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Assessment of Soils Developed on Various Formations in Maroua (Far North, Cameroon) for Production of Compressed Earth Bricks
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作者 Bertin Pagna Kagonbé Bakary Souleymanou +4 位作者 Viviane Djaoyang Bakaïné Raphael Essama Boum Belinga Bertrand Tatoh Aziwo Alexis Ngoniri Hamdja Likiby Boubakar 《Open Journal of Applied Sciences》 2023年第6期874-887,共14页
One of the most important materials in the building industry is earth brick. The current work focuses on the evaluation of Maroua soils and their potential usage in the manufacturing of Compressed earth blocks (CEB). ... One of the most important materials in the building industry is earth brick. The current work focuses on the evaluation of Maroua soils and their potential usage in the manufacturing of Compressed earth blocks (CEB). Four sites (Frolina, Goubeou, Mambang, and Djoulgouf) were chosen to conduct this study. One sample was collected at each location. Physico-chemical and mineralogical characteristics were obtained by using particle size, Atterberg limits, X-ray diffraction, and X-ray fluorescence analysis. Results revealed that sand is the most abundant fraction (36.9% - 50.5%) followed by clay (22.1% - 28.4%) and silt (11.3% - 23.8%). They mostly correspond to sandy soils. Liquid and Plastic limits range between 22.6% to 41% and 16.1% to 24.9% respectively and the plasticity index spans from 6.5% to 20.3%. Plasticity is low for Mambang and Djoulgouf and medium for Goubeou and Frolina soils. Mineralogical composition revealed the presence of smectite, kaolinite, and illite as clay minerals, associated with variable amounts of quartz, goethite, and K-feldspars. Geochemical analyses indicate a high silica content (47.1% - 72.8%) followed by alumina (10.9% - 22.8%) and iron (6.4% - 13.2%). The mineralogical, chemical and physical properties of the studied soils revealed that they are suitable for the manufacture of CEB according to the Cameroon Standards of CEB. 展开更多
关键词 Soil Physical Properties MINERALOGY GEOCHEMISTRY CEB Maroua-Cameroon
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Determining the effective elastic thickness through cross-correlation between isostatic disturbances
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作者 Nelson Ribeiro-Filho Cristiano Mendel Martins +2 位作者 Raissa Moraes Baldez Ivaldevingles Rodrigues de Souza Júnior Franck Eitel Kemgang Ghomsi 《Geodesy and Geodynamics》 EI CSCD 2024年第3期241-251,共11页
The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed t... The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data(representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region. 展开更多
关键词 ISOSTASY Elastic thickness Isostatic disturbance Moho depth CROSS-CORRELATION
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3D Modelling from New and Existing Gravity Data of an Intrusive Body in the Northern Part of Kribi-Campo Sub-Basin in Cameroon 被引量:4
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作者 Kue Petou Rokis Malquaire Owona Angue Marie Louise +1 位作者 Njingti Nfor Manguelle-Dicoum Eliezer 《International Journal of Geosciences》 2017年第8期984-1003,共20页
A new gravity survey was carried out in the northern part of the onshore Kribi- Campo sub-basin in Cameroon. The data were incorporated to the existing ones and then analyzed and modeled in order to elucidate the subs... A new gravity survey was carried out in the northern part of the onshore Kribi- Campo sub-basin in Cameroon. The data were incorporated to the existing ones and then analyzed and modeled in order to elucidate the subsurface structure of the area. The area is characterized in its north-western part by considerably high positive anomalies indicative of the presence of a dense intrusive body. We find, 1) from the analysis of the gravity residual anomaly map, the high positive anomalies observed are the signature of a shallow dense structure;2) from the multi-scale analysis of the maxima of the horizontal gradient, the structure is confined between depths of 0.5 km and 5 km;3) from the quantitative interpretation of residual anomalies by spectral analysis, the depth to the upper surface of the intrusive body is not uniform, the average depth of the bottom is h1 = 3.6 km and the depths to particular sections of the roof of the intrusion are h2 = 1.6 km and h3 = 0.5 km;4) and the 3D modeling gives results that are suggestive of the presence of contacts between rocks of different densities at different depths and a dense intrusive igneous body in the upper crust of the Kribi zone. From the 3D model the dense intrusive igneous block is surrounded by sedimentary formations to the south-west and metamorphic formations to the north-east. Both formations have a density of about 2.74 g/cm3. The near surface portions of this igneous block lie at a depth range of 0.5 km to 1.5 km while its lower surface has a depth range of 3.6 km to 5.2 km. The shape of the edges and the bottom of the intrusive body are suggestive of the fact that it forms part of a broader structure underlying the Kribi-Campo sub-basin with a great influence on the sedimentary cover. 展开更多
关键词 Kribi-Campo Sub-Basin GRAVITY Data 3D MODELLING SPECTRAL Analysis RESIDUAL ANOMALY
