The Ntem Complex is a well-known Province in Cameroon hosting a wide variety of mineralizations. This study investigates the mineralization potential, provenance and depositional setting of gold-bearing stream sediments from the Bipindi‒Kouambo prospect in Cameroon. Bulk stream sediment samples were collected and analyzed geochemically using the inductively coupled plasma-mass spectrometry method. The sediments demonstrate mean concentrations of Fe, P, Ti, Au, Ag, U, Th, Bi and La greater than upper continental crust (UCC) thresholds and plot above the UCC on UCC-normalized plots, suggesting potential mineralizations. Al2O3/TiO2 ratio (0.17 – 8.27), Sc vs. Th, Th/Sc vs. La/Sc*100 and La/Cr vs. Th/Cr*100 source discrimination systematics show predominantly a mafic geogenic origin for the sediments. The sediments demonstrate low values of ICV (0.22 – 0.83), very high weathering indices values (PIA: 85.49 – 99.39, CIW: 86.45 – 99.39, CIA: 81.09 – 98.52 MIA: 62.18 – 97.03), potentially indicating severe chemical weathering and maturity of the sediments. Sr/Ba ratio (0.09 ‒ 0.55), CIA vs. Al2O3, Ba vs. Sr/Ba, K2O/Al2O3 vs. Ga/Rb and Rb vs. Rb/Sr cross-plots indicate sediments deposition under humid climatic condition. V/Cr (0.46 – 1.73), Ni/Co (0.92 – 4.83) and U/Th (0.02 – 0.05) ratios, as well as Ni/Co vs. V/(V + Ni) and Ni/Co vs. V/Cr cross-plots reveal an oxic environment of deposition. Also, the Log(MgO/Al2O3) vs. log(K2O/Al2O3) and MgO vs. Fe2O3 diagrams show a non-marine depositional environment. The Au, Ag, W and Pb association in the studied sediments are the suggested pathfinders for primary orogenic gold in this study. This study provides baseline geochemical data for follow-up mineral exploration in the Bipindi‒Kouambo prospect, Cameroon.
The Ngwi area, along the central Cameroon shear zone (CCSZ), features two-mica granite and hornblende-biotite granite intrusive into paragneisses and amphibolites. This work provides insights into the kinematic evolution and emplacement mechanism of the Ngwi pluton, highlighting the complex tectonic history of the region, with implications for understanding the Pan-African tectonics. Structural data analysis reveals: (i) D1 flattening (similar to 622-613 Ma) defined by NW- to WNW-striking S1 foliation in paragneisses; (ii) D2 sinistral shearing (similar to 613-590 Ma) with NE-SW to NNE-SSW and NW-SE rotational evolution, developed S2 foliation in host-rocks and Sm2 magmatic fabric in pluton; (iii) D3 dextral shearing (similar to 585-540 Ma) with NE-SW to ENE-WSW and NW-SE rotational evolution, induced a mylonitic fabric towards the pluton margins. Microstructural and kinematic data analysis suggest the Ngwi pluton emplaced into a high-strain sheared crustal domain during the D2-D3 phases, with a continuous evolution from magmatic to solid-state deformation (i.e., 700 degrees C <= T <= 300 degrees C) under high-grade amphibolite to low-grade greenschist conditions. The pluton's emplacement likely occurred within tension gashes opened in the paragneiss host rocks under a sinistral transpressive tectonics along the CCSZ, consistent with similar shear zones in Chad, Central African Republic and northeastern Brazil.
This paper is aimed at establishing the theoretical study and microcontroller validation of the resistive-capacitive shunted Josephson junction (JJ) circuit with 2 pi - and 4 pi - periodic superconducting current components (RCSJJ2-4PSCC). According to the Routh-Hurwitz criteria, the rate equations for the RCSJJ2-4PSCC exhibit different behaviors based on operating conditions. When the system operates strictly in the 2 pi - or 4 pi - periodic regime, it may have either no equilibrium points or two equilibrium points, which are a stable-node and a saddle-node, influenced by the excitation current. In contrast, when the RCSJJ2-4PSCC functions under conditions where both the 2 pi - and 4 pi - periodic regimes coexist, it displays no equilibrium points, or two, four, or even eight equilibrium points. The stability of these points varies, particularly with the emergence of a pitchfork bifurcation based on the fractional parameter and stimulation current source. The hysteresis loop is sensitive to variation of the fractional parameter of the RCSJJ2-4PSCC. The RCSJJ2-4PSCC reveals various behaviors, including regular, period-doubling, bistable regular, bistable chaotic, and chaotic characteristics, as well as the coexistence of these states. These dynamical attractors show qualitative agreement with the results from the microcontroller implementation. By introducing via addition, a boosting parameter to the voltage, the orientations of the chaotic signals are adjusted dynamically by altering the boosting parameter.
This study presents a detailed mineralogical and crystallochemical characterisation of clay deposits from Mbengwi (Northwest Region, Cameroon) to evaluate their suitability for industrial applications. Three samples collected at depths of 10.7 m (BGW1), 8.8 m (BGW2) and 6.5 m (BGW3) were analysed using x-ray fluorescence, x-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis and differential scanning calorimetry. Across all sampled depths, high-purity kaolinite consistently dominates the mineralogical composition (similar to 90%), with minor occurrences of illite (1.5%), quartz (3%), goethite (1.3%) and anatase (1.4%). The SiO2/Al2O3 ratio closely aligns with the theoretical value for ideal kaolinite (1.17). The absence of distinct crystalline iron-bearing phases suggests either isomorphic substitution of Fe3+ within the kaolinite lattice or the presence of poorly crystalline iron minerals. Crystallinity indices - including the Hinckley Index, the size of the coherent scattering domain (D), the slope ratio and the FTIR-derived P0 and P2 factors - indicate a progressive enhancement of structural order with increasing depth. Thermal analyses corroborate this trend: deeper samples exhibit higher dehydroxylation temperatures and sharper endothermic peaks, reflecting least defect density and high kaolinite purity. These findings highlight the superior crystallinity and purity of deeper kaolinitic layers, positioning Mbengwi clays as promising candidates for high-performance applications such as ceramics, paper, catalyst supports and polymer industries.
We develop the stochastic two-scale convergence method in the framework of Orlicz-Sobolev spaces, in order to deal with the homogenization of coupled stochastic-periodic problems in such spaces. One fundamental in this topic is the extension of compactness results for this method to the Orlicz setting. For the application, we show that the sequence of minimizers of a class of highly oscillatory minimizations problems involving integral functionals with convex and nonstandard growth integrands, converges to the minimizer of a homogenized problem.
