Journal of African Earth Sciences (and the Middle East)最新文献

{"title":"Editorial: Software survey section","authors":"","doi":"10.1016/0899-5362(93)90169-Q","DOIUrl":"https://doi.org/10.1016/0899-5362(93)90169-Q","url":null,"abstract":"","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"16 1","pages":"Pages I-V"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(93)90169-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138236778","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}

{"title":"The transvaal sequence: an overview","authors":"P.G. Eriksson ,&nbsp;J.K. Schweitzer ,&nbsp;P.J.A. Bosch ,&nbsp;U.M. Schereiber ,&nbsp;J.L. Van Deventer ,&nbsp;C.J. Hatton","doi":"10.1016/0899-5362(93)90160-R","DOIUrl":"10.1016/0899-5362(93)90160-R","url":null,"abstract":"<div><p>The 15 000 m of relatively unmetamorphosed clastic and chemical sedimentary and volcanic rocks of the 2550-2050 Ma Transvaal Sequence as preserved within the Transvaal and correlated Griqualand West basins of South Africa, and in the Kanye basin of Botswana are described. Immature clastic sedimentary and largely andesitic volcanic rocks of the Wolkberg, Godwan and Buffelsfontein Groups and the Bloempoort and Wachteenbeetje Formations probably represent rift-related sequences of Ventersdorp age. The thin sandstones of the Black Reef Formation, developed at the base of both the Kanye and Transvaal basin successions and correlated with the basal Vryburg siltstones of the Griqualand West Sequence, are considered here to be the basal unit of the Transvaal Sequence. The Black Reef fluvial deposits grade up into the epeiric marine carbonates of the Malmani Subgroup. These stromatolitic dolomites and interdbedded cherts were laid down within a steepened carbonate ramp setting; transgressions from an initial Griqualand West compartment towards the northeast covered both the Kanye and Transvaal basins. Iron formations of the succeeding Penge Formation and Griqualand West correlates are envisaged as relatively shallow water shelf deposits within the carbonate platform model; siliceous breccias of the Kanye basin are interpreted as reflecting subaerial brecciation of exposed silica gels. The Duitschland Formation overlying the Penge iron formations is seen as a final, regressive clastic and chemical sedimentary deposits as the Malmani-Penge sea retreated from the Transvaal basin.</p><p>The interbedded sandstones and mudstones of the uncomformity-bounded Pretoria Group probably represent a combination of alluvial fan and fluviodeltaic complexes debouching into the largely lacustrine Transvaal and Kanye basins. A strong glacial influence in the lower Pretoria Group is reflected in the correlated Makganyene diamicities of the Griqualand West Sequence. Sedimentation across all three basins was interrupted by the extrusion of the Hekpoort-Ongeluk andesites. Upper Pretoria Group sediments of the Silverton and Magaliesberg Formations probably reflect a marine transgression. These rocks are not present in the Griqualand West basin, and were affected by Bushveld Complex-related thermal doming in the Transvaal basin; post-Magaliesberg sedimentation continued thereafter in separate eastern and western fluviodeltaic-lacustrine sub-basins.</p><p>The largely volcanic Rooiberg Group (sensu lato) began with catastrophic basin floor collapse and Leeuwpoort Formation fluvial sedimentation in the western sub-basin. The succeeding Smelterskop and Makeckaan Formations reflect a transition from fluvial deposition to volcanism, and are succeeded by the widespread and voluminous, predominantly felsitic lavas of the Dullstroom, Damwal and Selonsrivier Formations. The correlated Loskop, Glentig and Rust de Winter Formations which overlie the felsites conformably, represent th","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"16 1","pages":"Pages 25-51"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(93)90160-R","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53886483","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}

{"title":"Geology and development editorial","authors":"Cornelius A. Kogbe (Editor-In-Chief)","doi":"10.1016/0899-5362(93)90157-L","DOIUrl":"10.1016/0899-5362(93)90157-L","url":null,"abstract":"","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"16 1","pages":"Page v"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(93)90157-L","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"103165650","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}

{"title":"General introduction","authors":"P.G. Eriksson ,&nbsp;S.A. de Waal ,&nbsp;R.J. Thomas ,&nbsp;S. McCourt ,&nbsp;E.B. Förtsch ,&nbsp;Grantham","doi":"10.1016/0899-5362(93)90158-M","DOIUrl":"https://doi.org/10.1016/0899-5362(93)90158-M","url":null,"abstract":"","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"16 1","pages":"Pages 1-4"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(93)90158-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138236727","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}