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Subsurface Structural Mapping Using Combined Terrestrial and Grace Gravity Data of the Adamawa Plateau (North-Cameroon) 被引量:1
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作者 Bouba Apollinaire Kamguia Joseph +4 位作者 Tabod Charles Tabod Yap Loudi Nouayou Robert Kande Houetchak Ludovic Oyoa Valentin 《International Journal of Geosciences》 2017年第7期869-887,共19页
In order to analyze and determine the geological structures of the Adamawa plateau, the terrestrial gravity data were combined to data computed from GGM02C gravity model. The dense gravity net obtained were further in... In order to analyze and determine the geological structures of the Adamawa plateau, the terrestrial gravity data were combined to data computed from GGM02C gravity model. The dense gravity net obtained were further introduced into qualitative and quantitative interpretations. The resulting Bouguer anomaly map obtained from combined data shows NE-SW direction which nearly coincides with the main direction of the fractures affecting the basement in the region and indicates strong gradients marking the presence of discontinuities between heavy and negative gravity anomaly. In order to conduct the quantitative interpretation of the combined gravity data, three profiles were drawn on the residual Bouguer anomaly map and therefore were interpreted using spectral analysis method and 3D density inversion. The knowledge of the depth and density of the geological structures show an uplift of dense rocks under the granite-gneiss substratum. This dense material found in the ENE-WSW direction of the Adamawa Plateau is interpreted as basaltic intrusion probably resulting from tectonic processes. According to this study, the depths of 3.83 km and 9.62 km are the new values of depths obtained for futures investigations in the Adamawa plateau. 展开更多
关键词 GGM02C Adamawa PLATEAU Bouguer ANOMALY 3D Density Model SPECTRAL Analysis
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Refinement of Bouguer anomalies derived from the EGM2008 model,impact on gravimetric signatures in mountainous region:Case of Cameroon Volcanic Line,Central Africa 被引量:1
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作者 Paul Gautier Kamto Cyrille Mezoue Adiang +2 位作者 Severin Nguiya Joseph Kamguia Loudi Yap 《Earth and Planetary Physics》 CSCD 2020年第6期639-650,共12页
Global geopotential models have not included the very high frequencies of the Earth’s external gravity field.This is called omission error.This omission error becomes more important in mountainous areas(areas with hi... Global geopotential models have not included the very high frequencies of the Earth’s external gravity field.This is called omission error.This omission error becomes more important in mountainous areas(areas with highly variable topography).The work reported here consists in reducing the omission error in measurements of Bouguer gravity anomalies,by refining the global geopotential model EGM2008 using the spectral enhancement method.This method consists in computing the residual terrain effects and then coupling them to the gravimetric signal of the global geopotential model.To compute the residual terrain effects,we used the Residual Terrain Model(RTM)technique.To refine it required a reference surface(ETOPO1)developed up to degree 2190(the maximum degree of the EGM2008 model)and a detailed elevation model(AW3D30).Computation was performed with the TC program of the GRAVSOFT package.The topography of the study area was assumed to have a constant density of 2670 kg/m3.For the inner and outer zones,the respective integration radii of 10 km and 200 km have been chosen.We obtained very important RTM values ranging from−53.59 to 34.79 mGal.These values were added to the gravity anomalies grid of the EGM2008 model to improve accuracy at high frequencies.On a part of the Cameroon Volcanic Line and its surroundings(mountainous area),we made a comparison between the residual Bouguer anomalies before and after refinement.We report differences ranging from−37.40 to 26.40 mGal.We conclude that the impact of omission error on gravimetric signatures is observed especially in areas with high variable topography,such as on the Cameroon Volcanic Line and around the localities of Takamanda,Essu,Dumbo,and Ngambe.This finding illustrates the great influence that topography has on accurate measurement of these gravity anomalies,and thus why topography must be taken into account.We can conclude that in preparing a global geopotential model,a high resolution DTM must be used to decrease the omission error:the degree of expansion has to increase in order to take the higher frequencies into account.The refined Bouguer anomalies grid presented here can be used in addition to terrestrial gravity anomalies in the study area,especially in mountainous areas where gravimetric data are very sparse or nonexistent. 展开更多
关键词 residual Terrain Model EGM2008 Omission error refined Bouguer anomalies mountainous area
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Evidence for the Upwelling of Mafic Bodies into the Upper Crust beneath the N40-50&#176;E Branch of the Pan-African Central Cameroon Shear Zone from Gravity Studies 被引量:1
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作者 Loudi Yap Robert Nouayou +2 位作者 Depesquidoux Tchaptchet Tchato Joseph Kamguia Apollinaire Bouba 《Open Journal of Geology》 2018年第3期278-297,共20页
