Journal of African Earth Sciences (1983)最新文献_第10页

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 Epub Date: 2010-07-13 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><p>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.</p><p>The central delta sediments, with an average SiO<sub>2</sub> 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 SiO<sub>2</sub> 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.</p></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

Pétrologie du massif volcanique du Guilliz (Maroc oriental). Cristallisation fractionnée, mélanges de magmas et transferts de fluides dans une série shoshonitique 吉利兹火山地块(摩洛哥东部)的岩石学。shoshonitic系列中的分馏结晶、岩浆混合和流体输送

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90053-9

J. Hernandez

{"title":"Pétrologie du massif volcanique du Guilliz (Maroc oriental). Cristallisation fractionnée, mélanges de magmas et transferts de fluides dans une série shoshonitique","authors":"J. Hernandez","doi":"10.1016/0899-5362(86)90053-9","DOIUrl":"10.1016/0899-5362(86)90053-9","url":null,"abstract":"<div><p>The Guilliz volcano is composed of upper miocene and pliocene suites (8.0–4.9 Ma) of shoshonitic and alkaline affinity. The shoshonitic suite is comprised of absarokites, shoshonites, latites and trachytes. Lavas with intermediate compositions are characterized by the presence of biotite and K-feldspar.</p><p>Alkaline lavas are, for the most part, hawaiites. The hawaiites are found as aphanitic inclusion in the shoshonitic series. Amphibole bearing absarokites and shoshonites erupted in the pliocene have compositions similar to that of the hawaiite inclusions.</p><p>Electron microprobe analyses of oxides, olivines, pyroxenes, amphiboles, biotites, feldspars and glasses indicate a multi-stage evolutionary process. Shoshonitic lavas appear to differentiate through crystal fractionation, leading to a zoned magma chamber. An attempt has been made to calculate the mineral assemblages and the proportion involved in the fractionation process.</p><p>The existence of an episode of magma mixing is evidenced by geological observations, and corroborated by chemical evolution of the lavas. The mixing occurs between shoshonitic and hawaiitic liquids. The mixing liberates a K-rich vapor phase from the hawaiitic magma, and this vapor contributes to the K-enrichment of the liquids present in the upper parts of the magma chamber.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"5 4","pages":"Pages 381-399"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(86)90053-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53876715","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: 6

Les Algues du ‘Calcaire rosé de Timahdite’ (eocène inférieur) dans le Moyen-Atlas (Maroc): description d'Halimeda nana Pia, 1932, dans sa localité-type et son paléoenvironnement 中阿特拉斯(摩洛哥)“timahdite rose Calcaire”(下始新世)中的藻类:halimeda nana Pia, 1932年在其类型位置和古环境中的描述

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90059-X

Geneviève Segonzac , Bernard Peybernès , Idriss Rahhali

引用次数: 7

Fabrics of meteoric phreatic diagenesis: inferences from the petrographic analysis of the Turonian Wadatta Limestone, Nigeria 大气潜水成岩作用的构造:来自尼日利亚Turonian Wadatta石灰岩岩石学分析的推论

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90031-X

C.S. Nwajide

引用次数: 0

KAr geochronology of the Karisimbi volcano (Virunga, Rwanda-Zaire) KKarisimbi火山的地质年代学(维龙加，卢旺达-扎伊尔)

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90023-0

M. De Mulder , P. Pasteels

引用次数: 16

Un gisement polymétallique en milieu volcanosédimentaire du Protérozoïque supérieur: Tessalit (Adrar des Iforas, Mali) 上元古代火山沉积介质中的多金属矿床:Tessalit (Adrar des Iforas，马里)

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90011-4

M. Leblanc, J.F. Sauvage

{"title":"Un gisement polymétallique en milieu volcanosédimentaire du Protérozoïque supérieur: Tessalit (Adrar des Iforas, Mali)","authors":"M. Leblanc, J.F. Sauvage","doi":"10.1016/0899-5362(86)90011-4","DOIUrl":"10.1016/0899-5362(86)90011-4","url":null,"abstract":"<div><p>The Tessalit deposit comprises a massive sulphide mineralization (up to 7% Zn, 1–2% Pb and less than 1% Cu) associated with carbonate and magnetite layers. It lies within a submarine acid dominated volcanic and pyroclastic complex belonging to an Upper Proterozoic island arc system (Tilemsi Group). A dome of porphyric rhyolite, brecciated <em>in situ</em> and pyritized occurs 1 km north from the Tessalit deposit; this dome is surrounded by laminated acid tuffs and tuffites. It is proposed that like many massive base metal sulphide bodies, the Tessalit deposit formed by volcanogenic and exhalative processes. The Tessalit mineralization comprises bedded sulphides associated with carbonate and iron rich exhalites and with waterlain acid tuffs. The orebody displays a mineral zoning with an upward change from a magnetite facies to a carbonate-copper sulphide, then a carbonate-sphalerite facies. Pan-African deformations have determined the actual complex geometry of the ore lenses. Other sulphide mineralization occurrences are known in other parts of the Tilemsi Group or equivalent volcano-sedimentary series. Gold occurrences may be also expected in these series.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"5 3","pages":"Pages 201-207"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(86)90011-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53875802","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: 3

