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Sample records for dahomey

  1. Morphological Characterization of African Bush Mango trees (Irvingia species) in the Dahomey Gap (West Africa)

    NARCIS (Netherlands)

    Vihotogbe, R.; Berg, van den R.G.; Sosef, M.S.M.

    2013-01-01

    The variation of the morphological characters of bitter and sweet African bush mango trees (Irvingia species) was investigated in the Dahomey Gap which is the West African savannah woodland area separating the Upper and the Lower Guinean rain forest blocks. African bush mangoes have been rated as

  2. A Critical Review of the Oil and Tar Sands of the Dahomey Basin

    International Nuclear Information System (INIS)

    Osundina, A.; Mustapha, A.; Nzewi, T.

    2002-01-01

    The Benin Basin previously referred to as the Dahomey embayment has been designated as a frontier basin within Nigeria due to its potentially high prospects, but comparatively low exploitation campaign to date. The basin offers a promising opportunity for heavy oil exploration in a narrow belt extending westward from Edo State to the republic of Benin; while offshore, there are high prospects for finding more conventional hydrocarbon.The eastern Dahomey embayment is known to have an extensive reserve of hydrocarbons (bitumen and tar sands). The sediments occur in a 5 8 km belt stretching 120km from the fringes of Lagos State through Ogun, Ondo and Edo States. The estimated reserve potentials exceed 30 billion barrels of oil equivalent.Recently acquired seismic data in OPL 309 and 310, and subsequent drilling of 2 wells on the narrow continental shelf, have shown the presence of closed structures over Basement Highs and other related structural styles in the basin and confirm that conventional light oils and condensates hydrocarbons occur in commercial quantity. These hydrocarbons are reservoired in stratigraphic sequences of Albian Cenomanian age.This paper hopes to expose the hidden riches of this Basin and hopefully get the attention of the big players in refocusing their interests in the basin that attracted attention of the early petroleum explorers to Nigeria approximately 100 years ago

  3. (Dahomey) Basin

    African Journals Online (AJOL)

    Timothy Ademakinwa

    porosity versus depth curve of Bond and Kominz. (1984) (Fig. 7). .... accommodation space and water loads as a result of local or global ...... be deposited in marine outer shelf environment characterised by ..... exploration geology. American ...

  4. STRATIGRAPHIC EVOLUTION, PALEOENVIRONMENTS AND HYDROCARBON POTENTIALS OF THE BENUE/DAHOMEY BASINS, NIGERIAN AND POTIGUAR/CEARA BASINS, NE BRAZIL

    International Nuclear Information System (INIS)

    Akande, S.O; Adekeye, O.A.; Oj, O.J; Erdtmann, B.D.; Koutsokous, E.I.

    2004-01-01

    The stratigraphy, facies relationship and paleoenvironment of selected West African and the Brazillian rift basins permit the recognition of at least two major petroleum systems apart from the prolific Niger Delta petroleum system. The Lower Cretaceous fluivio-lacustrine petroleum system and Upper Cretaceous to Lower Tertiary, marine dominated petroleum system. Our combined studies of the stratigraphic, structural framework, paleoenvironment and time-space relationships of the petroleum systems in the Benue/Dahomey and the Potiguar/Ceara basins indicated that rifting and subsequent drifting during the opening of the South Atlantic controlled subsidence, sediment deposition and facies associations in individual basins. Whereas in the Potiguar/Ceara basins, the best developed source rocks are within the Neomacin-Aptian fluvio- lacustrine sequence of the Pendencia and Alagamar Formations which generated reserved hydrocarbon in the Acu Formation, empirical evidence for this petroleum system in the contiguous Benue/Dahomey basins are only based on the geochemical characteristics of the lower parts of the Bima Formation and the Abeokuta Group. In contrast, the Upper Cretaceous-Lower Tertiary marine petroleum system, which is constrained by poor development of reservoirs in the Potiguar/Ceara basin is productive in the Benue/Dahomey basins where source rocks, reservoir and sealing facies occur at this interval. Considering the recent hydrocarbon discoveries of the East Niger basin, the Doba (southern Chad), the Muglad basin (southern Sudan) sourced from the fluvio-lacustrine rift sequences, we suggest that this petroleum system needs more detailed exploration and has some potentials in the Benue/Dahomey frontier basins

