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Sample records for oldoinyo lengai tanzania

  1. Peralkaline silicate lavas at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Klaudius, Jurgis; Keller, Jörg

    2006-10-01

    A detailed study of Oldoinyo Lengai has led to the recognition of two major cone-building stages. An early, predominantly phonolitic stage, Lengai I, forms the southern cone. The recent nephelinitic Lengai II developed following a major sector collapse event over Lengai I. Petrography of Lengai II lavas show that nephelinite is combeite- and wollastonite-bearing. All Oldoinyo Lengai lavas are peralkaline and highly evolved in terms of low Mg#, Ni and Cr values. Within the unique Lengai II combeite-wollastonite-nephelinite (CWN) peralkalinity increases with time to extreme values (Na + K)/Al = 2.36. Mineralogical expression of peralkalinity is the presence of combeite and Na-rich clinopyroxene. In addition, exceptionally high Fe 2O 3 (up to 10.28 wt.%) in nepheline is an indicator for alumina deficiency. Combeite also shows high Fe 3+. Phonolite and CWN of Lengai I and Lengai II show similarly enriched LILE and LREE values and generally parallel patterns in PM normalized and REE plots.

  2. Magnesium isotope fractionation during carbonatite magmatism at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Li, Wang-Ye; Teng, Fang-Zhen; Halama, Ralf; Keller, Jörg; Klaudius, Jurgis

    2016-06-01

    To investigate the behaviour of Mg isotopes during carbonatite magmatism, we analyzed Mg isotopic compositions of natrocarbonatites and peralkaline silicate rocks from Oldoinyo Lengai, Tanzania. The olivine melilitites from the vicinity of Oldoinyo Lengai have homogeneous and mantle-like Mg isotopic compositions (δ26Mg of -0.30 to -0.26‰), indicating limited Mg isotope fractionation during mantle melting. The highly evolved peralkaline silicate rocks not related to silicate-carbonatite liquid immiscibility, including phonolites from the unit Lengai I, combeite-wollastonite nephelinites (CWNs) from the unit Lengai II A and carbonated combeite-wollastonite-melilite nephelinites (carbCWMNs), have δ26Mg values (from -0.25 to -0.10‰) clustered around the mantle value. By contrast, the CWNs from the unit Lengai II B, which evolved from the silicate melts that were presumably generated by silicate-carbonatite liquid immiscibility, have heavier Mg isotopes (δ26Mg of -0.06 to +0.09‰). Such a difference suggests Mg isotope fractionation during liquid immiscibility and implies, based on mass-balance calculations, that the original carbonatite melts at Lengai were isotopically light. The variable and positive δ26Mg values of natrocarbonatites (from +0.13 to +0.37‰) hence require a change of their Mg isotopic compositions subsequent to liquid immiscibility. The negative correlations between δ26Mg values and contents of alkali and alkaline earth metals of natrocarbonatites suggest Mg isotope fractionation during fractional crystallization of carbonatite melts, with heavy Mg isotopes enriched in the residual melts relative to fractionated carbonate minerals. Collectively, significant Mg isotope fractionation may occur during both silicate-carbonatite liquid immiscibility and fractional crystallization of carbonatite melts, making Mg isotopes a potentially useful tracer of these processes relevant to carbonatite petrogenesis.

  3. Melilite-group minerals at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Wiedenmann, Daniel; Keller, Jörg; Zaitsev, Anatoly N.

    2010-07-01

    Oldoinyo Lengai and the volcanic centres of the Lake Natron-Engaruka province contain melilite as a widespread mineral. Extraordinarily Na-Al-rich melilites (up to 6 wt.% Na 2O and 9 wt.% Al 2O 3) from recent explosive eruptions are among the most Na-rich ever reported. Their unusual mineral composition leads to optical properties with vivid birefringence colours of 2nd order. The continuous variation in mineral composition from common åkermanite to Na-Al-melilite ( alumoåkermanite) is documented and reflects the whole peralkaline trend of Oldoinyo Lengai. The data presented allow the volcano's evolution from primitive olivine melilitites to highly evolved and peralkaline combeite-wollastonite nephelinites to be traced. Melilite compositions of Oldoinyo Lengai extend the magmatic field in the Ca 2Fe(Si 2O 7)-Ca 2Mg(Si 2O 7)-(CaNa)Al(Si 2O 7) end-member ternary compositional diagram.

  4. Holocene carbonatite-nephelinite tephra deposits of Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Hay, Richard L.

    1989-03-01

    Natrocarbonatite and nephelinite tephra have been erupted together from Oldoinyo Lengai over the past few thousand years. The oldest deposits with recognizable natrocarbonatite are thin tuff beds probably between 2000 and 5000 years in age. Tuffs and agglomerates with an age of about 1250-2000 years contain evidence strongly suggestive of natrocarbonatite ash. The volcano is mantled by nephelinite-carbonatite ash deposits, termed the Footprint Tuff, that were erupted about 600 years ago. Evidence is contradictory as to whether natrocarbonatite was discharged during the cone-building phase of eruptions, which ended about 15,000 years ago. Nephelinite-carbonatite ash erupted in 1966 contains an unidentified mineral, designated NCS, with a chemical composition of Na 4.09Ca 2.76Si 5O 14.81. It may be genetically related to natrocarbonatite magma as it has thus far been identified only in the younger tephra deposits of Oldoinyo Lengai, most of which contain evidence of natrocarbonatite. A tephra deposit termed the Footprint Tuff contains footprints thought to be preserved by the rapid recrystallization of primary natrocarbonatite. Calcite of natrocarbonatite origin forms an estimated 15-20% of the airfall tuffs, and natrocarbonatite probably equalled or exceeded the volume of nephelinite tephra at the time of eruption. Nyerereite ([Na 0.82K 0.18] 2 Ca[CO 3] 2) and gregoryite ([Na 0.78K 0.05] [Ca 0.17CO 3]) were primary minerals in the natrocarbonatite, as in modern lavas of Oldoinyo Lengai. Unlike modern lavas, the groundmass contained a substantial amount of silicate material. Noncarbonate minerals in the Footprint Tuff include nepheline, melilite, augite, wollastonite, melanite, fluorite, and NCS. The Footprint Tuff was cemented soon after deposition, very likely by trona. Gaylussite, pirssonite, or both, were probably later alteration products in the transformation of natrocarbonatite ash to form calcite. Oxygen and carbon isotopic re-equilibration were essentially

  5. Physicochemical properties of alkali carbonatite lavas:Data from the 1988 eruption of Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.; Pinkerton, H.; Norton, G. E.; Pyle, D. M.

    1990-03-01

    Alkali carbonatite lavas extruded from Oldoinyo Lengai, Tanzania, in November 1988 are similar in composition to lavas extruded in 1960. Extrusion temperatures are 585 ±10 °C. Apparent viscosities in this temperature range are between 0.3 and 120 Paṡs, the highest values coming from very frothy and phenocryst-rich magma. The viscosities and temperatures are the lowest known for terrestrial magmas.

  6. Mineralogical and chemical transformation of Oldoinyo Lengai natrocarbonatites, Tanzania

    NASA Astrophysics Data System (ADS)

    Zaitsev, Anatoly N.; Keller, Jörg

    2006-10-01

    The minerals of Oldoinyo Lengai natrocarbonatite lavas are unstable under atmospheric conditions. Subsolidus mineral assemblages in natrocarbonatites were studied in 105 samples from contemporary eruptions ranging from present day to about 100 years old. The subsolidus minerals in natrocarbonatites were formed (i) along cracks on the lava surface from hot gases escaping during cooling, (ii) as atmospheric alteration by solution of water-soluble minerals, in particular halides and gregoryite, and by hydration of nyerereite under the influence of meteoric water and (iii) by reaction with fumarole gases. After solidification, the lavas were cut by a network of thin cracks, the edges of which are covered by polymineralic encrustations. Samples collected 2-24 h after eruption contain nahcolite, trona, sylvite, and halite with accessory kalicinite and villiaumite. Atmospheric humidity results immediately (≥ 2 h after eruption) in alteration of black lavas that is marked by the appearance of white powdery thermonatrite with nahcolite on the lava surface. Subsequent reaction (weeks, months, years) of natrocarbonatite with meteoric water and the atmosphere results in the formation of pirssonite, gaylussite, shortite, trona, thermonatrite, nahcolite and calcite. Generally, the first important step is the formation of pirssonite and the end-members are calcite carbonate rocks or loose aggregates. Fumarolic activity is common for the active northern crater of the volcano. Reaction of hot (54-141 °C) fumarolic gases with natrocarbonatite leads to the formation of sulphur, gypsum, calcite, anhydrite, monohydrocalcite, barite and celestine. Changes in mineralogy of the natrocarbonatite lead to substantial chemical transformation. The most obvious chemical changes in this process are the loss of Na, K, Cl and S, combined with an increase in H 2O, Ca, Sr, Ba, F and Mn. The oxygen and carbon isotopic composition of altered natrocarbonatites shows a significant shift from the

  7. Peralkaline nephelinite-natrocarbonatite immiscibility and carbonatite assimilation at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.

