Hydrocarbon accumulation history in Lower Cretaceous in northern slope of Bongor Basin in Chad,Central Africa

Based on the analysis of the fluid inclusion homogenization temperature and apatite fission track on the northern slope zone of the Bongor Basin in Chad,this paper studied the time and stages of hydrocarbon accumulation in the study area.The results show that:(1)The brine inclusions of the samples from the Kubla and Prosopis formations in the Lower Cretaceous coexisting with the hydrocarbon generally present two sets of peak ranges of homogenization temperature,with the peak ranges of low temperature and high temperature being 75–105℃ and 115–135℃,respectively;(2)The samples from the Kubla and Prosopis formations have experienced five tectonic evolution stages,i.e.,rapid subsidence in the Early Cretaceous,tectonic inversion in the Late Cretaceous,small subsidence in the Paleogene,uplift at the turn of the Paleogene and Neogene,and subsidence since the Miocene,in which the denudation thickness of the Late Cretaceous and after the turn of the Paleogene and Neogene are~1.8 km and~0.5 km,respectively.The cumulative denudation thickness of the two periods is about 2.3 km;(3)Using the brine inclusion homogenization temperature coexisting with the hydrocarbon as the capture temperature of the hydrocarbon,and combining with the apatite fission track thermal history modeling,the result shows that the Kubla and Prosopis formations in the Lower Cretaceous on the northern slope of the Bongor Basin have the same hydrocarbon accumulation time and stages,both of which have undergone two stages of hydrocarbon charging at 80–95 Ma and 65–80 Ma.The first stage of charging corresponds to the initial migration of hydrocarbon at the end of the Early Cretaceous rapid sedimentation,while the second stage of charging is in the stage of intense tectonic inversion in the Late Cretaceous.

Epidemiological Profile of Men Who Have Sex with Men: First Data about Male Sex Workers in Central African Republic (CAR)

Objectives: Sex work is not well documented among African men. The aim of this study was to describe the epidemiological profile of men who have sex with men (MSM) and eventually to determine the proportion of sex workers (SW) among them, as well as the proportion of MSM who have been victims of gender-based violence (GBV). Material and Methods: A cross-sectional study coordinated by the Direction de la Médecine du Travail was carried out at the headquarters of the association ALTERNATIVES in Bangui Bangui from July 1 to October 31, 2021. Consenting MSM present during the study period were systematically included. Sociodemographic variables, those relating to the future vision of the activity and to GBV were collected and analyzed using Epi-Info version 7 software. Results: Forty MSM with an average age of 23 years and mainly secondary education (75.0%) were included. The vast majority of MSM were unemployed (85.0%). 45.0% had been victims of GBV and wanted to stop working as an MSM (47.5%), and almost 2/3 (65.0%) would accept another income-generating activity in exchange for the MSM. Violence was sexual (32.5%), economic (22.5%), physical (20.0%), verbal (12.5%) and psychological (12.5%). Conclusion: The MSM were mainly young, poorly educated, unemployed, and almost half were victims of GBV. The desire to change MSM activity to another income-generating activity alongside that of MSM shows that many of them are SW, workers in the informal sector. This must be taken into account in prevention activities, even if the data needs to be confirmed on a much larger sample.

Farming Features of African Bonytongue Fish Heterotis niloticus in Cameroon, Central Africa

The characterization of African bonytongue Heterotis niloticus fish farming was conducted in the Bi-modal agro-ecological zone of Cameroon from January to May 2021, Thirty-two fish farmers were interviewed and SPSS 6.2 Version was used to analyse the data. The results showed that the majority of fish farmers (81%) are men above 51 years, all of whom are Christians with more than fifty percent of them married. About 43% of them have university level education, and more than 6% of them considered the farming of Heterotis niloticus as their main income-earning activity. The main objective of Heterotis niloticus farming is sales (50%) and the uses (56%) of waged labour. A majority of the farmers produced reared African bonytongue in a polyculture system and 65% of them raised Heterotis niloticus in derivation ponds.