  5. A Case of Cyperus spp. and Imperata cylindrica Occurrences on Acrisol of the Dahomey Gap in South Benin as Affected by Soil Characteristics: A Strategy for Soil and Weed Management

    Directory of Open Access Journals (Sweden)

    Brahima Kone

    2013-01-01

    Full Text Available Because of the limiting efficacy of common weed control methods on Cyperus spp. and Imperata cylindrica their occurrences in tropical agroecologies and the effect of soil properties in suppressing these species were investigated in south Benin (Cotonou, a typical ecology of the Dahomey gap. Weeds and soil samples were collected twice early and later in the rainy season in 2009 at four topographic positions (summit, upper slope, middle slope, and foot slope. Sampling was done according to Braun-Blanquet abundance indices (3 and 5 and the absence (0 of Cyperus and Imperata in a quadrat, respectively. The relationship between their respective abundances and soil parameters (texture, C, N, P, K, Na, Ca, Mg, and Fe was explored. Weed occurrence was less related to soil texture, and Imperata growth was more influenced by soil nutrients (K, Ca, and Fe than Cyperus spp. Soil cation ratios of K : Mg and Ca : Mg were the main factors that could be changed by applying K and/or Mg fertilizers to reduce Cyperus and/or Imperata occurrence. Maintaining high Fe concentration in soil at hillside positions can also reduce Imperata abundance, especially in the Dahomey gap.

  6. La culture de l'amarante, légume-feuilles tropical : avec référence spéciale au sud-Dahomey

    NARCIS (Netherlands)

    Grubben, G.J.H.

    1975-01-01

    1. INTRODUCTION

    Amaranth is the most cultivated leaf vegetable of the humid tropics and as such comparable to spinach in the temperate regions. Efforts to improve the crop are hampered by a shortage of knowledge. The object of this study is to fill up a part of this gap. The

  7. Characterization of African Bush Mango trees with emphasis on the differences between sweet and bitter trees in the Dahomey Gap (West Africa)

    NARCIS (Netherlands)

    Vihotogbe, R.

    2012-01-01

     African bush mango trees (ABMTs) are economically the most important species within the family of Irvingiaceae. They are priority trees producing non-timber forest products (NTFPs) and widely distributed in the humid lowland forests of West and Central Africa. To boost their production and

  8. particle size distribution and control on bitumen saturation of some

    African Journals Online (AJOL)

    vicadmin

    REVIEW OF THE STRATIGRAPHY OF THE. DAHOMEY BASIN. The study area lies between latitudes 60301 to 60351. N and longitudes 40301 to 60451 E and falls within the eastern. Dahomey Basin (Fig. 3).The work of Omatsola and Adegoke. (1981) on the Cretaceous stratigraphy of the Dahomey basin has recognized ...

  9. Impacts of the diversity of traditional uses and potential economic value on food tree species conservation status: case study of African bush mango trees (Irvingiaceae) in the Dahomey Gap (West Africa).

    NARCIS (Netherlands)

    Vihotogbé, R.; Kakai, R.G.; Bongers, F.; Andel, van T.; Berg, van den R.G.; Sinsin, B.; Sosef, M.S.M.

    2014-01-01

    Background and aims – Bitter and sweet African bush mango trees belong to the family Irvingiaceae and produce valuable non-timber forest products in humid lowland areas of West and Central Africa. The bitter and sweet types are treated as distinct taxa at the variety or species level. They have not

  10. germination of seeds from earlier fruits of bitter and sweet african ...