    2009-11-01

    This study presents petrographic and compositional data for coexisting peralkaline silicate glass and quenched natrocarbonatite melt in nepheline phenocrysts from the 24 September 2007 and July 2008 eruptions of the natrocarbonatite volcano Oldoinyo Lengai (Tanzania). Data are also given for peralkaline residual glass in combeite nephelinite ash clasts occurring in the March-April 2006 large volume natrocarbonatite flow. These data are considered to demonstrate the occurrence of liquid immiscibility between strongly peralkaline Fe-rich nephelinite melt and natrocarbonatite at Oldoinyo Lengai. Compositional data for coexisting silicate-carbonate pairs in conjunction with previous experimental studies suggest that the size of the field of liquid immiscibility for carbonated nephelinitic magmas is a function of their peralkalinity. It is shown that peralkaline combeite wollastonite nephelinite was present at Oldoinyo Lengai prior to, and during, the 24 September 2007 ash eruption. It is postulated that the driving force for this major eruption was assimilation and decomposition of previously emplaced solid natrocarbonatite. Assimilation resulted in the formation of the unusual hybrid nepheline-andradite-melilite-combeite-phosphate magma represented by the 24 September 2007 ash.

  8. Contrasting carbonatite volcanism at the Kerimasi and Oldoinyo Lengai volcanoes, northern Tanzania

    NASA Astrophysics Data System (ADS)

    Mattsson, Hannes B.; Bosshard-Stadlin, Sonja A.; Weidendorfer, Daniel; Balashova, Anna

    2014-05-01

    The two neighboring volcanoes, Kerimasi and Oldoinyo Lengai, located 12 km apart in the eastern branch of the East African Rift in northern Tanzania display many similarities but also significant differences in terms of the types of magmas being erupted. The carbonatites of Kerimasi have a rather large compositional span (MgO=0-14 wt.% and CaO=32-56 wt.%). This is in sharp contrast to the very uniform Na-carbonatites typically erupted at Oldoinyo Lengai. As a result of this the Kerimasi carbonatites classify as Ca-carbonatites and they are all virtually devoid of alkalis. The trace elements patterns are rather uniform for the Kerimasi carbonatites and the patterns are similar to Ca-carbonatites found elsewhere. They differ to the natrocarbonatites by having considerable higher Zr and Hf concentrations. The slope of the REE ([La/Yb]N) are considerably flatter for the Kerimasi rocks (12 to 45) in comparison to natrocarbonatites (>1000) or even Ca-carbonatite dykes from Oldoinyo Lengai (~100). Interestingly, the Trig Point Hill debris avalanche deposit of Kerimasi is dominated by carbonatitic material in the form of blocks comprising intrusions, cumulates and vesicular lava flows (calculated to have a total volume of approximately 0.6 to 1.2 km3). This strongly indicates that the collapsed part of volcanic edifice at Kerimasi is in fact dominated by carbonatitic material with only minor amounts of silicate rocks. At Oldoinyo Lengai the carbonatitic material mainly occur inside the summit crater as small lava flows (with a combined volume of <0.02 km3) with minor amounts of sövitic intrusions also being present at depth (as indicated by accidental lithics picked-up during explosive eruptions). The effusive to mildly explosive activity characteristic of the Oldoinyo Lengai natrocarbonatites are bracketed by more explosive episodes involving nephelinitic magmas (such as in 1966-67 and 2007-08). It is suggested here that during explosive episodes carbonatite magma mix

  9. Satellite measurements of recent volcanic activity at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Vaughan, R. Greg; Kervyn, Matthieu; Realmuto, Vince; Abrams, Michael; Hook, Simon J.

    2008-06-01

    Oldoinyo Lengai (OL) is the only active volcano in the world that produces natrocarbonatite lava. These carbonate-rich lavas are unique in that they have relatively low temperatures (495-590 °C) and very low viscosity. OL has been erupting intermittently since 1983, mostly with small lava flows, pools and spatter cones (hornitos) confined to the summit crater. Explosive, ash-producing eruptions are rare, however, on September 4, 2007 the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) captured the first satellite image of an ash plume erupting from OL, which may be indicative of a new phase of more silica-rich products and explosive activity that has not occurred since 1966-1967. In the months prior to the eruption, thermal infrared (TIR) satellite monitoring detected an increasing number of thermal anomalies around OL. Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor analyzed with the MODLEN algorithm detected more than 30 hot spots in the last week of August and first week of September 2007, some of which were from bush fires ignited by lava flows or spatter around the volcano. Higher-resolution ASTER data confirmed the location of these burn scars associated with lava flows. ASTER also detected the appearance of an anomalous hot spot at the summit of OL in mid-June with temperatures ~ 440 °C, the presence of several new lava flows in the crater in July and August, and on September 4 measured higher temperatures (~ 550 °C) possibly suggesting a more silicate-rich eruption. ASTER spectral emissivity data were interpreted to indicate a mixture of carbonate and silicate ash in the eruption plume from September 4. Based on the analysis of both ASTER and MODIS data combined with occasional field observations, there appear to have been 2 distinct eruptive events so far in 2007: a typical natrocarbonatite eruption confined to the summit crater in June-July, and a more intense eruption in August-September consisting of

  10. Geologic map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and surroundings, Arusha Region, United Republic of Tanzania

    USGS Publications Warehouse

    Sherrod, David R.; Magigita, Masota M.; Kwelwa, Shimba

    2013-01-01

    The geology of Oldonyo Lengai volcano and the southernmost Lake Natron basin, Tanzania, is presented on this geologic map at scale 1:50,000. The map sheet can be downloaded in pdf format for online viewing or ready to print (48 inches by 36 inches). A 65-page explanatory pamphlet describes the geologic history of the area. Its goal is to place the new findings into the framework of previous investigations while highlighting gaps in knowledge. In this way questions are raised and challenges proposed to future workers. The southernmost Lake Natron basin is located along the East African rift zone in northern Tanzania. Exposed strata provide a history of volcanism, sedimentation, and faulting that spans 2 million years. It is here where Oldonyo Lengai, Tanzania’s most active volcano of the past several thousand years, built its edifice. Six new radiometric ages, by the 40Ar/39Ar method, and 48 new geochemical analyses from Oldonyo Lengai and surrounding volcanic features deepen our understanding of the area. Those who prefer the convenience and access offered by Geographic Information Systems (GIS) may download an electronic database, suitable for most GIS software applications. The GIS database is in a Transverse Mercator projection, zone 36, New (1960) Arc datum. The database includes layers for hypsography (topography), hydrography, and infrastructure such as roads and trails.

  11. Ra-Th disequilibria systematics: Timescale of carbonatite magma formation at Oldoinyo Lengai volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Williams, Ross W.; Gill, James B.; Bruland, Kenneth W.

