 | | Journal (article/letter/editorial) | | 1992 ABSTRACT Peridotite xenoliths from the Olmani cinder cone, northern Tanzania, possess distinctive...to result from interaction of ultra-refractory peridotite residues with carbonatite melts. Chief among...unusually low AI20 3 clinopyroxene and the lack enstatite in refractory dunites (with olivines up to Fo94)...apatite in refractory harzburgite and wehrlite xenoliths, respectively. (3) LREE enrichment and strong...strong Ti depletion relative to Eu in all but one peridotite. Ca/AI ratios of the clinopyroxene-bearing dunites |  | | 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 |  | 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...38 carbonaceous, ordinary and enstatite chondrites including 9 chondrite groups (CI, CM, CO, CV, L, LL...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 |  | Canil, D., O'Neill, H.St.C., Pearson, D.G., Rudnick, R.L., McDonough, W.F., Carswell, D.A. (1994) Ferric iron in peridotites and mantle oxidation states. Earth and Planetary Science Letters, 123 (1) 205-220 doi:10.1016/0012-821x(94)90268-2 | Journal (article/letter/editorial) | | pyroxenite and peridotite xenoliths from central France, southeastern Australia, northern Tanzania, southern...based on the Fe 3+ content of garnets from peridotite xenoliths suggest fO 2 values for the garnet lherzolite...facies similar to those for spinel lherzolite xenoliths [4] and kimberlitehosted ilmenites [5,6]. In contrast...Reference Locality Siberia dun, protogranular Olmani gt harz, coarse gt harz, coarse Lashaine Lashaine...Lashaine wehr, protogranular harz, protogranular Olmani Olmani MassifCentral Frl a Lherz sp lherz = Iherzolite; |  | | 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) | | 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) | | reaction at low pressures transforms the bulk peridotite composition from that of a harzburgite or lherzolite...erupting carbonatite volcano, Oldoinyo Lengai in Tanzania, has an alkali-rich composition dominated by sodium...complex, Malawi [3]) and volcanic (e.g., Kerimasi, Tanzania [4]) settings, and although they do occur in isolation...number of studies of the properties of carbonated peridotite at high pressures. At pressures greater than...kbar, free CO 2 cannot exist in equilibrium with peridotite but reacts with silicates through a series of |  | | 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...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 |  | | Journal (article/letter/editorial) | | Springer-Verlag 1986 Petrology of spinel harzburgite xenoliths from the Kishb Plateau, Saudi Arabia Lung-Chuan...48109, USA Abstract. Two spinel harzburgite xenoliths from a Pleisto- cene alkali basalt unit erupted...closely associated with neoblasts of olivine, enstatite, and diopside. Sparse exsolution lamellae of high-Ca...high-Ca pyroxene occur in all the enstatite porphyroblasts. Olivine neoblasts are, in many cases, in...in spinel and olivine, whereas zoning of A1 in enstatite and diopside indicates that chemical equilibrium |  | | Journal (article/letter/editorial) | | carbonate-bearing spinel wehrlite, lherzolite and harzburgite xenoliths from the Newer Volcanics, southeastern Australia...ascending dolomitic carbonatites crossed the reaction enstatite + dolomite = forsterite + diopside + CO2 at ~1·5–2·0...direct partial melts of carbonatebearing mantle peridotite (i.e. primary carbonatites; Wyllie & Huang, 1975;...primary carbonatites modified by interactions with peridotite wall-rock in the upper mantle (Wallace & Green...carbonate melts can exist in equilibrium with peridotite over a range of upper-mantle conditions of pressure |  | | 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...at several centres, such as at the Kibo cone on Kilimanjaro, and at Tarosero, continued into the Pleistocene |  | | Journal (article/letter/editorial) | | 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...refractory mantle is recorded in the Lashaine xenoliths by an almost continuous variation from ultra-depleted...more gradual. KEY WORDS: Archean; metasomatism; peridotite; pyrope garnet; Tanzanian Craton I N T RO D...garnets, found in harzburgite and lherzolite xenoliths from near the eastern margin of the Tanzanian |  | | 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 |  | 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) | | 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...3°S where it extends from the Plio-Quaternary Kilimanjaro volcano in the east to the large Late Pleistocene...include the poorly studied Gelai near the Kenya–Tanzania border, and the nearby well-known Oldoinyo Lengai...Lemagrut Sadiman Ngorongoro Kibo Mawenzi Kilimanjaro Tarosero 3°S 10’ Meru Monduli Ngurtoto crater |  | Koornneef, Janne M., Davies, Gareth R., Döpp, Sonja P., Vukmanovic, Zoja, Nikogosian, Igor K., Mason, Paul R.D. (2009) Nature and timing of multiple metasomatic events in the sub-cratonic lithosphere beneath Labait, Tanzania. Lithos, 112. 