Journal of African Earth Sciences (1983)最新文献_第8页

Resédimentations d'âge sénonien dans le Rif central (Maroc): conséquences sur les divisions paléogéographiques et structurales de la chaîne Rif中部(摩洛哥)塞尼时代的重新构造:对古地理和链结构划分的影响

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90103-5

Lahcen Asebriy, Patrick de Luca, Jacques Bourgois, Pierre Chotin

引用次数: 18

Structure et cinématique des peridotites feldspathiques du Cap Bougaroun (Algérie) 阿尔及利亚布加隆角长石橄榄岩的结构和运动学

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90009-1

M. Misseri

引用次数: 6

S-type granite from Jabal Al Hasawnah, west central Libya 来自利比亚中西部Jabal Al Hasawnah的s型花岗岩

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90043-1

K.M. Oun, M.T. Busrewil

引用次数: 2

Fluvio-deltaic environment and in situ pedogenesis of Middle Miocene kaolinitic sandstones of the Pugu coastal area of Tanzania 坦桑尼亚普谷沿海地区中中新世高岭石砂岩的河流三角洲环境与原位成土作用

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90064-9

M.K.D. Mutakyahwa

引用次数: 3

Variable intra-plate igneous activity in central and north-east Sudan 苏丹中部和东北部多变的板块内火成岩活动

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90088-1

P.M. Klemenic

{"title":"Variable intra-plate igneous activity in central and north-east Sudan","authors":"P.M. Klemenic","doi":"10.1016/0899-5362(87)90088-1","DOIUrl":"10.1016/0899-5362(87)90088-1","url":null,"abstract":"<div><p>Four Phanerozoic alkaline igneous complexes from central and north-eastern Sudan are compared petrologically. Despite many similarities in terms of mineralogy, petrography and major element geochemistry significant differences are found when trace element and particularly isotopic data are considered. In particular the complexes from north-eastern Sudan have markedly lower <sup>87</sup>Sr/<sup>86</sup>Sr ratios and overall RE element content than those occurring in central Sudan. Such differences could be accounted for by variation in the degree of metasomatic alteration associated with non-hydrous volatiles. However, there is no evidence to suggest that the effect of volatiles has been more prominent in any particular geographic location or complex. The chemical character of the north-eastern complexes is similar to the oceanic island leucocratic lavas of St. Helena and Ascension. Further, the complexes of north-eastern Sudan are associated with a prominnent dyke swarm, suggesting a tensional tectonic environment which may have facilitated the passive emplacement of mantle derived magma. In central Sudan there is no direct evidence of rifting and the alkaline rocks are clearly chemically and isotopically similar to anorogenic rocks which are considered to have evolved from mixtures of mantle and crustal derived material. It is suggested that the differences between the alkaline complexes of eastern and central Sudan are due to the charccter of the source material rather than the effect of metasomatic alteration, although mantle source heterogeneity cannot be ruled out.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 4","pages":"Pages 465-474"},"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)90088-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53877447","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

The development of the Late Cenozoic alkali basaltic Marsabit Shield Volcano, northern Kenya 肯尼亚北部晚新生代碱玄武质马萨比特盾状火山的发育

