 | | Report (chapter) | | ocean island basalts from the South Atlantic: Ascension, Bouvet, St. Helena, Gough and Tristan da Cunha...Cunha Barry L. Weaver, David A. Wood, John Tarney and Jean Louis Joron Geological Society, London, Special...ocean island basalts from the South Atlantic: Ascension, Bouvet, St. Helena, Gough and Tristan da Cunha...David A. Wood, John Tarney and Jean Louis Joron S U M M A R Y: Basaltic and hawaiitic lavas from the S...Atlantic Ocean islands of Ascension, Bouvet, St. Helena, Gough and Tristan da Cunha have been analysed for |  | | Report (chapter) | | Geochronology (Ar/Ar and K– Ar) of the South Atlantic post-break-up magmatism M. C. GERALDES1*, A. MOTOKI1...integrates the available geological information and geochronology data for the Cretaceous– Recent magmatism...onshore and offshore magmatic events, including the oceanic islands along the transform faults and near...igneous rocks and their tectonic settings allows new insights into the evolution of the African and Brazilian...a common characteristic of almost all Brazilian and West African marginal basins. However, rocks ascribed |  | Graham, David W., Jenkins, William J., Schilling, Jean-Guy, Thompson, Geoffrey, Kurz, Mark D., Humphris, Susan E. (1992) Helium isotope geochemistry of mid-ocean ridge basalts from the South Atlantic. Earth and Planetary Science Letters, 110 (1) 133-147 doi:10.1016/0012-821x(92)90044-v | Journal (article/letter/editorial) | | Earth and Planetary Science Letters, 110 (1992) 133-147 Elsevier Science Publishers B.V., Amsterdam ...Schilling c, Geoffrey T h o m p s o n Mark D. Kurz a and Susan E. Humphris a a a Woods Hole Oceanographic...Graduate School of Oceanography, University of Rhode Island, Kingston, RI 02881, USA Received May 13, 1991;...between I°N and 47°S. 3He/4He in South Atlantic mid-ocean ridge basalts (MORB) varies between 6.5 and 9.0 R...from high 3He/aHe hotspots such as Iceland. He, Sr and Pb isotopes show systematic relationships along the |  | | Book | | de Luxembourg With 106 Figures and 95 Tables =e in the text and on 8 Folders 1970 GEBRUDER BORNTRAEGER...character- ized, with scarce an exception, by vulcanism, and the yulcanological evolution, rock suites, geomorphological...intimate acquaintance with all the Atlantic islands, and there is every reason to believe this applies even...southern islands separate, for reasons given above, and no less to furnish a volume of reasonable magnitude...general, shown little interest, and indeed the American J.C. Branner and the Belgian, A. RENARD, are the |  | | Journal (article/letter/editorial) | | Mineralogy and Petrology 9 Springer-Verlag 1990 Geochemistry of highly-undersaturated ocean island basalt...Ocean: Fernando de Noronha and Trindade islands Barry L. Weaver School of Geology and Geophysics, University...de Noronha and Trindade comprise a diverse magmatic series ranging from nephelinites and basanites to...to phonolites and, on Fernando de Noronha, trachytes. All rock types are highly silica undersaturated...Noronha trachytes), and have high abundances of incompatible trace elements and strongly LREE (light |  | | Journal (article/letter/editorial) | | ELSEVIER Earth and Planetary Science Letters 171 (1999) 575–589 www.elsevier.com/locate/epsl First...22 July 1999 Abstract Resolving the time–space (and compositional) evolution of volcanism along long-lived...understanding the connection between hotspot volcanism and mantle plumes. 