 | | Report (issue) | | activity and geology of the northern sector of the Kenya Rift Valley British Geological Survey Research...activity and geology of the northern sector of the Kenya Rift Valley P N Dunkley, M Smith, D J Allen and...activity and geology of the northern sector of the Kenya Rift Valley P N Dunkley, M Smith, D J Allen and...springs along its western shores. Geographic index Kenya Suf>jecr index Geothermal exploration, geology...activity and geology of the northern sector of the Kenya Rift Valley. British Geological Survey Research |  | | 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...northern set of centres (the Barrier, Emuruangogolak, Silali and Paka) basalt is a major component and mugearites...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) | | magmatism in both rifts, and within the interposing Turkana re Depression. Notwithstanding the independent...independent evolution of the Main Ethiopian Rift and Kenya lP Rift prior to their quaternary linkage, magmatic...evolved compositions (flood na phonolites in Kenya, rhyolites in Ethiopia) dominated the landscape...impacted the entire region from the Afar margin to Kenya, though activity in the south Jo slightly predates...silicic volcanoes. Magmatic activity within the Turkana Depression broadly parallels that in both rifts |  | | 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, comprising the Barrier, Emuruangogolak, Silali and Paka, E-mail address: r.macdonald@lancaster...Olkaria, the southern group constitutes the Central Kenya peralkaline province (CKPP) of Macdonald and Scaillet |  | | Journal (article/letter/editorial) | | situated, 12 km apart, on the western flank of the Kenya Rift Valley (McCall, 1964; Jennings, 1971; Jones...succession, are sanidine in the early flows, with anorthoclase forming up to 35% of the later flows. The groundmass...I/ Tanzania ) .Nair0bi FIG. 1. Index map of Kenya, showing location of Kilombe, K, and Londiani, L...(Sceal and Weaver, 1971), Menengai (McCall, 1967), Silali (McCall and Hornung, 1972), Ribkwo and Nasaken...lanthanide concentrations in some specimens from Eburru, Kenya. Of all the lanthanides, Ce is the most readily |  | Black, Stuart, Macdonald, Ray, Barreiro, Barbara A., Dunkley, Peter N., Smith, Martin (1998) Open system alkaline magmatism in northern Kenya: evidence from U-series disequilibria and radiogenic isotopes. Contributions to Mineralogy and Petrology, 131 (4) 364-378 doi:10.1007/s004100050398 | Journal (article/letter/editorial) | | Smith Open system alkaline magmatism in northern Kenya: evidence from U-series disequilibria and radiogenic...(<10 ka) and trachytes from the volcano Emuruangogolak in the Kenya Rift Valley. The basalts are mildly...conduits closely spaced around the summit of the volcano. Introduction The nature and eÂciency of diÂerentiation...evolution of the basanite-phonolite Laacher See volcano in Germany. DiÂerentiation of parental basanite...Emuruangogolak basalt-trachyte complex in northern Kenya, and to quantifying the timescales of magmatic evolution |  | 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) | | the Eburru volcanic complex, East African Rift, Kenya Minghua Ren a,â, Peter A. Omenda b , Elizabeth Y...785, KenGen, Moi South Lake Road, Naivasha 20117, Kenya c Department of Earth Sciences, Eastern Kentucky...Quaternary Eburru volcanic complex in the south-central Kenya Rift consists of pantelleritic trachytes and pantellerites...2006 Elsevier B.V. All rights reserved. Keywords: Kenya; Eburru volcanic complex; Trachyte; Pantellerite;...Olkaria Volcanic Complex (GOVC) in the south-central Kenya rift, where Pb isotopes and U-series disequilibria |  | Macdonald, R., BagiĆski, 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... In Fig. 7a, an andesine core is mantled by anorthoclase showing a slight increase in K/Na ratio towards...D regular decrease in An content within the anorthoclase field. A more complex zonation is PT E shown... MA comenditic, with scarce phenocrysts of anorthoclase. A third component (or components) contained... Although comendites from the Olkaria complex, Kenya, PT E have F contents >1 wt% (Macdonald et al |  | | Journal (article/letter/editorial) | | Suite from the Southern Part of the Gregory Rift, Kenya Brian H. Baker 1, G o r d o n G. Goles 1, William...faulting. 