 | | Journal (article/letter/editorial) | | Oversaturated Peralkaline Glassy Trachytes from Kenya by R. MACDONALD,1 D. K. BAILEY, 1 and D. S. SUTHERLAND2...becomes questionable, the relationship between trachyte and rhyolite must also be re-examined. Other possibilities...a more basic parent without passing through a trachyte stage (Noble, 1965), to crustal anatexis around...Peralkaline felsic lavas from the central part of the Kenya Rift Valley were used by Bowcn as an illustration...crystallization in nature. Despite the importance of trachyte to this and other theories on the evolution of |  | | Journal (article/letter/editorial) | | Kilombe Caldera, Kenya by G. J. H. McCALL Received 14 June 1963; taken as read 7 November 1964 CONTENTS...... CALDERA GENESIS COMPARISON OF KILOMBE AND MENENGAI WITH LUNAR CRATERS ACKNOWLEDGMENTS REFERENCES...is compared, together with that of the nearby Menengai caldera, with the beak structure of many lunar...as Eldalat), an extinct volcano situated near the town of Eldama Ravine in Kenya, forms a conspicuous mountain...G. J. H . McCALL giant calderas nearby (e.g. Menengai 35 square miles, Suswa outer caldera 40 square |  | 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...stabilities are not clear. It appears that peralkaline trachyte–rhyolite sequences evolve along many crystallisation...East African Rift System. Volcanic centres in the Kenya Rift Valley where pantelleritic trachytes have been |  | | Report (issue) | | NATURAL RESOURCES GEOLOGICAL SURVEY OF KENYA GEOLOGY OF THE NAKURU-THOMSON'S FALLSLAKE HANNINGTON AREA...number concerned. | , ', ' I GEOLOGY OF THE NAKURU-THOMSON'S FALLSLAKE HANNINGTON AREA DEGREE SHEET...Drainage into Ol Punyata Swamp (5) Drainage into Lake Nakuru and the surrounding plain (6) Drainage into Lake...(c) Dispei-Lake Hannington Phonolites (d) Lower Menengai Volcanics .. (e) Sirrkon Volcanics (ƒ) Bahati...Porphyritic Trachyte (b) Nakuru Lake Syndicate Quarry Phonolite .. (c) Mbaruk Basalt.. (d) Gilgil Trachyte (e) |  | | Journal (article/letter/editorial) | | 73 www.elsevier.com/locate/lithos The central Kenya peralkaline province: Insights into the evolution...Available online 30 May 2006 Abstract The central Kenya peralkaline province comprises five young (< 1 Ma)...fractionation of basaltic magma via metaluminous trachyte and in turn generated pantellerite by the same... Keywords: Kenya; Petrogenesis; Peralkaline magmas 1. Introduction In the central Kenya Rift Valley...complexes. Three are trachytic caldera volcanoes (Menengai, Longonot and Suswa) and two are rhyolitic complexes |  | | Report (chapter) | | 2015 Tectonics and volcanism of the southern Kenya Rift Valley and its influence on rift sedimentation...SUM M A RY: Volcanism in the northern half of the Kenya Rift Valley began at 30 Ma, and in the southern...and a narrow inner graben, but in the Naivasha-Nakuru sector voluminous trachytic volcanism completely...into closed structural basins. Evolution of the Kenya Rift Valley during the last 30 Ma is now moderately...outline of the history of the southern part of the Kenya Rift gives an account of the structural style and |  | 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...The first stage saw the emplacement of trachyte flows followed by peralkaline trachytic and rhyolitic...normative quartz (q) between 17% and 31%. Taking the trachyte-rhyolite boundary at the conventional 10% q, all...experimental glasses, Scaillet and Macdonald (2003); Menengai, Macdonald et al. (2011) In peralkaline trachytes |  | | | | February 2009, Vol. 73(1), pp. 1–16 The central Kenya peralkaline province: a unique assemblage of magmatic...peralkaline salic complexes in the south-central Kenya Rift Valley, stressing new developments of general...be generated by fractional crystallization of trachyte and high-silica rhyolite. Melts of comenditic...composition were also formed by fractionation of trachyte but also locally by partial melting of syenites...very low viscosity of the magmas. K EY WORDS : Kenya Rift, peralkaline salic rocks, petrogenesis, plumbing |  | | Journal (article/letter/editorial) | | elsevier.com/locate/lithos The volcano–pluton interface; The Longonot (Kenya) and Kûngnât (Greenland) peralkaline...Available online 18 March 2014 Keywords: Longonot volcano Kûngnât syenite complex Evolution of complementary...magma reservoir(s). The trachytic caldera volcano Longonot (Kenya Rift Valley) and the