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Submarine fans are deposits of coarse sediments of continental origin in the deep sea, and are generally characterized by a complex depositional architecture, due to the multiple triggering mechanisms of deep-water sediment gravity flows. Consequently, this poses great challenges to deep water petroleum exploration and development. We analyzed the geomorphologic evolution and architecture of Campanian, deeply buried, submarine fans in the Kribi-Campo sub-basin, offshore Cameroon. Using a 3D seismic reflection data set and logs from two wells, we mapped seven horizons, including the fan base, fan top and five internal horizons. In cross-section, the fan is characterized by a high amplitude seismic facies exhibiting an aggradational pattern with parallel and continuous reflectors. The stacked fan-shaped morphology is up to 340 ms TWT thick, extends over an area of 600 km2 and oriented NE-SW, near the Kribi High. The analysis of lobes and channels on each horizon provided a timelapse that captures the major geomorphologic transformations of the submarine fan from its initiation, growth, and abandonment. The submarine fan is composed of depositional lobes whose beds consist of sand, silt and mud. The detailed structure of these lobes has a finger-like morphology and is generally oriented at high angles to the channel that delivered the sediment to the lobes. The finger-like features are interpreted as thick massive sands, formed as a result of sediment-gravity flows which branched off the main flow eroding into pelagic clay substrate. Two types of channel morphology were identified (straight and sinuous). Our results show that channel and sand-body architecture evolve in a predictive manner, primarily controlled by fan aggradation. The elongated shape and morphology of the submarine fan may arise from the interaction of the fault-related folds and Kribi High, with sandstone deposition within the intervening topographic lows, sourced from the east. The 3D seismic geomorphological analysis of the submarine fan, as presented in this study, is essential to better understand their geometries, facies distribution, stacking patterns and depositional architecture to improve reservoir predictions.

In this study, a seismic reflection dataset and well-log data were integrated to investigate the geometry and internal configuration of a turbidite channel system within the Late Cretaceous interval of the deep-water Kribi-Campo sub-basin, offshore Cameroon. This interval is characterized by a well-developed submarine channel system consisting of an early and a late-stage channel. Morphologically, the submarine channel system has a northeast-southwest trend and is U-shaped in cross-section with a length of 56 km within the study area. The early-stage channel has a relatively straight morphology and varies in width and depth from 3 to 5 km and 89 to 197 m, respectively. However, the late stage of the channel is characterized by a narrower (1 to 3 km) and shallower (41 to 103 m) incision, with sinuous morphology carved into the early channel infill. The changing interaction of differential tectonic subsidence, relative sea level, source sediment supply and slope gradient change are considered to be the major control on the geometry and internal characteristics of the submarine channel system. Sag subsidence during the Campanian led to basin deepening and the widespread development of basinal sediments as submarine fans and promotion of submarine channel system development. The filling of the channel system occurred during a long-term Maastrichtian relative sea level rise, punctuated by falls in relative sea level. Sand appears to have been fed to the channel system by the palaeo-Sanaga and palaeo-Nyong Rivers, with sand rich aprons developed were these rivers debouched into the study area. The early stage of the submarine channel is dominated by coarse-grained sediments in the southwest and fine-grained sediments in the northeast, while the late-stage channel is mainly filled with fine-grained sediments. The presence of coarse-grained sediments occur within the submarine channel axis downstream represents a potential for hydrocarbon reservoirs with enhanced petrophysical qualities due to a low depositional gradient. The geomorphological analysis of this ancient submarine channel system along the western African margin, as presented in this study, has broad implications in the understanding of the distribution of deep-water sediments with potential for hydrocarbon exploration in the region.