Geometry and kinematics of brittle deformation in the Central Cameroon Shear Zone (Kékem area): Implication for gold exploration within the Central Africa Fold Belt in Cameroon

The Central Africa Fold Belt(CAFB)is a collision belt endowed with gold deposits in Eastern Cameroon area mined for about 50 years.However,favorable areas for gold exploration are poorly known.This paper presents(1)the kinematics of the brittle deformation in the Kékem area in the SW portion of the Central Cameroon Shear Zone and(2)constraints gold mineralization events with respect to the collisional evolution of the CAFB.The authors interpret that the conjugate ENE to E and NNW to NW trending lineament corresponds to the synthetic(R)and the antithetic(R’)shears,which accompanied the dextral slip along the NE to ENE striking shear.The latter coincides with the last 570-552 Ma D3 dextral simple shear-dominated transpression,which is parallel to the BétaréOya shear zone hosting gold deposits.Gold mineralizations,which mainly occurred during the last dextral shearing,are disseminated within quartz veins associated to Riedel’s previous structures reactivated due to late collisional activities of the CAFB as brittle deformation.Gold mineralizations occurred mainly during the 570-552 Ma D3 event.The reactivation,which might be due to dextral simple shear during mylonitzation,plausibly remobilized the early gold deposits hosted in syn-compressional rocks and/or possibly focused deep-sourced fluid mixed with those released by dehydration.Therefore,the Central Cameroon Shear Zone where Kékem is located,and which shows similar petrographical and structural features to those controling Batouri gold district,is a target area for gold exploration in Cameroon.

Assessment of Hydraulic Parameters and Protection Zones of Catchment Aquifers for Water Supply Network in NdéDivision, West-Cameroon (Central Africa)

Ndé Division in West-Cameroon is facing with water supply although many attempts of restoring existing SCANWATER facilities by Bangangté Municipality. In order to address the issue, we assess the exploitable pumping flow rate of catchment aquifers and its hydraulic properties by using Jacob and Theis method, and define protection zones with Hoffman and Lillich method. It emerges that the hydraulic conductivity of aquifer is in the order of 10-4 m/sec, transmissivity varies from 10-4 to 10-6 m2/sec. Aquifer pumping flow rate (Q) varies between 1.5 and 10.5 m3/h. In volcanic rocks, aquifer is more productive (4.5 ≤ Q ≤ 10.5 m3/h). Transfer time of pollutants to aquifer varies from 3 to 56 days depending on rock-types and groundwater slope (0.03 - 0.13 m/m). Furthermore, 113,624 m and 1123 m are radius to be implemented for a better protection of groundwater against any form of pollutant.

On the Differences in the Intraseasonal Rainfall Variability between Western and Eastern Central Africa: Case of 25 - 70-Day Oscillations

The intraseasonal timescale is critical in Central Africa, because the resources of the region are highly rainfall dependent. In this paper, we use 1DD GPCP rainfall product to investigate the differences in the space-time structures of the 25 - 70-day intraseasonal variability of rainfall, over the Western Central Africa (WCA) and the Eastern Central Africa (ECA), with different climate features. The results of Empirical Orthogonal Functions (EOFs) analysis have shown that the amount of variance explained by the leading EOFs is greater in ECA (58.4%) than in WCA (49.8%). For both WCA and ECA, the power spectra of the Principal Components (PCs) peaked around 40 days, indicating a MJO signal. The seasonality of ISO is evident, but this seasonality is much noticeable in ECA where almost 80% of the total yearly ISO power occurs during November-April season, against only around 60% for WCA. Moreover, the lagged cross correlations computed between WCA and ECA PCs time series showed that most of the WCA PCs led ECA PCs time series with a timescale of 8 - 12 days, revealing that the eastward propagation could potentially be the relationship between WCA and ECA modes. The interannual variations in the ISO activity are weak in WCA, when compared with ECA where the signal exhibits larger interannual variations, quite linked with ENSO.