    African Journals Online (AJOL)

    ACSS

    2014-11-18

    Nov 18, 2014 ... Dahomey Gap. In this area, bush mango trees are found in natural forests, forest gardens (in the. Volta Forest Region, South-western Togo) and most abundantly in intensive cultivation systems: home gardens, orchards, agroforestry parks all over in the Dahomey Gap (Vihotogbé et al., 2014). In general, the ...

  11. CARBONATE MICROFACIES AND MAJOR ELEMENT CONTENT ...

    African Journals Online (AJOL)

    DJFLEX

    lagoon environment, formed during the Maastrichtian sea flooding into Dahomey Basin. The porosity and ... sedimentary domain on the continental margin of the. Gulf of Guinea. ... separation of South America plate from Africa plate is.

  12. Vegetation patterns and environmental gradients in Benin

    NARCIS (Netherlands)

    Adomou, A.

    2005-01-01

    Key words: West Africa, Benin, vegetation patterns, floristic areas, phytogeography, chorology, floristic gradients, climatic factors, water availability, Dahomey Gap, threatened plants, biodiversity, conservation.Understanding plant species distribution patterns and the underlying factors is a

  13. petrography, compositional characteristics and stable isotope

    African Journals Online (AJOL)

    PROF EKWUEME

    African and South American lithospheric plates (Burke et al., 1971). The basin ...... Tectonic evolution Cretaceous stratigraphy of the. Dahomey Basin.Journal of Mining and Geology, ... theory and application of trace element technique.

  14. petrography, compositional characteristics and stable isotope ...

    African Journals Online (AJOL)

    PROF EKWUEME

    Subsurface samples of the predominantly carbonate Ewekoro Formation, obtained from Ibese core hole within the Dahomey basin were used in this study. Investigations entail petrographic, elemental composition as well as stable isotopes (carbon and oxygen) geochemistry in order to deduce the different microfacies and ...

  15. Training for Agriculture: Annual Review of Selected Developments.

    Science.gov (United States)

    United Nations Food and Agriculture Organization, Rome (Italy).

    The topics covered by review articles are: Training for Rural Development (with special reference to Chile); Field Training--Theory into Practice (for women extension workers in Malaysia); A New Look is Needed for Extension (Latin America); 4-D Rural Youth Clubs in Dahomey; Sociological Aspects of Rural Training; Population Education in the…

  16. Geophysical mapping of the occurrence of shallow oil sands in ...

    African Journals Online (AJOL)

    ISHIOMA

    studied the tectonic evolution and stratigraphy of the. Dahomey basin in which they subdivided the sequence into stratigraphic units namely Ise formation, Afowo formation and Araromi formation based on the lithos- tratigraphic study of some boreholes from the area. The. Ise formation lying uncomfortably on the basement.

  17. Distribution spatiale du singe à ventre rouge, Cercopithecus ...

    African Journals Online (AJOL)

    danger et endémique du Dahomey Gap est très peu documenté au Togo. Pour connaître sa ..... chaque secteur prospecté ainsi que celui du complexe en entier. ..... 2008-009 portant loi-cadre sur l'environnement au Togo. JO du 06 juin. 2008.

  18. Forest gradients in West Africa : a spatial gradient analysis

    NARCIS (Netherlands)

    Rompaey, van R.S.A.R.

    1993-01-01

    The tropical rain forests of West Africa, west of the Dahomey interval, once covered some 40 million ha. Being on the western fringe of the African continent, they receive abundant rainfall from the SW monsoon. Further inland, rainfall gradually decreases and the forests give way to savanna and

  19. The Audio-Visual Services in Fifteen African Countries. Comparative Study on the Administration of Audio-Visual Services in Advanced and Developing Countries. Part Four. First Edition.

    Science.gov (United States)

    Jongbloed, Harry J. L.