The existence of mafic bodies at mid crustal level beneath the Pan-African Central Cameroon Shear Zone is still a matter of debate. To provide additional constrains on this issue, the crust of the west region of Camer... The existence of mafic bodies at mid crustal level beneath the Pan-African Central Cameroon Shear Zone is still a matter of debate. To provide additional constrains on this issue, the crust of the west region of Cameroon has been investigated using gravity data. Analyses of these data show N40-50&#176;E oriented iso-anomal contours in the Bafoussam area, interpreted as the N40-50&#176;E branch of the Central Cameroon Shear Zone. In addition, spectral analysis and 2.5D gravity modeling reveal intrusions of mafic bodies at depth between 3.2 and 14.2 km under N40-50&#176;E aligned volcanic centers, namely Mt Bambouto and Mt Mbapit. The above observations suggest a structurally controlled emplacement of the mafic bodies. In the light of the recent geophysical data, the interaction between the NE-ward channel flow operating at the bottom of the lithosphere or the asthenosphere upwelling and the Cameroon Shear Zone could better explain the magma upwelling in the upper crust. This result is the novelty of the present work. 展开更多
关键词 West Region MAFIC BODIES CENTRAL Cameroon Shear Zone GRAVITY 2.5D Modelling
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Monitoring and Environmental Assessment of Seawater in West Central Africa: Case of the Kribi Industrial and Urban Port Complex in Cameroon, Guinea Gulf 被引量:1
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作者 Mioumnde Arthur Paterne Kusi Micheline Michelle-Alexia Ngum +7 位作者 Kag Simon Pierre Kue Petou Rokis Malquaire Mumbfu Ernestine Mimba Botny-Capel Anne-Eunice Dissombo Edimo André Noel Masso Kody Christelle Zebaze Jiofack Kevine Bessong Moise 《Journal of Geoscience and Environment Protection》 2021年第6期167-183,共17页
This study is the first of a series of a project on the development and implementation of environmental protection policies, before<span style="font-family:Verdana;">,</span><span style="... This study is the first of a series of a project on the development and implementation of environmental protection policies, before<span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> during and after the construction of the </span><i><span style="font-family:Verdana;">Kribi</span></i> <i><span style="font-family:Verdana;">Industrial</span></i> <i><span style="font-family:Verdana;">and</span></i> <i><span style="font-family:Verdana;">Urban</span></i> <i><span style="font-family:Verdana;">Port</span></i> <i><span style="font-family:Verdana;">Complex</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">KIPC</span></i><span style="font-family:Verdana;">). The results will equip the State and scientific structures concerned with the protection of people, water resources and the environment as a whole. This includes reference data on the state of marine pollution in the region dating from the end of realization of the first phase of KIPC known as </span><i><span style="font-family:Verdana;">Kribi</span></i> <i><span style="font-family:Verdana;">Deep-Water</span></i> <i><span style="font-family:Verdana;">Harbor</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">KDWH</span></i><span style="font-family:Verdana;">). Accordingly, the aim of this work is to assess the current state of KIPC and its surrounding by quantifying the preliminary parameters of suspended matter (SM);to analyze the physical and chemical parameters, chemical pollution indicators for anions and major cations and organic pollution indicators of four water samples taken from four different sites in the project area by filtration and weighing, pH meter, turbid meter, titration, colorimetry and titrimetric methods. The analysis of these samples and these parameters provide</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> results which are slightly similar to international standards. This suggests that the environment remains relatively healthy. Hence, continuous management and monitoring of the parameters and pollution factors is strongly recommended.</span> 展开更多
关键词 Kribi Industrial Port Complex Seawater Monitoring and Environmental Assessment
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Structure of the Crust Beneath the South Western Cameroon, from Gravity Data Analysis 被引量:1
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作者 Marcel Jean E. J. M. Abate +4 位作者 P. Njandjock Nouck H. E. Ngatchou V. Oyoa C. T. Tabod E. Manguelle-Dicoum 《International Journal of Geosciences》 2016年第8期991-1008,共19页
