 | | Journal (article/letter/editorial) | | Oversaturated Peralkaline Glassy Trachytes from Kenya by R. MACDONALD,1 D. K. BAILEY, 1 and D. S. SUTHERLAND2...Peralkaline felsic lavas from the central part of the Kenya Rift Valley were used by Bowcn as an illustration...newly analysed trachyte obsidians, from the Menengai volcano, with the pantellerites from other centres...GEOLOGY The central sector of the Rift Valley of Kenya is characterized by an abundance of felsic peralkaline...south-west of Lake Naivasha). To the south, the volcano of Longonot consists largely of trachytes, some |  | Macdonald, R., Bagiński, B., Leat, P.T., White, J.C., Dzierżanowski, P. (2011) Mineral stability in peralkaline silicic rocks: Information from trachytes of the Menengai volcano, Kenya. Lithos, 125 (1) 553-568 doi:10.1016/j.lithos.2011.03.011 | Journal (article/letter/editorial) | | rocks: Information from trachytes of the Menengai volcano, Kenya R. Macdonald a,b,⁎, B. Bagiński a, P.T...2011 Available online 17 March 2011 Keywords: Menengai volcano Peralkaline trachytes and rhyolites Mineral...silicaoversaturated trachytes from the Menengai volcano, Kenya Rift Valley. The dominant phenocryst assemblage...feldspar–hedenbergite–fayalite–titanomagnetite–apatite. Aenigmatite, amphibole and quartz occur rarely in more peralkaline...are variable, for reasons not yet understood. Aenigmatite crystallisation is at least partly controlled |  | Macdonald, Ray, Bagiński, Bogusław, Ronga, Fiorenzo, Dzierżanowski, Piotr, Lustrino, Michele, Marzoli, Andrea, Melluso, Leone (2012) Evidence for extreme fractionation of peralkaline silicic magmas, the Boseti volcanic complex, Main Ethiopian Rift. Mineralogy and Petrology, 104 (3) 163-175 doi:10.1007/s00710-011-0184-4 | Journal (article/letter/editorial) | | Geological setting The Boseti complex is a young volcano in the northern sector of the Main Ethiopian Rift...simultaneously with the formation of Gudda, the Bariccia volcano (Pleistocene-Holocene) formed in two stages. The...and charged with microlites of pyroxene and aenigmatite. The various components are mixed at scales between...to bright green rims. There are rare olivine, aenigmatite, FeTi-oxide and sulphide (micro)phenocrysts....matrix, with alkali feldspar, aegirine-augite, aenigmatite, quartz and tiny grains of ilmenite (Fig. 3d) |  | 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) | | PAPER Peralkaline felsic magmatism at the Nemrut volcano, Turkey: impact of volcanism on the evolution of...open access at Springerlink.com Abstract Nemrut volcano, adjacent to Lake Van (Turkey), is one of the most...intermediate-rhyolitic magmas. Keywords Nemrut volcano · Peralkaline magmatism · Magma mixing · Open-system...peralkaline eruptive rocks at the Nemrut caldera volcano, Turkey. Nemrut is the most active centre in Turkey...both Nemrut and the adjacent subalkaline Süphan volcano. We have selected a suite of tephra samples covering |  | Romano, Pierangelo, Scaillet, Bruno, White, John C., Andújar, Joan, Di Carlo, Ida, Rotolo, Silvio G. (2020) Experimental and thermodynamic constraints on mineral equilibrium inpantelleritic magmas. Lithos, 376. 105793pp. doi:10.1016/j.lithos.2020.105793 | Journal (article/letter/editorial) | | clinopyroxene and amphibole, fayalitic olivine, aenigmatite) and since then there have been many studies...Liszewska et al., 2018; Eburru, Kenya: Ren et al., lP 2006; and Menengai, Kenya: Macdonald et al., 2011)....pantellerites. ur governing the occurrence of aenigmatite, olivine, ilmenite and sodian amphibole phases...trachytic Montagna Grande-Monte Gibele shield volcano and several other pantellerite shields and lava...fayalitic olivine, sodian na amphibole, quartz and aenigmatite minerals. Mineral assemblages with Fe-Ti oxides |  | Macdonald, R., Bagiński, B., Belkin, H.E., White, J.C., Noble, D.C. (2019) The Gold Flat Tuff, Nevada: Insights into the evolution of peralkaline silicic magmas. Lithos, 328. 