Petrology and Structural Characterization of Post-Neoproterozoic Dolerites from the Kimberlite Fields in the Kéniéba Region (Western Mali)

Post-Neoproterozoic dolerites from the Kéniéba region (Western Mali) are often associated with kimberlites. The rarity of kimberlite outcrops led to the study of doleritic rocks, spatially associated with them. The petrographic and lithogeochemical study showed that the dolerites of the Kéniéba kimberlitic fields are of tholeiitic nature and of the E-MORB (Enriched-Mid Ocean Ridge Basalt) type. This reflects an enrichment over time, compared to the Birimian dolerites of the volcano-sedimentary greenstone belt of Toumodi, in central C?te d’Ivoire. Furthermore, these dolerites are enriched in SiO2, TiO2, Zr and poor in Fe2O3, MgO. These dolerites would have formed in a late to post-orogenic intracontinental context during the breakup of Gondwana. Structurally, Kéniéba dolerites are often associated with kimberlite pipes, fractures and large deep structures identified using aeromagnetic images. Taking into account the fact that kimberlites do not outcrop in the Kéniéba region, the geochemical study coupled with the interpretation of aeromagnetic data proved to be very useful for the search for pipes.

Contribution of GIS to Soil Landscape Mapping by Multi-Criteria Analysis Using Weighting: The Case of the Square Degrees of M’Bahiakro (Centre) and Daloa (Centre-West) in Ivory Coast

As part of the drive to improve coffee and cocoa production in Ivory Coast, studies are carried out to identify soils that are favourable for these crops. It is therefore necessary to orientate soil investigations based on reliable criteria that best discriminate soil cover. With this in mind, this study is being carried out to help improve survey methods by mapping soil landscapes. It uses GIS and weighted multicriteria analysis. To do this, satellite images were processed and the geological map of the square degrees of M’Bahiakro and Daloa was reclassified. The results show that relief is the main factor in soil landscape differentiation, with respective weights of 0.58 and 0.67 for the forest and pre-forest zones. In contrast, the weight of geological formation in soil landscape differentiation remains low (0.05 for the forest zone and 0.07 for the pre-forest zone). The criteria used on the base of aggregation sum methods have made it possible to formulate soil landscape mapping prediction functions according to agro-ecological environments in the humid intertropical zone. This is essential for the orientation of soil survey work. Nevertheless, other comparative methods, such as the coding mapping method, could provide elements for discussion to validate the models.

Multicriteria Analysis by Codification for the Determination of Soil Landscape Units in Forest and Pre-Forest Zones of Cote D’Ivoire: The Case of the Square Degrees of M’Bahiakro and Daloa

The present study, carried out in the forest (Daloa) and pre-forest (M’Bahiakro) zones of Cote d’Ivoire, aims to determine soil landscape units using the coding method. Geological maps and satellite images (SRTM and Landsat) were used for this purpose. The methodological approach adopted consisted in producing maps of slope, geology, land use and topography using the codification method. These various maps, integrated into a GIS using the coding aggregation method, were used to generate soil landscape maps. Twenty-seven (27) soil landscapes have been identified for the pre-forest zone (M’Bahiakro), with a strong dominance of acid rock over a moderate relief under savannah, forest/degraded forest and crops/fallow. However, the forest zone (Daloa), with forty-one (41) soil landscapes identified over the entire zone, is characterized by a majority of mafic rocks on a medium altitude under forest/degraded forest, water and crops/fallow. The criteria used from the codification method (sum of aggregations) made it possible to predict the spatial distribution of soil map units according to agro-ecological environments in the humid intertropical zone. This is essential for the orientation and reinforcement of soil survey tools. However, a comparative evaluation of the different multicriteria analysis methods for coding and weighting soil landscape unit mapping would enable us to identify the most suitable and efficient method for drawing up base maps for soil surveys.

Response of the Maize Variety EV87-28 to a Fertilization Strategy Involving Indorama Granular Urea on Ferralsol in the Central Ivory Coast

In Côte d’Ivoire, the decline in soil fertility strongly impacts the productivity of maize (Zea mays L.) on heavily leached ferralitic soil. In this study, the general objective was therefore to improve the productivity of maize EV87-28 on the Ferralsols in pre-forested areas during different cropping seasons. Eight (8) micro-plots were set up according to a total randomization device with three repetitions. Two factors were studied: nitrogen fertilizer modalities (main factor) and crop season (secondary factor). Growth, flowering and yield parameters were measured and analyzed. The results showed that there was no interaction between the nitrogen fertilizer factor and the cropping season factor. In addition, this study showed the short rainy season had the most positive impact on growth, flowering and yield parameters than the long rainy season. The results also showed that the different nitrogen fertilizer modalities had no statistically different effects on growth, flowering and yield parameters. However, quantitative differences were reported, highlighting one nitrogen fertilizer modality, which is the combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure). The combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure) had the best effect on corn grain yield. So, the combination of urea (75%) and manure (25%), that resulted in yield gain, could be recommended for corn fertilization during the small rainy season.