The study area is located in the south western Cameroon and includes part of the Cameroon Volcanic Line (CVL). Volcanic activity has been recorded in this area, precisely on the Mount Cameroon which recently erupted i... The study area is located in the south western Cameroon and includes part of the Cameroon Volcanic Line (CVL). Volcanic activity has been recorded in this area, precisely on the Mount Cameroon which recently erupted in 2002. In addition, deadly carbonic gas was emitted by crater lakes (Monoun and Nyos) in 1984 and 1986 respectively. Potential field model EGM2008 has been used to investigate the structure of the crust. A regional/residual separation is performed using upward continuation and polynomial separation methods. The results from this operation show a similarity between the regional anomalies resulting from both methods. The regional anomaly maps present an increasing gradient trending ENE-WSW above and below latitude 5?N. Moreover, six nearly parallel profiles were drawn on the CVL in addition to two other profiles at the northern edge of Congo craton. These profiles were used to estimate the depths of the Moho discontinuity and some shallow sources by the means of the Bouguer and the residual anomalies respectively. The results show that the Moho discontinuity depths vary from 19 - 25 km (under Mount Cameroon) to 28 - 34 km (in Kumbo), while the southern neighbouring zone presents a Moho discontinuity depth ranging between 23 - 31 km (in Ngambe) and 22 - 32 km (in Eseka). These findings agree with the previous seismic and gravity researches lead in the area. EGM2008 is therefore a reliable tool to investigate the subsurface structures. 展开更多
关键词 South Western Cameroon EGM2008 Bouguer Anomaly Spectral Analysis Moho Discontinuity
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In vitro biological activities of aqueous extracts of Tetrapleura tetraptera(Schumach. & Thonn.) taub. and Aframomum citratum(C. Pereira) K.Schum from three Agroecologic Zones in Cameroon
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作者 Eyenga Manga Marie Laure Fauconnier +2 位作者 Judith Laure Ngondi Akoumou Manga Ngando Marianne Sindic 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2020年第2期71-80,共10页
Objective:To investigate some phytochemical constituents and biological activities of twelve samples of Tetrapleura tetraptera(Schumach&Thonn.)taub.and nine samples of Aframomum citratum(C.Pereira)K.Schum fruits c... Objective:To investigate some phytochemical constituents and biological activities of twelve samples of Tetrapleura tetraptera(Schumach&Thonn.)taub.and nine samples of Aframomum citratum(C.Pereira)K.Schum fruits collected in the bimodal forest zone(ZONEⅤ),the unimodal forest zone(ZONEⅣ)and the highlands zone(ZONEⅢ)in Cameroon.Methods:Fresh fruits extracts were obtained by aqueous infusion(100℃during 15 min)and evaluated by spectrophotometric methods for total polyphenol(TPP),total flavonoids(TFLV)contents and antioxidant(DPPH,total antioxidant capacity by the phosphomolybdenum method,iron reducing power or ferric reducing antioxidant power and inhibition of beta carotene discoloration assays)and anti-inflammatory(inhibitions of protein denaturation and 5-LOX represented by INH.PROT and INH.5-LOX respectively)properties.Principal component analysis was performed.Results:For both species,fruits from ZONEⅤhave the highest TPP,TFLV levels and biological activities.TPP and TFLV content of Aframomum citratum and Tetrapleura tetraptera fruits are positively and significantly(P<0.05)correlated.The biological activities of all extracts(0.25,2.5,25,250 mg/mL)were dosedependent and the extracts have shown strong antioxidant and antiinflammatory activities,but less than references(ascorbic acid,diclofenac,quercetin,and butylated hydroxytoluene).There was a positive correlation between TPP,TFLV and total antioxidant capacity,ferric reducing antioxidant power,and inhibition of beta carotene discoloration assays,and inverse correlations were observed with the IC50(g/mL)of DPPH,INH.5-LOX and INH.PROT assays for both species.Conclusions:The fruits exhibit variabilities and those from ZONEⅤfor both species are economically and healthcare challenging for herbalists,pharmaceutical firms,scientists and consumers.Indeed,most important extraction yield of bioactive compounds correlated with significant biological activities and the use of less material compared with an implementation in other Agro-ecologic Zones with the same results are noted. 展开更多
关键词 BIOLOGICAL ACTIVITIES Non-Timber forest products ANTIOXIDANT ANTI-INFLAMMATORY Agro-ecologic Zone Protein DENATURATION
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Sedimentological Studies of Alluvium Deposits along Ngovayang-Bipindi of Lokoundje River,Southwestern Cameroon 被引量:1
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作者 Mioumnde Arthur Paterne Mboui Felicite Audrey Katia +3 位作者 Kue Petou Rokis Malquaire Kabir Shola Ahmed Bessong Moise Liqiang Zhang 《International Journal of Geosciences》 2019年第1期119-139,共21页
In an area of about 305 km2, Seventeen stream sediment samples were taken from alluvium on the banks and floodplain of the Lokoundjé River and its tributaries. Sand samples after being dried in an oven, are subje... In an area of about 305 km2, Seventeen stream sediment samples were taken from alluvium on the banks and floodplain of the Lokoundjé River and its tributaries. Sand samples after being dried in an oven, are subjected to sedimentological analyses in laboratory. Amongst the analysis carried out;the particle size analysis helped to establish a precise textural description of the sediment and to understand the active mechanisms which occur during transport and particle deposition. The morphoscopy of quartz grains consists in determining the mode and duration of transport of the grains, thus allowing reconstructing the geological