    1986-06-01

    Carbonatite magma can form and erupt within 7 to 18 years, and the event seems associated with prior volcanic eruptions. This determination of magma age is possible because the carbonatite lava and ash which were erupted in 1960-1966 from Oldoinyo Lengai volcano, Tanzania, have the most extreme disequilibria between U and Th series nuclides yet measured in volcanic rocks. At the time of eruption: ( 228Ra) /( 232Th) ≈ 27 and ( 226Ra) /( 230Th) > 60 ; ( 238U) /( 232Th) > 10 , while ( 232Th) /( 232Th) = 1.0 ; and ( 210Pb) /( 226Ra) ≈ 0.3 . Three end-member models are presented which enable interpretation of these disequilibria. If the disequilibrium formed instantaneously, the event occurred about 7 years before initial eruption, and just before the last preceding but small eruption of Oldoinyo Lengai. If, instead, the disequilibrium formed continuously, the process must have begun 15 to 18 years before initial eruption, just after the last preceding major eruption. The disequilibria data confirm that the carbonatites are not fused trona, but do not distinguish between other genetic options (mantle fusion, selective assimilation, liquid immiscibility). However, the shortness of magma-formation time together with mass-balance considerations suggest formation due to the continuous exsolution of 2 to 20% of carbonatite from nephelinite which was itself Ra-enriched.

  12. Temperature Measurements in Carbonatite Lava Lakes and Flows from Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Krafft, Maurice; Keller, Jorg

    1989-07-01

    The petrogenesis of carbonatites has important implications for mantle processes and for the magmatic evolution of mantle melts rich in carbon dioxide. Oldoinyo Lengai, Tanzania, is the only active carbonatite volcano on Earth. Its highly alkalic, sodium-rich lava, although different in composition from the more common calcium-rich carbonatites, provides the opportunity for observations of the physical characteristics of carbonatite melts. Temperature measurements on active carbonatitic lava flows and from carbonatitic lava lakes were carried out during a period of effusive activity in June 1988. Temperatures ranged from 491 degrees to 519 degrees C. The highest temperature, measured from a carbonatitic lava lake, was 544 degrees C. These temperatures are several hundred degrees lower than measurements from any silicate lava. At the observed temperatures, the carbonatite melt had lower viscosities than the most fluid basaltic lavas. The unusually low magmatic temperatures were confirmed with 1-atmosphere melting experiments on natural samples.

  13. Temperature measurements in carbonatite lava lakes and flows from oldoinyo lengai, Tanzania.

    PubMed

    Krafft, M; Keller, J

    1989-07-14

    The petrogenesis of carbonatites has important implications for mantle processes and for the magmatic evolution of mantle melts rich in carbon dioxide. Oldoinyo Lengai, Tanzania, is the only active carbonatite volcano on Earth. Its highly alkalic, sodium-rich lava, although different in composition from the more common calcium-rich carbonatites, provides the opportunity for observations of the physical characteristics of carbonatite melts. Temperature measurements on active carbonatitic lava flows and from carbonatitic lava lakes were carried out during a period of effusive activity in June 1988. Temperatures ranged from 491 degrees to 519 degrees C. The highest temperature, measured from a carbonatitic lava lake, was 544 degrees C. These temperatures are several hundred degrees lower than measurements from any silicate lava. At the observed temperatures, the carbonatite melt had lower viscosities than the most fluid basaltic lavas. The unusually low magmatic temperatures were confirmed with 1-atmosphere melting experiments on natural samples. PMID:17787875

  14. Altered former alkalic carbonatite lava from Oldoinyo Lengai, Tanzania: Inferences for calcite carbonatite lavas

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.; Garson, M. S.; Roberts, B.

    1987-08-01

    The active volcano Oldoinyo Lengai, Tanzania, is well known for its extrusions of alkalic carbonatite lava, first witnessed in 1960. An older carbonatite flow from the volcano was originally also rich in Na and K, but replacement of nyerereite by pirssonite as a result of leaching of these elements (together with soluble components such as SO3, Cl, and Rb) and addition of Ca has resulted in a rock intermediate in bulk composition between the unique 1960 Lengai lavas and calcite-rich carbonatite flows reported from other localities. Further replacement of Na by Ca could theoretically result in a pure calcite rock, and we suggest that the partially altered alkalic lava described here is the “missing link” between lavas that are now calcitic but which had a high alkali content when originally extruded. The suggested link between alkali carbonate precursors and present-day calcium carbonate “lavas” explains the apparent paradox between the existence of calcite-rich “flows” and the experimental evidence that denies the possibility of hot, liquid calcium carbonate.

  15. Potassium loss during metasomatic alteration of mica pyroxenite from Oldoinyo Lengai, northern Tanzania: contrasts with fenitization

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.; Smith, J. V.

    1992-11-01

    Mica pyroxenite xenoliths, occurring as the cores of nephelinite and ijolite bombs in the pyroclastic deposits of the active volcano Oldoinyo Lengai, have undergone metasomatism in which K was lost and Fe2+ and Ti gained. This is unlike the alkali and ferric iron addition that typifies most examples of metastomatism adjacent to peralkaline igneous rocks in carbonatite complexes.

  16. Reprint of "Geochemistry and petrogenetic significance of natrocarbonatites at Oldoinyo Lengai, Tanzania: Composition of lavas from 1988 to 2007"

    NASA Astrophysics Data System (ADS)

    Keller, J.; Zaitsev, A. N.

    2012-11-01

    The natrocarbonatites of Oldoinyo Lengai, Tanzania, are unique in magmatic petrology. The historical activity of Oldoinyo Lengai has seen changes from nephelinitic to natrocarbonatitic character of the emitted magmas. Since 1983 the activity was characterized by the effusion of fluid natrocarbonatite lava from which we have collected and analyzed fresh samples in the summit crater from 1988 to 2007. The available compositional data set forms the basis for presenting and discussing the typical composition and variation of natrocarbonatites and their relationship to the silicate magmas of Oldoinyo Lengai. The "type" natrocarbonatite major and trace element composition is derived for an average of 25 samples with low standard deviation. Oldoinyo Lengai carbonatites are unique in almost all aspects of their petrological and geochemical characteristics and are characterized as extremely alkali-rich, with Na2O + K2O generally about 40 wt.%, and with high CaO contents of 14-18 wt.%. This composition results from the presence of phenocrysts of nyerereite (Na,K)2Ca(CO3)2 and gregoryite (Na,K,Cax)2-x(CO3) dominating the highly porphyritic natrocarbonatite lavas, with sylvite and fluorite as main groundmass minerals. The significance of particular trace element concentrations and ratios of equally incompatible elements (REE, Ba, Sr, Th/U, Nb/Ta, Zr/Hf) is evaluated for models of liquid-liquid separation. In defining a "type" natrocarbonatite composition, we also distinguish special variations in chemical and/or mineralogical compositions as follows: (1) silicate-bearing natrocarbonatites, characterized by the occurrence of nephelinite spheroids, as in the 1993 and 2006 lavas; (2) residual melt compositions as described from the 1988 eruptive period as represented by the aphyric, filter-pressed interstitial melt of solidifying porphyritic lavas; (3) an interlude during 2000 when natrocarbonatites with sylvite and fluorite microcrysts were emitted. After 25 years of mostly mild

  17. Geochemistry and petrogenetic significance of natrocarbonatites at Oldoinyo Lengai, Tanzania: Composition of lavas from 1988 to 2007

    NASA Astrophysics Data System (ADS)

    Keller, J.; Zaitsev, A. N.

    2012-09-01

    The natrocarbonatites of Oldoinyo Lengai, Tanzania, are unique in magmatic petrology. The historical activity of Oldoinyo Lengai has seen changes from nephelinitic to natrocarbonatitic character of the emitted magmas. Since 1983 the activity was characterized by the effusion of fluid natrocarbonatite lava from which we have collected and analyzed fresh samples in the summit crater from 1988 to 2007. The available compositional data set forms the basis for presenting and discussing the typical composition and variation of natrocarbonatites and their relationship to the silicate magmas of Oldoinyo Lengai. The "type" natrocarbonatite major and trace element composition is derived for an average of 25 samples with low standard deviation. Oldoinyo Lengai carbonatites are unique in almost all aspects of their petrological and geochemical characteristics and are characterized as extremely alkali-rich, with Na2O + K2O generally about 40 wt.%, and with high CaO contents of 14-18 wt.%. This composition results from the presence of phenocrysts of nyerereite (Na,K)2Ca(CO3)2 and gregoryite (Na,K,Cax)2-x(CO3) dominating the highly porphyritic natrocarbonatite lavas, with sylvite and fluorite as main groundmass minerals. The significance of particular trace element concentrations and ratios of equally incompatible elements (REE, Ba, Sr, Th/U, Nb/Ta, Zr/Hf) is evaluated for models of liquid-liquid separation. In defining a "type" natrocarbonatite composition, we also distinguish special variations in chemical and/or mineralogical compositions as follows: (1) silicate-bearing natrocarbonatites, characterized by the occurrence of nephelinite spheroids, as in the 1993 and 2006 lavas; (2) residual melt compositions as described from the 1988 eruptive period as represented by the aphyric, filter-pressed interstitial melt of solidifying porphyritic lavas; (3) an interlude during 2000 when natrocarbonatites with sylvite and fluorite microcrysts were emitted. After 25 years of mostly mild

  18. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania

    USGS Publications Warehouse

    Kervyn, M.; Ernst, G.G.J.; Keller, J.; Vaughan, R. Greg; Klaudius, J.; Pradal, E.; Belton, F.; Mattsson, H.B.; Mbede, E.; Jacobs, P.M.