Kûngnât syenite complex...Kelleher and Cameron, 1990) and the Olkaria complex, Kenya (Macdonald et al., 2008; Marshall et al., 2009)...which can be considered to be a complementary volcano–pluton pair. Although the histories of the two |  | | Report (chapter) | | peralkaline silicic rocks and caldera volcanoes of Kenya R. Macdonald Geological Society, London, Special...of Kenya R. Macdonald S U M M A R Y: The late-Quaternary trachytic caldera volcanoes of the Kenya rift...these centres. The southern basalt-absent centres (Menengai, Longonot and Suswa) show Krakatoa-style collapse...plutonic processes while the volcano is at the magmatic stage. In Kenya the late-Quaternary caldera volcanoes...on the seven centres of the inner trough of the Kenya rift (Fig. 1) but, where relevant, information from |  | | 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...group of calderas (Menengai, Longonot and Suswa) are composed almost entirely of trachyte, although mafic...Olkaria, the southern group constitutes the Central Kenya peralkaline province (CKPP) of Macdonald and Scaillet |  | | Journal (article/letter/editorial) | | 12 – 9 Ma) is poorly represented in the Southern Kenya Rift, though magmatic activity is recorded in the...– 4 Ma) is particularly well-represented in the Kenya Rift. Large-scale magmatic events include: commencement...Divergence (NTD) and Mt. Kenya, Rungwe Volcanic Province, and the Southern Kenya Rift. The Stratoid Phase...magmatic events at ca. 3 to 2.5 Ma within the Southern Kenya Rift and NTD. This phase manifests as basalts and...that flood the newly formed graben in the Southern Kenya Rift. This phase also correlates with the main phase |  | | Report (chapter) | | extensional regime at each volcano. We found that extension in northern Kenya is orthogonal, whereas that...that in southern Kenya is oblique. Elliptical calderas in northern Kenya are orientated NW–SE, aligned...perpendicular to recent rift faults. In southern Kenya, the calderas are aligned NE–SW and lie oblique...Barrier; E, Emuruangogolak; Si, Silali; P, Paka; M, Menengai; L, Longonot; and Su, Suswa. (a) Digital Elevation...Kenyan Dome is marked. (b) Summary geological map of Kenya after BEICIP (1987). Red arrows show the motion |  | | Report (chapter) | | Special Publications Outline of the petrology of the Kenya rift alkaline province B.H. Baker Geological Society...October 28, 2014 Outline of the petrology of the Kenya rift alkaline province B. H. Baker S U M M A R Y...eastern branch of the E African rift system in Kenya and northern Tanzania contains nearly the whole...majority of wellstudied suites of alkaline rocks in Kenya, including some unpublished data. Apart from questions...the province The alkaline volcanic province in Kenya and northern Tanzania is associated with the development |  | 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...to form peralkaline trachyte, followed by fractional crystallisation of the trachyte to form peralkaline...peralkaline eruptive rocks at the Nemrut caldera volcano, Turkey. Nemrut is the most active centre in Turkey |  | | Journal (article/letter/editorial) | | evolution of peralkaline trachyte and phonolite from the Suswa volcano, Kenya rift John Charles White...Tower, Upper Hill, P.O. Box 10076–00101, Nairobi, Kenya a r t i c l e i n f o Article history: Received...Available online 3 February 2012 Keywords: Trachyte Phonolite Central Kenya Peralkaline Province a b s t r a...the southernmost volcanic center in the Central Kenya Peralkaline Province (CKPP) and represents the only...silica-undersaturated lavas and tuffs (trachyte, nepheline trachyte and phonolite). The eruptive products |  | 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) | | recorded it in comendites of the Olkaria complex, D Kenya Rift Valley, where it forms hexagonal crystals up...They have certain similarities to the benmoreite-trachyte globules described in peralkaline ignimbrite ‘TL’...absence of melt compositions less evolved than trachyte, it is impossible to identify precisely the l... Although comendites from the Olkaria complex, Kenya, PT E have F contents >1 wt% (Macdonald et al...These features suggest that GF1 is a mix of a trachyte/rhyolite magma and a magma less RI REE-rich |  | 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) | | Archirafi 22, 90123 Palermo, Italy. Jo Peralkaline trachyte and rhyolite (peralkalinity index calculated as...of mineral