Sedimentological methods such as granulometry, morphoscopy and heavy minerals analysis have been carried out to characterize alluvial gold deposits of Betare-Oya and its surroundings, with the aim to determine their origin and conditions in which they are formed and also to determine the mineralogical content of these deposits, their nature and distribution. It came out from this study the following: The alluvial deposits studied are sand, constituting of coarse fraction (grains), medium grains in abundant and fine grains. The average values of sorting index (S0) and coefficient of asymmetry (A) are respectively 2.53 and 0.73. These values indicate that the sand is poorly arranged and poorly sorted with a better classification or arrangement in the coarse fraction (grains). These are sediments that are deposited together by high competent currents. It would therefore probably be torrential deposits and or streams from short transport. Unused grains are dominating (80.5%) which translate a proximal source of the sediments. So it would be probably from the dismantling of the surrounding landforms. The heavy minerals studied revealed the presence of the following minerals; zircon, gold, sphene, green hornblende, tourmaline, rutile, augite, hypersthene, sillimanite, glau-cophane, biotite, staurotide, and the opaque. These minerals belong to the cortege of plutonic and metamorphic rocks from a single proximal distributing province.

The north-central Cameroon is located at the northern edge of Archean Congo–Sao Francisco craton and at the east of the West African craton. This area includes various Neoproterozoic to Holocene geological litho-structural units. It corresponds to a juvenile crust resulting from the collision of the above cratons. Geological features associated with the Poli–Ounianga–Kebir heavy gravity line trending NE–SW crosscuts the study area and hosts several deposits, chiefly auriferous and uraniferous ore deposits. Uraniferous bodies are described at the SW and NE sides of the Benue Trough and are related to hydrothermal processes and structural events in Neoproterozoic granitoids of Poli (Cameroon) and Zabili (Chad). Gold ore deposits are found around faulted zones mostly in the Tchollire shear zone. Gravity data derived from the Earth Gravitational Model EGM2008, combining terrestrial, maritime and satellite-derived data, were used to model the crust of the north-central Cameroon. The geophysical filtering enabled to highlight that the most fractured areas with the deepest faults are situated on the positive anomalies of the mineralized volcano-sedimentary belts of Poli and Bibemi. The Benue Trough that crosscuts the volcano-sedimentary belts exposes few structural features due to the weak gravity signal of Cretaceous sedimentary cover. The radially averaged power spectrum analysis brought out the density contrast depths of some geological belts and revealed the Moho discontinuity of the study area at about 24 km depth. This Moho depth is in accordance with the assumption of a thin crust and a mantle upwelling in the study area proposed by previous works. Thus, the presence of geological formations of mantle, crustal and mixed crustal-mantle origin such as mafic rocks as well as calc-alkaline to alkaline granitoid outcropping in the study area may be the consequence of the proximity of the upper mantle to the surface. Moreover, fractures highlighted in this work brought out the crustal permeability in the study area illustrating migratory passages for mantle formations found at the surface. Based on the gravity field analysis, the proposed models of basement in this study provide geological architecture highlighting the presence of more or less dense rocks and hydrothermal fluids migration along faults as key elements for ore deposits formation.

The study area is located at the southern part of the Cameroon Atlantic Margin (CAM) in the Gulf of Guinea. This work analyses 20 wells and 02 Cameroon Span seismic lines to re-examine the stratigraphical nature of the Top Albian surface of the CAM for a better understanding of the basin evolution. The results obtained by wells analysis show that, from the Douala sub-basin (Dehane) onshore to the Kribi-Campo continental slope, the Top Albian surface has an erosive shape. The seismic analysis reveals that this surface has two characters: erosive from the continental shelf to continental slope and concordant in the deep basin. This observation indicates that the Top Albian surface corresponds to an unconformity (u/c) on shallow waters with its correlative conformity (cc) in deep basin. The erosive form was amplified by erosion caused by the margin uplift. The combination of seismic and wells data reveals that in shallow waters, the Top Albian u/c erodes Aptian-Albian deposits. These sediments mainly consist of sandstones, shales and evaporitic unit. The occurrence of dark shales before late Albian epoch, suggests that the Douala/Kribi-Campo (DKC) Basin was already transgressed by marine sediments at this time. Hence, the Top Albian surface resulted probably from a relative sea-level fall, mainly caused by the tectonic uplift. The 3D modeling carried out provides a better resolution of its distribution in the study area. This surface boundary has regional extension on the DKC Basin. Furthermore, the Top Albian surface seals both good sandstones reservoir rocks and dark shales source-rocks in the studied basin.

