 | | Journal (article/letter/editorial) | | High-Ca, low-alkali carbonatite volcanism at Fort Portal, Uganda Daniel S. Barker 1 and Peter H. Nixon 2 ...Abstract. A Quaternary volcanic field at Fort Portal, SW Uganda, contains approximately 50 vents that erupted...the KatweKikorongo volcanic field 75 km SW of Fort Portal. The groundmass of fresh carbonatite lava consists...consists of tabular calcite, spurrite, periclase, hydroxylapatite, perovskite, spinel, pyrrhotite, and...where meteoric water had access, spurrite and periclase are lacking, and some calcite is recrystallized |  | Campeny, Marc, Kamenetsky, Vadim S., Melgarejo, Joan C., Mangas, José, Manuel, José, Alfonso, Pura, Kamenetsky, Maya B., Bambi, Aurora C.J.M., Gonçalves, Antonio O. (2015) Carbonatitic lavas in Catanda (Kwanza Sul, Angola): Mineralogical and geochemical constraints on the parental melt. Lithos, 232. 1-11 doi:10.1016/j.lithos.2015.06.016 | Journal (article/letter/editorial) | | carbonatite lavas have been identified in this region and considering the mineralogical, textural and...silicocarbonatite lavas, which are enriched in periclase, present very different mineralogical, compositional...African Rift area (Woolley, 2001) such as Fort Portal, Uganda (von Knorring and Du Bois, 1961; Nixon and...carbonatite lavas located in the western African MA margin, are in a tectonic region affected by the break-up...mines in The volcanic activity in the Catanda region has never been precisely dated. Silva and Pereira |  | Bailey, Ken, Lloyd, Felicity, Kearns, Stuart, Stoppa, Francesco, Eby, Nelson, Woolley, Alan (2005) Melilitite at Fort Portal, Uganda: Another dimension to the carbonate volcanism. Lithos, 85 (1) 15-25 doi:10.1016/j.lithos.2005.03.019 | Journal (article/letter/editorial) | | elsevier.com/locate/lithos Melilitite at Fort Portal, Uganda: Another dimension to the carbonate volcanism...Abstract Because the calciocarbonatite lavas at Fort Portal were the first ever described they have received...contain melilitite previously unreported from Fort Portal. The rock is a mix of crust and mantle debris...only low Mg calcite in the assemblage calcite–periclase (consistent with low pressure carbonate melt crystallisation)...ultramafic-carbonate volcanism to the south, in Uganda, and parallels with that in Italy. D 2005 Elsevier |  | | Journal (article/letter/editorial) | | among others. Fresh carbonatite lavas at Fort Portal, Uganda (Barker and Nixon 1989), and Oldoinyo Lengai...larnite; mont monticellite; ne nepheline; per periclase; prv perovskite; sell sellaite; spurr spurrite;...forsterite Ca5 SiO4 2 CO3 spurrite SiO2 2MgO periclase NaAlSiO4 nepheline liq SiO2 2Ca2 MgSi2...zircon and titanite in carbonatites containing periclase, monticellite, spurrite, larnite polymorphs or...carbonatite dike at Fort Portal, Uganda (Barker and Nixon 1989). Other Fort Portal carbonatite samples |  | | Journal (article/letter/editorial) | | Ultraalkaline District has been observed only in the western branch of the Eastern African Rift and in the southern...1985) and in the carbonatite lavas from Fort Portal, Uganda (Barker and Nixon, 1989). Whole Rock Chemistry...only in the calciocarbonatites from the Fort Portal area, Uganda (Barker and Nixon, 1989), the Saguenay...the Rufunsa area, Zambia (Bailey, 1990). The Fort Portal carbonatite (Kalyango lava flow) is the rock...diagram of Fig. 6A, the Polino carbonatite and the Fort Portal carbonatite fields are very close. Following |  | | Report (chapter) | | represent the final residua expelled from the source region. Most large carbonatite intrusions seem to have...