1. Introduction The Gregory rift in Kenya is a part of the eastern branch of the Afro-Arabian...genetic associations have been distinguished in the Kenya rift alkaline province: a strongly alkaline association...transitional basalts, trachytes, and occasional Kenya-type phonolites, pantellerites, and comendites....Rift located immediately north of Olorgesailie volcano has been remapped (Fig. 1) and the stratigraphy |  | | Journal (article/letter/editorial) | | elsevier.com/locate/lithos The volcanoâpluton interface; The Longonot (Kenya) and KĂ»ngnĂąt (Greenland) peralkaline...Available online 18 March 2014 Keywords: Longonot volcano KĂ»ngnĂąt syenite complex Evolution of complementary...magma reservoir(s). The trachytic caldera volcano Longonot (Kenya Rift Valley) and the KĂ»ngnĂąt 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 volcanoâpluton pair. Although the histories of the two |  | | Journal (article/letter/editorial) | | interactions in volcanic rocks from the northern Kenya rift: geochemical evidence Kurkura Kabeto a,b,)...2 ) 54 wt.%. lavas from Samburu Hills, northern Kenya rift, exhibit significant variations in major and...Elsevier Science B.V. All rights reserved. Keywords: Kenya rift; Bimodal volcanism; SrâNd isotopes; AFC; Mantle;...carbonatiteânephlinitic, and basaltic rocks in Kenya and adjacent areas indicate derivation from heterogeneous...Hills area is located in the eastern edge of the Kenya rift, on the northern flank of the Fig. 1. Map |  | | Journal (article/letter/editorial) | | augite, pigeonite and Ti-magnetite, instead of anorthoclase, sodic sanidine, aegirine-augite and ilmenite...and geochemical study on the Quaternary Gedemsa volcano in the Main Ethiopian Rift, Ayalew et al. (2001)...plateau rhyolites, which consists exclusively of anorthoclase and sodic sanidine (An ÂŁ 3, Or25â46; Fig. 3a)...clinopyroxene and FeâTi oxides, followed by anorthoclase which may contain oligoclase cores; and (2)...suite from the southern part of the Gregory Rift, Kenya. Contrib Mineral Petrol 64:303â332 Baker JA, Macpherson |  | Macdonald, R., BagiĆski, B., Leat, P.T., White, J.C., DzierĆŒanowski, 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) | | Information from trachytes of the Menengai volcano, Kenya R. Macdonald a,b,â, B. BagiĆski a, P.T. Leat...Available online 17 March 2011 Keywords: Menengai volcano Peralkaline trachytes and rhyolites Mineral stability...silicaoversaturated trachytes from the Menengai volcano, Kenya Rift Valley. The dominant phenocryst assemblage...East African Rift System. Volcanic centres in the Kenya Rift Valley where pantelleritic trachytes have been...Macdonald et al., 1970), Nasaken (Weaver et al., 1972), Silali (Macdonald et al., 1995), and Emuruangogolak (Black |  | | Journal (article/letter/editorial) | | of the Late Pliocene (5·7 to 4·2 Ma) Mt Sidley volcano, Marie Byrd Land, is examined using major and trace...extreme Mt Sidley, an Early Pliocene composite volcano, is at the south end of the Executive Committee...through a suite of coexisting rocks at a single volcano, often because of the preponderance of either basaltic...GEOLOGY Mt Sidley (4181 m) is a large (>200 km3) volcano composed primarily of phonolitic and trachytic...high-precision 40Ar/39Ar ages reveal a complex, polygenetic volcano built in successive stages from 5·7 to 4·2 Ma (Panter |  | | Report (volume) | | continents. Field work was conducted in Chad, Ethiopia, Kenya, Malawi, Nigeria, Sudan, Tanzania and Uganda. However...Baker, B.FL Tectonics and volcanism of the southern Kenya Rift Valley and its influence on rift sedimentation...and sedimentation in the Kenya Rift from the equator northwards to Lake Turkana ... 59 Swain, C.J., Skinner...R.T. Volcano-tectonic control on sedimentation in the Koobi Fora sedimentary basin. Lake Turkana. 85 ...landtorm evolution in a rift valley basin, northern Kenya. Frostick, L.E. & Reid, I. Evolution and sedimentary |  | | Book | | fossil vertebrates in tuffs of the spectacular volcano that I had mapped in 19909. Thereafter, from 1959...sedimentological and palaeontological studies in the Kenya Rift Valley project. This, indeed, worked exceedingly... GREGORY RIFT VALLEY TANZANIA; OLORGESAILIE, KENYA I51 10. MARY D, LEAKEY. Olduvai Gorge 1911-1975:...SHACKLETON. Geological Map of the Olorgesailie Area, Kenya 171 12. 