896-912 doi:10.1016/j.lithos.2009.04.039 | Journal (article/letter/editorial) | | in the sub-cratonic lithosphere beneath Labait, Tanzania Janne M. Koornneef a,⁎, Gareth R. Davies a, Sonja...April 2009 Available online 6 June 2009 Keywords: Tanzania Cratonic lithospheric mantle Xenolith Metasomatism...and Sm–Nd systematics of xenoliths from Labait volcano, north-central Tanzania, document multiple metasomatic...Generally, the rift-related metasomatism beneath Tanzania has caused formation of interstitial clinopyroxene...sub-continental lithospheric mantle (SCLM) beneath Tanzania has experienced multiple metasomatic events related |  | 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...the East African Rift Valley in 23 northern Tanzania. The volcano is dominated by peralkaline silicate...relative to the compositions of modeled 37 garnet peridotite-derived melts, suggesting that they were derived |  | 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) | | Petrography and mineral chemistry of mantle xenoliths in a carbonate-rich melilititic tuff from Mt....petrographic and mineralogical data for 21 mantle xenoliths (12 lherzolites, 8 wehrlites and 1 composite)...Formation, Mt. Vulture volcano, southern Italy. The xenoliths are rounded, coarse- to porphyroclastic-textured...chrome-spinel (14 20% MgO, ~30 40% Cr2O3). Many xenoliths contain partial melt glasses and accessory sulphide...garnet (pyrope; Mg84). Secondary veins in several xenoliths contain carbonate with significant Sr levels (~0 |  | | 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...Gelai, Ketumbeine, and Kilimanjaro (Fig. 1). Although the Kibo cone on Kilimanjaro is still classified as...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 |  | | Journal (article/letter/editorial) | | of Si-rich alkaline glass inclusions in mantle xenoliths Received: 24 August 1998 / Accepted: 2 December...similar in composition to that seen in mantle xenoliths. Dissolution rates are rapid and dependent on...natural Si-rich alkaline glass in mantle-derived xenoliths. The most Siand alkali-rich melts are restricted...with the original solvent. In the low pressure region, anhydrous and hydrous solvent melts yield glass...reaction is a common process during the ascent of xenoliths. However, reaction in situ within the mantle will |  | | Journal (article/letter/editorial) | | Springer-Verlag 1977 Recent Volcanism at Schonchin and Cinder Buttes, Northern California S.A. Mertzman, Jr....andesite spatter and cinder cones and their associated flows. Two particular structures, Cinder Butte and Schonchin...possible changes in the mineralogy within the source region of these volcanic rocks. Apatite and priderite...are two particular cinder cones plus their associated flows: Schonchin Butte and Cinder Butte. Flows of...locations given in Figure 1. Since materials from these cinder cones are not found in contact with one another |  | | Journal (article/letter/editorial) | | i CONTRASTING TYPES OF CHROMIUM-SPINEL PERIDOTITE XENOLITHS IN BASANITIC LAVAS, WESTERN GRAND CANYON...June 28, 1974 Several hundred xenoliths of Cr-diopside-spinel peridotite from basanitic lavas in the western...these textures seem unique to this locality. Xenoliths display varying degrees of depletion in basaltic...coarse exsolution intergrowths of diopside and enstatite whose reconstructed composition has about 15 wt...found worldwide in mantle-derived Cr-spinel peridotite xenoliths of more or less equivalent composition suggests |  | | Journal (article/letter/editorial) | | isotopic studies of the deepest fertile peridotite xenoliths show that they retain evidence of ancient...samples are rare diamond inclusions and some xenoliths inverted from majoritic garnet, which are unlikely...lowermost lithosphere, and may be represented by xenoliths of fertile garnet peridotites in alkali basalts...conductive geotherm with the fluid-saturated solidus of peridotite may mark the division of the lithosphere into...composition of the SCLM, as reflected in mantle-derived xenoliths and exposed massifs, is complex; it reflects an |  | | Journal (article/letter/editorial) | | clinopyroxene are commonly observed in hydrous mantle xenoliths hosted by Pliocene-Quaternary basalts from Yemen...the upper mantle. Keywords: Yemen, Ataq, Peridotite xenoliths, Magnesiokatophorite, Carbonatite, Metasomatism...is a well-documented phenomenon both in mantle xenoliths and in massif peridotites (e.g., Roden and Murthy...2006). Our chemical analyses of hydrous mantle xenoliths from Ataq, Yemen, reveals the presence of an unusual...phlogopite. Amphibole analyses from the Ataq xenoliths have been reported by Varne (1970), Varne and |  | | Journal (article/letter/editorial) | | S0016-7037(00)00566-4 Osmium isotopic compositions of mantle xenoliths: A global perspective THOMAS MEISEL,1,* RICHARD...systematics of spinel- and garnet-bearing mantle xenoliths from North and Central America, Europe, southern...southern Africa, Asia, and the Pacific region were determined to define more precisely the isotopic composition...was defined on the basis of 117 spinel-bearing xenoliths from this work and data from the literature, including...range of compositions defined by ordinary and enstatite chondrites, not carbonaceous chondrites. Spinel-bearing |
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