Sequential Analysis in the Identification of 3rd Order System Tract in the Abidjan Margin

The use of sequential stratigraphy concept, based on well logs, sedimentology, and biostratigraphy, has shed light on the complex mechanisms controlling sedimentary accumulations. Consequently, identifying these mechanisms allows us to predict the hydrocarbon generation potential of source rocks. In the Ivorian offshore sedimentary basin, certain studies have contributed to understanding and characterizing the petroleum system. However, these previous works did not integrate biostratigraphic data to highlight sedimentary facies. This study, conducted on two wells in the Abidjan margin, is crucial as it helps us comprehend the geometry of fossil sediments in relation to sea level variations. It will also aid in reconstructing the basin-filling history and predicting the distribution of rocks capable of trapping oil, determining lowstand systems tracts (reservoir rocks), transgressive systems tracts, and highstand systems tracts (cap rocks). Lithological analysis revealed predominantly clayey sedimentation with sandy layers. Well log data facilitated the delineation of formation boundaries and highlighted reservoirs consisting of sands, sandstones, limestones, and occasionally intercalated shales. Integrating these analysis results with biostratigraphic interpretations based on foraminifera and palynomorphs revealed that the traversed formations were deposited in a transitional environment ranging from Coniacian to Maastrichtian ages. Applying sequential stratigraphy concept from well logging resolved dating issues encountered in microfossil-poor or microfossil-free zones. The results of the Coniacian-Maastrichtian age sequential subdivision were aligned with the chart.

Effects of Calcium and Magnesium on Phosphorus Availability in Ferralsols and Rice Production in Forest Zones of Côte d’Ivoire

Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of the NERICA 5 rice accession to various doses of calcium, magnesium and phosphorous. The experiment was conducted using a randomized split-plot design. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg·Ca·ha-1) and magnesium sulfate (0, 25, 50 and 75 kg·Mg·ha-1) and Togo natural phosphate (0, 25, 50 and 75 kg·P·ha-1) were determined at each production cycle. The results showed that single-dose natural phosphate supplementation for three cropping cycles resulted in an average enrichment of around 2 mg·P·kg-1 after each trial following its continuous dissolution, with an increase in DSP (33.31% to 70.52%). The study revealed one strategy for managing and enhancing native P with cations and another for exogenous P: there would be a synergy of Ca/Mg on native P, whereas an antagonism would characterize the two parameters in phosphate fertilization.

Calcium-Magnesium Ca/Mg Ratios and Their Agronomic Implications for the Optimization of Phosphate Fertilization in Rainfed Rice Farming on Acidic Ferralsol in the Forest Zone of Ivory Coast

This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha−1) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha−1) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha−1 of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha−1) and potassium (K) (50 kg KCl ha−1) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha−1 for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha−1, 34 kg Mg ha−1 in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha−1, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.

Litho-Structural and Geochemistry Analysis of Granitoids from Mount Fouimba and Goma in Seguela Area (Central-Western Côte d’Ivoire)

The petrogeochemical analysis of the granitoids of Mount Fouimba and Mount Goma in the Seguela region (central-western C?te d’Ivoire) is the subject of this study. This analysis combines remote sensing, geophysics, petrography and geochemistry, in order to determine the major characteristics of the granitoids in the study area, and above all to participate in the detailed mapping of all the Ivorian terrains. The granitoids encountered in this region are essentially two-mica granites, granodiorites and porphyry basalts. Chemical analysis indicates that these granitoids are of the ferrous and magnesian type with peraluminous to weakly metaluminous characteristics. They originate from the mantle and were emplaced in an active continental margin context.

3D Modeling and Estimation of the Tonnage of the Granite Quarry of Linguésso (North-West of Côte d’Ivoire) by Electrical Methods

A survey and evaluation was carried out on a potential granitoid quarry site in the locality of Linguésso (North West of Ivory Coast) with the aim of identifying and estimating the quantity of exploitable granite based on the electrical resistivity methods. The combination of electrical trailing, sounding and tomography techniques allowed the determination of the characteristics of the rock deposit, namely the electrical signature (between 19,259 Ωm and 86,316 Ωm), the extension (N90°), the rooting (between 0 and 45 m) and the fracturing (between N14° and N160°) of the granitic formation sought. The modeling resulted in an estimated mineable rock volume of 2,936,250 m3 providing a production quantity of 7,927,875 tonnes.

