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The Bafoussam volcanic series:origin and evolution of the volcanism along the Cameroon volcanic line

Acta Geochimica 2022年第6期41卷 1049-1068页

作者： Philippe Essomba Gilles Chazot Nicaise Blaise Tchuimegnie Ngongang Arnaud Agranier Pierre Kamgang hervébellon Philippe Nonnotte Pierre Wotchoko Innocent Badriyo Département Des Sciences de La Terre FacultéDes SciencesUniversitéde YaoundéIB.P.812YaoundéCameroun Geo-Ocean CNRSIfremerUMR6538Univ Brest29280PlouzaneFrance Département Des Sciences de La Terre FacultéDes SciencesUniversitéde DoualaDoualaCameroun Department of Geology Higher Teacher Training CollegeUniversity of BamendaBambiliBamendaCameroon Département de Séismologie et Géologie Observatoire Volcanologique de Goma-RDCGomaRépublique Démocratique du Congo

The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic *** rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and *** age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 *** alkaline volcanism is younger,with ages ranging from10 to 4.5 *** evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing *** the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic *** lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional *** La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the *** cannot be used for discussing the mantle source of the volcanic rocks from this *** elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle *** magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic *** mantle source is present in all the oldest lavas from the *** magmas formed from an HIMU-like mantle sourc

关键词： Cameroon Volcanic Line Bafoussam Mafic volcanic rocks Felsic volcanic rocks Mantle source

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藏北可可西里地区新生代钾质adakitic火成岩:板内下地壳的熔融

藏北可可西里地区新生代钾质adakitic火成岩:板内下地壳的熔融

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2004年全国岩石学与地球动力学研讨会

作者：王强许继峰 Marc J Defant 朱迎堂 Frank McDermott herv é bellon 中国科学院广州地球化学研究所中国科学院广州地球化学研究所 Department of Geology University of South Florida Tampa FL 33620 USA 青海地质调查研究院 Department of Geology University College Dublin Belfield Dublin 4 Ireland Laboratoire de géocgronologie et UA 1278 Université de Bretagne Occidentale 29287 Brest France

＜正＞一般认为藏北松潘-甘孜地块中的新生代钾质火山岩由富集的岩石圈地幔熔融形成。我们最近的年代学、元素和同位素地球化学研究表明,松潘-甘孜地块中部的可可西里地区存在中新世早期（～15-18 Ma）的富钾adakite。我们认为这些岩...

＜正＞一般认为藏北松潘-甘孜地块中的新生代钾质火山岩由富集的岩石圈地幔熔融形成。我们最近的年代学、元素和同位素地球化学研究表明,松潘-甘孜地块中部的可可西里地区存在中新世早期（～15-18 Ma）的富钾adakite。我们认为这些岩石形成于一个与板片俯冲无关的板内背景中,可能由增厚下地壳的熔融形成。可可西

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New Fusion Approach of Spatial and Channel Attention for Semantic Segmentation of Very High Spatial Resolution Remote Sensing Images

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Open Journal of Applied Sciences 2024年第2期14卷 288-319页

作者： Armand Kodjo Atiampo Gokou hervé Fabrice Diédié Unité de Recherche et d’Expertise du Numerique (UREN) Université Virtuelle de Céte d’Ivoire Abidjan Ivory Coast Laboratoire de Mathématiques et Informatique Université Peleforo Gon Coulibaly Korhogo Ivory Coast

The semantic segmentation of very high spatial resolution remote sensing images is difficult due to the complexity of interpreting the interactions between the objects in the scene. Indeed, effective segmentation requires considering spatial local context and long-term dependencies. To address this problem, the proposed approach is inspired by the MAC-UNet network which is an extension of U-Net, densely connected combined with channel attention. The advantages of this solution are as follows: 4) The new model introduces a new attention called propagate attention to build an attention-based encoder. 2) The fusion of multi-scale information is achieved by a weighted linear combination of the attentions whose coefficients are learned during the training phase. 3) Introducing in the decoder, the Spatial-Channel-Global-Local block which is an attention layer that uniquely combines channel attention and spatial attention locally and globally. The performances of the model are evaluated on 2 datasets WHDLD and DLRSD and show results of mean intersection over union (mIoU) index in progress between 1.54% and 10.47% for DLRSD and between 1.04% and 4.37% for WHDLD compared with the most efficient algorithms with attention mechanisms like MAU-Net and transformers like TMNet.