The Challenges Faced on Transit Transport Corridors by Landlocked Countries in Central Africa: Literature Review

The landlocked countries are the one without access to the sea and can be assimilate as countries around the world with a disadvantage of geography situation location. Chad and the Central African Republic are two of the 40 landlocked countries around the world that transport 80% of their goods by road and rail, and as much as almost more than 50% of their passengers through a transit country with a transit transport system which is crucial for their trade and exchanges. The study aims to introduce the importance to have a good and efficiency transport network infrastructure in Central Africa to facilitate the trade for the landlocked countries of Central Africa (Chad and the Central African Republic), member of CEMAC trade area and proposes some measures that can be adopted to improve their conditions and ameliorate the trade for those countries.

Port Logistics in West and Central Africa: A Strategic Development under Globalization

The main idea of this study is to provide help to West and Central Africa port logistics authorities in making, evaluating and realizing their decisions on port development/management, all in an effort to guaranty port efficiency and operational brilliance to profit the different ports, their hinterlands and their related clients. Consequently, an examination is made as far as port sector is concerned, with an ever more demanding enhancement in operational efficiency. Moreover, a past research on West and Central Africa Ports, as well as an overview on port logistics was made, making it possible to determine what has been done (prospects) and what is still to be done (ineffectiveness), in prospective of a more reformed and efficient port. One of the principles of this paper is also to confer all the aspects that operate as obstacles to the WCA port’s improvement and development;using thus the evaluation model called EWCA (Evaluation of West and Central Africa Ports), which gives a descriptive analysis of the present situation of the latter’s port logistics, including the aid of multiple regression model to determine an impact of explanatory variables on the study probability. Applying the method of strategic development, this paper thus deals with exploring typical problems and quandaries of West and Central Africa ports. The findings suggested how to fight back or overcome the constrictions and strangulations;enabling West and Central Africa port logistics attain their desired strategic development aims, despite the ineffectiveness. Tremendous efforts were made, giving a vital shoot on African economy and development;even though there is still a lot to do, for the data and variables showed how the port logistics augment and descend frequently without a long period of stability.

Early management of sickle cell anemia in central Africa:is it possible?

Sickle cell disease(SCD) is a worldwide hemoglobinopathy that concerns about 250000 affected children everv year.The majority of them are living in tropical regions,particularly in sub-Saharan Africa,India and Middle East.Life expectancy and quality of life of SCD patients have improved since the newborn screening and early management have been introduced in USA and Jamaica.Experts of hemoglobinopathies strongly encouraged WHO to develop in the endemic areas networks based on the Thalassaemia International Federation(TIF) model in order to conduct activities for developing medical services for care and prevention of hemoglobin disorders. Despite the inherent practical,political and economic difficulties,early diagnosis and a comprehensive health care program for SCD could be implemented in most of the African countries where the prevalence is high;but many challenges have to be first resolved.Based on pilot studies conducted in some central African countries,this article proposed some strategies and discusses the different ways of implementing initiatives that are indispensable for decreasing the mortality and morbidity rate of SCD in Central Africa.

Long-Term Variation of Sunshine Duration and Their Inter-Action with Meteorogical Parameters over Chad, Central Africa