    2010-01-01

    On September 4, 2007, after 25 years of effusive natrocarbonatite eruptions, the eruptive activity of Oldoinyo Lengai (OL), N Tanzania, changed abruptly to episodic explosive eruptions. This transition was preceded by a voluminous lava eruption in March 2006, a year of quiescence, resumption of natrocarbonatite eruptions in June 2007, and a volcano-tectonic earthquake swarm in July 2007. Despite the lack of ground-based monitoring, the evolution in OL eruption dynamics is documented based on the available field observations, ASTER and MODIS satellite images, and almost-daily photos provided by local pilots. Satellite data enabled identification of a phase of voluminous lava effusion in the 2 weeks prior to the onset of explosive eruptions. After the onset, the activity varied from 100 m high ash jets to 2–15 km high violent, steady or unsteady, eruption columns dispersing ash to 100 km distance. The explosive eruptions built up a ∼400 m wide, ∼75 m high intra-crater pyroclastic cone. Time series data for eruption column height show distinct peaks at the end of September 2007 and February 2008, the latter being associated with the first pyroclastic flows to be documented at OL. Chemical analyses of the erupted products, presented in a companion paper (Keller et al.2010), show that the 2007–2008 explosive eruptions are associated with an undersaturated carbonated silicate melt. This new phase of explosive eruptions provides constraints on the factors causing the transition from natrocarbonatite effusive eruptions to explosive eruptions of carbonated nephelinite magma, observed repetitively in the last 100 years at OL.

  19. Chemical composition of nyerereite and gregoryite from natrocarbonatites of Oldoinyo Lengai volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Zaitsev, A. N.; Keller, J.; Spratt, J.; Jeffries, T. E.; Sharygin, V. V.

    2009-12-01

    Alkali carbonates nyerereite, ideally Na2Ca(CO3)2 and gregoryite, ideally Na2CO3, are the major minerals in natrocarbonatite lavas from Oldoinyo Lengai volcano, northern Tanzania. They occur as pheno- and microphenocrysts in groundmass consisting of fluorite and sylvite; nyerereite typically forms prismatic crystals and gregoryite occurs as round, oval crystals. Both minerals are characterized by relatively high contents of various minor elements. Raman spectroscopy data indicate the presence of sulfur and phosphorous as (SO4)2- and (PO4)3- groups. Microprobe analyses show variable composition of both nyerereite and gregoryite. Nyerereite contains 6.1-8.7 wt % K2O, with subordinate amounts of SrO (1.7-3.3 wt %), BaO (0.3-1.6 wt %), SO3 (0.8-1.5 wt %), P2O5 (0.2-0.8 wt %) and Cl (0.1-0.35 wt %). Gregoryite contains 5.0-11.9 wt % CaO, 3.4-5.8 wt % SO3, 1.3-4.6 wt % P2O5, 0.6-1.0 wt % SrO, 0.1-0.6 wt % BaO and 0.3-0.7 wt % Cl. The content of F is below detection limits in nyerereite and gregoryite. Laser ablation ICP-MS analyses show that REE, Mn, Mg, Rb and Li are typical trace elements in these minerals. Nyerereite is enriched in REE (up to 1080 ppm) and Rb (up to 140 ppm), while gregoryite contains more Mg (up to 367 ppm) and Li (up to 241 ppm) as compared with nyerereite.

  20. Petrology of the Oldoinyo Lengai volcano and the origin of the Lake Natron Footprint Tuff (northern Tanzania)

    NASA Astrophysics Data System (ADS)

    Balashova, A.

    2015-12-01

    During its evolution the Oldoinyo Lengai volcano (northern Tanzania) has erupted magmas with a compositional range from nephelinites to phonolites and carbonatites. Intrusive, metasomatic and cumulate enclaves are commonly found in all silicate products of the volcano. New and detailed geochemical and mineralogical study of 132 samples of fresh volcanic silicate material from four debris avalanches, and the volcanic edifice, indicates that phonolites and nephelinites associated with carbonatites were generated via different evolutionary paths. Temporally, the first stage of evolution included the phonolitic path, whereas the second, modern stage includes the production of combeite-wollastonite-bearing nephelinites, associated with carbonatites. Our data supports the two-stage evolutionary model previously presented by Klaudius and Keller (2006). The modern stage is characterised by the mildly explosive natrocarbonatitic activity, which is alternating with highly explosive, nephelinitic eruptions. Distal products of these nephelinitic eruptions cover a wide area around the volcano, however only the recent eruptions have been documented. In this context, special emphasis was paid to the origin of the Lake Natron Footprint Tuff which has preserved hominid footprints that received considerable interest within the anthropological community in recent years. The so-called Footprint tuff is the most significant volcaniclastic horizon in the area around Oldoinyo Lengai. Based on the geochemical, mineralogical and magnetic data we collected from this site, we can deduce that the footprint-bearing horizon was deposited during one or several big eruptions of the Oldoinyo Lengai volcano (corresponding to the late nephelinitic stage of volcanism) and was slightly reworked by water. The material that comprises the upper horizon, which covers the footprints, was derived as aeolian sediments from the Lake Natron - Engaruka Monogenetic Volcanic Field (i.e., melilititic in

  1. Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Koepenick, K. W.; Brantley, S. L.; Thompson, J. M.; Rowe, G. L.; Nyblade, A. A.; Moshy, C.

    1996-06-01

    As a comparison to airborne infrared (IR) flux measurements, ground-based sampling of fumarole and soil gases was used to characterize the quiescent degassing of CO2 from Oldoinyo Lengai volcano. Aerial and ground-based measurements are in good agreement: ˜75% of the aerially measured CO2 flux at Lengai (0.05-0.06 × 1012 mol yr-1 or 6000-7200 tonnes CO2 d-1) can be attributed to seven large crater vents. In contrast to Etna and Vulcano Island, where 15-50% of the total CO2 flux emanates diffusely through the volcanic flanks, diffuse emissions were measured only within 500 m of the crater rim at Lengai, contributing <2% of the total flux. The lack of extensive flank emissions may reflect the dimensions of the magma chamber and/or the lack of a shallow fluid flow system. Thermodynamic restoration of fumarole analyses shows that gases are the most CO2-rich and H2O-poor reported for any volcano, containing 64-74% CO2, 24-34% H2O, 0.88-1.0% H2, 0.1-0.4% CO and <0.1% H2S, HCl, HF, and CH4. Volatile emissions of S, Cl, and F at Oldoiyno Lengai are estimated as 4.5, 1.5, and 1.0 × 107 mol yr-1, respectively. Accuracy of the airborne technique was also assessed by measuring the C emission rate from a coal-burning power plant. CO2 fluxes were measured within ±10% near the plant; however, poor resolution at increased distances caused an underestimation of the flux by a factor of 2. The relatively large CO2 fluxes measured for alkaline volcanoes such as Oldoinyo Lengai or Etna may indicate that midplate volcanoes represent a large, yet relatively unknown, natural source of CO2.

  2. Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania

    USGS Publications Warehouse

    Koepenick, K.W.; Brantley, S.L.; Thompson, J.M.; Rowe, G.L.; Nyblade, A.A.; Moshy, C.