history of the latter. Heavy minerals are suitable to know the nature of the rock in which they come from and equal to specify their distributing province. The morphometry of pebble makes contributes for a better understanding to apprehension of the agents responsible for the transport of these materials. It appears that the alluvium of the Lokoundjé and its Bipindi tributaries are very fine to coarse. They are well segregated, classified, and homometric. It is the result of the actions of a hydrodynamic turbulent which is sometimes abrupt. From a morphoscopic point of view, using a binocular microscope, grains mainly belong to three categories based on their surface appearance: Grain unworn, the sub-dull and dull shiny. From the morphometric point of view, there is evidence of flattening and dissymmetry of pebbles which are slightly worn to form sub-spherical shapes. With regard to the study of heavy minerals, it has identified two mineralogical processions, which include a metamorphic process with the presence of Sillimanite and Andalusite. In addition, there is the presence of minerals such as green’s Hornblende, Tourmaline, and reflecting magmatic distribution. However, there are specific minerals such as zircon, which can be economically viable where the contents sometimes exceed 10 kg/m3. In the same vein, it has been noted the presence of gems like Topaze and Monazite which are real precursor auriferous accumulation. 展开更多
关键词 SEDIMENTOLOGY Alluvium Deposits Lokoundje River Ngovayang-Eseka
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Dynamics of the Vegetation Landscapes of the Mbere Valley’s National Park and Its Southern Periphery
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作者 Narke Jean Cyrille Aoudou Doua Sylvain 《Open Journal of Ecology》 2017年第6期392-405,共14页
The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-... The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-twining of natural, anthropic and institutional factors, predispose its vegetation cover to a dynamic which can be progressive or regressive according to the dominant factor. The present study aims at reconstituting the various space-time variations of the MVNP vegetation cover and its periphery between 1987 and 2014, and at determining the processes and the factors having supported these space-time variations of vegetation cover. The methodological step consists of an association of fieldwork and remote sensing in order to characterize the vegetation cover, to reconstitute the evolution of the vegetation cover and to determine the main factors of the processes of this evolution or dynamic. The diachronic analysis shows that the dynamics of the vegetation cover was marked by a progressive evolution between 1987 and 1999, and a regressive evolution between 1999 and 2014. On the base of fieldwork observations and the socio-economic surveys, it arises that the dynamics of the vegetation cover of the valley of Mbere and its periphery is subjected to the combined influence of the natural conditions, from the recurring anthropic disturbances as well as the weight of regulatory measures. 展开更多
关键词 DYNAMICS Landscapes VEGETATIONS National PARK PERIPHERY Mbere VALLEY
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Interpretation of locally high gravity anomalies using terrestrial gravity data in Bagodo, North Cameroon
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作者 Apollinaire Bouba Kasi Njeudjang +3 位作者 Loudi Yap Bouba Saidou Joseph Kamguia Tabod Charles Tabod 《Earth and Planetary Physics》 EI CSCD 2022年第4期378-384,共7页
In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a loca... In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a local study.Thus,we undertook a regional-residual separation of the gravity anomalies by using the polynomial method.Geophysical signatures of near-surface small-extent geological structures were revealed.To conduct a quantitative interpretation of the gravity anomalies,one profile was drawn on a residual Bouguer anomaly map and then interpreted by spectral analysis,the ideal body solution,and 2.5-dimensional modeling.Our results showed that the intrusive body in the Bagodo area consists of two trapezoidal blocks.The first and second blocks have roofs approximately 7.5 and 14 km deep,respectively,whereas their bases are approximately 17 km deep.These values are in agreement with those obtained by the ideal body solution,which showed two cells with a density contrast of 0.3 g·cm^(−3) in comparison with the surrounding rocks.The density of this body was estimated to be approximately 3 g·cm^(−3).The topography of these rocks showed that they are basaltic rocks that would have cooled in fracture zones as an intrusion. 展开更多
关键词 spectral analysis ideal body solution 2.5-dimensional modeling
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Local Initiatives of Land Rehabilitation in the Sudano-Sahelian Region: Case of <i>Hardé</i>Soils in the Far North Region of Cameroon
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作者 Désiré Tsozué Bertand Roger Haiwe +1 位作者 Jean Louleo Jean Pierre Nghonda 《Open Journal of Soil Science》 2014年第1期6-15,共10页