(Lengai) 2. Calcio-c (Kerimasi) 3. Calcio-c (Ft. Portal) 4. Calcio-c (Polino) 5. Calcio-c (Kaiserstuhl)...by 1961 the Recent carbonatite lava flow at Fort Portal had been described (von Knorring & Du Bois 1961)...tufts cemented by calcium carbonate. In the Fort Portal lava flow, olivine, diopside and phlogopite xenocrysts...xenocrysts, are enclosed in a groundmass of calcite, periclase, perovskite, apatite and spurrite, consistent |  | | Journal (article/letter/editorial) | | Tamazert, Morocco Fort Portal, Uganda Katwe-Kikorongo, Uganda Bunyaraguru, Uganda Tinderet, Kenya C...large volcanoes or SVEs. An exception is the Fort Portal occurrence which comprises numerous carbonatitic...mantle origin. The identification of some of the Fort Portal carbonatitic tuffs as ignimbrites (Barker and...appear to be unique to that volcano, whilst the Fort Portal lava and lava bombs are apparently also unique...mineral assemblages including primary spurrite and periclase. 3. Associated silicate rocks Table 2 indicates |  | | Journal (article/letter/editorial) | | s Geochemistry and petrogenesis of the Fort Portal, Uganda, extrusive carbonatite G. Nelson Eby a,⁎...Quaternary Fort Portal volcanic field occurs at the northern end of the Western Rift in Uganda. The eruptive...Quaternary Fort Portal volcanic field, is the subject of this paper. The Quaternary Fort Portal and Kasekere...Kasekere volcanic fields of southwest Uganda (Fig. 1) were first mapped and described by von Knorring and Du...associated with the western branch of the East African rift system. Fort Portal and Kasekere are part |  | Abersteiner, Adam, Kamenetsky, Vadim S., Graham Pearson, D., Kamenetsky, Maya, Goemann, Karsten, Ehrig, Kathy, Rodemann, Thomas (2018) Monticellite in group-I kimberlites: Implications for evolution of parental melts and post-emplacement CO2 degassing. Chemical Geology, 478. 76-88 doi:10.1016/j.chemgeo.2017.06.037 | Journal (article/letter/editorial) | | Forsterite + Carbonate (melt) ⇌ Monticellite + Periclase + CO2 This reaction is supported by the preservation...preservation of abundant primary inclusions of periclase and to a lesser extent Fe-Mg-oxides in monticellite...MANUSCRIPT preservation of primary periclase inclusions, we infer that periclase also existed in the groundmass...formation. MA Key words: kimberlite, monticellite, periclase, melt inclusions, alkali-carbonate, CO2 PT E...bodies (Tyni (1997)) and is located on south- D western margin of the Archean Karelian Craton in eastern |  | | Journal (article/letter/editorial) | | liquids. The carbonate liquidus volume is a forbidden region for carbonate-rich magmas derived from silicate...of bulk composition and pressure (vapor-absent region increasing as pressure increases). An indication...Cc, calcite; Cd, dolomite; Cm, magnesite; Pe, periclase. (b) Liquidus fields and boundaries in (a) projected...because at this pressure, carbonate is replaced by periclase (Pe, oxide) on the higher-temperature, more magnesian...point d approaches h with increased pressure, and periclase is completely replaced by magnesite at some pressure |  | | Journal (article/letter/editorial) | | present in the Canary and Cape Verde Islands, Kenya, Uganda and Zambia, and may be predicted with confidence...such as Fort Vulture, Italy (Bailey et al., compositions are in for other volcanic Portal, Uganda and 2005b)...the solidi are similar in form and lie within the region shown in Fig. 6. A recent anhydrous solidus is...dissociation assemblage comprising calcite + periclase + vapour. The pyroclastic eruptive style and the...expression of melts such as the lava at Fort Portal, Uganda and, as noted by Stoppa et al. (2005), most |  | | Report (chapter) | | recognized by King (1949) at the Napak complex in Uganda. Tuttle & Gittins (1966) and Heinrich (1966) wrote...(non-carbonatitic) volcanic centres corresponding to the Kenyan region of the outer zone shown in Fig. 2. Between these...rift valley, particularly those in the Kishalduga region, are almost identical (cf. Figs 6(a) and 6(b),...Large central High Frequent Very rare W Kenya E Uganda Malawi Siberia Amba Dongar, India in the deciphering...nepheline syenite in the sub-volcanic complexes of E Uganda (Tyler & King 1967) and W Kenya (Le Bas 1977, and |  | Mangler, Martin F., Marks, Michael A.W., Zaitzev, Anatoly N., Eby, G. Nelson, Markl, Gregor (2014) Halogens (F, Cl and Br) at Oldoinyo Lengai volcano (Tanzania): Effects of magmatic differentiation, silicate–natrocarbonatite melt separation and surface alteration of natrocarbonatite. Chemical Geology, 365. 