    1996-01-01

    As a comparison to airborne infrared (IR) flux measurements, ground-based sampling of fumarole and soil gases was used to characterize the quiescent degassing of CO2 from Oldoinyo Lengai volcano. Aerial and ground-based measurements are in good agreement: ???75% of the aerially measured CO2 flux at Lengai (0.05-0.06 ?? 1012 mol yr-1 or 6000-7200 tonnes CO2 d-1) can be attributed to seven large crater vents. In contrast to Etna and Vulcano Island, where 15-50% of the total CO2 flux emanates diffusely through the volcanic flanks, diffuse emissions were measured only within 500 m of the crater rim at Lengai, contributing < 2% of the total flux. The lack of extensive flank emissions may reflect the dimensions of the magma chamber and/or the lack of a shallow fluid flow system. Thermodynamic restoration of fumarole analyses shows that gases are the most CO2-rich and H2O-poor reported for any volcano, containing 64-74% CO2, 24-34% H2O, 0.88-1.0% H2, 0.1-0.4% CO and < 0.1% H2S, HCl, HF, and CH4. Volatile emissions of S, Cl, and F at Oldoiyno Lengai are estimated as 4.5, 1.5, and 1.0 ?? 107 mol yr-1, respectively. Accuracy of the airborne technique was also assessed by measuring the C emission rate from a coal-burning power plant. CO2 fluxes were measured within ??10% near the plant; however, poor resolution at increased distances caused an underestimation of the flux by a factor of 2. The relatively large CO2 fluxes measured for alkaline volcanoes such as Oldoinyo Lengai or Etna may indicate that midplate volcanoes represent a large, yet relatively unknown, natural source of CO2.

  3. Geophysical Investigation of Oldoinyo Lengai

    NASA Astrophysics Data System (ADS)

    Scheiber, S. E.; Webb, S. J.; Dirks, P. H.

    2006-12-01

    Oldoinyo Lengai, which means "Mountain of God" in Maasai, is a 2886 m high stratovolcano situated in Northern Tanzania, next to one of the large fault scarps that defines the western edge of the East African Rift Valley. Lengai is the only volcano in the world that erupts natrocarbonatite lava and has been in a state of near-eruption since 1983. A large amount of work has been done in terms of the geology and petrology of this unique volcano, but very little has been done in terms of geophysics. A research team from the University of the Witwatersrand, South Africa will be conducting a gravity and differential GPS survey on Lengai during December 2006 and January 2007. Seismic monitoring of the volcano will also take place for the duration of the survey using vertical 1 Hz geophones. A gravity profile collected over the volcano by the British Schools Exploring Society in 2004 shows a negative anomaly of approximately 185 mGals. This is after a terrain correction is applied to the data using 1:50000 digitized maps and a vertical prism formula. A single seismometer, with a frequency of 1Hz and then 0.033 Hz, was set up on the volcano in 2001 and 2002 by a graduate student from the University of Washington. A few local volcanotectonic (VT) events were recorded; however the research team was unable to conclude whether the events were from Lengai or the nearby rift. A sustained non-harmonic tremor signal with a fairly broad spectral peak was also observed, but no very long-period (VLP) signals. The gravity and DGPS data collected during the 2006/2007 survey will be processed and used as a baseline for future measurements on the volcano. The data will also be modeled in an attempt to determine the size and position of the magma chamber. These gravity data will be compared with the profile collected in 2004 in an attempt to see whether there have been any large subsurface mass changes over the past two years, or the extent of weathering. Recorded seismicity will be used

  4. Volatile-rich silicate melts from Oldoinyo Lengai volcano (Tanzania): Implications for carbonatite genesis and eruptive behavior

    NASA Astrophysics Data System (ADS)

    de Moor, J. Maarten; Fischer, Tobias P.; King, Penelope L.; Botcharnikov, Roman E.; Hervig, Richard L.; Hilton, David R.; Barry, Peter H.; Mangasini, Frederick; Ramirez, Carlos

    2013-01-01

    This study presents volatile, trace, and major element compositions of silicate glasses (nepheline-hosted melt inclusions and matrix glass) from the 2007-2008 explosive eruption at Oldoinyo Lengai volcano, Tanzania. The bulk compositions of the heterogeneous ash erupted in 2007-2008 are consistent with physical mixing between juvenile nephelinite magma and natrocarbonatite emplaced during the preceding ˜25 years of effusive carbonatite eruption. The melt inclusions and matrix glasses span a wide range of silica-undersaturated compositions, from ˜46 wt% SiO2 and (Na+K)/Al˜3 in the least evolved melt inclusions to 38 wt% SiO2 and (Na+K)/Al up to 12 in the matrix glass. The depletion in SiO2 between melt inclusions and matrix glass is accompanied by strong enrichment in all of the incompatible trace elements measured (Ba, Nb, La, Ce, Sr, Zr, Y), which is consistent with fractional crystallization of a bulk mineral assemblage with SiO2 higher than that of the melt inclusions but inconsistent with silicate melt evolution by assimilation of carbonatite. The melt inclusions are volatile-rich with 2.7 wt% to 8.7 wt% CO2 and 0.7 wt% to 10.1 wt% H2O, indicating that Oldoinyo Lengai is a hydrous system. This is contrary to the long-held assumption that Oldoinyo Lengai is relatively anhydrous, which is based on the observation that natrocarbonatite lavas are water-poor. We argue that natrocarbonatites are derived from hydrous carbonate liquid that degas H2O at low pressure. The silicate glass data show that H2O concentration is negatively correlated with incompatible element enrichment, which we attribute to crystallization of the melt in response to decompression degassing of H2O. The eruptive cycle at Oldoinyo Lengai reflects changes in bulk silicate magma viscosity due to extensive H2O-driven crystallization and explosive eruptions occur when volatiles (i.e. H2O>CO2 gas, and carbonate liquid) cannot separate from the crystal-rich nephelinite magma. Melt H2O content

  5. Ra-Th disequilibria: Timescale of carbonatite magma formation at Oldoinyo Lengai volcano, Tanzania

    SciTech Connect

    Williams, R.W.; Gill, J.B.; Bruland, K.W. )

    1988-04-01

    This paper discusses geologic models dealing with the formation of carbonatites from recent lavas of the Oldoninyo Lengai volcano, Tanzania. This paper also acts as a rebutal to an earlier writing which discussed potential flaws in the collection and dating of the carbonatites. The paper goes on to provide activity ratios from different carbonatites and discussion the lack of evidence for fractional crystallization in a olivine sovite magma.

  6. June 1993 eruption of Oldoinyo Lengai, Tanzania: Exceptionally viscous and large carbonatite lava flows and evidence for coexisting silicate and carbonate magmas

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.; Pinkerton, H.; Pyle, D. M.; Nyamweru, C.

    1994-09-01

    Alkali carbonatite lavas and ashes that erupted from Oldoinyo Lengai, Tanzania, in June 1993 provide evidence for coexisting carbonatite and silicate magmas. The lavas and ashes contain immiscible silicate spheroids of ijolitic composition, which themselves contain carbonatite segregations. In contrast to earlier, very mobile flows, the 1993 lava flows were very viscous; the viscosity of one crystal-rich flow is within the range for rhyolites. They are also the largest carbonatite flows yet recorded from the volcano.

  7. Open-path Fourier transform spectroscopy of gas emissions from Oldoinyo Lengai volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Oppenheimer, Clive; Burton, Mike R.; Durieux, Jacques; Pyle, David M.

    2002-02-01

    We report here novel field spectroscopic measurements of the proportions of H 2O, CO 2, CO and SO 2 in gas emissions from Oldoinyo Lengai, the world's unique, active carbonatite volcano. We found that CO 2 constitutes <40 mol% of emissions from a lava lake, and 25 mol% from a cooler fumarole vent. These results suggest that H 2O is the predominant gas phase rather than CO 2, as reported in previous studies based on conventional sampling (Trans. Am. Geophys. Union 69 (1998) 1466; J. Geophys. Res. 101 (1996) 13819), though it is possible that water is introduced by remelting of older hydrated lava flows. We also observed rapid variations in CO 2/CO molar ratios (between 450 and 750 in 1 h) in the lava lake emissions, which could reflect mixing of gases exsolved from deep and shallow magma. Lengai's measured CO 2 flux (J. Geophys. Res. 101 (1996) 13819; Geology 23 (1995) 933) exceeds the time-averaged magma discharge rate, suggesting efficient separation of carbon and water-rich fluids from unerupted silicate magma. This may play an important role in parental magma differentiation.