This study aims to evaluate the long-term variations of sunshine duration and to estimate its interaction with meteorogical parameters from 1950 to 2010 in Chad, Central Africa. The results show that Chad is the one of world’s sunniest countries. Each year, Chad receives more than 3030.91 ± 176.33 hours of sunning corresponding to 8.9 hours daily. Likewise, a strong north-south gradient is noted over Chad. For instance, the daily insolation is 10 ± 0.41 hours in the north, 8.85 ± 1.1 hours in the center and 7.75 ± 1.8 hours in the south. Furthermore, there is a marked seasonality of sunshine duration with maximums in dry season and minimums during the rainy season. The lowest values of sunshine duration are found in August. On the contrary, maximums are recorded from November to February with values greater than 9.5 hours per day. Moreover, the annual anomalies study allowed determining three great periods in terms of sunshine variability in Chad. Firstly, the period between 1950 to 1970 (named humid period) is characterized by the lowest values of sunshine duration in Chad. Secondly, from 1970 and 1990, the region suffered an unprecedented drought which resulted in an increase of sunstroke duration in Chad. And finally, the period from 1990 to 2010 called the return period is characterized by a rapid year-to-year fluctuations of insolation duration. Unlike to surface temperature, we have also shown that there is a direct relation between the duration of insolation and the meteorological parameters such as precipitations and relative humidity.

The Challenging Place of Natural Hazards in Disaster Risk Reduction Conceptual Models:Insights from Central Africa and the European Alps

Based on a literature review and two case studies,this article presents the difficulties inherent in the main disaster risk reduction conceptual models.The method used to highlight such evidence is to compare two programs on disaster risk reduction with mainstream conceptual models.The authors participated in these programs,which were confronted with the need to integrate contributions and insights from both earth and social sciences.Our analysis found that the existing main conceptual models were unable to do justice to disaster risk reduction needs.This finding encouraged us to critique these models.Further effort led us to present possible solutions to compensate for the shortcomings of current models while taking into account the contextualization and dynamics of phenomena,as well as grappling with the more explicit integration of hazards and hazard risk into model design.

Ebola Die-Off:Gorilla Losses Tallied in Central Africa

曾经在非洲肆虐的埃伯拉病毒已夺走了254人的生命,然而更令人震惊的是,它已杀死了5500多只非洲大猩猩。这种致命的高传染性病毒不仅危害灵长目的动物,还向包括小羚羊在内的其他目种伸出了魔爪。科学家们正在努力研究对应病毒侵害的办法,并试图研究出疫苗以阻止它继续侵害人类。

Comparison of trends and frequencies of drought in central North China and sub- Saharan Africa from 1901 to 2010

This study compares the trends and frequencies of drought between central North China(CNC) and(SSA) for the periods 1901–2010 and 1951–2010. The Standardized Precipitation Evapotranspiration Index(SPEI) and Self-Calibrating Palmer Drought Severity Index(sc-PDSI) are used to assess the drought trends and frequencies. In general, the results exhibit downward trends of drought index values and upward trends of drought frequencies over CNC and SSA. A high rate of the trends' slopes for the drought index and a low rate of the frequencies' slopes is found over CNC with respect to SPEI and sc-PDSI. Furthermore, some abrupt changes are revealed after applying the sequential Mann–Kendall test to detect change points. These findings offer insight into the trends and frequencies of drought over the regions studied. Further analysis needs to be undertaken to understand the mechanisms underlying the occurrence of drought in these areas.

中非乍得Bongor盆地北部斜坡下白垩统油气成藏期次

基于流体包裹体均一温度测试和磷灰石裂变径迹分析,对乍得Bongor盆地北部斜坡下白垩统油气成藏时间和期次开展研究。研究表明,下白垩统Kubla组和Prosopis组储集层样品中与油气共生的盐水流体包裹体均一温度总体上表现为高、低温两组峰值区间,低温峰值区间和高温峰值区间分别为75~105℃和115~135℃;Kubla组和Prosopis组样品均经历了5个构造演化阶段,即早白垩世发生快速沉降,晚白垩世晚期发生构造反转,古近纪发生小幅沉降,古近纪与新近纪之交抬升,中新世以来则处于沉降阶段;其中晚白垩世剥蚀厚度约1.8km,古近纪与新近纪之交剥蚀厚度约0.5 km,两期剥蚀叠加厚度约2.3 km。与油气包裹体共生的盐水包裹体的均一温度用以作为油气捕获温度,结合磷灰石裂变径迹热演化史模拟研究,结果表明Bongor盆地北部斜坡下白垩统Kubla组和Prosopis组具有一致的油气成藏时间和期次,均在距今80~95 Ma和65~80 Ma分别经历了两期油气充注。第1期充注对应于油气初始运移,为早白垩世快速沉积末期,第2期充注处于晚白垩世构造强烈反转阶段。