{"title":"The tectonic evolution of southern Africa: an overview","authors":"R.J. Thomas ,&nbsp;M.W. von Veh ,&nbsp;S. McCourt","doi":"10.1016/0899-5362(93)90159-N","DOIUrl":"10.1016/0899-5362(93)90159-N","url":null,"abstract":"<div><p>This paper provides an overview of recent ideas concerning the tectonic framework and evolution of the southern African subcontinent from the Early Archaean to the present. Mid-Archaean crustal growth of ancient continental fragments resulted from episodic terrane accretion, a process that culminated in the juxtaposition of the Kaapvaal and Zimbabwe granitoid-greenstone terranes during the Limpopo orogeny at ∼2.7 Ga. Whilst intracratonic sedimentary basins developed on this stable cratonic block from the late Archaean to Mid-Protorozoic (3.0–2.4 Ga), crustal growth occurred during the successive Eburnian (∼2.0–1.7 Ga), Kibaran (∼1.2−1.0 Ga) and Pan-African (∼500 Ma) global accretionary events. The Palaeozoic evolution of southern Africa following the assembly of the Gondwana supercontinent is dominated by the development of the Cape and Karoo basins and their subsequent inversion to produce the Cape Fold Belt (∼280−230 Ma). Mesozoic fragmentation of Gondwana (∼180−130 Ma) was associated with continental rift volcanism and fault reactivation. Minor tectonic activity continues to the present day.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"16 1","pages":"Pages 5-24"},"PeriodicalIF":0.0,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(93)90159-N","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53886469","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}

{"title":"Photogeological and geophysical studies on the Basement rocks in Wadi El Miyah, Eastern Desert of Egypt","authors":"A.F. Kamel,&nbsp;H.M. Abdel Hadi","doi":"10.1016/0899-5362(92)90023-6","DOIUrl":"10.1016/0899-5362(92)90023-6","url":null,"abstract":"<div><p>Wadi El Miyah area is located in the central part of the Eastern Desert of Egypt. It is covered mainly by Basement rocks of Precambrian age, overlain on its western side by Nubian sandstones. The basement rocks comprise igneous and metamorphic rocks. The different types of rocks were studied photogeologically and checked in the field radiometrically and magnetically from the air to differentiate between these rock types and to delineate the contacts between them. All the information and results obtained were used to improve and correct the geological map previously constructed for the same area. It was found that the different structural features interpreted photogeologically could be correlated with the aeroradiometric results. Besides the centers of high structural intensities in the structural contour map were found to be comparable with the centers of high radioactivity on the aeroradiometric map.</p><p>Photogeological interpretation indicated that each type of rocks has its characteristics and the contacts between the main rock types are clear using the criteria of topographic expression, photographic tone, surface texture and drainage density.</p><p>Radioactivity of the rock exposures was found to vary with the different rock types and each group of the same rock type has nearly the same background aeroradioactivity. The serpentinites and the geosynclinical volcanics have the lowest radioactivity level, (0.83–6.00 Ur) the geosynclinal sediments have moderate radioactivity level (3.33–5.00 Ur), the synorogenic plutonites have high radioactivity level (2.5–12.67 Ur) and the late orogenic plutonites have very high level of radioactivity (4.17–25.00 Ur). The aeroradiometric contacts were quite clear when there is marked difference in the radiometric level between the studied rock exposures and the surrounding rocks.</p><p>The aeromagnetic survey showed that the NE-SW and WNW-ESE tectonic trends are the prominent structural trends in the studied area. They represent faults and dykes. There are other trends namely the NNE-SSW, N-S, NW-SE which affect nearly all types of rocks in the Basement complex.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"15 3","pages":"Pages 385-398"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(92)90023-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53883848","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}