  8. The Organic Chemistry of Volcanoes: Case Studies at Cerro Negro, Nicaragua and Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Teague, A. J.; Seward, T. M.; Gize, A. P.; Hall, T.

    2005-12-01

    Though it has long been known that volcanoes emit organic compounds within their fumarolic gases, it is only in recent years that a concerted attempt has been made to catalogue and quantify the species and fluxes. Two general lines of interest dominate this study. Firstly, volcanic gases represent some of the most likely environments in which the precursor molecules necessary for the origin of life were synthesised. The existence of an active, abiotic, organic chemistry in such settings today is fundamental to our understanding of the early Earth. Secondly, the presence of halogenated organic compounds is of interest to the atmospheric sciences, particularly with respect to their ozone depleting potential. It is clear that natural sources of halocarbons must exist, and though current natural fluxes are low with respect to the anthropogenic signature, volcanogenic halocarbons may have proved to be significant during the eruption of supervolcanoes and continental flood basalts. In this study, gases were collected from fumaroles in the craters of two, very different, active volcanoes. Cerro Negro, a young basaltic cinder cone belonging to the Central American Volcanic Belt, could be defined as a typical subduction zone volcano. Gases were collected from Cerro Negro during March 2003 and 2004 from a single fumarole discharging close to the crater floor. In contrast, Oldoinyo Lengai is the world's only active carbonatite volcano and represents the most extreme case of alkali volcanism in the East African Rift system. Fieldwork was conducted in the northern summit crater of Lengai over 8 days in October 2003. In this period, the volcano was in near continuous eruption and gases were sampled from two fumaroles situated within 20m of the eruptive centre, though measured gas temperatures were low at around 195°C. Organic compounds were collected using a variety of activated carbon, molecular sieve type adsorbents, packed into glass cartridges. The water and acid matrix of

  9. The Lava sequence of the East African Rift escarpment in the Oldoinyo Lengai - Lake Natron sector, Tanzania

    NASA Astrophysics Data System (ADS)

    Neukirchen, Florian; Finkenbein, Thomas; Keller, Jörg

    2010-12-01

    A 500 m sequence of horizontal lava flows forms the Gregory rift escarpment of the western rift shoulder between Lake Natron and Oldoinyo Lengai. A detailed volcanic stratigraphy of this >1.2 Ma evolution of the EAR in Northern Tanzania is presented. The sequence is formed by several distinct rock suites, with increasing alkalinity from base to top. Alkali olivine basalts of the Waterfall Sequence at the base are followed by a basanite series, and by a range of evolved nephelinites forming the upper part of the escarpment. Numerous dykes and Strombolian scoria deposits indicate local fissure eruptions as opposed to or in addition to more distant sources. Primitive compositions within each of the series indicate variable candidates for primary magmas. The composition of the basanite suite ranges from primitive mantle melts (high Mg#, Cr, Ni) to more evolved rocks, in particular hawaiites, generated by fractionation of olivine, pyroxene and magnetite. Inter-bedded within the basanite suite, one single olivine melilitite flow with high Mg# and abundant olivine and pyroxene megacrysts is the only primitive candidate for the nephelinite suite. However, in view of the large compositional gap and marked differences in incompatible element ratios, a relation between this flow and the nephelinites remains hypothetical. The variation within the evolved nephelinite series can be partly explained by fractionation of pyroxene, apatite, perovskite (and some nepheline), while magma mixing is indicated by zonation patterns of pyroxene. The most evolved nephelinite, however, differs significantly from all other nephelinites in major and trace elements. Thus the entire sequence is petrologically not a coherent evolution, rather the result of different mantle melts fractionating under variable conditions. Carved into the rift scarp of the study area west of Engare Sero is a young explosion crater, the Sekenge Crater. Sekenge Tuffs are olivine melilitites, similar to other craters and

  10. Carbonate-silicate immiscibility and extremely peralkaline silicate glasses from Nasira cone and recent eruptions at Oldoinyo Lengai Volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Dawson, J. Barry

    2012-11-01

    Phenocrysts of garnet, pyroxene and nepheline in peralkaline nephelinite from the Nasira parasitic cones at Oldoinyo Lengai contain quenched immiscible silicate (peralkalinity = 2-13) and Na-Ca-carbonate melts. Their bulk compositions further define the limits of liquid immiscibility for peralkaline carbonated nephelinite magmas and confirm this process was operative at Oldoinyo Lengai during older stages of activity. Groundmass glasses in Nasira nephelinites are peralkaline (peralkalinity = 5.5-9.5) but less evolved than melt inclusion glasses (peralkalinity = 8-13) in nepheline phenocrysts, implying that these magmas are hybrids formed by magma mixing. Groundmass glass in diverse peralkaline combeite nephelinite ash clasts with and without melilite and/or wollastonite formed in the January-June 2008 eruptions of Oldoinyo Lengai are also exceptionally peralkaline. Two trends in their compositions are evident: (1) increasing peralkalinity from 6 to 10 with SiO2 decreasing from 42 to 33 wt.%; (2) increasing peralkalinity from 6 to 16 with SiO2 decreasing from 45 to 40 wt.%. All recent glasses are considered to be more evolved than groundmass glass in Nasira combeite nephelinite. These data indicate that several varieties of nephelinite exist at Oldoinyo Lengai. Their parental magmas are considered to have been initially enriched in alkalis during partial melting of their metasomatized asthenospheric sources and further by subsequent assimilation, or re-solution, of previously exsolved natrocarbonatite melt in the magma chamber(s) underlying Oldoinyo Lengai. On this basis, none of the bulk compositions of peralkaline stage II lavas at Oldoinyo Lengai, including Nasira, are considered to represent those of liquids as their compositions are determined by rheological factors (phenocryst accumulation; cumulate disruption) and assimilation processes. The formation of combeite is considered to be a consequence of natrocarbonatite melt assimilation.

  11. Primary magmas at Oldoinyo Lengai: The role of olivine melilitites

    NASA Astrophysics Data System (ADS)

    Keller, Jörg; Zaitsev, Anatoly N.; Wiedenmann, Daniel

    2006-10-01

    The paper describes olivine melilitites at Oldoinyo Lengai, Tanzania, and from tuff cones from the Tanzanian rift valley in the vicinity of Oldoinyo Lengai. Oldoinyo Lengai is the only active carbonatite volcano and is distinguished by its alkali-rich natrocarbonatites. Lengai is also unique for its extreme peralkaline silicate lavas related directly to the natrocarbonatites. Primitive olivine melilitites are, according to their Mg# and Ni, Cr contents, the only candidates in the Lengai area for primary melt compositions. Incompatible trace elements, including REE, constrain the melting process in their sub-lithospheric sources to very low degrees of partial melting in the garnet stability field. The strong peralkaline trend at Oldoinyo Lengai is already recognisable in these primary or near-primary melts. More evolved olivine melilitites, with Mg# < 60 allow the fractionation line in its major and trace element expressions to be followed. Nevertheless, a large compositional gap separates the olivine melilitites and olivine-poorer melilitites from the phonolites and nephelinites that form the bulk of the Lengai cone. These silicate lavas show a high degree of peralkalinity and are highly evolved with very low Mg, Ni and Cr. Prominent examples of the recent evolution are the combeite-wollastonite nephelinites that are unique for Lengai. In their Sr, Nd, and Pb isotope relationships the olivine melilitites define a distinct group with the most depleted Sr and Nd ratios and the most radiogenic Pb isotopes. They are closest to a supposed HIMU end member of the Lengai evolution, which is characterised by an extreme spread in isotopic ratios, explained as a mixing line between HIMU and EM1-like mantle components.

  12. ASTER Observations of Recent Thermal Activity and Explosive Eruption at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Vaughan, R. G.; Abrams, M. J.; Kervyn, M.; Hook, S. J.

