 | | Journal (article/letter/editorial) | | Lavas and Associated Plutonic Inclusions of Ascension Island by CHRIS HARRIS1 Dept. of Geology and Mineralogy...in revisedform 5 May 1983) INTRODUCTION Ascension Island is a large composite volcano situated at approximately...the South Atlantic Ocean (Fig. 1). The Island is 98 km2 in area and represents the uppermost portion of...March 29, 2014 ABSTRACT The lavas and pyroclastics of Ascension Island contain a suite of plutonic inclusions...trachyandesite and trachyte to comendite. Basalt sensu stricto is relatively rare and there is a scarcity |  | | Journal (article/letter/editorial) | | silicate melt inclusions in Ascension Island granite xenoliths J. D. WEBSTER1,* and C. R. REBBERT2 1 Department...Department of Earth and Planetary Sciences, American Museum of Natural History, Central Park West at 79th...alkaline volcanic rocks of Ascension Island were analyzed for 29 major, minor, and trace elements. For most...are similar to those of the volcanic whole rocks and the xenoliths; we interpret the glasses to be chemically...alkaline; contain low S and P abundances; and are enriched in H2O, Cl, F, and Na relative to K. Inclusions |  | | Journal (article/letter/editorial) | | Contr. Mineral. and Petrol. 36, 33--48 (1972) 9 by Springer-Verlag 1972 Evolution of La Palma, CanaryArchipelago...A. K. M i d d l e m o s t Department of Geology and Geophysics The University of Sydney, Sydney 2006...northwestern island in the Canary archipeIago. The island is volcani- cally active and in recent years...eruptions (1949 and 1971). The oldest rocks that crop out on the island are altered spilitic lavas and they are...are intruded by numerous dykes and a number of marie and ultramafic plutonic rocks. These rocks form part |  | | Journal (article/letter/editorial) | | m / l o c a t e / l i t h o s The geochemistry and evolution of Palaeogene phonolites, central Namibia...collectively exhibit a narrow compositional range and represent a single magma system of highly evolved...Na2O, Rb, Th, Zr, Zn, Pb, and REE and very low abundances of MgO, P2O5, Sr and Ba. No mafic rocks are associated...associated with the Aris phonolites and their ultimate petrogenetic origin remains obscure. The more abundant...sanidine (and nepheline) and pyroxene. The behaviour of REE is decoupled from Zr, Nb, and Th in this |  | | Report (volume) | | Carlton Victoria 3053, Australia DISTRIBUTORS USA and Canada Blackwell Scientific Publications Inc PO Box...granted by The Geological Society for libraries and other users registered with the Copyright Clearance...Typeset, printed and bound in Great Britain by William Clowes Limited, Beccles and London Library of...metasomatism--perspective and prospect vii ix 1 MENZIES, M. Alkaline rocks and their inclusions: a window...experimental studies 29 LE Bhs, M. J. Nephelinites and carbonatites 53 TWYMAN, J. D. & GITTINS, J. Alkalic |  | | Report (issue) | | Crystals short prismatic, to 0.5 mm, dominated by f101g and pinacoids k to [001]. Twinning: Not uncommon, with...Physical Properties: Cleavage: Distinct on f101g and f010g, indistinct on f100g. Tenacity: Brittle. Hardness...912(2) ® = 106± 14(2)0 X-ray Powder Pattern: Ascension Island. 4.20 (vs), 3.58 (vs), 3.08 (vs), 5.90 (s)...02 0.11 0.04 15.60 0.04 100.91 99.94 (1) Ascension Island; corresponds to (K1:79 Na0:32 )§=2:11 Zr1:01...of alkalic granite in trachytic and basaltic tu®s (Ascension Island); in syenite (Serra de Agua de Pau |  | | Book (volume) | | THE OCEAN BASINS AND MARGINS Volume | The South Atlantic THE OCEAN BASINS AND MARGINS Volume 1:...The North Atlantic Volume 3: The Gulf of Mexico and the Caribbean Volume 4: The Mediterranean Volume...Ocean ‘THE OCEAN BASINS AND MARGINS, A. Edited by-AlanjE. M. Nairn and Francis G. Stehli Department...de Geociéncias e Astronomia and Centro de Pesquisas Geocronolégicas da Universidade de Sao Paulo, Brazil...Instituto de Geociéncias e Astronomia and Centro de Pesquisas Geocronolégicas da Universidade de Sao Paulo, Brazil |  | | Report (issue) | | commonly as subrounded