    As the fourth part of a comparative study on the administration of audiovisual services in advanced and developing countries, this UNESCO-funded study reports on the African countries of Cameroun, Republic of Central Africa, Dahomey, Gabon, Ghana, Kenya, Libya, Mali, Nigeria, Rwanda, Senegal, Swaziland, Tunisia, Upper Volta and Zambia. Information…

  20. Etude de l’hybridation inter-spécifique entre espèces du genre Coffea en Nouvelle-Calédonie : distribution des niches favorables et structuration de la diversité

    OpenAIRE

    Gomez , Céline

    2009-01-01

    Coffee trees are originated from inter-tropical forests of Africa and Madagascar and their diversification origin areas are highly threatened. Among the 103 species of the Coffea genus, only three are cultivated: C. arabica, C. canephora and C. liberica. C. canephora has the widest natural distribution in tropical African forests, and its genetic diversity is structured in five distinct groups. The study of the genetic diversity structuring has revealed a particular importance of the Dahomey ...

  1. Drosophila mitotypes determine developmental time in a diet and temperature dependent manner.

    Science.gov (United States)

    Towarnicki, Samuel G; Ballard, J William O

    2017-07-01

    It is well known that specific mitochondrial (mt) DNA mutations can reduce organismal fitness and influence mitochondrial-nuclear interactions. However, determining specific mtDNA mutations that are beneficial has been elusive. In this study, we vary the diet and environmental temperature to study larval development time of two Drosophila melanogaster mitotypes (Alstonville and Dahomey), in two nuclear genetic backgrounds, and investigate developmental differences through weight, feeding rate, and movement. To manipulate the diet, we utilize the nutritional geometric framework to manipulate isocaloric diets of differing macronutrient ratios (1:2 and 1:16 protein: carbohydrate (P:C) ratios) and raise flies at three temperatures (19°C, 23°C and 27°C). Larvae with Dahomey mtDNA develop more slowly than Alstonville when fed the 1:2 P:C diet at all temperatures and developed more quickly when fed the 1:16 P:C diet at 23°C and 27°C. We determined that Dahomey larvae eat more, move less, and weigh more than Alstonville larvae when raised on the 1:16 P:C diet and that these physiological responses are modified by temperature. We suggest that 1 (or more) of 4 mtDNA changes is likely responsible for the observed effects and posit the mtDNA changes moderate a physiological trade-off between consumption and foraging. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Atomic prospects in four African states

    International Nuclear Information System (INIS)

    1961-01-01

    A preliminary assistance mission of the International Atomic Energy Agency visited Ghana in March-April this year; members of the mission also visited three other African States: Dahomey, Liberia and Nigeria. As in the case of the six earlier Agency missions of this kind, the visits were made at the request of the Governments of these countries. The purpose was to study at first hand the prospects of atomic development in these countries, to advise the Governments on the broad formulation of atomic energy programs, and to determine how the Agency could assist in the carrying out of these programs

  3. Geostatistical exploration of dataset assessing the heavy metal contamination in Ewekoro limestone, Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Kehinde D. Oyeyemi

    2017-10-01

    Full Text Available The dataset for this article contains geostatistical analysis of heavy metals contamination from limestone samples collected from Ewekoro Formation in the eastern Dahomey basin, Ogun State Nigeria. The samples were manually collected and analysed using Microwave Plasma Atomic Absorption Spectrometer (MPAS. Analysis of the twenty different samples showed different levels of heavy metals concentration. The analysed nine elements are Arsenic, Mercury, Cadmium, Cobalt, Chromium, Nickel, Lead, Vanadium and Zinc. Descriptive statistics was used to explore the heavy metal concentrations individually. Pearson, Kendall tau and Spearman rho correlation coefficients was used to establish the relationships among the elements and the analysis of variance showed that there is a significant difference in the mean distribution of the heavy metals concentration within and between the groups of the 20 samples analysed. The dataset can provide insights into the health implications of the contaminants especially when the mean concentration levels of the heavy metals are compared with recommended regulatory limit concentration.