    2007-12-01

    Oldoinyo Lengai (OL) is the only active volcano in the world that produces natro-carbonatite lava. These carbonate-rich lavas are unique in that they have relatively low temperatures (500-600 C) compared with typical silicate lavas (600-1100 C), and they have a low viscosity, behaving more like a mud flow than a lava flow. OL has been erupting on and off since 1983, mostly resulting in small lava flows, pools and spatter cones (hornitos) confined to the summit crater. Explosive, ash-producing eruptions here are rare, however, an ASTER observation from September 4, 2007 caught the first satellite image of an ash plume erupting from OL, which may be indicative of a new phase of more silica-rich products and explosive activity that has not occurred here since the 1960s. Thermal infrared satellite monitoring has detected an increasing number of thermal anomalies around OL in recent months. MODIS MODVOLC data detected >30 hot spots in the last week of August and first week of September 2007, some of which may have been brush fires started by lava flows or spatter; ASTER detected the appearance of an anomalous hot spot at the summit of OL as early as mid-June. We will present up-to date information about the progress of the eruption and results from the analysis of the spectral composition of new eruption products and thermal anomalies that occurred prior to the recent explosive eruption. OL is one of many volcanoes in the world, and especially Africa, that is not regularly monitored. It is only through sporadic reports from locals or tourists in the area, and satellite data that we know anything at all about this volcanic eruption. Continued satellite monitoring along with studies of past thermal activity will help determine how future eruptions may be forecasted.

  13. Pyroclast texture and chemical composition of the 2007-2008 explosive eruption at Oldoinyo Lengai, Tanzania: Evidence for magma mixing

    NASA Astrophysics Data System (ADS)

    Bosshard, S. A.; Mattsson, H. B.

    2012-12-01

    The last explosive eruption of Oldoinyo Lengai in northern Tanzania started on the night from the 3rd to 4th September 2007 and lasted until April 2008. This eruption terminated 25 years of effusive natrocarbonatitic activity and was at times highly explosive with an eruption plume that reached up to 15 km into the atmosphere. We sampled tephra fallout on September 7th (i.e. on the third day of eruption) with additional samples from the 24th. During fieldwork in May 2011 we measured 140 profiles for their dominating grain size and collected representative samples. The tephra layers show variable grain-sizes from fine ash (< 1mm) to fine lapilli (2-30 mm). Most locations revealed three distinct layers with different dominating grain sizes, but especially on the western flank of the volcano, where the tephra deposits were thicker overall (due to the wind direction during the eruption), up to seven layers with alternating grain-sizes were visible. All pyroclasts are well-rounded with euhedral silicate minerals (commonly nepheline, pyroxene, garnet, wollastonite) in the center, surrounded by a moderately vesiculated melt film. The first tephra fallout contains variable amounts of silicate fragments, natrocarbonatite droplets and a mixture between the two magmas. These deposits are interpreted to reflect incomplete mixing between a natrocarbonatitic and a nephelinitic magma. Tephra collected two weeks later (24th September 2007) have a composition that is consistent with being a hybrid between a nephelinite and a natrocarbonatite. The natrocarbonatitic magma is completely assimilated into the new hybrid magma (tephra of natrocarbonatitic composition is no longer observed). It has previously been suggested that CO2, which exsolved from the natrocarbonatite melt during mixing with more silicic, nephelinitic melt is the driving force for these violent explosive, mixed eruptions. Our data support this hypothesis based on CO2 content, which decreases towards the end of the

  14. Apparent tidal influence on magmatic activity at Oldoinyo Lengai volcano, Tanzania, as observed in Moderate resolution Imaging Spectroradiometer (MODIS) data

    NASA Astrophysics Data System (ADS)

    van Manen, Saskia M.; Kervyn, Matthieu; Blake, Stephen; Ernst, Gerald G. J.

    2010-01-01

    This paper investigates the relative timing of solid Earth tides and thermal anomalies associated with volcanic activity at Oldoinyo Lengai (OL), Tanzania, from 2000 to 2008. The low viscosity of OL's carbonatite magmas may make it particularly susceptible to tidal stresses. Thermal data from the Moderate resolution Imaging Spectroradiometer (MODIS) were filtered using the MODLEN algorithm and Earth tides were modeled using TSoft. Application of the Schuster and Chi-squared tests resulted in apparent correlations between times of thermal anomalies and the phase of the semi-diurnal and biannual solid Earth tides. However, for semi-diurnal and biannual tides limited acquisition times of the MODIS data account for the apparent correlations. Re-examining the data while accounting for the bias introduced by the limited acquisition times, correlations are no longer found. Onset times of eruptive events and times of thermal anomalies show no statistically significant correlation with the fortnightly tide, indicating this is not an influence on activity at OL. Tidal influences on magmatic activity, if at all present, cannot be observed in coarse resolution thermal data on semi-diurnal and fortnightly time scales. Based on the available data, correlations on biannual timescales cannot be ruled out.

  15. Trace element geochemistry of nyerereite and gregoryite phenocrysts from natrocarbonatite lava, Oldoinyo Lengai, Tanzania: Implications for magma mixing

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Kamenetsky, Vadim S.

    2012-11-01

    The abundances of Li, P, Cl, V, Mn, Rb, Sr, Y, Cs, Ba, Pb, Th, U and REE, within and between, phenocrysts of nyerereite and gregoryite occurring in natrocarbonatite lavas erupted from the active volcano Oldoinyo Lengai (Tanzania) have been determined by electron microprobe, LA-ICP-MS and SIMS. These data show that, in general, nyerereite is enriched in Rb (71-137 ppm), Sr (14,485-23,240 ppm), Y (2.0-8.9 ppm), Cs (1.6-5.3 ppm), Ba (4000-11,510 ppm), but poorer in Li (21-91 ppm), P (820-1900 ppm) and V (5.1-47 ppm) relative to gregoryite (Rb = 43-106; Sr = 4255-7275; Y = 0.3-4.0; Cs = 0.6-5.1; Ba = 1125-7052; Li 84-489; P = 6790-15,860; V = 33-155 ppm). Nyerereite is highly enriched in REE (La = 236-973; Ce = 395-1044 ppm) relative to gregoryite (La = 59-309; Ce = 59-301 ppm). Chondrite normalized REE distribution patterns for nyerereite and gregoryite are parallel and linear with no Eu anomalies. They show extreme enrichment in light REE and depletion in heavy REE (nyerereite La/YbCN = 1759-7079; gregoryite La/YbCN = 1051-10,247). Significant differences exist in the abundances of trace elements within and between coexisting crystals occurring in diverse natrocarbonatite flows, although there do not appear to be any significant secular variations in phenocryst compositions in lavas erupted from a given vent. It is concluded that both major, minor and trace element compositional data for nyerereite and gregoryite phenocrysts occurring in natrocarbonatite lavas are derived by the crystallization of several different batches of magma in a continuously replenished fractionating magma chamber. Natrocarbonatite lavas are considered to be hybrids formed by the mixing of both crystals and melts formed from several batches of natrocarbonatite magma; thus bulk rock compositions cannot represent the compositions of the primary magma composition before the onset of fractionation. Differentiation of natrocarbonatite melts leads to enrichment of residua in Ba and Mg.

  16. Silicate-natrocarbonatite liquid immiscibility in 1917 eruption combeite-wollastonite nephelinite, Oldoinyo Lengai Volcano, Tanzania: Melt inclusion study

    NASA Astrophysics Data System (ADS)

    Sharygin, Victor V.; Kamenetsky, Vadim S.; Zaitsev, Anatoly N.; Kamenetsky, Maya B.