Local initiatives of hardé soils rehabilitation in Maroua region have been analyzed. Fieldwork consisted of conducting observations and surveys beside farmers in two study sites, Mizileng and Zokok. Investigation... Local initiatives of hardé soils rehabilitation in Maroua region have been analyzed. Fieldwork consisted of conducting observations and surveys beside farmers in two study sites, Mizileng and Zokok. Investigations on perception of land degradation signs by farmers show that appearance of encrusted surfaces and loss of vegetation cover are signs more expressed in both study sites. Causes expressed include acceleration of water and wind erosion processes, excessive falling of trees, inappropriate farming techniques and climatic hazards. The main consequences are declining of crop yields, lack of farming land and loss natural pastures. Rehabilitation actions undertaken by local communities surveyed include earth dikes, tillage including cart or hoe ploughing, application of organic matter, integrating farming techniques such as fallowing, association and rotation of crop, and lastly, parking of animals on plots to be rehabilitated. Populations assert in their majority perceive in six months to three years signs of real change on planning plots. Constraints to those rehabilitation actions include material requirements that are mostly not available or accessible to farmers in the study area and access to land. Globally, there is no integration of local knowledge in the implementation of projects and consequences are localized and ephemeral efficiency, but also not conclusive results. Implementation of an innovation in rural areas must take into account the factors of ownership and inscribe in a well-defined trajectory. This trajectory must be dynamic and reflexive where local knowledge will cope with expert knowledge to ensure impact and sustainability of innovation. 展开更多
关键词 LOCAL Initiative Hardé SOILS Land Degradation Rehabilitation Cameroon
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Geoelectric Structure of the Crust along the Mbere Trough (South Adamawa) from Audio-Magnetotelluric Data
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作者 Ludovic Houetchak Kande Joseph Kamguia +1 位作者 Jean Marie Tadjou Robert Nouayou 《International Journal of Geosciences》 2013年第8期1215-1227,共13页
The South Adamawa trough represents a major structure associated to the tectonic activity in the Adamawa region. The Mbere and the Djerem troughs represent the eastern and the western parts of the South Adamawa trough... The South Adamawa trough represents a major structure associated to the tectonic activity in the Adamawa region. The Mbere and the Djerem troughs represent the eastern and the western parts of the South Adamawa trough respectively. The audio-magnetotelluric (AMT) method is used to study the Mbere trough and to bring out tectonic features that affect the basement of this region during the Cretaceous. From analysis and interpretation of AMT data, based on pseudo-section and geoelectric section, two geologic models are constructed across the trough at Belel and Nyambaka. Those models bring more information on the sediments thickness and the borders faults of the trough compared to previous studies. The results shows that the Mbere trough is dissymmetric, and bounded on its northern side by an intra-gneissic fault and on its southern side by two faults with at least one considered as a faulted contact between the granitic and gneissic rocks. The sediments filling of the trough are consist mainly of conglomerates on which lay sandstones. The thickness of these sediments is about 2060 m at Belel and decreases to about 1800 m at Nyambaka, with a low sandstones thickness, which does not exceed 360 m. The basement consists of granite in the South of the trough and gneiss in the North, with resistivity more than 10,000 Ω.m. The Moho is located between 25 and 35 km in the South Adamawa region. 展开更多
关键词 Adamawa TROUGH Fault RESISTIVITY Pseudo-Section GEOELECTRIC SECTION
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Research of Directory Service Model for Geographic Information
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作者 Chengming Li Xuewang Yuan +1 位作者 Wei Sun Xiaoli Liu 《Journal of Geographic Information System》 2018年第4期476-489,共14页
With the deepening application of geographic information web services, as a significant part, geographic information directory service sets up a service transaction platform between the service providers and the servi... With the deepening application of geographic information web services, as a significant part, geographic information directory service sets up a service transaction platform between the service providers and the service requestors, providing one-stop registration, access and management functions of geographic information web services, so it is very important to carry out the research on geographic information directory service. According to the domestic and overseas metadata standards, the service expression-oriented metadata information model for geographic information web service is established, and the discovery mechanism dominated by geographic information service registration and active discovery is realized accordingly. After that, overall design of directory service model is made, and finally the research results are integrated into the geographic information service software NewMapServer and deployment test is made under the Google Cloud Environment Google App Engine, providing a certain reference for sharing the Smart City construction achievements. 展开更多