Petrochemical Studies of Fouimba and Goma Mounts, Central-West of Cote d’Ivoire: Implication on Petrogenesis Tectonic Setting

Petrogeochemical analysis of mafic rocks of Fouimba and Goma Mount in the Séguéla region (central-western Côte d’Ivoire) is the subject of this study. This analysis combines remote sensing, geophysics, petrography and geochemistry, in order to determine the major characteristics of the mafic formations in the said area, and above all to participate in the detailed mapping of all the Ivorian terrains. The mafic formations encountered in this region are essentially metatonalites to metadiorites, amphibolites, amphibole bearing pyroxenites and porphyry basalts. Chemical analysis indicates that these mafic formations are tonalitic to monzonitic. They are thought to have derived from mantle depleted magmas.

Evidence of the Albo-Cenomanian Unconformity Using Chemical Elements Case Study of Sediments from the Eastern Abidjan Margin

Sedimentological and chemostratigraphical studies using accessory elements on 322 samples of cuttings from oil wells located in the submerged sedimentary basin (offshore) of Côte d’Ivoire. This basin covered the chronostratigraphic interval from the Upper Albian to the top of the Maastrichtian. The aim of this study was to determine the major accident, the Albo-Cenomanian unconformity, using chemical elements. To achieve this goal, we had to count the accessory elements glauconite, pyrite and carbonaceous debris, and identify all the chemical elements present in each cuttings sample. The results clearly indicate that: the sediments are essentially composed of carbonaceous debris and pyrite, with a high potassium content for sediments dating from the Abian period;and glauconite, carbonaceous debris, pyrite, and a sharp decrease in potassium content for sediments dating from the Cenomanian to the Maastrichtian period. Threshold values for ratios of source-indicating chemical elements (Zr, Ti, Y, Th) and paleoenvironmental elements (K, Rb, Mg, Al,) highlighted the MS1 and MS2 mega-sequences in the study area. The difference observed in the threshold values of these ratios can be explained by changes in sedimentary dynamics. The depositional environment varies from an inner continental shelf with strong littoral influence (Upper Albian) to an increasing subsidence outer continental shelf (Cenomanian-K/Pg boundary).

Fouimba and Goma Mounts Greenstone Belts Litho-Structural Analysis Related to Côte D’Ivoire Birimian Geodynamic Setting and Implying in West-Africa Craton Gold Deposits

Mount Fouimba and Mount Goma (Seguela) greenstone belts petro-structural studies combine remote sensing, geophysics, petrography and structural analysis. In view of establishing mapping details of paleoproterozoic geological formations, geological setting rocks observed are essentially magmatic formations, such as two-mica granite, granodiorites, and porphyritic basalts;and a few metamorphics which are metatonalite, amphibolites and amphibo-lopyroxenites. Remote sensing, such as Landsat 8 OLI satellite imagery and geophysical data, has been combined to show regional NNE-SW shear zone. Tectonic structures and microstructures have enabled to identify two main deformation phases: D1 phase corresponding to compression, and D2 is a transpression phase. Mechanisms responsible for deformations are respectively flattening and transpression. Geological formations derived from mantle origin but contain crustal components, and their tectonic setting occurred during subduction.

Aeromagnetic Imagery as a Tool to Help Identify the Structures Controlling the Emplacement of the Kenieba Kimberlite Pipes (Western Mali, West African Craton)

A kimberlite field, represented by fertile and sterile kimberlite pipes (chimneys) is located in the region of Kenieba (West Mali, Kédougou-Kenieba inlier, West African Craton). Thirty pipes and kimberlite dykes have been identified in the birimian formations, composed mainly of metasediments and granitoids, covered by sedimentary formations (sandstones and conglomerates) of Neoproterozoic age. All these formations are injected with dykes and doleritic sills of Jurassic age. The study of kimberlite pipes is still stammering in Mali, and thus no previous study has allowed to characterize the structures controlling their implementation. The reinterpretation of aeromagnetic data validated by field work indicates that the major structures of the Kenieba region are oriented NNE-SSW, NE-SW, E-W and NW-SE. These structures (faults and kimberlite pipes) are often associated with dolerite dykes, which would imply an injection of dolerite magma into the other formations. The location of the known kimberlite pipes makes it possible to say that the direction NW-SE is the most favorable for the exploration of kimberlites in the region of Kenieba.