13. GLYNN LL. IsAAc. The Olorgesailie...Contents B. Tue Lake Barinco Basin, KENYA 14. GREGORY R. CHAPMAN Basin, Kenya & MAUREEN BROOK. Ghronostratigraphy |  | | 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 |  | Upton, B. G. J., Macdonald, R., Odling, N., RĂ€mö, O. T., BagiĆski, B. (2013) KĂ»ngnĂąt, 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...change from crystallization of ternary feldspar (anorthoclase) to sanidine. All the feldspars, however, were...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 |  | Macdonald, R., Belkin, H. E., Fitton, J. G., Rogers, N. W., Nejbert, K., Tindle, A. G., Marshall, A. S. (2008) The Roles of Fractional Crystallization, Magma Mixing, Crystal Mush Remobilization and VolatileâMelt Interactions in the Genesis of a Young BasaltâPeralkaline Rhyolite Suite, the Greater Olkaria Volcanic Complex, Kenya Rift Valley. Journal of Petrology, 49 (8) 1515-1547 doi:10.1093/petrology/egn036 | Journal (article/letter/editorial) | | Rhyolite Suite, the Greater OlkariaVolcanic Complex, Kenya Rift Valley R. MACDONALD1,2*, H. E. BELKIN3, J....rhyolite dome and lava field in the south^central Kenya rift valley that has been marked over the past 20...(Olkaria), and the neighbouring centres on the Kenya Dome (Eburru, Longonot and Suswa). From Heumann...O F T H E G OVC The GOVC is part of the central Kenya peralkaline province (CKPP; Macdonald & Scaillet...with an area of crustal upwarping known as the Kenya Dome. Crustal thickness beneath the Dome is 30^35 |  | | Journal (article/letter/editorial) | | magma would not produce the alkali feldspars (anorthoclase) found in the TI rocks (Fig. 8c-8d). of These...8b, Table 2 and 3). One alkaline group with anorthoclase (3-6 wt.% K2O), alkali feldspars and magnesio-hornblende...Leat, P. T. 1995. Petrogenesis of Silali volcano, Gregory Rift, Kenya. Journal of the Geological Society...andesitic scoria from the 1995 eruptions of Ruapehu volcano, New Zealand. Journal of petrology, 43, 2279-2303...compositions. The TI feldspars contain oligoclase, anorthoclase, and sanidine. b) Quadrilateral pyroxene diagram |  | Ayalew, Dereje, Barbey, Pierre, Marty, Bernard, Reisberg, Laurie, Yirgu, Gezahegn, Pik, Raphael (2002) Source, genesis, and timing of giant ignimbrite deposits associated with Ethiopian continental flood basalts. Geochimica et Cosmochimica Acta, 66 (8) 1429-1448 doi:10.1016/s0016-7037(01)00834-1 | Journal (article/letter/editorial) | | micro-phenocrysts (⏠1 mm). Absent in Were Ilu. Anorthoclase and sodic sanidine (Or25â46, Anâ±3); small normal...suite from the southern part of the Gregory Rift, Kenya. Contrib. Mineral. Petr. 64, 303â332. Baker P. A...an alkali basalttrachyte suite from Jebel Marra volcano, Sudan, through assimilation and fractional crystallization...Leat P. T. (1995) Petrogenesis of Silali volcano, Gregory Rift, Kenya. J. Geol. Soc. London 152, 703â720...Ethiopian Rift: a case history of the Gedemsa volcano. SINET: Ethiopian J. Sci. 18, 23â50. Peccerillo |  | | Report (issue) | | (Bottom) Carbonatite lava at Oldoinyo Lengai volcano, northern Tanzania. Courtesy Alexander J. Teague...upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the...and natrocarbonatite lavas at Oldoinyo Lengai volcano, Tanzania. . . . . . . . . . . . . . . . . . ....fingerprints of mantle metasomatism beneath Nyos volcano (Cameroon volcanic line) . . . . . . . . . . ....40Ar-39Ar ages and petrogenesis of the Massif dâAmbre volcano, northern Madagascar . . . . . . . . . . . . . |  | | Book (volume) | | Radenhein (Austria), Liaotung (China), and Clark County, Nevada (USA). Evaporites The evaporite chemical...carbonate sediment. Trenton Series, Ordovician, Centre County, Pennsylvania, USA. (C) Silicified bioclastic sandstone...Wavellite sprays (up to 30 mm across) from Montgom ery County, Arkansas, USA. Museum Victoria specimen M27840...produced by solonization in an inceptisol near Narok, Kenya. Hammer handle is 25 cm. horizons dominated by...(Middle Miocene fossil quarry near Fort Ternan, Kenya). Figure 3 The sharply truncated top and abundant |
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