关键词： Spatial-Channel Attention Super-Token Segmentation Self-Attention Vision Transformer

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青藏高原东缘汶川-茂县断裂韧性变形对龙门山早期隆升的制约

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地质学报 2024年

作者：葛成隆李海兵 Philippe hervé LELOUP 张蕾郑勇刘栋梁 Clémentine FELLAH 叶小舟张进江中国地质科学院地质研究所北京大学地球与空间科学学院法国里昂大学地学实验室中国地质科学院地质力学研究所

青藏高原东缘的汶川-茂县断裂是龙门山构造带中发育有深层次韧性变形的断裂,对于揭示龙门山隆升中的深部过程有着重要的意义。本文通过断裂带物质组成、宏观/微观构造变形和石英组构的分析,对断裂带内韧性变形的运动学、流变特征和变形... 详细信息

青藏高原东缘的汶川-茂县断裂是龙门山构造带中发育有深层次韧性变形的断裂,对于揭示龙门山隆升中的深部过程有着重要的意义。本文通过断裂带物质组成、宏观/微观构造变形和石英组构的分析,对断裂带内韧性变形的运动学、流变特征和变形条件进行了约束。结果表明:1断裂带内存在宽约3 km、向北西陡倾的韧性剪切带;2在剪切带内部识别出两期剪切变形:早期北西向正断剪切和晚期东向逆冲剪切;3石英晶格组构特征显示逆冲韧性变形以石英底面滑移为主,伴随膨凸重结晶作用,指示变形温度为300～400℃;正断韧性变形以石英柱面滑移为主,伴随亚颗粒旋转重结晶作用,对应温度为350～650℃。结合已发表的地质年代学和低温热年代学数据,我们认为汶川-茂县断裂带在渐新世发生了北西向的正断韧性剪切,在中新世发生东向的逆冲韧性变形。汶川-茂县断裂在中晚新生代期间的强烈活动导致了龙门山后缘大量深部物质的抬升,最终形成了现今构造地貌雏形。

关键词：龙门山汶川-茂县断裂韧性变形石英组构 EBSD

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

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Open Journal of Geology 2024年第6期14卷 655-670页

作者： Gbele Ouattara Baco Traore Ziandjêdé hervé Siagné Aboubacar Denon Souleymane Sangare Marc Ephrem Allialy Laboratoire des Sciences Gographiques du Gnie Civil et des Gosciences Institut National Polytechnique Flix HOUPHOUT-BOIGNY (INP-HB) Yamoussoukro Cte dIvoire EUREKAGEO Sarl Consulting Mining Company Bamako Republic of Mali Unit de Formation et de Recherche des Sciences de la Terre et des Ressources Minires (UFR-STRM) University of Cocody Abidjan Cte dIvoire

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.

关键词： Dolerites Kimberlitic Fields Petrology Structures Kéniéba Mali

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Petrographic, Geochemical and Metallogenical Context of the Geological Formations of the Goumere Region (North-East of Cote D’Ivoire): Implication to the Knowledge of Gold Mineralization

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International Journal of Geosciences 2024年第2期15卷 180-203页

作者： Fossou Jean-Luc hervé Kouadio Alain Nicaise Kouamelan Topka Kakeu Lionel Boya Roger Nicaise Kanga Laboratory of Geology Mineral and Energy Resources (LGRME) Faculty of Earth Science and Mineral Resources Félix Houphou&#235t Boigny University Abidjan C&#244te d’Ivoire

The Gouméré region is located in the North-East of Côte d’Ivoire and is located in the South-West of the Bui furrow. In order to highlight the geology of the area studied, 14 samples were taken for studies using petrographic, geochemical and metallogenic methods. The study of macroscopic and microscopic petrography made it possible to highlight two major lithological units: 1) a volcano-plutonic unit, formed of gabbros, basalt, volcaniclastics and rhyodacite;2) a sedimentary unit (microconglomerate). From a geochemical point of view, the results obtained indicate that the plutonites are gabbro and gabbro diorite while the volcanics have compositions of basaltic andesites, rhyolite and dacites. The sediments have a litharenitic to sublitharenitic character. The metallogenic study made it possible to highlight hydrothermal alterations and metalliferous paragenesis on the formations studied. Hydrothermal alteration is characterized by the presence of carbonation, silicification, sericitization, sulfidation and to a lesser degree chloritization. Metalliferous paragenesis consists of pyrite, chalcopyrite, hematite and magnetite.