  4. Disease, religion and medicine: smallpox in nineteenth-century Benin Doenças, religião e medicina: a varíola no Benim, século XIX

    Directory of Open Access Journals (Sweden)

    Elisée Soumonni

    2012-12-01

    Full Text Available The essay examines, with special reference to smallpox, the perception and interpretation of disease in pre-colonial Dahomey, present-day Republic of Benin. Because disease is seen primarily as a punishment from the gods and not just as a medical problem or a bodily disorder, traditional cult priests play a leading role in making diagnoses and prescribing remedies, mostly based on medicinal plants. The prominence of Sakpata, god of smallpox, coupled with the influence of its priests is evaluated within the context of Dahomey's political history and the spread of the disease. This pivotal position was to constitute a challenge to the French colonial campaign to vaccinate against smallpox.O ensaio examina - com especial atenção à varíola - as percepções e interpretações das doenças no Daomé pré-colonial, atual República do Benim. Uma vez que as doenças eram vistas antes de tudo como punição divina, e não como problema ou distúrbio do corpo, os sacerdotes tradicionais exerciam papel central no seu diagnóstico e na prescrição de remédios, com base principalmente em plantas medicinais. A importância do culto a Sakpata, deus da varíola, juntamente com a influência dos sacerdotes é avaliada dentro do contexto da história política do Daomé e da disseminação das doenças. A posição crucial desse culto constituiu-se como um desafio para a campanha colonial francesa de vacinação contra a varíola.

  5. Organisation et contrôle de l’espace dans l’aire culturelle aja-fon (Sud-Togo et Bénin – XVIIe-XIXe siècle The organization and control of territory in the aja-fon cultural zone (southern Togo and Benin, 17th-19th centuries

    Directory of Open Access Journals (Sweden)

    Dominique Juhé-Beaulaton

    2011-02-01

    Full Text Available Les migrations des populations, la fondation de nouveaux villages conduisent les hommes à appréhender leur environnement, leur nouveau territoire et leurs occupants en s’appuyant sur des principes religieux à la base du fonctionnement des sociétés de l’aire culturelle aja-fon, ou aja-tado. Les traditions orales, la toponymie, les sources écrites européennes montrent comment l’espace s’est structuré à partir de la perception de l’environnement. Le contrôle du milieu naturel par l’organisation sociale aboutit à sa territorialisation. Les migrants ou les conquérants (selon les contextes déploient des stratégies pour maîtriser l’espace et les hommes qui l’occupent par le biais concomitant des alliances matrimoniales et des déplacements de divinités. Dans le cadre des royaumes de la côte des Esclaves (Ouidah, Allada, Dahomey, un réseau d’implantations royales, toujours associées à des divinités installées dans l’objectif de contrôler les mouvements des hommes et des biens, permettait d’assurer la domination politique sur l’ensemble du territoire dominé.Human migrations and the foundation of new villages led people to reckon with their environment, with the new territory and its occupants, by referring to the religious principles that underlay the social organization of Aja-Tado societies. Oral traditions, toponyms and writings by Europeans provide evidence about how this territory took shape out of a perception of this environment. The control of the natural environment exercised by the society led to its territorialization. Migrants or conquerors, depending on the context, adopted strategies that involved making matrimonial alliances and moving divinities so as to control a territory and its occupants. Among the Slave Coast kingdoms (Ouidah, Allada, Dahomey, a network of royal settlements, likewise associated with divinities, controlled the movement of people and goods, and thus asserted political

  6. Research activities in the fields of radiochemistry and neutron activation analysis using the LENA nuclear plant in Pavia

    International Nuclear Information System (INIS)

    Caramella-Crespi, V.; Case, M. Di; Gallorini, M.; Ganzerli-Valentini, M.