关键词 DIRECTORY SERVICE METADATA SERVICE REGISTRATION SERVICE DISCOVERY OGC CSW
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Evaluation of the Advanced Minning Front Craft in and around National Parks of the Benue and Bouba-Ndjidda in North Cameroon
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作者 Aoudou Doua Sylvain Narke Jean Cyrille Mayen Ndiong Bertille 《Journal of Geographic Information System》 2018年第4期461-475,共15页
This study focuses on the assessment of “the advancement of the mining front (gold panning) in and around protected areas”. The aim of this article is to evaluate, using geomatics tools, the recent advance of the mi... This study focuses on the assessment of “the advancement of the mining front (gold panning) in and around protected areas”. The aim of this article is to evaluate, using geomatics tools, the recent advance of the mining front (gold panning) in Benue National Park (PNB) and Bouba-Ndjidda (PNBN) for their planning purposes. We adopted a methodological approach articulated from the field surveys to the processing of satellite images and the integration of the data into a GIS. Thus, 30 gold panning sites were visited, including 16 in the PNB and 14 in the PNBN. From the mapping of the pressures exerted by this activity, it appears that 143.8 km and 73.8 km of cumulated linear were exploited respectively in the GNP and the PNBN;moreover, the results allowed us to detect that the surfaces degraded by gold panning are more important in Benue than in Bouba Ndjidda. The massive influx of migrants from the more populated areas of the Far North of Cameroon as well as neighboring countries (Chad, Nigeria and the Central African Republic) has not only brought about the growth of a pioneering agricultural front, but also the mining front, following the gold rush from 2009;which has led to huge environmental consequences in these protected areas. 展开更多
关键词 MINING FRONT Artisanal MINING FRONT NATIONAL Parks Benue
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Application of Coefficient of Anisotropy to the Geophysical Prospecting of Campo—Ma’an Area of the Ntem Complex in Cameroon
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作者 Njingti-Nfor   Owona Angue Marie Louise +2 位作者 Kue Petou Rokis Malquaire Bisso Dieudonné Lando Tsakou Julyo Achille 《Open Journal of Geology》 2017年第12期1801-1818,共18页
Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determin... Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determine the tectonic settings and the nature of the contacts between the sedimentary formation of the Kribi-Campo basin and the cratonic Ntem Complex. The results of this study show that apart from the sedimentary formation, the metamorphic formation in this area comprises two metamorphic blocks: a regional metamorphic block which might be igneous or granitic in nature and composition and seem to be Precambrian and plutonic in origin and a contact or transitional metamorphic block, which might represent schist or gneiss rocks. The contact or transitional metamorphic block might be as a result of a long period of contact between regional metamorphic rocks and rocks of sedimentary formation. These contact/transitional metamorphic rocks which are found sandwiched between rocks of sedimentary formation and rocks of the regional metamorphic block and at varied depths confirm the existence of vertical and sub-vertical contacts between the Kribi-Campo basin and the cratonic Ntem complex. Two types of rock contacts have been identified: a sedimentary-schist contact which is found at the boundary between the sedimentary formation and the transitional metamorphic block and a schist-granite contact between the transitional and regional metamorphic blocks. Two main formations: a sedimentary formation, which is found in the Kribi-Campo sub-basin and the Ntem River bed and its flood plains and the metamorphic formation which includes both the transitional and regional metamorphic rocks have also been identified in the area of study. Subsurface rocks and rock materials have been observed to be highly resistive and occupying almost the entire subsurface in the area of study confirming the high vertical tectonic stability of the Ntem Complex even at contact with the sedimentary Kribi-Campo basin. 展开更多
关键词 ANISOTROPY Telluric Geo-Electric SUBSIDENCE ISOTROPIC Vertical FAULTS TECTONICS
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Determination of Structural and Geometrical Parameters of the Kribi-Campo Sedimentary Sub-Basin Using Gravity Data
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作者 Kue Petou Rokis Malquaire Owona Angue Marie Louise Clotilde +2 位作者 Njingti Nfor Ndougsa-Mbarga Théophile Manguelle-Dicoum Eliezer 《International Journal of Geosciences》 2017年第9期1210-1224,共15页
