 | | Report (chapter) | | have resulted from later regional mapping by the Tanzania Geological Survey, together with radiometric dating...half graben, and in the east, lavas from the Kilimanjaro massif filled the depression to the north of...Monduli and the Shira and Mawenzi centres of Kilimanjaro). Some of these basaltic volcanoes, Ngorongoro... 1972) but there is no equivalent in northern Tanzania of the earlier Kenyan flood phonolites, dated...several centres, such as at the Kibo cone on Kilimanjaro, and at Tarosero, continued into the Pleistocene |  | | Journal (article/letter/editorial) | | from Pleistocene–recent volcanism in northern Tanzania J.B. Dawson ⁎ Grant Institute of Geosciences,...canoes in the Gregory Rift Valley of northern Tanzania (termed the Younger Extrusives) comprise one of...volcanism in northern Tanzania The Late Tertiary–Recent volcanic province of northern Tanzania is the most recently...and northern Tanzania. Because of its relatively young age (b~6 Ma), the northern Tanzania province contains...B. Dawson / Lithos 152 (2012) 3–10 Table 1 N. Tanzania — structural and volcanic chronology. Ma bp ~ |  | | Journal (article/letter/editorial) | | carbonates in peridotite xenoliths from northeastern Tanzania Received: 30 July 1999 / Accepted: 5 February...xenoliths from the East African Rift in northeastern Tanzania occur as intergranular patches with accessory...entire xenolith and through primary mineralogy Pello hill 1D PEL2 Spinel Zeolite-bearing calcite harzburgite...xenolith localities in the East African Rift: Labait, Pello, Eledoi, and Monduli volcanoes (see Dawson 1992...beneath Labait extends to depths of about 150 km. Pello Hill and Eledoi are side-by-side Quaternary tu cones |  | | Journal (article/letter/editorial) | | Natron–Engaruka monogenetic volcanic field, northern Tanzania Hannes B. Mattsson ⁎, Rohit H. Nandedkar, Peter...Monogenetic Volcanic Field (LNE-MVF) in northern Tanzania consists of more than 150 vents of Upper Pleistocene...monogenetic volcanic field (LNE-MVF) in northern Tanzania comprises more than 150 vents spread across an...(LNE-MVF) is located in the Gregory Rift of northern Tanzania (Fig. 1). The monogenetic volcanic field comprises...metasomatic veins of upper-mantle peridotites from Pello Hill (i.e., TiO2 = 1.0 to 5.0 wt.%, Al2O3 = 10.5 to |  | | Journal (article/letter/editorial) | | Engineering, University of Dar Es Salaam, Dar Es Salaam, Tanzania open system with carbonate–silicate immiscibility...Liquid immiscibility · Rift initiation · Hanang · Tanzania · East African Rift Introduction The East African...structural and magmatic features of the North Tanzania Rift. Volcanoes: B. Burko, Em. Embagai, Es. Essimingor...Ol. Oldoinyo Lengai, OS. Ol Donyo Sambu, P. Pello hill, Sd. Sadiman, S. Shira, Sh. Shombole, T. Tarosero...boundary extension, from the initiation of the rift (Tanzania, Manyara basin) to oceanic accretion (Afar Triple |  | | Journal (article/letter/editorial) | | describes olivine melilitites at Oldoinyo Lengai, Tanzania, and from tuff cones from the Tanzanian rift valley...the essential basis for the present work: Armykon Hill at the southern shore of Lake Natron, Lalarasi Cone...Nokoschoke” is a flat tuff ring about 3 km SSW of Armykon Hill between Oldoinyo Lengai and Lake Natron. Its bedded...as olivine poor, mica porphyritic melilitite. Pello Hill, Eledoi and Loluni craters are renowned xenolith...Lee et al., 2000). The magmatic component of Pello Hill, derived from a quite altered host scoria, is |  | | Journal (article/letter/editorial) | | microstructure of oxidized mantle olivine from Dish Hill, California Jrr.r-r,lN F. B.lNrrpr.o Department...metasomatizedolivine crystals from peridotite xenoliths from Dish Hill, California, have been studied by transmission electron...detailed study of the petrology