Journal of African Earth Sciences (1983)最新文献_第9页

Potential groundwater discharges and safe yields of drainage basins in southwestern Nigeria 尼日利亚西南部流域的潜在地下水排放和安全产量

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90033-9

O.O. Ogunkoya

{"title":"Potential groundwater discharges and safe yields of drainage basins in southwestern Nigeria","authors":"O.O. Ogunkoya","doi":"10.1016/0899-5362(87)90033-9","DOIUrl":"10.1016/0899-5362(87)90033-9","url":null,"abstract":"<div>The potential safe yields of aquifers in the rocks and saprolites of third-order drainage basins on the Pre-Cambrian Basement Complex of southwestern Nigeria are determined and presented using the Total Potential Groundwater discharge (QTP) model of Butler (1957) and Meyboom (1961). The safe yield values range from 22 1 min−1 to 2156 1 min−1. These values compare with those from the Basement Complex in some other parts of Nigeria but most of them appear very low when compared with yields of between 640 and 1740 1 min−1 reported for sedimentary rocks within the same region. The relatively high values of between 642 and 2156 1 min−1 reported in this study were obtained from aquifers located within the highly fissured quartzitic rocks and their associated coarse grained saprolites.The potential safe yield values from the basins may thus show that apart from those areas underlain by quartzites and such other highly fissured rocks overlain by coarse grained saprolites e.g. porphyritic/coarse grained granites (and these are not widespread on the Basement Complex), the Basement Complex is an area of poor groundwater yield.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 6","pages":"Pages 773-779"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90033-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Diagnetic pyrite framboids in the phosphate deposits of Abu-Tartur area, Western Desert, Egypt 埃及西部沙漠Abu-Tartur地区磷矿床中的成岩黄铁矿

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90037-6

Mohamed A. El-Dahhar

引用次数: 4

Paleozoic oolitic ironstones of the Algerian Sahara: a review 阿尔及利亚撒哈拉古生代鲕粒铁矿评述

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90102-3

Salah Guerrak

{"title":"Paleozoic oolitic ironstones of the Algerian Sahara: a review","authors":"Salah Guerrak","doi":"10.1016/0899-5362(87)90102-3","DOIUrl":"10.1016/0899-5362(87)90102-3","url":null,"abstract":"<div>The Paleozoic sediments are present over the greatest part of the SaharanPlatform, from the border of Morocco, Rio de Oro and Mauritania in the W, to the Libyan frontier in the E. They outcrop in the Ougarta chains, the Gourara and the Touat, the Northern border of the Reguibat Shield and constitute a sedimentary girdle around the Touareg Shield, namely the Azzel Matti, the Ahnet, the Mouydir, the Ajjers Tassilis, the Tafassasset Tassilis and the Ouan Ahaggar Tassilis.In all these formations, numerous oolitic ironstones occur, particularly in Ordovician, Devonian and Lower Carboniferous rocks. We can distinguish essentially two types of oolitic ironstones (OIS): OIS with constant thin beds and horizontal extension: they will be named EXID type (Extensive Iron Deposition), and OIS of local extension and irregular thickness: they will be named LOID type (Local Iron Deposition).The EXID type is located in the Ordovician, the Middle Devonian and in the very Lower Carboniferous (Tournaisian) sedimentary rocks. The LOID type occurs in the Lower and Upper Devonian rocks and appears as the economically interesting type.From the Zemmour to the Fezzan, a real Paleozoic oolitic iron belt appears 3000 km long, determining a N Gondwanian oolitic iron province, formed during cold to temperate climates.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 1","pages":"Pages 1-8"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90102-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53877627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 20

Major and trace element geochemistry of Albian and Turonian shales from the Southern Benue trough, Nigeria 尼日利亚Benue海槽南部Albian和Turonian页岩主要元素和微量元素地球化学特征

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90002-9

L.C. Amajor

引用次数: 46

Mississippian foraminiferal marble from Wadi Heimur Area, Eastern Desert, Egypt 埃及东部沙漠Wadi Heimur地区的密西西比有孔矿物大理石

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90006-6

Abd-Elmohsen A. Ahmed

引用次数: 1

Environmental and diagenetic implications for the rare earth element geochemistry of sediments of the Niger Delta 尼日尔三角洲沉积物稀土元素地球化学的环境和成岩意义

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90045-5

B.N. Olorunfemi , W.S. Fyfe , J.O. Etu-Efeotor , B. Kronberg

{"title":"Environmental and diagenetic implications for the rare earth element geochemistry of sediments of the Niger Delta","authors":"B.N. Olorunfemi , W.S. Fyfe , J.O. Etu-Efeotor , B. Kronberg","doi":"10.1016/0899-5362(87)90045-5","DOIUrl":"10.1016/0899-5362(87)90045-5","url":null,"abstract":"<div>The REE (rare earth element) contents of the bulk, heavy mineral fraction and various size fractions (0.250-0.037 mm) of recent sediments of the Niger Delta vary considerably. ΣREE varies from 26 to 5140 ppm in the bulk samples, 54–77,400, in the heavy mineral fraction, while the 0.125 mm size is the most enriched. All samples are enriched in La, the lower and the intermediate REE (compared to the average shale). There is a correlation of REE with mineralogy.The central delta sediments, with an average SiO2 content of 82% and kaolinite as the dominant clay, have a low REE content. The heavy minerals contribute a large fraction of the REE content. The pH and Eh conditions favour the leaching of REE. The eastern delta, with high smectite content and an average SiO2 of 58%, has the highest ΣREE and pronounced negative Eu and Ce anomalies. The higher REE content in eastern and coastal delta sediments is attributed to the basic conditions, the organic matter and REE exchange between sea water and the smectitic clays.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 6","pages":"Pages 861-868"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90045-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lithosphere metasomatism and the petrogenesis of the Chilwa Province of alkaline igneous rocks and carbonatites, Malawi 马拉维Chilwa省碱性火成岩和碳酸岩的岩石圈交代作用和岩石成因