In order to produce a more detailed structural and geometrical information, and determine sediments thickness along the Kribi-Campo sub-basin, statistical spectral analysis and horizontal gradient analysis of residual... In order to produce a more detailed structural and geometrical information, and determine sediments thickness along the Kribi-Campo sub-basin, statistical spectral analysis and horizontal gradient analysis of residual anomalies coupled with the Euler deconvolution approach were applied on the gravity data in the area. The results obtained from the 2D spectral analysis on anomaly grids gave a depth to the basement rocks of the basin from 0.60 km to 3.93 km. This represents the thickness of the sedimentary formations overlying the basement. The interpretation of the spectral analysis results indicated that the potential hydrocarbon field areas are situated between Kribi and Lolabe and at Campo given that those areas have the highest sedimentary thicknesses values. From the analysis of the horizontal gradient, deep faults mainly striking SW-NE have been traced and a structural map of the area has been produced. By applying the Euler deconvolution method to the gravity data, information about the depth and trend of the main subsurface structures have been obtained. 展开更多
关键词 SEDIMENT Thickness Spectral Analysis Horizontal GRADIENT Structural Map Kribi-Campo Sub-Basin GRAVITY Data
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Exploration of Potential Ore Deposits along the Cameroon Volcanic Line from Gravity and Magnetic Studies
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作者 Fosso Téguia M. Estelle Eric Nana Gaelle Vanessa +5 位作者 Lepatio Tchieg Sterve Alain Ntomb Biboum Edouard Olivier Eyike Yomba Albert Zanga Amougou Alain Atéba Bekoa Ntepe Nfomou 《Open Journal of Geology》 2020年第10期1009-1026,共18页
A gravity and magnetic study has been carried out along the continental part of the Cameroon Volcanic Line (CVL), with the aim to explore the possibility of ore’s presence into the basement of this region. Different ... A gravity and magnetic study has been carried out along the continental part of the Cameroon Volcanic Line (CVL), with the aim to explore the possibility of ore’s presence into the basement of this region. Different processing techniques have been applied, including the isostatic residual, the analytic signal and the Euler deconvolution to compute the Bouguer and magnetic anomalies. Following Euler solutions (result of Euler deconvolution) and the analytic signal results, four profiles crossing main structures on the isostatic residual have been used to enhance the structure of intrusions in the studied area. Despite the lack of constraints in the studied region, the results show that the basement is intruded by bodies of different density (2.57<span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">g/cm</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> to 2.87</span></span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">g/cm</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">), different size and shape, with depths between 1 and 10 kilometers. These bodies have been interpreted as old rocks then as potential reservoirs of rare ores. In addition, volcanic rocks modeled have constituted potential reserves of other ores like graphite, sulfur, copper, iron.</span></span> 展开更多
关键词 Ores Deposits Cameroon Volcanic Line (CVL) GRAVITY MAGNETIC
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Analysing Mismatches in the Demand and Supply of Classrooms in the Basic and Secondary Education Sectors in Cameroon
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作者 Aloysious Kohtem Lebga Aristide Yemmafouo +2 位作者 Chretien Ngouanet Anehmbom Ghoutum Bienvenu Magloire Takem Mbi 《Journal of Geographic Information System》 2022年第3期175-192,共18页
The present work analyzed the contribution of Cameroon’s public contracts and territorial planning policies toward the reduction of classroom disparities across the country. Many localities in Cameroon suffer due to ... The present work analyzed the contribution of Cameroon’s public contracts and territorial planning policies toward the reduction of classroom disparities across the country. Many localities in Cameroon suffer due to misallocation of classrooms on one hand and inefficient public contracting-execution system on the other hand. This paper uses a hypothetico-deductive method to understand the nexus of public contracting-territorial planning within the educational sector in Cameroon. To do this we made use of existing infrastructural data collected from various Ministerial Departments and public contracts data from 2016 to 2022. Findings show that there is a great disparity of existing classrooms, injustice in the allocation of classrooms and bad governance practices in the award and execution of allocated classrooms that directly contribute to this uneven repartition. At the national scale, the Centre and Littoral regions seem to be saturated with about 20,574 and 10,436 classrooms respectively, the Far North which is part of the Priority Education Zone is in dying need of about 11,293 classrooms while on the local or regional scale these two saturated regions show some degree of insufficiency in term of available classrooms. Therefore, much needs to be done by the Cameroonian authorities in order to ensure inclusive, equitable quality education and promote lifelong learning opportunities for all as stipulated by the Sustainable Development Goal 4. 展开更多
关键词 Public Contracts Territorial Planning Territorial Disparities GOVERNANCE Classroom Cameroon
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