 | | Report (chapter) | | have resulted from later regional mapping by the Tanzania Geological Survey, together with radiometric dating...Extrusive basaltic centres. The term ‘peralkaline volcano’ is used here to indicate that the structure is...(unpublished) state that the oldest lavas from this volcano are melanephelinites and melilitites of the Bast...Bast Hills and Birera, to the west of the main volcano. These, as with early lavas from some other centres...Ngorongoro, Oldeani, Gelai, Ketumbeine, Tarosero, Monduli and the Shira and Mawenzi centres of Kilimanjaro) |  | | Journal (article/letter/editorial) | | • l wne-garnet reaction in peridotites from Tanzania ARCH. M. R E I D & J. B. D A W S O N Reid,...from Tanzania. Lithos 5, 115-24. T h e composition of the p r i m a r y phases in garnet peridotite inclusions...inclusions in carbonatitic tufts from the Lashaine volcano in northern TanzarJa indicates formation at...illustrates the transition from the garnet peridotite to the spinel peridotite facies, presumably as a consequence...Neogene carbonate tuff cones ol die Monduli-Arusha area of Northern Tanzania contain a variety of ultramafic |  | | Report (chapter) | | contemporaneous volcanism in southern Kenya and northern Tanzania, the differences taking place abruptly at a latitude...contemporary volcanism in south Kenya and north Tanzania Table 8.1 summarizes the volcanic stratigraphy...northern Tanzania, mainly from c. 8 Ma, i.e. the age of the oldest known activity in northern Tanzania at Essimingor...case of Essimingor, the oldest of the northern Tanzania volcanoes, are similar to the peralkaline volcanoes...basaltic rocks show some resemblances to those in Tanzania (Appendix 2, Dawson 2008) in terms of the dominance |  | | Journal (article/letter/editorial) | | 143Nd/144Nd have lighter δ60/58Ni Ultramafic xenoliths show systematic but limited inter-mineral δ60/58Ni...reported for 22 peridotite xenoliths from the USA (Kilbourne Hole, New Mexico), Tanzania, and Cameroon...spanning nearly the entire range observed in peridotite worldwide. Dunites (n=2) are lighter in δ60/58Ni...as -0.38‰. The δ60/58Ni in the Kilbourne Hole xenoliths correlate negatively with bulk-rock Fe concentration...Klaver et al., 2020). The data for ultramafic xenoliths show a range in δ60/58Ni = +0.04‰ to +0.36‰ (Ratié |  | | Journal (article/letter/editorial) | | Mantle beneath the Tanzanian Craton: Evidence from Lashaine Pre-metasomatic Garnet-bearing Peridotites S....previously been identified in global suites of mantle xenoliths or diamond inclusions. They occur in certain harzburgite...xenolith suite from the Lashaine tuff cone, northern Tanzania. The Lashaine ultra-depleted garnets are...Metasomatism of refractory mantle is recorded in the Lashaine xenoliths by an almost continuous variation from ultra-depleted...depths (125 km) in the lithosphere than most Lashaine lherzolites and we suggest that long-term survival |  | | Journal (article/letter/editorial) | | of peridotite and one specimen of garnet lherzolite from the Lashaine volcano, northern Tanzania. Introduction...sure, kimberlite and its included ultrabasic xenoliths 17 Contr.Mineral. and Petrol., Vol. 22 234 ...ascent. I n addition, although in the garnet peridotite xenoliths there is often mica in the reaction coronae...and AottI, 1968). Mica-Bearing Peridotites /rom Tanzania During a petrological and geochemical study of...suite of ejected blocks from the Lashaine volcano, northern Tanzania, primary mica has been found in rocks |  | | Journal (article/letter/editorial) | | Ultrabasic Xenoliths and Lava from the Lashaine Volcano, Northern Tanzania by J. B. DAWSON,1 D. G. POWELL...INTRODUCTION T H E Neogene volcanic province of northern Tanzania, which is part of the more extensive volcanic...of Winnipeg on September 6, 2015 ABSTRACT The Lashaine tuff-ring consists of carbonatite tuff and glassy...lherzolite and its phases resembles that of garnet peridotite nodules in kimberlite