to irregularly shaped grains and aggregates of such grains. Twinning: Twin plane f010g...to (Na; K; Ca)2:00 Zr0:96 Si 3:91O 11 : (2) Ascension Island; corresponds to (Na; K; Ca)2:02 Zr0:97 Si...phase in nepheline syenites, syenitic pegmatites, and along the contact zone of a di®erentiated alkalic...cavities in ejected blocks of peralkalic granite (Ascension Island). Association: Eudialyte, microcline, albite...arfvedsonite, magnesio-katophorite, aegirine, aenigmatite, fayalite, pyrochlore, apatite, °uorite. Distribution: |  | Harris, C., Cressey, G., Bell, J. D., Atkins, F. B., Beswetherick, S. (1982) An occurrence of rare-earth-rich eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine, 46 (341) 421-425 doi:10.1180/minmag.1982.046.341.02 | Journal (article/letter/editorial) | | eudialyte from Ascension Island, South Atlantic C. HARRIS, G. CRESSEY, J. D. BELL, F. B. ATKINS, AND S. BESWETHERICK...BESWETHERICK Department of Geology and Mineralogy, Parks Road, Oxford ABSTRACT. A mineral closely resembling...perthite granites. The only singlecrystal X-ray pattern and chemistry has been found specimen found to contain...Post area on 30(1)] falls within group (iii). Ascension Island. To our knowledge, eudialyte has not Petrographically...silicates, consists of perthite and quartz (often showing dalyite and vlasovite.Textural evidencesuggests |  | | Journal (article/letter/editorial) | | 227 A second occurrence of dalyite and the petrology of some ejected syenite blocks from $5o Miguel...Miguel, Azores By J. R. CAN~ Department of Mineralogy and Petrology, Downing Place, Cambridge1 [Taken as read...century (Hartung, 1860; Miigge, 1883; Osann, 1888) and have been studied occasionally since those times...geological cruise, and the opportunity was taken to visit Serra de Agua de Pau and to collect a number...for comparison with the granite blocks of Ascension Island concurrently being studied (Cann, 1965). Serra |  | White, J. C., Ren, M., Parker, D. F. (2005) VARIATION IN MINERALOGY, TEMPERATURE, AND OXYGEN FUGACITY IN A SUITE OF STRONGLY PERALKALINE LAVAS AND TUFFS, PANTELLERIA, ITALY. The Canadian Mineralogist, 43 (4) 1331-1347 doi:10.2113/gscanmin.43.4.1331 | Journal (article/letter/editorial) | | MINERALOGY, TEMPERATURE, AND OXYGEN FUGACITY IN A SUITE OF STRONGLY PERALKALINE LAVAS AND TUFFS, PANTELLERIA...ABSTRACT Eight samples of pantelleritic lava and tuff and a lithic inclusion of trachyte from Pantelleria...classified by the presence of fayalite, aenigmatite, ilmenite, and magnetite: (1) augite + fayalite + ilmenite...ilmenite + aenigmatite + quartz, (4) sodian hedenbergite or aegirine-augite + ilmenite + aenigmatite + quartz...quartz ± ferrorichterite, and (5) aegirine-augite + aenigmatite + quartz. Alkali feldspar (Or35–37) is present |  | | Journal (article/letter/editorial) | | s i o n B y S. G. FLEET and J. R. CAN~1 D e p a r t m e n t of Mineralogy and Petrology, D o w n i n g..., previously reported as monoclinic by Pyatenko and Voronkov from an occurrence in the Kola Peninsula...from Ascension Island in a triclinic twinned modification. The obliquity is very slight (~ and ~, differ...differ from 90 ~ by less than l~ and X-ray photographs show arrays of paired spots corresponding to diffraction...followed on a single-crystal X-ray heating camera, and the obliquity is found to have successively smaller |  | Jeffery, A. J., Gertisser, R., Jackson, R. A., O'Driscoll, B., Kronz, A. (2016) On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores. Mineralogical Magazine, 80 (4) 547-565 doi:10.1180/minmag.2016.080.018 | Journal (article/letter/editorial) | | JACKSON1, B. O’DRISCOLL1,2 AND A. KRONZ3 1 2 3 School of Physical and Geographical Sciences, Keele...Staffordshire ST5 5BG, UK School of Earth, Atmospheric and Environmental Sciences, The University of Manchester...the placement of substituting Hf and Ti in the octahedral site, and highlight the overall complexity...Fe, Mg and Ba. The combined dataset reveals that dalyite found within peralkaline granites and syenites...is generally defined by