43-53 doi:10.1016/j.chemgeo.2013.11.027 | Journal (article/letter/editorial) | | Oldoinyo Lengai, Kerimasi ENGW1 rock samples Fort Portal water samples Panda Hill escarpment OL 804...DOD-77 DOD-91 Sukulu, UG Panda Hill, TZ Fort Portal, UG Fort Portal, UG Tinderet, EAK Kerimasi, TZ Homa Bay...of the Bol'shaya Tanga Massif, the eastern Sayan Region. Dokl. Earth Sci. 408, 542–546. Bagdasarayan, G...High-Ca, low-alkali carbonatite volcanism at Fort Portal, Uganda. Contrib. Mineral. Petrol. 103, 166–177....calcitized alkalicarbonatites from Homa Mountain, western Kenya: a reinterpretation. Geol. Mag. 123, 683–692 |  | | Journal (article/letter/editorial) | | analyses were: fluorite (FKa); albite (NaKa); periclase (MgKa); synthetic Al2O3 (AlKa); diopside (SiKa);...areas (Issa Filho et al., 1991): (1) the central– western area (Catanda); (2) the central area (Monte Verde...intrusions partially disrupt earlier structures on the western side. The carbonatites form annular structures...26.6 wt.% UO2) in carbonatitic tuffs near Fort Portal, Uganda. Thorium occurs in many carbonatites worldwide...Geochronological review of the Precambrian in western Angola: links with Brazil. Journal of African Earth |  | Galuskina, I. O., Lazic, B., Armbruster, T., Galuskin, E. V., Gazeev, V. M., Zadov, A. E., Pertsev, N. N., Jezak, L., Wrzalik, R., Gurbanov, A. G. (2009) Kumtyubeite Ca5(SiO4)2F2 — A new calcium mineral of the humite group from Northern Caucasus, Kabardino-Balkaria, Russia. American Mineralogist, 94 (10) 1361-1370 doi:10.2138/am.2009.3256 | Journal (article/letter/editorial) | | reinhardbraunsite were presented from carbonatites of Fort Portal, Uganda (Barker and Nixon 1989), but the low total...rocks. Perovskite, ferrigarnet of kimzeyite type, periclase, and sphalerite are considerably less abundant...cm–1 (Fig. 3). In the low-frequency (<1000 cm–1) region, the Raman spectra of kumtyubeite and reinhardbraunsite...kumtyubeite grain measured with microATR accessory in the region: A = 1250–400 cm–1, B = 3600–3450 cm–1. 2007b):...kumtyubeite (1) and reinhardbraunsite (2) in the region: A = 1200–200 cm–1, B = 3700–3300 cm–1. Figure |  | | Journal (issue) | | and the St.:1..'nic fossil beds of 1hc Barstow region. L1.:avc tht.: coll...:gc on Friday ;H 7:30 a.111...Ve uvius. Aloisiitc, as a c<:ment in tuff at Fort Portal. Ug:rnda. Alunogen, from Vesuvius. J\lunite,...deposits at Vesuvius. Paraffin, in basaltic lava. Periclase, i:1 white l imestone of Vesuvius. Perovskite |  | | Journal (article/letter/editorial) | | hydrous melt, periclase and CO2 (Persikov and Bukhtiyarov 2013). The scarcity of periclase in carbonatites...dolomite, L = liquid, Mgs = magnesite, Prc = periclase, V = vapor. b CaCO3–SrCO3–BaCO3 at T=550 °C and...dry systems, dissociates to Mg-rich calcite, periclase and vapor: CaMgðCO3 Þ2 ⟺ ð1 þ xÞ ð1Þ Ca0:99−0:81xþ0:32x2...experimental systems (Carlson 1980). Additionally, a region of disordered rhombohedral ternary carbonates appears...(1979) Petrology of ocellar lamprophyres from western Otago, New Zealand. Petrol 20:139–163 Coto B, Martos |  | Guzmics, Tibor, Mitchell, Roger H., Szabó, Csaba, Berkesi, Márta, Milke, Ralf, Abart, Rainer (2011) Carbonatite melt inclusions in coexisting magnetite, apatite and monticellite in Kerimasi calciocarbonatite, Tanzania: melt evolution and petrogenesis. Contributions to Mineralogy and Petrology, 161 (2) 177-196 doi:10.1007/s00410-010-0525-z | Journal (article/letter/editorial) | | optically distinct carbonate phase. Rarely oxides and periclase can be found in calcite inclusions (not illustrated)...East African ijolites and Tororo carbonatites (Uganda), respectively. Fall et al. (2007) have also studied...effects on the carbonatite– silicate immiscible region in the pseudoternary (Fig. 12) and pseudoquaternary...Kerimasi magmas the temperature could have been in the region of 900–1,000°C (Fig. 12). This conclusion is in...websterite xenolith from the Pannonian Basin, western Hungary: evidence for release of quartz-saturated |  | | Book | | margin of the Atlantic (Namibia, Angola) or the western African kimberlites do not fulfil the above criteria...carbonatitic-alkaline province outcropping on the Kenya-Uganda border which have recently received significant...East-African Rift volcanism, both in its eastern and western branches. The abundance of available data varies;...LILE- enriched ultra-alkaline volcanism of the Western rift is also examined in the light of trace element...Africa .................................. 