    1976-01-01

    The activity of the Radiochemistry Laboratory and National Research Council Center for Radiochemistry and Activation Analysis in the past two years has been mainly devoted to the following subjects: Several elements (V, Mn, Cu, Cd, Zn, Cr, Co, Fe, Cs, Rb, Sc) have been determined in biological, geological and cosmological matrices (as sediments, river waters, vegetables, foods, Italian condritic meteorites). Comparative measurements have been carried out using different techniques, such as atomic absorption and X-ray fluorescence; comparative investigations have been developed with different radioanalytical methods for Cr trace determination. A new rapid separation procedure of Hg, Se and As has been set up, based on selective behaviour toward granular copper. The evaluation of trace elements amount in Sardinian coal samples has been also accomplished. In the field of biomedical applications levels of trace elements were determined in the principal usual foods used by people of the lower Dahomey to the purpose of studying the correlation between the food content of these elements and the population's intake. Inorganic exchangers studies have been carried out on molybdenum dibromide, tantalum carbide and metallic copper retention properties and on the related absorption mechanism. X-ray fluorescence has been used as an analytical tool to integrate neutron activation analysis in the determination of Cr, Zn, Fe in environmental matrices. (author)

  7. Benin.

    Science.gov (United States)

    1984-11-01

    Focus in this discussion of Benin is on the following: the people; geography; history; government and political conditions; economy; defense; foreign relations; and relations between the US and Benin. The population totaled 3.8 million in 1983 with an annual growth rate of 2.6%. The infant mortality rate is 45/1000 and life expectancy 46.9 years. The population comprises about 20 sociocultural groups. 4 groups -- the Fon, Aja, Bariba, and Yoruba -- account for more than half of the population. The name was changed from Dahomey to the People's Republic of Benin in 1975. 2 years after the military coup d'etat in 1972, Marxism-Leninism was declared the guiding philosophy of the new government. Marxism-Leninism remains the official doctrine, but the government has moved to take account of popular resistance to a radical social transformation, as well as problems encountered in attempting to establish a centrally directed economy. Benin is ranked as 1 of the world's 35 poorest countries. The commercial, industrial, and agricultural sectors are all experiencing severe problems. The government's newest 5 year plan for 1983-88 places a stronger emphasis on developing agriculture. In so doing, the government hopes to assure its own domestic needs and to become a supplier of basic foodstuffs to the region. Benin's Armed Forces number about 3000 personnel. Benin is a member of the Non-Aligned Movement and the Organization of African Unity. Relations with France are important because of historical, cultural, economic, and aid links. After 1972, relations between the US and Benin became strained as Benin moved to strengthen its ties with the Soviet Union and other socialist countries and mounted harsh propaganda attacks on the US.

  8. West Africa - A Safe Haven for Frogs? A Sub-Continental Assessment of the Chytrid Fungus (Batrachochytrium dendrobatidis)

    Science.gov (United States)

    Penner, Johannes; Adum, Gilbert B.; McElroy, Matthew T.; Doherty-Bone, Thomas; Hirschfeld, Mareike; Sandberger, Laura; Weldon, Ché; Cunningham, Andrew A.; Ohst, Torsten; Wombwell, Emma; Portik, Daniel M.; Reid, Duncan; Hillers, Annika; Ofori-Boateng, Caleb; Oduro, William; Plötner, Jörg; Ohler, Annemarie; Leaché, Adam D.; Rödel, Mark-Oliver

    2013-01-01

    A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni (“Vulnerable”) and Petropedetes natator (“Near Threatened”)) as well as the “Critically Endangered” viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis). PMID:23426141

  9. Synoptic Lithostratigraphy of The Niger Delta

    International Nuclear Information System (INIS)

    Nwajide, C.S.

