formations of the sector of study present in a variable manner, an impoverishment in LILE (Rb, Th and sometimes K). These results show that the metamorphites of the Ngovayang massif are the products of archaean granitoids deformed during the collision of the Congo and Sao Francisco cratonic blocks during the Eburnean orogeny.

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.

Map satellite lineaments served as study support for gold geochemical sampling of Lolodorf region in the southern part of the Eburnean Ngovayang massif in Cameroon. This technique is a major step in the search for clues metal geological and mineral exploration fractured zones. 228 samples were analyzed and the levels vary from 301ppb to -2ppb. These results showed that the probability of greater than 10ppb levels, which may lead to a gold anomaly is 67.48% for areas where the concentration areas weaving lineaments are superimposed on high density areas lineaments, 2.31% for the concentration of intersection surfaces lineaments, 28.92% for areas located in the high density areas levels of lineaments and only 1.28% for areas located in isolated lineaments. This study confirms the hypothesis that the areas of intersections and high density of lineaments are directly related to high concentrations of geochemical elements and mineral deposits.