1-13 doi:10.1016/j.lithos.2019.01.017 | Journal (article/letter/editorial) | | arfvedsonite and “rare primary fluorite and aenigmatite”. It is highly unlikely that all these phases...recorded it in comendites of the Olkaria complex, D Kenya Rift Valley, where it forms hexagonal crystals up...1983; Linnen and Keppler, 2002). The presence of aenigmatite phenocrysts noted by Minor et al. (1998) has... Although comendites from the Olkaria complex, Kenya, PT E have F contents >1 wt% (Macdonald et al...1000 bar, which may explain the absence of CE aenigmatite. Macdonald et al. (2011) described an antipathetic |  | | Journal (article/letter/editorial) | | a c t Young (b 1 Ma) volcanic complexes in the Kenya Rift Valley are used to outline recent progress...dome complexes, e.g. the Olkaria complex in the Kenya (Gregory) rift with an estimated volume of ~13 km...Ma) silicic complexes in the inner trough of the Kenya Rift Valley to outline recent progress in our understanding...scarce or absent. The southern group of calderas (Menengai, Longonot and Suswa) are composed almost entirely...Olkaria, the southern group constitutes the Central Kenya peralkaline province (CKPP) of Macdonald and Scaillet |  | Bianchini, Gianluca, Brombin, Valentina, Marchina, Chiara, Natali, Claudio, Godebo, Tewodros Rango, Rasini, Alessandro, Salani, Gian Marco (2020) Origin of Fluoride and Arsenic in the Main Ethiopian Rift Waters. Minerals, 10 (5) 453 doi:10.3390/min10050453 | Journal (article/letter/editorial) | | sectors of the East African Rift and other similar volcano-tectonic settings. Keywords: fluoride and arsenic;...Differentiated rhyolite magmas appeared late in the volcano-tectonic evolution of the area, marking the onset...MER, the rifting processes have formed various volcano-tectonic depressions, favouring the development... prevalently aegirine-augite clinopyroxene, aenigmatite, oxides, and apatite. This mineral assemblage... amphibole, aegirine-augite clinopyroxene, aenigmatite, oxides, and apatite. This mineral assemblage |  | Zaitsev, A.N., Marks, M.A.W., Wenzel, T., Spratt, J., Sharygin, V.V., Strekopytov, S., Markl, G. (2012) Mineralogy, geochemistry and petrology of the phonolitic to nephelinitic Sadiman volcano, Crater Highlands, Tanzania. Lithos, 152. 66-83 doi:10.1016/j.lithos.2012.03.001 | Journal (article/letter/editorial) | | petrology of the phonolitic to nephelinitic Sadiman volcano, Crater Highlands, Tanzania A.N. Zaitsev a, b,⁎...Mineral stability fields Sadiman volcano a b s t r a c t Sadiman volcano is located in the Crater Highlands...All rights reserved. 1. Introduction Sadiman volcano (3°11′S, 35°25′E), also known as Satiman, is part...as the 1.6–1.5 Ma Oldeani basalt–trachyandesite volcano (Dawson, 2008; Mollel et al., 2008; 2011). ⁎ Corresponding...Lemagarut, Oldeani and Ngorongoro (Fig. 1a). The volcano is well known having been previously cited as the |  | Spandler, Carl, Morris, Caitlin (2016) Geology and genesis of the Toongi rare metal (Zr, Hf, Nb, Ta, Y and REE) deposit, NSW, Australia, and implications for rare metal mineralization in peralkaline igneous rocks. Contributions to Mineralogy and Petrology, 171 (12) doi:10.1007/s00410-016-1316-y | Journal (article/letter/editorial) | | pantellerite trachytes from the Menengai and Longonot volcanos, central Kenya (from Macdonald et al. 1970;...pantellerite