Multiplex Rapid Test with Acceptable Diagnosis Performance as a Solution to Increase Diagnosis of Hepatitis B and C Viruses in Pregnant Women in an Area of High Prevalence of Both Hepatitis Viruses Associated with HIV

Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determine the prevalence of HIV, HCV and HBV co-infections in pregnant women at Bangui Community University Hospital and the cost of screening. Methods: A cross-sectional study involving consenting pregnant women who came for antenatal care was performed. HIV, HCV antibodies and HBV antigens were detected using Exacto Triplex? HIV/HCV/HBsAg rapid test, cross-validated by ELISA tests. Sociodemographic and professional data, the modes of transmission and prevention of HIV and both hepatitis viruses were collected in a standard sheet and analyzed using the Epi-Info software version 7. Results: Pregnant women aged 15 to 24 were the most affected (45.3%);high school girls (46.0%), and pregnant women living in cohabitation (65.3%) were the most represented. Twenty-five (16.7%) worked in the formal sector, 12.7% were unemployed housewives and the remainder in the informal sector. The prevalence of HIV, HBV, and HCV viruses was 11.8%, 21.9% and 22.2%, respectively. The prevalence of co-infections was 8.6% for HIV-HBV, 10.2% for HIV-HCV, 14.7% for HBV-HCV and 6.5% for HIV-HBV-HCV. All positive results and 10% of negative results by the rapid test were confirmed by ELISA tests. The serology of the three viruses costs 39,000 FCFA (60 Euros) by ELISA compared to 10,000 FCFA (15.00 Euros) with Exacto Triplex? HIV/HCV/AgHBs (BioSynex, Strasbourg, France). Conclusion: The low level of education and awareness of hepatitis are barriers to development and indicate the importance of improving the literacy rate of women in the Central African Republic (CAR). Likewise, the high prevalence of the three viruses shows the need for the urgent establishment of a national program to combat viral hepatitis in the CAR.

板内裂谷盆地构造反转驱动机制以及对油气的影响——以中非Bongor盆地为例

陆内裂谷盆地裂后反转的驱动机制一直存在争论,主要集中于垂直地幔上涌还是远端板块间相互挤压作用导致。解决这一问题的关键所在是精确限定盆地埋藏—抬升的时间和幅度,以及与同时期构造事件的匹配关系。笔者等采取磷灰石裂变径迹和热历史反演分析,识别出盆内两期主要反转事件:晚白垩世显著抬升,以及随后的始新世抬升剥蚀,均可以与区域不整合面对应。

Optimization of E-commerce Logistics Network in African Countries

The purpose of this research is to assist the Central African's logistics network authorities in making,evaluating,and realizing their decisions in regard to the development and management of e-commerce logistics network of companies・This article evaluated and used mathematical models which provided a descriptive analysis on the current situation of its'logistics network while applying the e-commerce logistics network optimization method in dealing with common issues of the logistics network in Central Africa,especially Chad.The suggested network in this study would promote the^from plant-to-from DC"ratio of 83%to 17%which conforms to the companies*objective in progressing towards direct plant shipments.In regard to that,it was proved that direct plant shipments could reduce the distribution costs from 12%to 3%of the net sales(approximately$135,000 in monthly savings).