关键词： Petrography Geochemistry Metallogeny Gouméré Côte d’Ivoire

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Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

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Energy and Power Engineering 2024年第2期16卷 79-96页

作者： Paul Nestor Djomou Djonga George Elambo Nkeng Madjoyogo hervé Sirma Ahmat Tom Thierry Tchamba Tchuidjang Department of Textile and Leather Engineering National Advanced School of Engineering of Maroua Maroua Cameroon Department of Civil Environmental and Architectural Engineering University of Padova Padova Italy Institut du Génie des Systèmes Industriels et textiles Ecole Polytechnique de Ouagadougou Ouagadougou Burkina-Faso Department of Energy Engineering University Institute of Technology University of Ngaoundere Ngaoundere Cameroon Department of Process Engineering National Advanced School of Agro-Industrial Sciences University of Ngaoundere Ngaoundere Cameroon

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

关键词： Bioethanol Cassava Peeling Pineapple Fibers Organosolv Process and Optimization

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Evaluation of Particle Properties of MgO/TiO₂ Material by Monte Carlo Simulation Method

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Journal of Materials Science and Chemical Engineering 2024年第2期12卷 49-60页

作者： Koffi N’guessan Placide Gabin Allangba Yves Kily hervé Fagnidi Hermann N’guessan Zié Traoré Koffi Arnaud Kamenan Physics Pedagogical Unit Laboratory of Environmental Science and Technology University Jean Lorougnon Guédé Daloa C&#244te d’Ivoire Laboratory of Fundamental and Applied Physics University Nangui Abrogoua Abidjan C&#244te d’Ivoire Department of Medical Physics University of Trieste and International Centre for Theoretical Physics (ICTP) Trieste Italy Department of Science and Technology University Alassane Ouattara Bouaké C&#244te d’Ivoire Nuclear Physics and Radiation Protection Team Laboratory of Material Sciences Environment and Solar Energy University Felix Houphouet-Boigny Abidjan C&#244te d’Ivoire Department of Mathematics Physics and Chemistry UFR Biological Sciences University Peleforo Gon Coulibaly Korhogo C&#244te d’Ivoire

The simulation by the Monte Carlo method executed by the software PyPENELOPE proved effective to specify the particle propagation characteristics by calculating the absorption fractions, backscattering and transmission of electrons and secondary photons under the incidence of 0.5 to 20 KeV range of primary electrons. More than 99.9% of the primary electrons were transmitted in the 125 nm thick MgO/TiO2 material at 20 KeV. This occurred because several interactions took place in the transmitted primary irradiation such as characteristic, fluorescence, and bremsstrahlung produced when of the occupation of the KL3, KL2, KM3, and KM2 shell and sub-shell of titanium and magnesium which are the elements with a high atomic number in the material. The transmission particle characteristic of this material is therefore an indicator capable of improving the electrical performance and properties of the sensor.

关键词： Monte Carlo PyPENELOPE Primary Electrons Transmission MgO/TiO2

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Hydrogeological and Physico-Chemical Study of the Groundwater of Mitendi South-East in the Commune of Mont-Ngafula around the Kimwenza Quarry (Province of Kinshasa, DR Congo)

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Journal of Geoscience and Environment Protection 2024年第4期12卷 96-114页

作者： Jonathan Mayi Nkolomonyi Ivon Ndala Tshiwisa hervé Khonde Mbumba Samuel Ingila Asanga Clement N’zau Umba-Di-Mbudi Geo-Hydro-Energy-Research Group Geosciences Department Faculty of Sciences and Technologies University of Kinshasa Kinshasa Democratic Republic of Congo Geosciences Department Faculty of Sciences and Technologies University of Kinshasa Kinshasa Democratic Republic of Congo Polytechnic Faculty President Joseph Kasa-Vubu University Boma Democratic Republic of Congo