40 Ar=39 Ar ages are reported here...southwest line extending from the vicinity of Saint Helena Island, and also for Circe Seamount. These seamounts...created in a midplate setting and could have formed rapidly (1 Myr). The St. Helena Seamount ages reveal a |  | | Journal (article/letter/editorial) | | 0022-3530/90 $3.00 Tristan da Cunha, South Atlantic: Geochemistry and Petrogenesis of a Basanite-Phonolite...Lava Series by ANTON P. LE ROEX 1 , R. A. CLIFF 2 AND B. J. I. ADAIR 1 1 Department of Geology, University...University of Leeds, Leeds, UK ABSTRACT The island of Tristan da Cunha, located at 37°S, 12°W in the South Atlantic...islands, the others being Nightingale and Inaccessible. Tristan da Cunha comprises a continuous series of...from ankaramitic basanite through phonotephrite and tephriphonolite to phonolite. Moderately porphyritic |  | | Journal (article/letter/editorial) | | fromGough, St. Helena andTdstan da Cunha lsIands; trachytes from cera:ral Victoria, Australia, and a leucitite...leucitite and phonclitic-tephrite series from Bufumbira, Uganda. In olivine crystals from basaltic lavas the...the Ca- and Mn-contents are low and Fe shows the most significant zoning from core to rim. in Fe-rich...Fe-rich oliviaes from trachytic differentiates Ca and Mn frequently show more significant variation than Fe...correlation with Mg (and hence Mn and Ni). Whi~e some olivines showed both Ca- and Fe-enrichmem towards |  | | Journal (article/letter/editorial) | | Contr. Mineral. and Petrol. 44, 101--115 (1974) 9 by Springer-Verlag 1974 Discovery Tablemount Basalt:...Basalt: Petrology and Geochemistry D. R. C. K e m p e Department of Mineralogy, British Museum (Natural History)...Graduate School of Oceanography, University of Rhode Island, Kingston, R.I. 02881, U.S.A. Received October...South Atlantic Ocean, has been described and analysed, and the rare earths determined. The basalt is...a quartznormative tholeiite but mineralogically and chemically (including trace elements) has affinities |  | Homrighausen, S., Hoernle, K., Hauff, F., Wartho, J.-A., van den Bogaard, P., Garbe-Schönberg, D. (2019) New age and geochemical data from the Walvis Ridge: The temporal and spatial diversity of South Atlantic intraplate volcanism and its possible origin. Geochimica et Cosmochimica Acta, 245. 16-34 doi:10.1016/j.gca.2018.09.002 | Journal (article/letter/editorial) | | Accepted Manuscript New age and geochemical data from the Walvis Ridge: The temporal and spatial diversity of...of South Atlantic intraplate volcanism and its possible origin S. Homrighausen, K. Hoernle, F. Hauff,...GarbeSchönberg, D., New age and geochemical data from the Walvis Ridge: The temporal and spatial diversity of...of South Atlantic intraplate volcanism and its possible origin, Geochimica et Cosmochimica Acta (2018)...manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published |  | | Journal (article/letter/editorial) | | 2089^2120 2010 doi:10.1093/petrology/egq050 Shona and Discovery Aseismic Ridge Systems, South Atlantic:...ANTON LE ROEX1*, CORNELIA CLASS2, JOHN O’CONNOR3 AND WILFRIED JOKAT4 1 DEPARTMENT OF GEOLOGICAL SCIENCES...Ridge^Meteor Rise^Agulhas Ridge^Cape Rise seamounts) and the Discovery Rise to the north have been argued...to represent the surface expressions of the Shona and Discovery mantle plumes, based on enriched samples...Mid-Atlantic Ridge, a single sample from Discovery Rise and tectonic reconstructions. Leg PS69 ANT XXIII/5 of |  | | Journal (article/letter/editorial) | | England Petrology of the Volcanic Rocks of Saint Helena Island, South Atlantic Abstract: Detailed field...of the two deeply eroded shield volcanoes of Saint Helena has permitted a reconstruction of their growth...textural and chemical variations from basic to salic ends of the series. Major oxide contents and a number...of known stratigraphic position. The intermediate and trachytic rocks are believed to be derived from a...processes of crystal fractionation. Volatile transfer and migration of alkali-rich late-crystallizing fluids |  | | Journal (article/letter/editorial) | | Contributions to Mineralogy and Petrology Contrib. Mineral. Petrol. 