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90048-0

A.R. Woolley

{"title":"Lithosphere metasomatism and the petrogenesis of the Chilwa Province of alkaline igneous rocks and carbonatites, Malawi","authors":"A.R. Woolley","doi":"10.1016/0899-5362(87)90048-0","DOIUrl":"10.1016/0899-5362(87)90048-0","url":null,"abstract":"<div>Rocks of the Chilwa Alkaline Igneous Province fall into three principal groups, namely: (1) syenite-quartz syenite-granite, (2) syenite-nepheline syenite, and (3) carbonatite-nephelinite-nepheline syenite. Dykes of all the principal rock types are abundant and there are numerous small agglomerate-filled volcanic vents. The nephelinites, which are minor, are the only basic silicate rocks found in the province, which is characterized by its overwhelmingly felsic character. The petrochemistry indicates that three fundamental magmas of trachytic, phonolitic and nephelinitic/carbonatitic composition are required to encompass all the rock types present. It is suggested that these three magma types were produced by partial melting at different depths of strongly metasomatized lithosphere, the whole igneous event having been preceded by a long period of focused metasomatism which produced anomalous lithosphere mantle, and lower crust, leading to isostatic uplift, rift faulting, and eventually volcanism. The trachytic melt was generated towards the base of the crust from rocks akin to fenites, and the phonolitic melt also directly, but at greater depths. It is suggested that although the carbonatite may have formed by immiscible separation from carbonate-rich nephelinite, it may also have been generated directly from a relatively carbonate-rich zone in the upper mantle concentrated by gradual upward creep of low viscosity carbonate melt.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 6","pages":"Pages 891-898"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90048-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 48

Les déformations eburnéennes de l'unité birrimienne de la comoé (côte d'ivoire) comoe (cote d'ivoire)的birrimian单位的eburan变形

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90056-X

M. Vidal

引用次数: 20

Hydrogeology of Lagos metropolis 拉各斯大都市的水文地质

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90058-3

E.O. Longe , S. Malomo, M.A. Olorunniwo

{"title":"Hydrogeology of Lagos metropolis","authors":"E.O. Longe , S. Malomo, M.A. Olorunniwo","doi":"10.1016/0899-5362(87)90058-3","DOIUrl":"10.1016/0899-5362(87)90058-3","url":null,"abstract":"<div>A study of the groundwater resources and aquifers underlying Lagos metropolis has been made. This is based on well-logs, pumping tests, well-production and water quality data. The data were obtained during construction and use of recent boreholes of the Lagos State mini water works programme.The sub-surface geology indicates a complex lithology of alternating sequence of sand and clay deposits. Three aquifer horizons were delineated. The first, a water table aquifer (average thickness of 8 m) is mostly exploited through dug wells. The other two, confined aquifers (thickness of 10–25 and 10–35 m respectively), are harnessed through boreholes and are the basis of the mini water works.Average values of transmissivity (T) and storage coefficients (S) are 3.53 × 10−3 m2 s−1 and 2.95 × 10−4 respectively for the second and 17.44 × 10−3 m2 s−1 and 3.29 × 10−4 for the third. The range of transmissitivity, the storage coefficient and also permeability indicate considerable inhomogeneity in the aquifers.Chemical quality determinations show that the harnessed aquifers waters are generally soft. They are suitable for use in domestic, agricultural and industrial processes, if the excessive iron occurring is removed.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 2","pages":"Pages 163-174"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90058-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 149

The Oligo-Miocene of Eil (NE Somalia): a prograding coral-Lepidocyclina system el(索马里东北部)渐新世-中新世:一个推进的珊瑚-鳞虫系统

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90098-4

A. Bosellini, A. Russo, M.A. Arush, M.M. Cabdulqadir

{"title":"The Oligo-Miocene of Eil (NE Somalia): a prograding coral-Lepidocyclina system","authors":"A. Bosellini, A. Russo, M.A. Arush, M.M. Cabdulqadir","doi":"10.1016/0899-5362(87)90098-4","DOIUrl":"10.1016/0899-5362(87)90098-4","url":null,"abstract":"<div>The Oligo-Miocene succession of Eil is the product of a depositional regression and constitutes a 120–150 m thick depositional sequence that prograded seaward for at least 20–25 km. Its time-transgressive stratigraphy is documented physically by well exposed tangential clinoforms (previously considered as evidence of a tectonic coastal flexure) and biostratigraphically by the occurrence of calcareous nannoplankton, planktonic and benthonic foraminifera, and a rich coral fauna. The upper boundary of the sequence is indicated by a reefal toplap, which constitutes the flat surface of the Nogal Plateau. Age (Chattian to Burdigalian) and toplap relationships of the sequence indicate clearly that progradation took place after the Late Oligocene flooding which followed the strong fall of sea-level during the Chattian.Because of the horizontal geometry of the entire sedimentary system, it has been possible to make a clear environmental reconstruction and a facies model with original water depths. A worldwide Tertiary facies—the Lepidocyclina beds— was confined to the front of the reef, at depths ranging from 35–40 to 120–130 m.</div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 4","pages":"Pages 583-593"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(87)90098-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53877595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 24