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90089-3

R.M. Key , B.P. Rop , C.C. Rundle

{"title":"The development of the Late Cenozoic alkali basaltic Marsabit Shield Volcano, northern Kenya","authors":"R.M. Key , B.P. Rop , C.C. Rundle","doi":"10.1016/0899-5362(87)90089-3","DOIUrl":"10.1016/0899-5362(87)90089-3","url":null,"abstract":"<div><p>The Marsabit Shield Volcano has a surface area of 6300 km<sup>2</sup> and a volume of about 910 km<sup>3</sup> of alkali basaltic lavas and pyroclastics to a maximum (summit) thickness of about 1200 m. Laterally extensive, fissure-sourced lava flow-units predominate with clinopyroxene, plagioclase ± olivine basal basla units followed by olivine basalts. Minor, youngest flows form narrow tongues from cone sources and are also olivine (± analcime) basalts. Cinder cones, block-and-ash cones and <em>maars</em> are concentrated in two belts controlled by fundamental crustal fractures. Hawaiian type volcanism commenced in the very late Pliocene followed by progressively more violent (Strombolian and Ultravulcanian) activity peaking at some stage in the Quaternary. Final vulcanism was relatively gentle and presently the volcano is extinct. The high concentrations of <em>maars</em> is unique to Marsabit in N. Kenya and due to the location of the Sheild over the major aquifer of the Chalbi Basin The volcanism, although contemporaneous with the tectonics of the Gregory Rift, is spatially separated and indicates a regional supply of mantle in N. Kenya. The lavas followed an alkali basalt fractionation trend from a periodotite (xenoliths present in maars) source. Little crust contramination of the source magma occurred, possiblly because of regional crustal tension during the Late Cenozoic in East Africa.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 4","pages":"Pages 475-480, IN1-IN5, 481-491"},"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)90089-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53877464","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: 21

Palynology of Albian-Cenomanian strata in Mersa Matruh well, Western Desert, Egypt 埃及西部沙漠Mersa Matruh井Albian-Cenomanian地层孢粉学

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90005-4

Ismail Z. Sultan

引用次数: 33

Chemical composition of some Senonian bivalvian shells and its significance in paleoecological studies, in the area of Abu Roash, Egypt 埃及阿布罗什地区塞涅世双壳类贝壳的化学成分及其古生态学意义

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90054-6

A.A. Abdel Aal, M.R. Mohammad, A.I. Rezk

引用次数: 3

Notes on some shear zones of northern Somalia 关于索马里北部一些剪切带的说明

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90075-3

Rosalino Sacchi , Adriano Zanferrari

引用次数: 5

La structure du rif externe (Maroc): mise au point sur le rôle des décrochements des chevauchements et des glissements gravitaires 外部rif的结构(摩洛哥):重点关注重叠和重力漂移的作用

Journal of African Earth Sciences (1983) Pub Date : 1987-01-01 DOI: 10.1016/0899-5362(87)90011-X

Dominique Frizon de Lamotte

{"title":"La structure du rif externe (Maroc): mise au point sur le rôle des décrochements des chevauchements et des glissements gravitaires","authors":"Dominique Frizon de Lamotte","doi":"10.1016/0899-5362(87)90011-X","DOIUrl":"10.1016/0899-5362(87)90011-X","url":null,"abstract":"<div><p>Regional structural field evidence in the Temsamane area, forming the eastern part of the Rifian external zones, indicate that deformation of this area results from N75° left lateral wrenching. The structural data do not fit the nappe interpretation pointed out in Western part of external zone. A review of the geological frame appears necessary; it forms the subject of the present paper.</p><p>Structurally, the external zones are subdivided into three groups of tectonic units: (a) the olistostromes and associated gravity-driven nappes which crop out all around the Rifian belt (‘slided external Rif’); (b) The tectonic windows situated beneath olistostromes and nappes (‘basal external Rif’); (c) The central area bounded by NW-SE thrust faults in the Western parts of the belt and by N75° (then N45°) wrench faults in the Eastern parts (‘Central Rif’).</p><p>Concerning the paleogeographic evolution, the deposits of external Rif show a different evolution from their direct foreland but comparable with areas actually situated far eastward: (a) the ‘tellian-like domain’ shows basinal-type facies similar to facies of the epitellian nappes into Algeria<sup>b</sup>, (b) the ‘Ker Ker-like domain’ shows platform facies similar to facies known in West Algerian and Northeast Moroccan forelands.</p><p>Thus, structural and paleogeographic data show that the all external zones of Rif moved westward along the African margin before sliding southward.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"6 5","pages":"Pages 755-766"},"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)90011-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876480","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: 19