of xenoliths from Dish Hill, California, demonstratedthat metasomaticreaction...glass slides using a thermoplastic cement. the Dish Hill cinder cone from the Deadman Lake Vol- Slices approximately...ofthe window on the detector, and exposedto the Dish Hill olivine exhibits only very weak bands (not Slupr |  | Zaitsev, A. N., Williams, C. T., Britvin, S. N., Kuznetsova, I. V., Spratt, J., Petrov, S. V., Keller, J. (2010) Kerimasite, Ca3Zr2(Fe23+Si)O12, a new garnet from carbonatites of Kerimasi volcano and surrounding explosion craters, northern Tanzania. Mineralogical Magazine, 74 (5) 803-820 doi:10.1180/minmag.2010.074.5.803 | Journal (article/letter/editorial) | | volcano and surrounding explosion craters, northern Tanzania A. N. ZAITSEV1,2,*, C. T. WILLIAMS2, S. N. BRITVIN3...and surrounding explosion craters in northern Tanzania. The mineral occurs as subhedral crystals up to...is given after the locality, Kerimasi volcano, Tanzania. K EY WORDS : kerimasite, kimzeyite, garnet,...structure, Kerimasi, Loluni, Kisete, Loolmurwak, Tanzania. * E-mail: burbankite@gmail.com DOI: 10.1180/minmag...Maimecha-Kotuy, Russia (Borodin and Bykova, 1963), Iron Hill, Colorado, USA (Dowty, 1971), Magnet Cove, Arkansas |  | | Journal (article/letter/editorial) | | stable. Fig. 2 shows that harzburgite (enstatite + forsterite ) is stable in the presence of pure H20 at least...means that mantle in this area consists of talc+forsterite (in the presence of excess H20 ). Because of...(OH) 2 + Mg2SiO4 talc (2a) forsterite All H20 reaching the mantle region immediately below the Moho...Mg7Si8022 ( O H ) 2 forsterite (2b) anthophyllite 14MgzSiO4 + 20MgSiO3 + 3 1 H 2 0 ~ forsterite enstatite fluid...+ MgCO3 forsterite fluid enstatite magnesite (3) The limiting mineral is olivine (forsterite). The equilibrium |  | Li, Wang-Ye, Teng, Fang-Zhen, Halama, Ralf, Keller, Jörg, Klaudius, Jurgis (2016) Magnesium isotope fractionation during carbonatite magmatism at Oldoinyo Lengai, Tanzania. Earth and Planetary Science Letters, 444. 26-33 doi:10.1016/j.epsl.2016.03.034 | Journal (article/letter/editorial) | | during carbonatite magmatism at Oldoinyo Lengai, Tanzania Wang-Ye Li a,∗ , Fang-Zhen Teng b,∗ , Ralf Halama...peralkaline silicate rocks from Oldoinyo Lengai, Tanzania. The olivine melilitites from the vicinity of...peralkaline silicate rocks from Oldoinyo Lengai, Tanzania. Our results demonstrate that compositionally...lies in the East African Rift Valley in northern Tanzania with volcanological observations more than 100...olomite values reflect stronger Mg–O bonds in forsterite versus weaker bonds in magnesite/dolomite. Such |  | | Journal (article/letter/editorial) | | from the Carbonatite Volcano, Oldoinyo Lengai, Tanzania Magmatic plutonic rocks in the Oldoinyo Lengai...others contain a high proportion of mica, northern Tanzania is the world's only active carbo- olivine and...African nephelinite (EAN—Oldoinyo Loolmurwak, Tanzania, Dawson et al., 1985). Normalized against chondrite...isotope plot, modffied uncompahgrites of the Iron Hill and Rangwa comafter Bell & Dawson (1995), olivine-mica...syenite). A, whole-rock and pyroxene data for Tanzania upper- indicated by texturally different types |  | | Report (issue) | | 2011006982 Cover: (Top) Mount Meru (4566 m high), Tanzania, from the western side. Courtesy Philippe Nonnotte...Carbonatite lava at Oldoinyo Lengai volcano, northern Tanzania. Courtesy Alexander J. Teague. 