Preliminary results from a pseudogravity study of the Benue Trough, Nigeria 尼日利亚贝努埃海槽伪重力研究的初步结果

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90009-6

Charles O. Ofoegbu

引用次数: 8

Felsic plutonic rocks of the Midyan region, Kingdom of Saudi Arabia—I. Distribution, classification and resource potential 沙特阿拉伯王国米甸地区的长英质深成岩- 1。分布、分类和资源潜力

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/S0899-5362(86)80068-9

Colin R. Ramsay , Alan R. Drysdall, Malcolm D. Clark

{"title":"Felsic plutonic rocks of the Midyan region, Kingdom of Saudi Arabia—I. Distribution, classification and resource potential","authors":"Colin R. Ramsay , Alan R. Drysdall, Malcolm D. Clark","doi":"10.1016/S0899-5362(86)80068-9","DOIUrl":"10.1016/S0899-5362(86)80068-9","url":null,"abstract":"<div><p>About 80 large felsic plutons were emplaced in the Midyan region of the northwestern Arabian Shield between 725 and 570 Ma ago. Polymetallic mineralization, including Mo, Nb, REE, Sn, Ta, U, W and Zr, is associated with particular varieties. Five intrusive suites of regional extent and five other plutons have been identified. The oldest extensive unit is the Muwaylih suite, consisting of trondhjemite, tonalite, diorite and gabbro, with generally trondhjemitic compositional affinities and no known mineral potential. The most voluminous is the Ifal suite, a heterogeneous assemblage of biotite—hornblende monzogranite, granodiorite and quartz monzodiorite in large, oval to irregular plutons characterized by numerous intraplutonic dikes, but with no known mineral potential. The Ifal suite is intruded by plutons of the Atiyah monzogranite, with a variable number of dikes. The Muwaylih, Ifal and Atiyah suites are chemically metaluminous, but the Midyan suite consists of alkali granite to alkali-feldspar granite which is metaluminous to peralkaline. Large, irregular plutons of the Haql suite are composed of perthite leucogranite which is metaluminous to marginally peraluminous or peralkaline.</p><p>Plutonic rock units of local significance include the Lawz complex, consisting of commonly granophyric syenogranite to monzogranite, the Mowasse quartz syenite and the Sawda (nepheline syenite) complex.</p><p>Polymetallic Nb<img>Zr deposits, such as those at Jabal Tawlah and Ghurayyah, are the most important known mineral resources and are related to alkali granite of the Midyan suite. Plumasitic specialized plutons, such as the Ratamah granite, have weak Sn<img>W<img>Ta<img>Nb mineralization, and are related to the Haql suite. Apical and contact zones of plutons of these suites are favorable exploration target areas.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"4 ","pages":"Pages 63-77"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0899-5362(86)80068-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"56385373","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: 34

Jabal Hamra REE-mineralized silexite, Hijaz region, Kingdom of Saudi Arabia Jabal Hamra ree矿化硅质岩，沙特阿拉伯王国Hijaz地区

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/S0899-5362(86)80088-4

Norman J. Jackson , Colin J. Douch

引用次数: 23

Geochemistry of spinel peridotite inclusions in basalts from Hoggar, Algeria 阿尔及利亚Hoggar玄武岩中尖晶石橄榄岩包裹体的地球化学

Journal of African Earth Sciences (1983) Pub Date : 1986-01-01 Epub Date: 2010-07-13 DOI: 10.1016/0899-5362(86)90012-6

C. Dupuy , J. Dostal , J.M. Dautria , M. Girod

{"title":"Geochemistry of spinel peridotite inclusions in basalts from Hoggar, Algeria","authors":"C. Dupuy , J. Dostal , J.M. Dautria , M. Girod","doi":"10.1016/0899-5362(86)90012-6","DOIUrl":"10.1016/0899-5362(86)90012-6","url":null,"abstract":"<div><p>Ultramafic xenoliths enclosed in Cenozoic alkali basaltic rocks from Hoggar (central Sahara, Algeria) are composed mainly of spinel peridotite. Some spinel lherzolites and harzburgites contain amphibole or its breakdown products or were cut by amphibolite veinlets. The spinel peridotites are upper mantle residue left after the removal of basaltic melt and were later affected by metasomatic processes which led to the formation of amphibole and the enrichment of several lithophile elements particularly in amphibole-bearing varieties. The model calculations using the total inverse method of Tarantola and Valette (<em>Rev. Phys. Space Phys.</em><strong>20</strong>, 219–232, 1982) indicate that the original upper mantle beneath the Hoggar had a composition similar to the estimated mantle of Jagoutz <em>et al.</em> (<em>Proc. 10th Lunar Planet. Sci. Conf.</em>, pp. 2031–2050, 1979) and Taylor (<em>Proc. 11th Lunar Sci. Conf.</em>, pp. 333–348, 1980) and that the host alkali basalts are not genetically related to the spinel peridotite xenoliths. The basalts were derived from a deeper, garnet-bearing source and scavenged the spinel peridotite xenoliths during their ascent.</p></div>","PeriodicalId":100749,"journal":{"name":"Journal of African Earth Sciences (1983)","volume":"5 3","pages":"Pages 209-215"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0899-5362(86)90012-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"106856025","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: 28