    2002-01-01

    The Tertiary Niger Delta is stratigraphically framed by the Dahomey, Anambra, Abakaliki, Afikpo and Calabar Flank basins. From the apex at Onitsha a fluvial plain splays southwards and translates progressively into a freshwater swamp, succeeded by a mangrove swamp belt. Along the coast is a strip of wave-washed barrier bars indented by large estuaries, fronted by submerged moth bars. Habitation in the delta is on levees, point bars, and barrier bars. These landforms provided the firm salients for buildings the ports that facilitated international trade from the pre-colonial times.There are four lithofacies-clean, pebbly, and muddy sandstones, and mudstones. Their subdivision, based on sedimentary structures, textures and fossil content yields twenty reservoir and seven nonreservoir classes. Their environments of deposition, identified using facies associations, fall into fluvial, wave-and tide-dominated, marginal, and shallow marine, with localised canyons incised into the delta front and filled with deeper marine facies.The reservoirs are composed of 70 90% quartz, 4 15% feldspar, and 3 13% clay matrix, with minor mica, bioclasts, carbonaceous debris, glauconite, and heavy minerals. Grain size varies from very fine to coarse and pebbly, implying the presence of sands of varying textural and compositional maturities. Silica, K-feldspar, and carbonates constitute the cements.Porosity in the reservoirs has remained about the same as at deposition due to low mechanical compaction occasioned by shallow burial. Meteoric water-flushed progradational sequence are characterised by cementation with quartz and kaolinite. In contrast, marine water-flushed transgressive sands show grain coating illite-smectite, chlorite and K-feldspar overgrowths

  10. West Africa - a safe haven for frogs? A sub-continental assessment of the chytrid fungus (Batrachochytrium dendrobatidis.

    Directory of Open Access Journals (Sweden)

    Johannes Penner

    Full Text Available A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd. While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni ("Vulnerable" and Petropedetes natator ("Near Threatened" as well as the "Critically Endangered" viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis.

  11. Geology and total petroleum systems of the Gulf of Guinea province of West Africa

    Science.gov (United States)

    Brownfield, Michael E.; Charpentier, Ronald R.

    2006-01-01

    The Gulf of Guinea Province as defined by the U.S. Geological Survey (USGS) consists of the coastal and offshore areas of Cote d'Ivoire, Ghana, Togo, and Benin, and the western part of the coast of Nigeria, from the Liberian border east to the west edge of the Niger Delta. The province includes the Ivory Coast, Tano, Central, Saltpond, Keta, and Benin Basins and the Dahomey Embayment. The area has had relatively little hydrocarbon exploration since 1968, with only 33 small to moderate-sized oil and gas fields having been discovered prior to the USGS assessment. Most discoveries to 1995 have been located in water depths less than 500 m. Since 1995, only eight new offshore discoveries have been made, with four of the discoveries in the deep-water area of the province. Although as many as five total petroleum systems exist in the Gulf of Guinea Province, only one, the Cretaceous Composite Total Petroleum System, and its assessment unit, the Coastal Plain and Offshore Assessment Unit, had sufficient data to allow assessment. The province shows two important differences compared to the passive-margin basins south of the Niger Delta: (1) the influence of transform tectonics, and (2) the absence of evaporites and salt deformation. The province also lacks long-lived, large deltaic systems that typically result in rapid source rock burial and abundant high-quality hydrocarbon reservoirs. The USGS assessed the potential for undiscovered conventional oil and gas resources in the Gulf of Guinea Province as part of its World Petroleum Assessment 2000, estimating a mean of 1,004 million barrels of conventional undiscovered oil, 10,071 billion cubic feet of gas, and 282 million barrels of natural gas liquids. Most of the hydrocarbon potential is postulated to be in the offshore, deeper waters of the province. Gas resources may be large, as well as accessible, in areas where the zone of hydrocarbon generation is relatively shallow.

  12. Very low frequency electromagnetic (VLF-EM) and electrical resistivity (ER) investigation for groundwater potential evaluation in a complex geological terrain around the Ijebu-Ode transition zone, southwestern Nigeria

    International Nuclear Information System (INIS)