10 9 8 7 6 5 4...low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell...lithospheric mantle beneath the East African Rift in Tanzania and its potential signatures in rift magmas ....and geochemistry of alkaline lava series, Kilimanjaro, Tanzania: New constraints on petrogenetic processes |  | | Journal (article/letter/editorial) | | patterns of continental rift volcanism beneath Tanzania Emily J. Chin1 Received: 3 May 2018 / Accepted:...recorded in deep crustal xenoliths from northern Tanzania. The xenoliths are interpreted as magmatic cumulates...the precursors to successful continental ruptures (Hill 1991). Such a large amount of magma intruded and...xenoliths from the East African Rift in northern Tanzania (Fig. 1). The xenoliths are interpreted as products...Geologic background East African Rift in northern Tanzania The East African Rift system has been active for |  | | Journal (article/letter/editorial) | | melilitite and lamproite In the Roman Comagmatic Region: the lavas of S. Venanzo and Cupaello A. Cundari...Melbourne, Parkville 3052, Australia 2 The Broken Hill Proprietary Co. Ltd., William Street, Melbourne...located at the NE margin of the Roman Comagmatic Region of Italy has provided new data to evaluate their...I, ,~ % ,oo, gm Fig. 1. Sketch map of Roman Region complexes, with locations of S. Venanzo and Cupaello...Cupaello 344 the R o m a n Comagmatic Region (Washington 1906), near the the township of San Venanzo |  | | Journal (article/letter/editorial) | | xenoliths from the Quaternary Labait volcano, Tanzania, document the influence of rift-related metasomatism...Rift Plume Cratonic lithospheric mantle Tanzania Introduction Xenolithic peridotites carried in...in rift-related alkali basalts from Tanzania offer a unique opportunity to investigate the effects of...rift, the eastern branch of the EAR system in Tanzania, cuts along the border between the Archean Tanzanian...since the mid Tertiary, leading to magmatism in Tanzania between 1 and 5 Ma (Dawson 1992). Voluminous basaltic |  | | Journal (article/letter/editorial) | | occurrences in Oka, Canada; Magnet Cove and Iron Hill, U.S.A.; Vuorijarvi and Gulinsk massif, Russia;...Negra, and Tapira in Brazil; Iron Hill in U.S.A. and Kerimasi in Tanzania (Mariano, 1989), although the Polino... the most comprehensive is by Walter (1963): forsterite + calcite = monticellite + periclase + CO 2...melilitite and lamproite in the Roman Comagmatic region: the lavas of S. Venanzo and Cupaello. Contrib...Metasomatized and veined upper-mantle xenoliths from Pello-Hill, Tanzania: evidence for anomalously light mantle beneath |  | | Journal (article/letter/editorial) | | Rift occupies a region between the Andean belt and the Brazilian cratonic area. The region could represent...1993) generated important thrust tectonics in this region (Seggiaro and Gallardo 2002). The folded Neopr...Huichaira Valleys. BYA 127 show a slight decrease in forsterite content from cores (Fo86) to rims (Fo84) but...different types can occur together in the same region and fortuitous juxtapositions of lamprophyres of...composition of the mantle under the Central Andes region. We have compared the Ayopaya alkaline province |  | | Journal (article/letter/editorial) | | The Western Branch of the East African Rift is a region with classic occurrences of ultra-potassic magmatism...preferred source for alkaline magmatism in this region (Foley, 1992). Mantle xenoliths from the alkaline...of the Eastern Branch (Kenya Rift) include the Pello Hill volcano (Dawson and Smith, 1988), Lashaine volcano...other provinces: the xenolith phlogopites of D Pello Hill (4.18 wt. %, Dawson and Smith, 1988), phlogopites...xenolith with the mica pyroxenite vein of Pello Hill volcano, Tanzania (sample BD3847 in Dawson and Smith, |  | | Journal (article/letter/editorial) | | southeast Australia (Yaxley et al., 1991) and Tanzania (e.g., Rudnick et al., 1993). Formation of these...Metasomatised and veined upper-mantle xenoliths from Pello Hill, Tanzania: evidence for anomalously-light mantle beneath...Kushiro, I. and Yoder, H.S., Jr. (1966) Anorthite-forsterite and anorthite-enstatite reactions and their bearing |  | | Journal (article/letter/editorial) | | xenolith suite from the Lashaine tuff cone, northern Tanzania. The Lashaine ultra-depleted garnets are characterized...xenoliths with those from elsewhere in northern Tanzania and discuss their origin and importance to our...been recorded from several locations in northern Tanzania (Fig. 1), including the 50 Ma Mwadui and Nzega...