66, 9 1 - 104 (1978) 9 by Springer-Verlag...Group Division of igneous rocks into subalkalic and alkalic groups was made first by Iddings (I892)....Harker (1896, 1909). By his thesis, the subalkalic and alkalic groups represent two large branches of igneous...includes rocks ranging from basic to acidic composition and represents a genetic series. The tectonic conditions...subalkalic and alkalic branches were regarded (by mistake) as being characteristic of the Pacific and Atlantic |  | | Journal (article/letter/editorial) | | Abstract The dominant petrochemical evolution of St. Helena volcanics is from undersaturated alkali olivine...nepheline normative trachybasalt and trachyandesite to trachyte and phonolite. A unique lava is described...extreme iron enrichment and internal fractionation towards a granitic mesostasis, and hence is quite unlike...volcanic rocks from this or any other Atlantic island. The unique chemistry is also reflected in the...remain enigmatic. Introduction St. Helena is a volcanic island situated in the South Atlantic (5'40'W; |  | | Journal (article/letter/editorial) | | 9 by Springer-Verlag 1975 Petrological Aspects and Evolution of the Leucite Bearing Lavas from Bufumbira...Bufumbira, South West Uganda A. K. Ferguson and A. Cundari School of Geology, University of Melbourne, Parkville...by the presence of leucite both as phenocrysts and in the groundmass. Samples studied from the Bufumbira...differentiates through phonolitictephrites to a trachyte and the other differentiates through leucitites to a...are discussed in terms of the coexisting phases and ultramafie inclusions observed in the lavas. Equilibrium |  | | Journal (article/letter/editorial) | | Geochemistry of Inaccessible Island volcanics R.A. ClifP, P.E. Baker b'~ and N.J. Mateer ~ ~Departmenl o[Earth...30, 1989; revised and accepted April 8, 1991 ) ABSTRACT Clift; R.A., Baker, P.E. and Mateer, N.J., 1991...Inaccessible Island volcanics. ('hem. Geol., 92: 251-260. Inaccessible Island, part of the Tristan da Cunha group...group, is older than Tristan itself but younger than Nightingale. It comprises an alkali basalt-trachybasalt-phonolitic...similar to but less alkaline than that of Tristan. ('heroical and isotopic analyses for a new suite of sixteen |  | Homrighausen, S., Hoernle, K., Geldmacher, J., Wartho, J.-A., Hauff, F., Portnyagin, M., Werner, R., van den Bogaard, P., Garbe-Schönberg, D. (2018) Unexpected HIMU-type late-stage volcanism on the Walvis Ridge. Earth and Planetary Science Letters, 492. 251-263 doi:10.1016/j.epsl.2018.03.049 | Journal (article/letter/editorial) | | Earth and Planetary Science Letters 492 (2018) 251–263 Contents lists available at ScienceDirect Earth...Earth and Planetary Science Letters www.elsevier.com/locate/epsl Unexpected HIMU-type late-stage volcanism...Germany V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Kosygin St. 19, 119991 Moscow...Walvis Ridge late-stage volcanism trace elements and isotope geochemistry 40 Ar/39 Ar dating high 238...Volcanic activity at many oceanic volcanoes, ridges and plateaus often reawakens after hiatuses of up to |  | | Journal (article/letter/editorial) | | 175-181. Primed in Great Britain Volcanism on Gough Island: a revised stratigraphy J. G. MAUND*, D. C....work on Gough Island combined with K-Ar dating of the lavas requires revision of the age and volcanic... Four main periods of volcanic activity on the island are recognized. These comprise the eruption of...Ma), voluminous trachyte extrusion (0.30-0.12 Ma) and finally to eruption of the Edinburgh Basalt (0.20-0...involving the eruption of pillow basalts and hyaloclastites when the island emerged from below sea level. This |  | | Journal (article/letter/editorial) | | phenocrysts from Tristan da Cunha and Gough Island lavas: variation with fractional crystallization and evidence...clinopyroxene and plagioclase) present in lavas from Tristan da Cunha and Gough Island. These islands...mantle plume, have enriched radiogenic isotope ratios and are, therefore, prime candidates for an oxygen isotope...pyroxene and feldspar in the Gough lavas show that the phenocrysts in the ma®c Gough Island lavas