    Osinowo, Olawale O; Olayinka, A Idowu

    2012-01-01

    Groundwater exploration in either a basement or sedimentary environment is often fairly well defined and focuses on delineating weathered/fractured rocks or saturated formations, respectively. Conversely, unique geological structures, the complex coexistence of different rock types and poorly defined basal/lateral contacts between basement and sedimentary rocks make groundwater development in a geological transition environment very challenging. Ijebu-Ode and its environs lie within such a problematic transition zone, between the Precambrian basement rocks and Cretaceous sediments of the Dahomey Basin, in southwestern Nigeria, where associated acute groundwater development challenges require adequate subsurface information to maximize its groundwater resource potential. This study integrated very low frequency electromagnetic (VLF-EM) and electrical resistivity (ER) geophysical prospecting techniques for a detailed terrain study of Ijebu-Ode in order to establish the reasons for the low groundwater resource potential in the area. Thirty five VLF-EM profiles, 140 vertical electrical soundings (VES) and relevant hydrogeological data were acquired along grids and profiles. Data were filtered, inverted and enhanced using appropriate software packages. The current density and geoelectric parameters of the VLF-EM and VES data were employed to generate terrain maps, the conductivity distribution and a subsurface basement model of the study area. Current density plots and geoelectric parameters identified up to three layers in the basement complex terrain which comprised lateritic topsoil, weathered basement and fresh basement rocks. The five layers encountered in the sedimentary terrain were topsoil, a lateritic unit, a dry sandy unit, a saturated sandy unit and fresh basement rocks. The hydraulic conductivity of the thick (3–18 m) lateritic unit was determined to be 1.32 × 10 −5 mm s −1 , while that of the underlying sandy units ranged from 2.65 × 10 −4 to 1

  13. Book Reviews

    Directory of Open Access Journals (Sweden)

    J. van Baal

    1965-01-01

    Full Text Available - R.J. Mohr, Bernard J. Siegel, Biennial Review of Anthropology 1963. Stanford University Press. Stanford, California, 1963. 306 pp. - P.E. de Josselin de Jong, Jean Poirier, Guide d’enquête monographique appliquée aux sociétés malgaches. Faculté des lettres et sciences humaines de Madagascar, Tananarive 1962. - P.E. de Josselin de Jong, Jean Poirier, L’inventaire ethno-topographique. Departement des sciences humaines, Faculté des lettres et sciences humaines, Université de Madagascar, Tananarive 1963. - H.Th. Fischer, P. van Emst, Panorama der Volken, I (Volken van Amerika en Oceanië, onder redactie van P. van Emst. Romen en zonen, Roermond 1964. 515 blz., vele ills. - C. Nooteboom, W. Frölich, Völkerkundliche Forschungen, Martin Heydrich zum 70. Geburtstag überreicht von Freunden und Schülern, herausgegeben von W. Frölich (Ethnologica, Neue Folge, Band 2, Köln, 1960. 557 S., 46 Tafeln, 116 Abb. - J. van Baal, Claude Levi-Strauss, Totemism. Translated from the French by Rodney Needham. Beacon Press, Boston, 1963. 116 pp. - J.J. Fahrenfort, Luc de Heusch, Le Pouvoir et le Sacré. Annales de Centre d’ Etude des Religions I. Université de Bruxelles. Institut de Sociologie (Solvay 1962. 228 pp. - H.J.M. Claessen, Montserrat Palau Marti, Le Roi-Dieu au Bénin, Sud Togo, Dahomey, Nigeria Occidentale. Collection Mondes d’Outre-mer, Série: Nations. Berger Levrault, Paris 1964. - P.E. de Josselin de Jong, F. Sierksma, Profiel van een incarnatie. G.A. van Oorschot, Amsterdam 1964. 244 blz. - B.A.L. Cranstone, Carl A. Schmitz, Wantoat: Art and religion of the Northeast New Guinea Papuans. Translated from the German by Mrs. G.E. van Baaren-Pape. Mouton (the Hague, Paris, 1963. 159 pp. 47 plates. - A.A. Gerbrands, William Fagg, Nigerian images. Lund Humphries, London, 1963. 47 pages, 144 plates by Herbert List. - A.A. Gerbrands, Marcelle Urbain-Faublée, L’art malgache. Presses Universitaires de France, Paris, 1963. 141 pag. 100