The exploitation of groundwater by drilling in the Mitendi South-East district constitutes a solution to the water shortage in this peripheral part of the Mont-Ngafula township in Kinshasa, the capital of the DR Congo. Individuals exploit groundwater in boreholes to serve the population without taking into account certain necessary aspects such as the origin of the groundwater table and the quality which constitute the major problems of this work such as: What is the quantity of water from the recharge of our aquifer? What is the state of the Mitendi South-East aquifer water in relation to some physico-chemical parameters? The cardinal objective of this work is to provide chemical data and trace elements in each analyzed borehole and determine the type of recharge of the underground aquifer. The specific objectives are as follows: analyze the potability of groundwater on a physico-chemical level and their chemical facies, take the geographical coordinates of water samples from the aquifer in each targeted borehole in order to develop the sampling map of the area under study;also check each parameter analyzed in relation to WHO standards. We carried out a general investigation of the study area by carrying out observations, sampling and in-situ measurements of each borehole, as well as the good conservation of the samples taken in a cooler. The various measurements that we took in-situ: pH, electrical conductivity, turbidity, salinity, temperature, and TDS were carried out by using a multi-parameter probe in the laboratory of appropriate methods such as titled-sorting, spectrophotometry, atomic absorption spectrometry, ArcGise and Excel software. With regard to the results from laboratory analysis (physical and chemical analysis), the parameters showed that the standards recommended by the WHO were not respected. We affirm that the water consumed in the Mitendi South-East district in Mont-Ngafula town ship is not drinkable. Since, it can cause several water-borne dis

关键词： Groundwater Aquifer Physicochemical Parameters Mitendi Kimwenza Quarry

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Assessment of Oral Anticoagulation with Vitamin K Antagonists in Patients Living in a Low-Income Country of West Africa

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World Journal of Cardiovascular Diseases 2024年第1期14卷 27-42页

作者： Komlavi Yayehd Tchaa Tcherou hervé Libérus A. Edorh Agossou Defodji Mohamed Kpelafia Ekpé Togbossi Ablawa Adzodo Soulemane Pessinaba Machihude Pio Soodogoua Baragou Findibe Damorou Department of Cardiology Faculty of Health Sciences University of Lomé Lomé Togo Department of Cardiology Faculty of Health Sciences University of Kara Kara Togo

Introduction: Despite the rise of direct oral anticoagulants (DOACs), vitamin K antagonists (VKA) remain the most widely used oral anticoagulants in developing countries. The aim of this study was to estimate the prevalence of good anticoagulation in patients treated with VKA in Lomé and describe associated factors. Methods: This was a cross-sectional study conducted from November 2019 to October 2020 in the cardiology departments of two University teaching hospitals in Lomé (CHU Sylvanus Olympio and CHU Campus), involving patients on VKA for ≥3 months, with a target international normalized ratio (INR) of 2.5 and a therapeutic margin between 2 and 3. The quality of anticoagulation was assessed by the time in therapeutic range (TTR) which was assessed by the Rosendaal method. Good anticoagulation was defined by a TTR > 70%. Results: A total of 344 patients were included (mean age = 58 ± 13.8 years, women = 56.1%). Indications for VKA treatment were represented by venous thromboembolic disease (43.3%), supraventricular arrhythmia (28.2%), severe left ventricular systolic dysfunction (19.8%) and pulmonary hypertension (8.7%). The average TTR was 47.6 ± 20.8%. The rate of good anticoagulation was 17.7%. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol (OR = 11.17;95% CI: 3.2 - 39.6;p = 0.0002), concomitant low-dose aspirin (OR 4.44;95% CI: 1.4 - 13.9;p = 0.01) and INR monitoring exclusively by the patient himself (OR = 4.92;95% CI: 1.5 - 16.3;p = 0.008). The rate of thromboembolic and hemorrhagic complications was each 2.6% and was not correlated with the quality of anticoagulation. Quality of anticoagulation by VKAs was poor in our practice. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol, concomitant low-dose aspirin and monitoring of INR exclusively by the patient himself. Conclusion: The quality of oral anticoagulation by VKAs could be improved in our practice by the creation of antico

关键词： Vitamin K Antagonists Time in Therapeutic Range Lomé Togo

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