diatremes, and the A1,O...per cent TiO,. The other group of ultramafic xenoliths, characterized by cumulate and idiomorphic textures |  | | Report (chapter) | | structure of the crust and upper mantle of the Tanzania Craton and the Gregory Rift Valley The past three...Lithosphere Experiment; Yirgu et al. 2006). In northern Tanzania, in 1994, A. A. Nyblade and co-workers established...array of broadband receivers in northern Tanzania, the Tanzania Broadband Seismic Experiment, TBSE (Nyblade...insights into the present-day structure of the Tanzania Craton and the Mozambique belt. Although in many...following section to observations on the northern Tanzania and southern Kenya sectors of the Gregory Rift |  | | Journal (article/letter/editorial) | | investigation of carbonates in peridotite xenoliths from northeastern Tanzania Received: 30 July 1999 / Accepted:...carbonates in peridotite xenoliths from the East African Rift in northeastern Tanzania occur as intergranular...microprobe analyses of mantle-derived carbonates (in xenoliths, xenocrysts, and megacrysts) reveals compositional...melts. Because most carbonate inclusions in peridotite xenoliths are calcitic, these authors are of the opinion...opinion that most, if not all, carbonates in mantle xenoliths are cumulates. Likewise, Ionov (1998) has argued |  | | Journal (article/letter/editorial) | | Metasomatised and veined upper-mantle xenoliths from Pello Hill, Tanzania: evidence for anomalously-light mantle...Abstract. Peridotite xenoliths from the Pello tuff cone in the Rift Valley of northern Tanzania, bear witness...previously depleted peridotite. Chemical and mineralogical gradients are present in the peridotite wall rocks...rocks, and hydrous phases developed in the peridotite are generally lower in Ti and Fe, but higher in Mg and...metasomatism has reduced the density of affected peridotite by up to 4.5%, supporting earlier geophysical |  | | Journal (article/letter/editorial) | | MAJOR ELEMENT GEOCHEMISTRY OF PERIDOTITE NODULES FROM SAMBURU DISTRICT, KENYA KEN-ICHIRO AOKI Instituteof...garnet-freeperidotitenodulesfromLashainevolcano,Tanzania,whichare clearlydifferent from chromianspinelperiodtitesin...Rift Valley in Kenya, eastern Uganda and northern Tanzania during the Miocene to Recent periods. Mafic rocks...nodules, of peridotite Ndonyuo Nairobi, chemical mantle the from Samburu the district, Kenya. A...Ridley to of represent fragments in the this region, included. GEOLOGY Ndonyuo situated area of |  | Casagli, Alessio, Frezzotti, Maria Luce, Peccerillo, Angelo, Tiepolo, Massimo, De Astis, Gianfilippo (2017) (Garnet)-spinel peridotite xenoliths from Mega (Ethiopia): Evidence for rejuvenation and dynamic thinning of the lithosphere beneath the southern Main Ethiopian Rift. Chemical Geology, 455. 231-248 doi:10.1016/j.chemgeo.2016.11.001 | Journal (article/letter/editorial) | | (Garnet)-spinel peridotite xenoliths from Mega (Ethiopia): Evidence for rejuvenation...Massimo, De Astis, Gianfilippo, (Garnet)-spinel peridotite xenoliths from Mega (Ethiopia): Evidence for rejuvenation...pertain. ACCEPTED MANUSCRIPT (Garnet)-spinel peridotite xenoliths from Mega (Ethiopia): Evidence for rejuvenation...(garnet)-spinel peridotite and pyroxenite xenoliths in Quaternary alkali-basalts at Mega (Sidamo region, Ethiopia)...adiabatic decompression path of about 40 km. Peridotite chemical compositions plot in an off-craton trend |  | | Journal (article/letter/editorial) | | structures up to the thermobarometry data of mantle xenoliths V.A. Glebovitsky, L.P. Nikitina, V.Ya. Khiltova...equilibria in garnet and garnet – spinel peridotite xenoliths from kimberlites (East Siberia, Northeastern...Geologic Processes and Objects 2000 44) for all xenoliths allowed us to avoid discrepancies in estimation...estimation of P – T equilibrium conditions of deep xenoliths, correspond to the age of crust tectonic structures...Elsevier B.V. All rights reserved. Keywords: Mantle; Xenoliths; Thermobarometry; Upper