higher Na↔K substitution and lower Ti↔Zr substitution relative to dalyite from |  | | Journal (article/letter/editorial) | | in Ejected Granitic Blocks from Ascension Island1 by EDWIN ROEDDER and D. s. COOMBS U.S. Geological...D.C., 20242 and Geology Department, University of Otago, New Zealand ABSTRACT Quartz and alkali feldspar...glass, with a small, very low-pressure gas bubble and sometimes a crystal offluorite(?).The original material...crystal (usually with other crystalline phases), and a large gas bubble containing some CO2. The original...temperature it consists of a dilute water solution and a very large, high-pressure CO2 gas bubble. Type |  | REN, M, OMENDA, P, ANTHONY, E, WHITE, J, MACDONALD, R, BAILEY, D (2006) Application of the QUILF thermobarometer to the peralkaline trachytes and pantellerites of the Eburru volcanic complex, East African Rift, Kenya. Lithos, 91 (1) 109-124 doi:10.1016/j.lithos.2006.03.011 | Journal (article/letter/editorial) | | QUILF thermobarometer to the peralkaline trachytes and pantellerites of the Eburru volcanic complex, East...south-central Kenya Rift consists of pantelleritic trachytes and pantellerites. The phenocryst assemblage in the trachytes...is sanidine + fayalite + ferrohedenbergite + aenigmatite ± quartz ± ilmenite ± magnetite ± pyrrhotite...fayalite + aenigmatite + ferrorichterite + pyrrhotite ± apatite, although fayalite, ferrohedenbergite and ilmenite...calculations for the trachytes range from 709 to 793 °C and for the pantellerites 668–708 °C, the latter temperatures |  | | Journal (article/letter/editorial) | | Mineralogy and Petrology 9 by Springer-Verlag 1976 Petrology, Volume and Age Relations of Alkaline and Saturated...Peralkaline Volcanics from Terceira, Azores Stephen Self* and Bernard M. Gunn Department of Geology, Imperial College...Azores group; three contain both basaltic and peralkaline and one only peralkaline rocks. A recently active...active basaltic fissure zone trends NW-SE across the island. The rocks fall into the alkaline olivine basalt...lavas of the oldest volcano and in some recent fissure zone basalts and hawaiites; 2) saturated, found |  | | Journal (article/letter/editorial) | | Islands) F. RIDOLFI1, A. RENZULLI1,*, P. SANTI1 1 2 AND B. G. J. UPTON2 Istituto di Vulcanologia e Geochimica...Urbino, I-61029 Urbino, Italy Department of Geology and Geophysics, University of Edinburgh, EH9 3JW Edinburgh...Islands) are divisible into (1) silica-undersaturated and (2) silica-saturated/oversaturated groups. The first...syenites of both groups crystallized at shallow depths and whole-rock geochemistry shows that they have compositions...during which most of the feldspar growth occurred; and (3) a late interstitial stage. Crystallization of |  | | Journal (article/letter/editorial) | | Contributions to Mineralogy and Petrology Contrib Mineral Petro! (1984) 86 : 155-158 9 Springer-Verlag...peralkaline melts can be explained. The high ks/ns and high Q calculated in some norms of peralkaline rocks...the mineral zircon in alkaline aqueous solutions and Goldschmidt (1954) concluded from available literature...then petrological (Chao and Fleischer 1960; Siedner 1964; Bowden 1966; Nicholls and Carmichael 1969; Weaver...Weaver et al. 1972) and experimental (Dietrich 1968 ; Larsen 1973) studies have provided growing evidence |  | | Journal (article/letter/editorial) | | Peralkaline Silicic Magmas and Petrogenetic Implications BRUNO SCAILLET1∗ AND RAY MACDONALD2 1 INSTITUT...tite solid buffer, temperatures between 740 and 660°C, and melt evolution under near H2O saturation conditions...have been established at 150 and 50 MPa, at oxygen fugacities of NNO − 1·6 and NNO + 3·6 (log fO2 relative...buffer), between 800 and 660°C and for melt H2O contents ranging between saturation and nominally anhydrous...fields of fayalite, sodic amphiboles, chevkinite and fluorite in natural hydrous silicic magmas are established |  | Macdonald, Ray, Sumita, Mari, Schmincke, Hans-Ulrich, Bagiński, Bogusław, White, John C., Ilnicki, Sławomir S. (2015) Peralkaline felsic