Geochemistry of Cretaceous Sea Rocks from the LEO-3X Well in the Eastern Abidjan Margin, Côte d’Ivoire Offshore Basin

In this study, we apply geochemical and statistical analyses to evaluate the source rocks and kerogen type of Cretaceous sediments from the Cote d’Ivoire sedimentary basin. The geochemical analysis includes pyrolysis data such as total organic carbon (TOC%), generation source potential (S2) and hydrogen index (HI). The results of the cluster analysis separated the source rocks in the study area into two main groups. 1) Source rocks characterized by HI > 300 (mg/g), TOC from 1.76% to 3.19% by weight, and S2 from 6.55 to 14.46 (mg/g), indicating good to excellent source rocks with type II kerogen and are capable of generating oil. 2) Source rocks characterized by HI between 200 and 300 (mg/g), TOC from 1.6 to 2.02 wt%, and S2 from 3.45 to 5.36 (mg/g) indicating medium to good source rocks with type II-III kerogen and capable of generating a mixture of oil and gas.

Influence of the Granular Class of Crushed Granites on the Litho-Stabilization of Samo Laterites (South-East of Côte d’Ivoire)

Most of the laterites found in Ivory Coast do not meet the technical conditions to be used in their natural state for the design of road foundations. Also, to meet the growing needs for road materials, various amendments are made to them, including litho-stabilization. Thus, this study proposes to understand the influence of the granular class of natural aggregates on the performance of laterites. To achieve this objective, different proportions of crushed granites of class 0/5, 0/15 and 5/15 have been incorporated into the soils of southern Côte d’Ivoire, especially in Samo. This modified soil has been subjected to mechanical tests such as the modified Proctor and CBR test. The results obtained show that the dry densities of the incorporated laterites containing crushed granites increase with the content of natural aggregates and decrease with the increase in the water content. Likewise, the CBR bearing indices at 95% of the Modified Optimum Proctor of the different compositions (laterites + crushed granites) increase with the proportion of aggregates. The addition of coarse aggregates to the laterites therefore promotes the establishment of a framework which improves its bearing capacity. From 20% to 30% crushed granites respectively of class 0/15;0/5 and 5/15, the values of the CBR obtained are greater than those of 30% therefore these modified soils can be used as a foundation layer for traffic of T1, T2 and T3 type. Likewise, the laterites’ mixtures with at least 40% crushed granites of class 0/15 and 0/5 can also be used for the foundation and base layers.

Mechanical Characterization of Rubber Latex-Based Carpets (Hevea bresiliensis): Influence of Rubber Latex Content and Fiber Fabrics (Cotton and Mosquito Nets) on Wear Resistance of Rubber Latex-Based Carpets

This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for shaping varies between 14% and 18% (latex/sand + latex ratio) for the carpet with the fabric of mosquito nets and between 16% and 18% for the one made with the fabric of cotton fiber. Thus, with a mixture of sand, fiber fabrics (cotton and mosquito nets) and rubber latex, carpets were developed. In addition, the wear test carried out on these samples indicates that it is possible to produce carpets with the new material made of rubber sand and latex: SABLATEX At room temperature. Following the characterization test, it resorts to only 16% latex with cotton fiber fabric, allowing to have carpets with good mechanical characteristics.

Influence of Plastic and Coconut Shell (Cocos nucifera L.) on the Physico-Mechanical Properties of the 8/6 Composite Rafter

In this paper, the authors aim to propose the use of waste plastics as a binder in a coconut shell reinforcement for the development of an 8/6 size composite rafter to replace the natural 8/6 size backbone in construction. Following a study into the choice of the best proportions, a total of 30 size 8/6 composite rafters with different proportions of 20%, 25%, 30%, 35%, 40% and 50% plastic content were developed. All the 8/6 composite rafters were subjected to mechanical (3-point bending strength and Monnin hardness) and physical (bulk density and water absorption) characterization analyses. The results show that flexural strength increases from 27.56 MPa to 33.30 MPa for proportions ranging from 20% to 35% plastic content. Above 35% plastic, the strength drops to 19.60 MPa for a 50% plastic content. Similarly, the Monnin hardness drops from 9 mm to 5 mm when the plastic content varies from 20 to 50%. As for the results of the physical characterisation, the values obtained for apparent density vary from 0.89 to 1 for proportions varying from 20% to 35% plastic content and drop to 0.94 for 50% plastic content. As for water absorption, values drop from 6.82% to 2.45% when the plastic content increases from 20% to 50%. These mechanical strengths stabilise at 35% plastic content. The development of an 8/6 chevron composite material based on plastic and coconut shell could therefore be a way of recovering waste and solving the problem of deforestation.