phases crystallising in peralkaline trachyte and peralkaline rhyolite (named as either Journal...locality for pantelleritic rocks, metaluminous trachyte and pantellerite comprise about 90% of the outcrop...Liszewska et al., 2018; Eburru, Kenya: Ren et al., lP 2006; and Menengai, Kenya: Macdonald et al., 2011)....compositionally zoned Green Tuff (pantellerite to trachyte, Williams et al., 2014), the caldera-forming ignimbrite |  | 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) | | REE within a small (ca. 0.3 km2), rapidly cooled trachyte laccolith. Toongi is part of regional Late Triassic...that is homogenously distributed throughout the trachyte body. The primary ore minerals are evenly dispersed...Na2O, peralkaline nature of the Toongi Deposit trachyte developed via extensive fractionation of an alkali...Morgan 1999). The bodies are predominately of trachyte composition, but also include two small syenite...deposits (Fig. 2b; Meakin and Morgan 1999). The trachyte bodies in the immediate vicinity of the Toongi |  | 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...implies crystallization from magmas evolving from trachyte (approximating to the minimum melting point on...those of the cotectics in similar benmoreite and trachyte crystallization. Temperatures and pressures of...inferred to have grown from volatile-rich quartz trachyte residues which were clearly carbonated and probably... such as the peralkaline trachytes of Menengai volcano, Kenya (Macdonald et al., 2011), and in experimental |  | Brenna, Marco, Pontesilli, Alessio, Mollo, Silvio, Masotta, Matteo, Cronin, Shane J., Smith, Ian E.M., Moufti, Mohammed Rashad Hassan, Scarlato, Piergiorgio (2019) Intra-eruptive trachyte-phonolite transition: Natural evidence and experimental constraints on the role of crystal mushes. American Mineralogist, 104 (12) 1750-1764 doi:10.2138/am-2019-6963 | Journal (article/letter/editorial) | | Volume 104, pages 1750–1764, 2019 Intra-eruptive trachyte-phonolite transition: Natural evidence and experimental...displaying compositional transition from benmoreite-trachyte to phonolite has been observed within the Al Shaatha...crystallization experiments on benmoreite and trachyte starting compositions to simulate the pressur...and anhydrous (for benmoreite) or hydrous (for trachyte) conditions. At low pressure (200 MPa), temperatures...high (>90%), and the residual glass obtained from trachyte experiments is characterized by peralkaline and |  | | 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...transitional basalt m a g m a is likely to produce trachyte and, with extreme fractionation, alkali rhyolite |  | | Journal (article/letter/editorial) | | in cogenetic basalt-trachyandesite-comenditic trachyte, while the composition of unzoned clinopyroxene...the cogenetic basalt-trachyandesite-comenditic trachyte magma of the Sanshui Basin. By integrating the...volcanic rocks are weakly peralkaline, comenditic trachyte, comendite, and pantellerite. These peralkaline...titan-magnetite in desite,comenditic 18ss014-1;trachyte, (d) T2 type clinopyroxene phenocryst and coexisting...clinopyroxene phenocryst in comenditic in trachyte, and trachyte, 19ss027-1; (e) T3 type clinopyroxene phenocryst |  | | Journal (article/letter/editorial) | | Springer-Verlag1986 Rise and fall of a basalt-trachyte-rhyolite magma system at the Kane Springs Wash...caldera floor shortly afterward, forming a central trachyte/syenite complex. Replacement of this magma by...parental magmas, ranging from alkali basalt to trachyte, were erupted before and after the peralkaline...Wash center are lavas ranging from mafic trachyte to trachyte, 353 Fig. 1. Geologic map of the Kane...porphyritic to seriate syenite bodies sheathed by trachyte lavas. Metaluminous amphibole-bearing rhyolite |  | | Report (issue) | | high-silica comendite, and zoned intermediate comenditic trachyte. The high-silica melt that formed the upper part...high-silica comendite to an intermediate comenditic trachyte. Post-collapse resurgent activity created a structural...plinian-phreatomagmatic eruption at the Laacher See volcano, Germany. In that eruption, the lithic fragments...intracaldera tuffs range from comendite to comenditic trachyte. Most of the analyzed rocks are either hydrated...Mahood and Hildreth (1986) at the peralkaline volcano of Pantelleria. Two compositions are distinguished |
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