magmatism at the Nemrut volcano, Turkey: impact of volcanism on the evolution of Lake Van (Anatolia) IV. Contributions to Mineralogy and Petrology, 169 (4) doi:10.1007/s00410-015-1127-6 | Journal (article/letter/editorial) | | dominated by peralkaline trachytes and rhyolites. Using onshore and Lake Van drill site tephra samples...samples, we document the phenocryst and glass matrix compositions, confirming a complete spectrum from very...dominantly silicic magmas. Magma mixing has been common and, along with the multi-lineage nature of the magmas...crustal magma reservoir at temperatures between 1100 and 750 °C, at fO2 close to the FMQ buffer. The silicic...24148 Kiel, Germany 4 Department of Geography and Geology, Eastern Kentucky University, Richmond, KY |  | | Journal (article/letter/editorial) | | EARTH AND PLANETARY SCIENCE LETTERS 18 (1973) 217-222. NORTH-HOLLAND PUBLISHING COMPANY [] POTASSIUM-...POTASSIUM- AND FLUORINE-RICH WITH PERALKALINE GRANITE HYDROUS PHASE COEXISTING IN SOUTH GREENLAND R. MACDONALD...Institute of Geology, University of Edinburgh, U.K. and J.E. THOMAS Department of Geology, University of...altered, with addition of notable amounts of K, F and H20. The granite sheets represent the residue of...the strong fractionation of trachytic magma, and the K and F bearing aqueous solutions are thought to have |  | Irwin, J.J., Roedder, Edwin (1995) Diverse origins of fluid in magmatic inclusions at Bingham (Utah, USA), Butte (Montana, USA), St. Austell (Cornwall, UK), and Ascension Island (mid-Atlantic, UK), indicated by laser microprobe analysis of Cl, K, Br, I, Ba + Te, U, Ar, Kr, and Xe. Geochimica et Cosmochimica Acta, 59 (2) 295-312 doi:10.1016/0016-7037(94)00285-t | Journal (article/letter/editorial) | | (Montana, USA), St. Austell (Cornwall, UK), and Ascension Island (mid-Atlantic, UK), indicated by laser microprobe...of Cl, K, Br, I, Ba + Te, U, Ar, Kr, and Xe J. J. IRWIN’.* and EDWIN ROEDDER’ ‘Department of Physics...California, Berkeley, CA 94720, USA ‘Department of Earth and Planetary Science, Harvard University, (Received...in rocks from Bingham, Utah, Ascension Island, mid-Atlantic Ocean, and St. Austell, Cornwall. Slightly...temperature FI occur at Butte, Montana. Argon, Kr, and Xe were extracted from FI by laser microprobe decrepitation |  | | Journal (article/letter/editorial) | | online 6 June 2006 Abstract The phase relationships and compositions of a pantellerite from the Eburru complex...Kenya Rift Valley have been determined at 150 MPa and under reducing conditions, 2 log units below the...temperature and melt water content on phase relationships have been explored. Alkali feldspar and quartz crystallise...melt water content. Below 700 °C, sodic amphibole and clinopyroxene also crystallise; the amphibole being...alkali feldspar and quartz in a crystal-poor pantellerite implies temperatures below 700 °C and melt water |  | | Journal (article/letter/editorial) | | differentiation * EDWIN ROEDDER Department of Earth and Planetary Science, Harvard University, Cambridge...review of recent work on melt inclusions in diamond and in normal magmatic environments, the nature of the...latestage water-rich fluids (yielding quartz veins and ore deposits), the composition of the residual liquid...polycomponent solutions (fluids), differing in properties and generally in composition. I believe that the great...silicate melt/low density vapor (i.e., vesiculation ), and, as presented in more detail in this paper, various |  | | Journal (article/letter/editorial) | | X-Ray and Optical Data for a Rare Earth-Poor Eudialyte from the North-Central Alaska Range By Neil E...Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, U.S...S.A. Mickey E. Gunter Department of Geology and Geological Engineering, University of Idaho, Moscow...A. Diana N. Solie Alaska Division of Geological and Geophysical Surveys, 3700 Airport Way, Fairbanks...U.S.A. Charles R. Knowles Department of Geology and Geological Engineering, University of Idaho, Moscow |
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