 | | 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 The term ‘peralkaline volcano’ is used here to indicate that the structure is...(unpublished) state that the oldest lavas from this volcano are melanephelinites and melilitites of the Bast...Bast Hills and Birera, to the west of the main volcano.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) | | of peridotite and one specimen of garnet lherzolite from the Lashaine volcano, northern Tanzania. Introduction...HzO) and that ~here are hydrous minerals (e.g. phlogopite, talc, glaucophane) that persist to very high...experimentally proved that the stability field of phlogopite extends into the upper mantle (MARKItOVet al...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 |  | | 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) | | 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...and orthopyroxene, chromiferous diopside, and phlogopite. Analyses are given for garnet lherzolite, lherzolite...lherzolite and its phases resembles that of garnet peridotite nodules in kimberlite diatremes, and the A1,O |  | | 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) | | 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 |  | 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) | | 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) | | 2020 Halogens in amphibole and mica from mantle xenoliths: Implications for the halogen distribution and...Cl) of amphibole and phlogopite derived from mantle xenoliths and one peridotite massif, for amphibole...amphibole and phlogopite megacrysts and ultramafic magmatic cumulates (hornblendites) found in alkaline volcanic...localities in Europe and Africa. Amphibole and phlogopite contain more F than Cl with F/Cl ratios reaching...compared to phlogopite (180 μg/g). The Cl contents and the F/Cl ratios in amphibole and phlogopite from mantle |  | 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...lithospheric mantle characterized by residual garnet, phlogopite and minor amphibole. The range of radiogenic...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 |  | 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 |  | | 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) | | 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 |  | | Journal (article/letter/editorial) | | (mica-amphibole-rutile-ilmenite-diopside) suite of xenoliths in kimberlite J. BARRY DAW~QN Department of Geology...during intrusion. Compared with minerals in peridotite xenoliths, the MARID ones are lower in A1,03 and Cr...crystallized. INTRODUCTION NODULES dominated by phlogopite occur in the Bultfontein, De Beers, Wesselton...described and have received less attention than peridotite and eclogite nodules. Some petrographic descriptions...ERLANK and FINGER (1970) and AOKI (1974). Although phlogopite usually dominates, amphibole, clinopyroxene, |  | | 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 |  | Burton, K.W., Schiano, P., Birck, J.-L., Allègre, C.J., Rehkämper, M., Halliday, A.N., Dawson, J.B. (2000) The distribution and behaviour of rhenium and osmium amongst mantle minerals and the age of the lithospheric mantle beneath Tanzania. Earth and Planetary Science Letters, 183 (1) 93-106 doi:10.1016/s0012-821x(00)00259-4 | Journal (article/letter/editorial) | | and the age of the lithospheric mantle beneath Tanzania K.W. Burton a;b; *, P. Schiano a;b , J.-L. Birck...of mantle rock types from xenoliths in recent volcanics in northern Tanzania. Re and Os abundances for...coexisting silicates in garnet lherzolites from Lashaine confirm that sulphide dominates the Os budget...00013) suggests a minimum age of 3.4 Gyr. Most xenoliths possess Os isotope compositions that are less...isotope ratios; mantle; Mozambique Belt; Tazania; xenoliths; melting; metasomatism; dunite 1. Introduction |  | 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...Four texturally equilibrated peridotites contain phlogopite and Cr-diopside inferred to be introduced by...Generally, the rift-related metasomatism beneath Tanzania has caused formation of interstitial clinopyroxene |  | | Journal (article/letter/editorial) | | Netherlands 209 [21 Isotope geochemistry of xenoliths from East Africa" implications for development...granulite xenoliths in Recent volcanics from Tanzania. A garnet lherzolite from the Lashaine vent has...mantle part of the continental lithosphere beneath Tanzania has components that have undergone a complex history...major chemical fractionations ca. 2.0 Ga ago. A phlogopite-amphibole vein from the Pello Hill sample has... Nd and Pb isotope systematics of ultramafic xenoliths do not conform with those of MORB, particularly |  | | Journal (article/letter/editorial) | | 1994 Quaternary kimberlitic volcanism on the Tanzania Craton J.B. Dawson Department of Geology and Geophysics...magmatic rocks on the Tanzania Craton. They consist of small xenoliths of phlogopite-calcite-garnet lherzolite...degrees of melting of a carbonate-apatite-bearing peridotite source at depths in excess of 110 km. Introduction...Introduction Quaternary magmatism in northern Tanzania is mainly confined to the immediate vicinity of the...kimberlite intrusion in the past (Dawson 1970), the Tanzania Craton is virtually devoid of Quaternary igneous |  | | Journal (article/letter/editorial) | | olivineorthopyroxene-clinopyroxene-garnet or spinel. Phlogopite mica and amphibole m a y ~ additional minor primary...orthopyroxene, 5°/garnet, 2% clinopyroxene and 0A % phlogopite. Using the average whole rock composition of...orthopyroxene, 6% garnet, 4% clinopyroxene and 1% phlogopite can be cal,,:ulated. This higher figure for phlognpite...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 |  | | 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) | | garnet, pyroxene and olivine from peridotite and eclogite xenoliths from African kimberlites F. C. BISHOP...garnet, pyroxene and olivine from peridotite and eclogite xenoliths from African kimberlites. Lithos il...from peridotite and eclogite xenoiiths from African kimberlites and volcanic rocks in Tanzania. Average...cause problems of interpretation. Direct study of xenoliths from the upper mantle appears more promising (e...microprobe to analyze trace elements in mantle xenoliths, not only to explore the chemistry of the upper |  | | Journal (article/letter/editorial) | | mantle than has been recognized previously. This region displays the fingerprints of mantle plume and lithospheric...originated from shallower, dominantly anhydrous peridotite. Looking more broadly across the East African...subcontinental lithospheric mantle beneath this region. Of particular interest is the degree to which...magmas are the products of partial melting of peridotite with pyroxenite or other fluid and magma metasomatized...magmas were melting progressively as the source region depth increased, the opposite trend of adiabatic |
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