mantle; Geotherms; Thermal |  | | Journal (article/letter/editorial) | | 2020 Halogens in amphibole and mica from mantle xenoliths: Implications for the halogen distribution and...amphibole and phlogopite derived from mantle xenoliths and one peridotite massif, for amphibole and phlogopite...phlogopite from mantle xenoliths exhibit large differences between samples of the same region, recording very...1990; Köhler et al. 2009). Therefore, mantle xenoliths from alkaline magmatic provinces represent the...HALOGENS IN AMPHIBOLE AND PHLOGOPITE FROM MANTLE XENOLITHS set provide insight into halogen storage and |  | Jung, Seung Gi, Choi, Sung Hi, Ji, Kang Hyeun, Ryu, Jong-Sik, Lee, Der-Chuen (2019) Geochemistry of volcanic rocks from Oldoinyo Lengai, Tanzania: Implications for mantle source lithology. Lithos, 350. 105223 doi:10.1016/j.lithos.2019.105223 | Journal (article/letter/editorial) | | Geochemistry of volcanic rocks from Oldoinyo Lengai, Tanzania: Implications for mantle source lithology Seung...Geochemistry of volcanic rocks from Oldoinyo Lengai, Tanzania: Implications for mantle source lithology, LITHOS...Geochemistry of volcanic rocks from Oldoinyo Lengai, Tanzania: 2 Implications for mantle source lithology...carbonatite volcano within the East African Rift Valley in 23 northern Tanzania. The volcano is dominated...relative to the compositions of modeled 37 garnet peridotite-derived melts, suggesting that they were derived |  | Mana, S., Furman, T., Carr, M.J., Mollel, G.F., Mortlock, R.A., Feigenson, M.D., Turrin, B.D., Swisher, C.C. (2012) Geochronology and geochemistry of the Essimingor volcano: Melting of metasomatized lithospheric mantle beneath the North Tanzanian Divergence zone (East African Rift) Lithos, 155. 310-325 doi:10.1016/j.lithos.2012.09.009 | Journal (article/letter/editorial) | | Geochronology and geochemistry of the Essimingor volcano: Melting of metasomatized lithospheric mantle beneath...associated with the centrally located Essimingor volcano. Although major element oxides show narrow compositional...development and history of the EAR. In northern Tanzania, magmatic activity and rifting are superimposed...1994; Fig. 1). Baker et al. (1972) referred to this region as the North Tanzanian Divergence zone ⁎ Corresponding...it extends from the Plio-Quaternary Kilimanjaro volcano in the east to the large Late Pleistocene caldera |  | Glebovitsky, V. A., Nikitina, L. P., Saltykova, A. K., Ovchinnikov, N. O., Babushkina, M. S., Egorov, K. N., Ashchepkov, I. V. (2007) Compositional heterogeneity of the continental lithospheric mantle beneath the Early Precambrian and Phanerozoic structures: Evidence from mantle xenoliths in kimberlites and alkaline basalts. Geochemistry International, 45 (11) 1077-1102 doi:10.1134/s001670290711002x | Journal (article/letter/editorial) | | Phanerozoic Structures: Evidence from Mantle Xenoliths in Kimberlites and Alkaline Basalts V. A. Glebovitskya...petro- and geochemical characteristics of mantle xenoliths in kimberlites, which sampled the mantle beneath...Western Olenek, Natal, and Halls Creek), and xenoliths in alkaline basalts, which sampled the mantle...between the Al2O3/MgO ratio and pressure in the xenoliths. (4) The Y, Zr, Ti, Sm, Gd, and Yb concentrations...INTRODUCTION Thermobarometry of upper mantle xenoliths [1–3] indicates that the thermal state of the |  | | 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...evidence for which is found in Tanzanian mantle xenoliths. An integrated model involves carbonated olivine–nephelinite...asthenosphere by melting of carbonate-bearing peridotite. Small amounts of the melt migrate rapidly and...volcanism in northern Tanzania The Late Tertiary–Recent volcanic province of northern Tanzania is the most recently |  | | Journal (article/letter/editorial) | | fractionation in xenolithic peridotite minerals: Examples from Tanzania Sonja Aulbach ⁎, Roberta L. Rudnick...Li redistribution Metasomatism Magma residence Peridotite xenolith