3.2 Western Africa ................................... 3.3 |  | | Book (edition) | | all localities), Canada, Germany, Norway, Sweden, Uganda, Tanganyika, Nyasaland, and India. This, like most...Progress and B. C. King and D. S. Sutherland (1960B) : Uganda Geological Survey and B. C. King (1949) : The American...the major contributors have been the following. Uganda: K. A. Davies (1956), C. E. Williams (1952, 1959)...breakdown is: U.S.A., 13; Canada, Dyke Brazil, il}s Western Europe and Greenland, 11; U.S.S.R., 35 (?); Africa...and others (discordant) of the Sangu complex in western Tanganyika and the Kaluwe carbonatite (concordant) |  | | Journal (article/letter/editorial) | | melt compositions are compared to kamafugites from Uganda (Tappe et al. 2003), to nakhlites parent magmas...also approach the composition of kamafugites from Uganda (Tappe et al. 2003)—ultrapotassic rocks sometimes...interpretation of natural samples of wüstite-periclase from Earth’s mantle samples. In Luobusa ophiolite...consistent with the idea that the nakhlite source region was metasomatized as proposed by Longhi and Pan...also approach the composition of kamafugites from Uganda, if siderite melt immiscibility or Fe/C redox interaction |  | | Book | | VULCANICITY AND CONTINENTAL EVOLUTION IN THE BARBERTON REGION, TRANSVAAL 27 M. J. Viljoen and R. P. Viljoen...Survey and Mines Department, P.O. Box 9, Entebbe, Uganda. Cauen, L., Musée Royal de l'Afrique Centrale,...Highlands and part in the Midland Valley. In the Western Highlands he and Richey established for the first...J. E.). The succession of the Moine Schists of western Invernessshire. Abstract. Rep. Brit. Ass. Adv....structure of the Moine Schists in the Morar district, western Inverness-shire. Abstract. Proc. geol. Soc. Lond |  | | Book | | Tanzania - Oldoinyo Lengai Region - Congresses. ism - Tanzania - Oldoinyo Lengai Region - Congresses. 3. Oldoinyo...April 1915. Schulze also records a flow on the western slopes between 1800 and 2000 m. 5 1917 and 1926...extrusion of combeite nephelinite lava onto the upper western slopes of the volcano; its stratigraphic position...extent that the small cone on the inner north-western wall of the crater (point X on Fig. 10) is now...around 30-40 m below the lowest point on the north-western rim of the crater. (Photo N. Patridge) which by |  | | Report (volume) | | biotites from the Poohbah Lake syenite in north-western Ontario have been dated at around 2.7 Ga (Mitchell...et al. (1983) for the Tupertalik carbonatite in western Greenland. At the present time, alkaline magmas...common phenomenon. It occurred, for example, in the western U.S.A. about 17 Ma ago and in parts of Africa and...biotites from the Poohbah Lake syenite in north-western Ontario have been dated at around 2.7 Ga (Mitchell...et al. (1983) for the Tupertalik carbonatite in western Greenland. At the present time, alkaline magmas |  | | Book (edition) | | Transitions from Continental Arc to Rift Associations in Western North America . . . . . . . . . . . . . . . . ...Minerals . . . . . . . . . Dora Maira Massif in the Western Alps . . . . . . . . . . . . . . . . . Dabie–Sulu...Calvin Miller (Vanderbilt University), Raj Sharma (Western Michigan), Suki Smaglik (Metro State College of...always flows from a hotter region, where atomic motion is greater, to a cooler region, where motion is less...plates converge, as in the island arcs of the western Pacific. These petrotectonic associations are discussed |
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