{"title":"Biogeographic and bathymetric distribution of benthic foraminifera in Paleocene El Haria Formation of Tunisia","authors":"P. Saint-Marc","doi":"10.1016/0899-5362(92)90029-C","DOIUrl":"10.1016/0899-5362(92)90029-C","url":null,"abstract":"<div><p>Qualitative and quantitative analysis of benthic foraminiferal fauna reveals the succession of five benthic assemblages in the Paleocene El Haria Formation of El Kef section (Tunisia). The <em>eugubina</em> Zone is characterized by <em>Anomalinoides acuta, A. praecuta, Cibicidoides alleni, C. susanaensis</em> and <em>Bulimina quadrata</em>, developed in a bathyal environment of relatively low oxygen conditions. The <em>pseudobulloides</em> Zone presents a “Velasco-type” fauna, with <em>Gavelinella beccariiformis, Osangularia plummerae, Cibicidoides alleni, C. susanaensis, N. truempyi</em> and textulariids. Microfauna suggests an oxic environment in the upper bathyal stage. A regressive sea movement becomes perceptible and benthic fauna indicates an outer shelf paleobathymetry during the interval comprised between the <em>trinidadensis</em> and the <em>pusilla</em> Zones. The assemblage, developed in oxic conditions, is characterized by <em>Alabamina midwayensis, Anomalinoides praeacuta and Cibicidoides susanaensis</em>. The fourth assemblage, observed during the <em>pseudomenardii</em> and <em>velascoensis</em> (lower part) Zones, is typical of the continental shelf (middle to inner neritic; “Midway-type” fauna) with <em>Alabamina midwayensis, Eponides elevatus, Anomalinoides midwayensis</em>, buliminids and lenticulinids. The upper part of the section (<em>velascoensis</em> Zone) presents an inner neritic assemblage dominated by <em>Stainforthia troosteri, Haplophragmoides excavata, Eponides elevatus</em> and lenticulinids.</p><p>These El Kef data are compared with Paleocene foraminiferal data of field sections of central and southern Tunisia. Statistical analysis (correspondence analysis) confirms the lowering of the sea level from the K/T boundary to Early Eocene and indicates precisely the paleogeographic scheme of the Paleocene deposits of Tunisia, with the restricted Gulf of Gafsa in the south, the emerged island of Kasserine in the west and an unstable shelf cut up into deep basins in the east and in the north.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"15 3","pages":"Pages 473-487"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(92)90029-C","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53883958","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}

{"title":"Distribution of lead and copper in the Ganawuri granite complex of Jos Plateau","authors":"M.I. Ogunbajo","doi":"10.1016/0899-5362(92)90021-4","DOIUrl":"10.1016/0899-5362(92)90021-4","url":null,"abstract":"<div><p>The significance of any trace element in an environment largely depends on the abundance of such element in the bedrock as well as its mobility/solubility in an aqueous solution. On the basis of these parameters, the trace elements lead (Pb) and copper (Cu) in the various rock units of the Ganawuri Granite Complex of Joss Plateau have been studied and their environmental significance evaluated.</p><p>The results of the study indicate that their levels of concentration are higher than their crustal abundance (i.e. Pb - 30 - 65; Cu = 10 – 50 ppm) and can, therefore, be considered hazardous and of environmental significance. The element copper with high mobility can be very hazardous in drinking water, plants etc. lead of this concentration can be very hazardous in drinking water in the presence of CO₂.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"15 3","pages":"Pages 369-373"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(92)90021-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53883678","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}

{"title":"Year-long variability of Rn-222 in a groundwater system in Nigeria","authors":"I.P. Farai,&nbsp;A.O. Sanni","doi":"10.1016/0899-5362(92)90024-7","DOIUrl":"10.1016/0899-5362(92)90024-7","url":null,"abstract":"<div><p>Radon 222 was measured continuously in a groundwater system in Nigeria for one year by γ-spectroscopy. The mean Rn concentration for a particular month is 15,1 Bq/l with a standard deviation of 1.0 Bq/l while the mean for the whole year is 14.8 Bq/l with a standard deviation of 1.4 Bq/l. All the values for the year lie essentially within ±δ of the mean. Rainfall appears to be the only major factor causing variations.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"15 3","pages":"Pages 399-403"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(92)90024-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53883856","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}

{"title":"Gravitational and diapiric structural history of the eastern portion of the Archean Murchison greenstone belt, South Africa","authors":"R.C.A. Minnitt ,&nbsp;C.R. Anhaeusser","doi":"10.1016/0899-5362(92)90026-9","DOIUrl":"10.1016/0899-5362(92)90026-9","url":null,"abstract":"<div><p>The structural history of the eastern portion of the Murchison greenstone belt can be explained in terms of three deformational events. Early high-angle faults, formed during gravity slumping of unstable ensimatic crust, provided a regional synformal framework for the preservation of linear homoclinal and synclinal greenstone belt assemblages. A second stage of deformation was initiated by the emplacement of discrete diapric gneiss plutons into and around the greenstone belt margins, leading to the development of the “granite/greenstone pattern”. Cleavage, lineation, flattening of early open folds, and reactivation of early faults developed concomitantly, and with increasing intensity, throughout the second stage of deformation. Syntectonic granitoids were emplaced into the greenstone belt assemblages along subvertical upthrusts and high-angled reverse faults. These faults are somewhat conformable with the regional lithological trends and developed between the first and second stages of deformation. A third and final deformation event is registered in the sinistral ductile shear zones of the Letaba shear zone along the northern flank of the Letaba schist belt. Kinkband, crenulation, and chevron folds are related to this final event of deformation.</p></div>","PeriodicalId":100750,"journal":{"name":"Journal of African Earth Sciences (and the Middle East)","volume":"15 3","pages":"Pages 429-440"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(92)90026-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53883892","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}