are...isotope composition as MORB. Phenocrysts in all the Gough lavas show a systematic increase in d18O value as |  | | Journal (article/letter/editorial) | | Petrological and geochemical variations along the Mid-Atlantic Ridge between 46”s and 32%: Influence...Influence of the Tristan da Cunha mantle plume* SUSAN E. HUMPHRIS and GEOFFREY THOMPSON Department of Chemistry...Institution, Woods Hole, MA 02543 and JEAN-GUY SCHILLING and RICHARD H. KINGSLEY Graduate School of...of Oceanography, University of Rhode Island, Kingston, RI 02881 (Received March 21, 1984: accepted in...Mid-Atlantic Ridge close to the active volcanic island of Tristan da Cunha in the South Atlantic have been analysed |  | | Journal (article/letter/editorial) | | Earth and Planetary Science Letters, 110 (1992) 121- 131 Elsevier Science Publishers B.V., Amsterdam...rocks from Saint Helena David W. G r a h a m a,b,* Susan E. Humphris a, William J. Jenkins a and Mark D....olivine and clinopyroxene phenocrysts in 7-15 m.y. old basaltic lavas from the island of St. Helena. Magmatic...extraction techniques, including in vacuo crushing, and stepwise heating or fusion of the powders following...following crushing. The inherited 3He/nile ratio at St. Helena is 4.3-5.9 R a. Helium isotope disequilibrium is |  | | Journal (article/letter/editorial) | | Lineages and Fractionation Trends in Undersaturated Volcanic Rocks from the East Otago Volcanic Province...Province (New Zealand) and Related Rocks by D. s. COOMBS and j . F. G. WILKINSON ABSTRACT The petrology...sodic lavas and shallow intrusives whose compositions range from alkali basalt, basanite, and nephelinite...nephelinite to trachyte and phonolite. A range of relatively potassic volcanic rocks is also developed in the... The degree of undersaturation and ratios such as (FeO+Fe2O3):MgO and K,O:Na,O vary widely in rocks with |  | | Journal (article/letter/editorial) | | Contr. Mineral. and Petrol. 43, 125--147 (1974) 9 by Springer-Verlag 1974 Petrology of the Ninety East...East Ridge in the Indian Ocean consist of basalts and oceanic andesites. The basalts from the Ninety East...content ( > 11% ), higher TiO 2 content (2-3%), and variable K20 content (0.2-1.5%). Volcanics from other...aseismie ridges, i.e. the Cocos, the Iceland-Faeroe and the Walvis ridges, show a trend of differentiation...The Ninety East and the Ieeland-Faeroe ridges contain mildly tholeiitic basalts and oceanic andesit~s |  | Christensen, Birgitte Printz, Holm, Paul Martin, Jambon, Albert, Wilson, J.Richard (2001) Helium, argon and lead isotopic composition of volcanics from Santo Antão and Fogo, Cape Verde Islands. Chemical Geology, 178 (1) 127-142 doi:10.1016/s0009-2541(01)00261-3 | Journal (article/letter/editorial) | | comrlocaterchemgeo Helium, argon and lead isotopic composition of volcanics from Santo Antao ˜ and Fogo, Cape Verde Islands...accepted 18 December 2000 Abstract Helium, argon and lead isotopic ratios have been determined for volcanics...of the youngest Cape Verde Islands, Santo Antao ˜ and Fogo. Helium isotopic ratios range from radiogenic...Pb s 18.90–19.63, 207 Pbr204 Pb s 15.526–15.621 and 208 Pbr204 Pb s 38.694–39.272, with volcanics from...isotopes, high CerPb, ZrrHf, low BarLa, LILErNb and low 40Arr36Ar indicate a significant contribution |  | | Journal (article/letter/editorial) | | Earth and Planetary Science Letters, 66 (1983) 223-242 Elsevier Science Publishers B.V., Amsterdam -...Ridge: implications for its origin and evolution Susan E. Humphris and Geoffrey Thompson Department of Chemistry...basalts from a suite of dredged and drilled samples (IPOD sites 525, 527, 528 and 530) from the Walvis Ridge...(REE) contents in order to investigate the origin and evolution of this major structural feature in the...from Sites 527, 528 and 530 show REE patterns characterised by an arcuate shape and relatively low (Ce/Yb)N |
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