中非铜钴成矿带地质特征及铜钴矿床资源量分析

中非铜钴成矿带是世界最大的沉积型铜钴成矿带、全球最大钴矿、第三大铜矿发现区。因铜钴价格持续走高和中资企业持续关注的迫切性,本文对中非铜钴成矿带地质特征、铜钴矿床资源分布规律、权益资源量情况进行分析研究。同时,系统收集研究区学术研究成果、商业数据库、企业年报等数据,分析认为Lufilian弧形构造带是中非铜钴成矿带构造背景,从北向南依次为弧外部褶皱推覆带、穹窿地区、复式向斜带、加丹加高原。地层分为孔德龙古、恩古巴、罗安三个群,地层年龄自<573±5 Ma至879±16 Ma。含矿层位主要是罗安群矿床组,下分R2.1、R2.2、R2.3三个含矿层。矿床类型主要为碳酸盐质巨型角砾岩型、含矿页岩型、含矿砂岩型、含矿基底型铜矿,构成6个铜钴矿集区,具有等间距分布特征,间距为±20 km。截至2021年,研究区探获铜资源量1.91亿t,钴资源量1404万t。以当量铜资源量排序,>100万t的矿床33个,>1000万t级别的矿床7个。共有14个国家55家矿业企业参与铜钴成矿带勘探及开发。我国权益铜钴资源量分别为6467万t、648万t。大于50万t权益铜资源量的企业有洛阳钼业、紫金矿业、中国有色集团等10家公司,大于2万t权益钴资源量的企业有洛阳钼业、宁德时代、中国有色等10家公司。

SO_(2)气体介入中非某铜钴矿钴还原浸出反应的新工艺探讨

针对中非某铜钴矿钴还原浸出工艺中存在钴浸出率低、SO_(2)气体利用较低、SO_(2)气体外逸污染环境等难题,通过SO_(2)气体浸出钴的机理研究并结合现场试验研究,创造性采用SO_(2)气体加压与常压联合介入的方式,通过3种工艺路径联合介入钴还原浸出反应,并研制了配套的专用装备。新工艺及其专用装备通过SO_(2)气体与溶液的充分混合,有效控制了气体的逸散,显著提升了SO_(2)气体的溶解度和利用率,加快了还原浸出剂Fe^(2+)的再生速率,通过增强SO_(2)与Fe^(2+)的协同还原浸出作用实现了钴的高效提取。现场试验数据显示:新工艺及其专用装备能实现SO_(2)气体利用率提升15个百分点以上,钴浸出率提高3个百分点,在提高钴产能的同时还降低了生产成本,并有效解决SO_(2)气体外逸污染环境问题。该研究成果能用于指导中非铜钴矿山企业优化改进现有的湿法提取铜钴矿物的生产工艺,显著提升钴的浸出效率,从而增加钴的产能,并通过提升SO_(2)气体利用效率,降低生产成本。

中非Doseo盆地油气地质条件及成藏控制因素分析

中非裂谷系Doseo盆地是白垩纪以来叠加了走滑和挤压反转等作用的复杂陆相裂谷盆地,具有优越的油气地质条件,且勘探程度较低,是当前油气勘探热点区域,但油气分布不均,不同构造带油气规模差异大。本文基于钻井和典型油气藏对比分析,系统阐述了盆地油气地质条件,并探讨了不同构造带油气成藏控制因素。研究表明,盆地经历了三个主要的构造-沉积演化阶段,形成“东西分区,南北分带,北陡南缓”的构造格局,构成了“下细上粗”的湖盆-三角洲-河流沉积充填序列。下白垩统强裂陷期两套优质成熟湖相烃源岩、多套储-盖组合以及一系列构造圈闭为油气聚集成藏提供了有利的石油地质条件。已发现油气藏以构造圈闭为主,但油气发现规模与烃源岩潜力严重不符。通过分析,油气成藏主要受储层、盖层和圈闭保存条件三个因素及匹配关系控制,而圈闭保存条件是全区共有最重要控制因素,且不同构造带油气成藏控制因素具有差异性。南部缓坡带成藏控制因素为盖层和圈闭保存条件,东部凸起构造带成藏控制因素为圈闭保存条件,北部陡坡带成藏控制因素为储层和圈闭保存条件。