(Dawson, 1994); from Lashaine, Labait, Olmani and Pello Hill [Quaternary rift-related melilititic magma localities;...geochemical history, mantle xenoliths from northern Tanzania may not at first sight appear to offer the best |  | | Journal (article/letter/editorial) | | Kilosa refers to the natural enstatite from Kilosa, Tanzania around 0.5 mg (within <0.002 % of total) and...Table 1. Xenocryst analogues included a synthetic forsterite crystal (synthesised by IKZ Berlin), San Carlos...single natural enstatite crystal from Kilosa, Tanzania. These were initially crushed dry in a metal pestle...enstatite, Ki Kilosa orthopyroxene, Fo synthetic forsterite and SC San Carlos olivine. Bulk H2O calculated...from the melt. c Sample En46 contains both a forsterite and an enstatite crystal due to the starting |  | | Journal (article/letter/editorial) | | that mantle wall rocks in the spinel lherzolite region are characterized by oxygen fugacities close to...apatite-bearing; G, glass present; ( ), trace amounts; Fo, forsterite component in olivine; SS T (°C), temperature...basalt-borne xenoliths from the Rift Valley of northern Tanzania [data from Dawson & Smith (1988)]; these five...are for five garnet-absent, hydrous samples from Tanzania. Pressure for all the garnet-bearing samples has...significantly different in/ O2 from the source region of basalts, which is inferred to be the asthenosphere |  | | Journal (article/letter/editorial) | | DOI 10.1007/s004100000216 J. B. Dawson á P. G. Hill á P. D. Kinny Mineral chemistry of a zircon-bearing...relatively small geographical areas such as northern Tanzania, xenoliths from dierent eruptive sites exhibit...perovskite. Sample description J. B. Dawson (&) á P. G. Hill Department of Geology and Geophysics, University...standards for most of the phases are given in Dawson and Hill (1998), and additional standards used in the present...harzburgite palaeosome Olivine The olivine is a low-Ca forsterite (Fo93; Table 1, analysis 1) which falls towards |  | | Journal (article/letter/editorial) | | of the curves to diverge or scatter in the LREE region. However, despite the scatter in the LREEs, the...curves all collapse to roughly the same trend in the region of small cationic radii, which corresponds to the...(this study). Black-circled line and yellow-shaded region correspond to partition coefficients determined on...in pyroxene and the forsterite component in olivine. Again, assuming the forsterite and enstatite activity...calculated values, are shown for comparison. Gray shaded region represents literature range from Fig. 1. 490 |  | Rooney, Tyrone O., Lavigne, Andrew, Svoboda, Chris, Girard, Guillaume, Yirgu, Gezahegn, Ayalew, Dereje, Kappelman, John (2017) The making of an underplate: Pyroxenites from the Ethiopian lithosphere. Chemical Geology, 455. 264-281 doi:10.1016/j.chemgeo.2016.09.011 | Journal (article/letter/editorial) | | resulted in the formation of the Mozambique Belt – a region of MA heterogeneous continental lithosphere that...reworked craton margins (e.g., adjacent to the Tanzania Craton), and craton TE D fragments incorporated...reactivated fault structures. Volcanism in the Dedessa region of the YTVL (the locality for this study), is thought...2010; Mammo, 2013). 2.4 Xenolith localities in the region Mantle xenoliths throughout the northern East African...xenoliths derived from the lithospheric mantle in this region suggest that an early subduction- PT related |
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