trachytes of the Menengai and Longonot volcanoes of central Kenya (Macdonald et al. 1970; Rogers...feldspar, fayalite, Fe–Ti oxide and (in some cases) aenigmatite, rather than two feldspars and aegirine. The...pantellerite trachyte magmas such as at Menengai and Longonot, Kenya. Nonetheless, the low TiO2 and CaO,...Fe-bearing phase (Marks et al. 2011). The absence of aenigmatite is likely due to the low TiO2 and relatively |  | | Journal (article/letter/editorial) | | late-magmatic minerals of the dyke rock, for example, aenigmatite (Na2Fe5TiSi6O20), coexisting with the most evolved...sodalite (Sdl), aegirine-rich clinopyroxene, aenigmatite (Ae, Na2Fe5TiSi6O20) and arfvedsonite ± eudialyte...alkali feldspar, Ol olivine, Nph nepheline, Ae aenigmatite a H2O activity (aH2O) and oxygen fugacity (fO2)...of the dyke rock, and b run 85, 750 °C, with aenigmatite. Crystal phases are abbreviated as Mag titano...alkali feldspar, Ol olivine, Nph nepheline and Ae aenigmatite 750 °C ([58 wt%), Ol may have been overlooked |  | Upton, B. G. J., Macdonald, R., Odling, N., Rämö, O. T., Bagiński, B. (2013) Kûngnât, revisited. A review of five decades of research into an alkaline complex in South Greenland, with new trace-element and Nd isotopic data. Mineralogical Magazine, 77 (4) 523-550 doi:10.1180/minmag.2013.077.4.11 | Journal (article/letter/editorial) | | magma chamber (or chambers) beneath a central-type volcano, exhibits various features of petrological interest...Upper Series by the appearance of intercumulus aenigmatite and ferrorichterite. The FIG. 1. Map of South... such as the peralkaline trachytes of Menengai volcano, Kenya (Macdonald et al., 2011), and in experimental...and peralkaline rhyolites of the Olkaria complex, Kenya (Macdonald et al., 2008). The trend is taken to...envisages a situation akin to that at the Aden volcano, Yemen, where a pyroclastic cone of trachytic tuff |  | | Report (volume) | | 273 BAKER, B. H. Outline of the petroIogy of the Kenya rift alkaline province 293 MACDONALD,R. Quaternary...peralkaline silicic rocks and caldera volcanoes of Kenya 313 WOOLLEY, A. R. & JONES, G. C. The petrochemistry...on the peralkaline silicic central volcanoes of Kenya and also favours an origin by crystal fractionation...pyroclastic deposits around central volcanoes in Kenya often show striking variations in the abundance...on the peralkaline silicic central volcanoes of Kenya and also favours an origin by crystal fractionation |  | | Book | | carbonatitic-alkaline province outcropping on the Kenya-Uganda border which have recently received significant...domain characterized East Africa from Madagascar and Kenya-Ethiopia to northeastern Sudan. It represents the...Popoff 1988a). Like the Atlantic Benue trough, the Kenya-Sudan Mesozoic trends could correspond to a failed...Segoufin and Patriat 1981; Mougenot et al. 1986). The Kenya-Sudan Mesozoic troughs hypothetized above could...East-African rift. This suggests that the Mesozoic NW-SE "Kenya-Sudan" rift-system has been reactivated, similarly |  | | Book | | Mineralogical Society of America (Fig. 6.6), Montserrat Volcano Observatory (Fig. 7.4a and the front cover image)...previously erupted products the hazard presented by a volcano to surrounding communities; • investigating magma...chamber that originally lay 5 km below an active volcano (but whose contents – or erupted products – are...alkali basalts that have erupted at later stages of volcano development. To show how this can be applied, the...accelerates the melt upward; vesiculation in a volcano vent therefore promotes lava fountaining at the |
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