a b s t r a c t Olivine, clinopyroxene...orthopyroxene in variably metasomatised peridotite xenoliths from three lithospheric mantle sections...sections beneath the East African Rift in Tanzania (Lashaine, Olmani, Labait) show systematic differences in...diffusion-driven kinetic Li isotope fractionation in mantle xenoliths (1) Li diffusion from grain boundary melt into |  | | Journal (article/letter/editorial) | | 00 Metamorphic Petrology of Xenoliths from Kenya and Northern Tanzania and Implications for Geotherms...December 1991) ABSTRACT Pyroxenitic and peridotitic xenoliths from the Quaternary volcanic field of Marsabit...of transformation from the garnet peridotite to the spinel peridotite stability field. On the basis of...of one composite xenolith consisting of type I peridotite and grt pyroxenite point to a common P-7evolution...Cr/(Cr + Al) ratios of spl are similar to those of peridotite type II. Pyroxenes show minor chemical zoning |  | | Journal (article/letter/editorial) | | L I T H S A N D H O S T - R O C K S , LASHAINE VOLCANO, TANZANIA R. HUTCHISON* Department of Earth Sciences...the ankaramitic and carbonatitic pyroclastics of Lashaine there is a suite of unaltered, ultrabasic fragments...includinggarnet-lherzolite, which typically occurs as xenoliths in kimberlite pipes. STSr/86Sr ratios and Rb and...host-rocks suggestingaccidenthLincorporationin the Lashaine magmas. Rb/Sr ratios are discussed and the conclusion...relatively high Rb content. 1. Introduction Lashaine volcano contains a wide variety of ultrabasic fragments |  | | Journal (article/letter/editorial) | | lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence) Céline Baudouin1 ·...Lengai and Kerimasi volcanoes. Hanang volcano is the southernmost volcano in the North Tanzanian Divergence...the earliest stage of rift initiation. Hanang volcano erupted silica-undersaturated alkaline lavas with...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 |  | | Report (issue) | | 2011006982 Cover: (Top) Mount Meru (4566 m high), Tanzania, from the western side. Courtesy Philippe Nonnotte...(Bottom) Carbonatite lava at Oldoinyo Lengai volcano, northern Tanzania. Courtesy Alexander J. Teague. 10 9...Africa—New data from lower-crustal and mantle xenoliths from the Bayuda volcanic field, Sudan . . . ....low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell...Ian D. Bastow, Derek Keir, and Eve Daly 5. Peridotite xenoliths from Ethiopia: Inferences about mantle processes |  | Teng, Fang-Zhen, Li, Wang-Ye, Ke, Shan, Marty, Bernard, Dauphas, Nicolas, Huang, Shichun, Wu, Fu-Yuan, Pourmand, Ali (2010) Magnesium isotopic composition of the Earth and chondrites. Geochimica et Cosmochimica Acta, 74 (14) 4150-4166 doi:10.1016/j.gca.2010.04.019 | Journal (article/letter/editorial) | | Cook-Austral chain); (3) 29 peridotite xenoliths from Australia, China, France, Tanzania and USA; and (4) 38... LL, H, EH and EL). Oceanic basalts and peridotite xenoliths have similar Mg isotopic compositions, with...and d26Mg = 0.25 ± 0.04 (2SD) for global peridotite xenoliths (n = 29). The identical Mg isotopic compositions...isotope fractionation during partial melting of peridotite mantle and magmatic differentiation of basaltic...mantle is derived largely from studies of peridotite xenoliths (Jagoutz et al., 1979; McDonough and Sun |  | | Journal (article/letter/editorial) | | Sobolev 1977) and the Colorado-Wyoming state line region of the U.S.A. (McCallum et al. 1975), a slightly...LITHOS 13 (1980) mantle geotherm beneath that region at the time of carbonatite emplacement was closely...hand, the Lasha~ne carbonatite/ankaramite volcano in Tanzania (Dawson et al. 1970; Reid et al. 1975) contains...present day upper mantle geotherm beneath the Lashaine volcano closely similar to that beneath southern Africa...(Mitchell 1977) and the Colorado-Wyoming state line district, U.S.A. (McCallum et al. 1975) and Al-spinel lherzolites |
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