Chemostratigraphic Characterization Tests on Sedimentary Formations in the Côte D’Ivoire Offshore Basin: Case of A-X and B-X Wells

The tests performed with two hundred and thirty-nine (239) samples from the A-X and B-X drillings help to know their sedimentological and chemostratigraphic characters. In sedimentological term formations are composed of sand, sandstone, limestone, siltstone and argillite that alternate along the drill. In chemostratigraphic term two megasequences (MS1 and MS2) have been identified. A correlation of chemostratigraphic data completed by the lithology results allowed a subdivision of oil wells that shows two main types of deposits environments. First, a proximal marine environment to continental and to Albian marked by a detrital flow deducted from the concentrations evolution of indicator elements of terrigenous material that are K, Mg, and Rb. On the other hand, a deep to shallow marine environment of Cenomanian to Paleocene marked by the presence of predominantly clay sediments and abundant glauconite in the lower Senonian. Nevertheless, there is a transition or intermediate environment that is characterized by the presence of glauconite and detrital flows.

Metallotectic Context of the Mineralization of the Tondabo Gold Prospect(Brobo,Center of Cote d’Ivoire,West Africa)

The gold mineralization of the Tondabo prospect, located in the northern part of the Oumé-Toumodi-Fettêkro greenstone belt, is mainly hosted in the rhyodacite and to a lesser extent in the mafic volcanics (volcanic lavas and volcanoclastites). These rocks were affected by a hydrothermal alteration marked by quartz veins and veinlets associated with crystals of carbonates, sericite, epidote and sulfides. This hydrothermal alteration induced a pervasive alteration of the surrounding bodies with silicification, chloritization, carbonation and sericitization of the feldspars. The metalliferous paragenesis contains an abundant pyrite, with rare pyrrhotite and chalcopyrite. This mineralization indicates that the Tondabo gold prospect exhibits lithological control. The mineralized deposits are generally affected by a S1 schistosity oriented mainly N000-010° and minority N040-050° with a general dip of 60°-80°to the West;however with rare N-S orientations with a dip of 60°-80° to the East. The drilling intervals show that the highest gold contents are linked to the quartz-carbonates veins and veinlets, which are located in the highly deformed zones, characterizing local shear zones.

Evaluation of the Geological and Metallogenic Potential of Koffissiokaha Permit, Area of Katiola, Côte d’Ivoire

The semi-industrial permit of Koffissiokaha, south-eastern area of Katiola, is located in the northern part of Fêtêkro Birimian Greenstone Belt (Côte d’Ivoire). This permit, applicated by the company Blue-Hill Exploration Sarl (BHEX), is in the southern continuity area of Lafigué permit (Endeavour Mining). Blue-Hill will have to work to highlight potential gold mineralization, quantify it (resource calculation) and initiate administrative procedures to obtain a Semi-Industrial Exploitation Authorization (AESI). Our recent works, including field mapping coupled with petrographic and microstructural studies, are therefore intended to contribute to the knowledge of the geology and to the evaluation of the gold potential of this permit. They suggest that Koffissiokaha permit includes four major lithologic units: 1) a sedimentary unit formed by metaarenites and metasiltites, 2) a unit of mafic pyroclastites (cinerites, tuffs and volcanic breccias) 3) a plutonic unit of metagabbro and finally, 4) a lode-type unit made up of metarhyodacites. The metamorphism that affected the volcano-sedimentary rocks is of low grade to greenschist facies. On the structural level, deformations with variable gradients are noted. The major planary structure, the schistosity, is oriented N20 - 40 with weak (°), moderate (50°- 60°) and steep dips (>70°) or subvertical. The faults generally correspond to narrow dextral or senestral shear-zones (75°) towards south-east or subvertical. They are most often intersected by late strike-slip faults-oriented NW-SE, NNW-SSE and N-S. Quartz veins are associated with faults or deformation zones. They are generally oriented N20 to N40, with weak (°), moderate (55°- 65°) and steep dips (>75°). Orientations of joints and fractures are mostly subparallel to the plans of schistosity, shears and most of quartz veins. However, ENE, WNW and N-S fractures are also distinguished. The sulphide paragenesis consists of pyrites (and pyrrhotites), arsenopyrites and chalcopyrites. Gold mineralization is controlled by both structural and hydrothermal parameters.