The study presented herein highlights the existence of a diversity of spontaneous sources of electric potential in weathering cover within the inter-tropical humid zone of south Cameroon. The study site presents a spatial mineralogical heterogeneity, which reveals the dominance of gibbsite more generally upslope, transitioning to a residual kaolinite downslope. The spatial characterization of these weathering mantles at the site revealed a general negative correlation between self-potential (SP), elevation, and sand and silt contents, confirming the existence of a dominant SP electrokinetic source. The main electrokinetic source is attributed to the presence of gibbsite, an abundant mineral at well drained relief summits of intertropical landscapes, likely resulting from the intense alteration of kaolinite. The electrofiltration phenomena related to fluid flow in the gibbsitic summit, quite rich in sand and silt, might justify this origin. A separate SP survey carried out in the kaolinitic mantles 5 km away, which lacked gibbsite, but was richer in clay, revealed a positive correlation between SP, elevation, and clay content of the surface horizons. The difference in correlation is attributed to the electrochemical nature of the SP within the second site. Thus, the diversity of sources of SP gives way to formulation of hypotheses on mineralogical differentiation and spatial characterization of lateritic covers.

This work presents an interpretation of gravity data derived from the Earth Gravitational Model EGM2008 in the Center north Cameroon and a correlation with previous tectonic geological and mining studies. EGM2008 Model provides high spatial resolution gravitational data integrating land, airborne, maritime gravity data, as well as satellite altimetry data. Significant similarities are underlined through Bouguer anomaly maps deduced from EGM2008 and land gravity data according to shape, orientation, and amplitude of anomalies. Furthermore, the statistical analysis of both datasets gives means of −38.25 and −38.21 mGal as well as standard deviations of 12.30 and 12.42 for EGM2008 and land data, respectively. Regional geological formations are largely interpreted and identified on EGM2008 Bouguer anomaly map. We applied regional/residual separation filtering, upward continuation and horizontal gradient methods to investigate the subsurface structure. Some known geological lineaments are highlighted such as Poli and Koum faults and Tchollire shear zone, while new ones are revealed. This work brings out main regional feature known as Poli-Ounianga-Kebir gravity heavy line trending SW-NE which contains uraniferous and auriferous deposits located along the same direction. This paper presents a coherent correlation between positive gravity anomalies, faults, and mineral indices in the Center-North Cameroon (Central Africa Fold belt), and thus brings new evidences of the efficiency of Earth Gravitational Model EGM2008 for structural investigation and mining exploration.

This study evaluates the use of the geoelectric self-potential (SP) method on a typically thick lateritic cover in the tropical rain forest of the Nsimi watershed of South Cameroon. In this respect, we have deployed SP and Wenner resistivity profiling along 10 tracks, which has enabled us to produce an SP map and a Wenner resistivity profile of the watershed. Because the application of the SP method is not ideal, the interpretation of our profiles is based on correlations between SP, elevation, electrical resistivity and well-constrained granulometric parameters in the watershed. The absence of a correlation between SP and electrical resistivity suggests that these natural potentials would not be the result of a simple circulating current by Ohm's law through the medium, but would be associated with electromotive forces, either electrokinetic or electrochemical potential. The positive correlation observed between SP and elevation enables us to discard an electrokinetic origin for the Nsimi watershed SP and to propose an electrochemical one instead. This is confirmed by a clear linear correlation between SP and the percentage of clay material in the lateritic covers. This further enables us to define loose clay-rich horizons in the laterites.

Aeromagnetic data of the Akonolinga-Mbama region are analyzed in order to elucidate the subsurface geology of the area. The available data in the form of a residual aeromagnetic map is interpreted as a vast magnetically quiet region, and complex zones which do not correlate with the surface geology of the region.Within the magnetically quiet zone, a high negative circular elongated anomaly zone seems to represent an intrusion of a plutonic rock into the metamorphic formations of the region. Spectral analysis and two-and-a-half dimensional (2½-D) modeling are used to estimate the depth of the causative bodies and determine the source rocks along three profiles crossing the suspected areas. Models from various zones of granitic intrusions are obtained, thereby proposing some shallow fault lines along zones of contact. This permits us to mark out the northern margin of the Congo Craton, thus enabling us to distinguish the cratonic formations from the Pan African fold belt. Part of the belt has been thrust over the northern portion of the Congo Craton in Cameroon.