    2012-11-01

    Primary silicate-melt and carbonate-salt inclusions occur in the phenocrysts (nepheline, fluorapatite, wollastonite, clinopyroxene) in the 1917 eruption combeite-wollastonite nephelinite at Oldoinyo Lengai. Silicate-melt inclusions in nepheline clearly show liquid immiscibility phenomena expressed in the presence of carbonate globules in silicate glass. The coexistence of inclusions with markedly different proportions of silicate glass + vapor-carbonate globule in the core of nepheline phenocrysts, the presence of carbonate-salt inclusions in fluorapatite and our heating experiments strongly suggest that their entrapment began at temperatures higher than 1130 °C in an intermediate chamber when initial carbonated nephelinite melt was heterogeneous and represented a mixture of immiscible liquids. Silicate-natrocarbonatite melt immiscibility took place at high temperature and immiscible nephelinite and carbonatite liquids coexisted over a wide temperature range from ≥ 1130 °C to 600 °C. Homogenization of a carbonate globule (dissolution of the gas bubble in carbonate melt) at 900-940 °C indicates that after separation from silicate magma the natrocarbonatite represented homogeneous liquid in the 900-1130 °C temperature range, whereas below these temperatures immiscible melts of different composition and fluid phase have separated from it. The bulk composition of homogeneous natrocarbonatite melt may be estimated as ≈ 20% CaF2, 40-60% (Na,K)2CO3 and 20-40% CaCO3 based on the coexistence of nyerereite, calcite and fluorite and the rapid phase transition (carbonate aggregate → carbonate liquid) at 550-570 °C observed in vapor-carbonate globules of nepheline-hosted silicate-melt inclusions and on the Na2CO3-CaCO3-CaF2 phase diagram. Silicate glasses of nepheline-hosted immiscible inclusions drastically differ from host nephelinite in the abundance of major and trace elements. They are high peralkaline ((Na + K)/Al — up to 9.5) and virtually free of water (H2

  17. Emplacement and inflation of natrocarbonatitic lava flows during the March-April 2006 eruption of Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Mattsson, Hannes B.; Vuorinen, Jaana

    2009-04-01

    The most voluminous eruption of natrocarbonatite lava hitherto recorded on Earth occurred at Oldoinyo Lengai in March-April 2006. The lava flows produced in this eruption range from blocky 'a'a type to smooth-surfaced inflated pahoehoe. We measured lava inflation features (i.e. one tumulus and three pressure ridges) that formed in the various pahoehoe flows emplaced in this event. The inflation features within the main crater of Oldoinyo Lengai are relatively small-scale, measuring 1-5 m in width, 2.5-24.4 m in length and with inflation clefts less than 0.4 m deep. Their small sizes are in contrast to a tumulus that formed on the northwestern slope of the volcano (situated ~1140 m below the crater floor). The tumulus is roughly circular, measures 17.5 × 16.0 m, and is cut by a 4.4 m deep axial inflation cleft exposing two separate flow units. We measured the elastic properties (i.e. shear- and bulk moduli) of natrocarbonatitic crust and find that these are similar to those reported for basaltic crust, and that there is no direct correlation between magmastatic head and pressure required to form tumuli. All inflated flows in the 2006 event were confined by lateral barriers (main crater, erosional channel or erosional gully) suggesting that the two most important factors for endogenous growth in natrocarbonatitic lava flows are (1) lateral barriers that prevent widening of the flow, and (2) influx of new material beneath the viscoelastic and brittle crust.

  18. Pyroclast textures in the explosive 2007-2008 eruption of Oldoinyo Lengai, Tanzania: Implications for magma ascent and fragmentation

    NASA Astrophysics Data System (ADS)

    Mattsson, H. B.; Bosshard, S. A.

    2011-12-01

    After more than 25 years of effusive natrocarbonatitic activity the Oldoinyo Lengai (OL) volcano in northern Tanzania started erupting explosively in September 2007. The eruption continued for 8 months and was surprisingly vigorous (occasionally the plume reached up to 15 km in altitude). It has previously been proposed that thermal decomposition of older natrocarbonatites (and release of CO2) inside the main crater of the volcano was responsible for the vigour associated with the explosive 1966-67 eruption. From the recent eruption we sampled the initial ash-fall (3 days after the onset) in Al-canisters during a 24 hour period, which was later complemented by tephra samples collected from 140 profiles around the volcano during a field campaign in May 2011. Petrologically, bulk-rock analyses show a trend from being a mechanical mixture of natrocarbonatitic and nephelinitic material in the beginning of the eruption, to being dominated by nephelinitic composition at the end of the eruption. SEM-studies of the first ash-deposits (i.e., September 7th) show a dominance of non-vesicular natrocarbonatitic droplets (containing nyerereite and gregoryite phenocrysts) mixed with a small amount of sub-spherical nephelinitic pyroclasts with low vesicularity (<25 vol.%). Deposits from the later phases of the eruption (as deduced from the tephra-stratigraphy) are dominated by well-sorted, near-spherical, lapilli. In these deposits, the natrocarbonatitic component is absent and individual tephra layers can be distinguished based on variations in grain-size. SEM studies of pyroclasts reveal that approximately 60% of the lapilli are cored by a crystal (predominantly nepheline, garnet, pyroxene, wollastonite) which is covered by a thin melt film. The nephelinitic melt film varies in vesicularity between 20 and 50 vol.% with a clear predominance of near-spherical vesicle shapes. An abundance of small particles and crystals are adhered/welded to the fluidal outer surface of the

  19. Short-lived decay series disequilibria in the natrocarbonatite lavas of Oldoinyo Lengai, Tanzania: constraints on the timing of magma genesis

    NASA Astrophysics Data System (ADS)

    Pyle, D. M.; Dawson, J. B.; Ivanovich, M.

    1991-08-01

    The 1988 natrocarbonatite lavas from Oldoinyo Lengai volcano, Tanzania have been analysed for 232Th, 230Th, 228Th, 238U, 228Ra/ 226Ra. These lavas are unique, in showing disequilibria between 228Th/ 232Th, and between 228Ra and 232Th. Aa and pahoehoe lavas have a mean ( 228Th 232Th) activity ratio of 5.5 ± 0.6 , and one lava has ( 228Ra/ 226Ra) = 0.11 ± 0.01 . The lavas have ( 230Th/ 238U) ˜ 0.1-0.2 , and [ UTh] weight ratios of 2.0-3.2. Late-stage samples, extruded from the lavas on cooling and interpreted as extreme fractionates of the original lavas are highly enriched in U and Ra relative to Th. These samples have measured [ UTh] weight ratios of 5.6-6.4, and a calculated ( 228Ra/ 232Th) activity ratio of 108 ± 5 . Disequilibria between 238U&z.sbnd; 230Th&z.sbnd; 226Ra are consistent with an origin by immiscibility of 4-22wt% natrocarbonatite from nephelinite magma. Disequilibria between 232Th&z.sbnd; 228Ra&z.sbnd; 228Th are consistent with either of two endmember models: (1) instantaneous separation of magma at depth, with eruption 20 ± 1 years later; (2) recharging of a steady-state magma chamber below Oldoinyo Lengai with a maximum volume of 1.5 ± 0.2 × 10 7 m 3 of carbonatite, and a mean magma residence time of 81 ± 9 years. The total time between natrocarbonatite generation and eruption is between 20 and 81 years.

  20. Magma mixing and forced exsolution of CO2 during the explosive 2007-2008 eruption of Oldoinyo Lengai (Tanzania)

    NASA Astrophysics Data System (ADS)

    Bosshard-Stadlin, Sonja A.; Mattsson, Hannes B.; Keller, Jörg

    2014-09-01

    Oldoinyo Lengai is probably most famous for being the only active volcano on Earth which is erupting natrocarbonatitic magma. However, the mildly explosive natrocarbonatitic activity is alternating with highly explosive, nephelinitic eruptions of which the most recent episode occurred in September 2007 (and lasted until April 2008). Here we present petrographic observations, mineral chemistry as well as major- and trace element analyses of samples covering the evolution of the eruption with time. In the early phases of the eruption, the phenocryst assemblages are dominated by the carbonate minerals nyerereite and gregoryite, but as the eruption progresses the mineralogy becomes dominated by silicate minerals like nepheline, pyroxene, garnet, alumoåkermanite, combeite and wollastonite. The observed major- and trace element variations during the 2007-2008 eruption indicate mixing between a natrocarbonatitic magma and a combeite-wollastonite-bearing nephelinitic magma (CWN), with higher portions of natrocarbonatite in the early stages of the eruption. Euhedral and uncorroded clinopyroxene crystals are abundant in the late 2007 deposits but quickly start to break-down and corrode as the eruption continues, indicating that the natrocarbonatite and the CWN are not in fact conjugate magmas derived from a single magma reservoir, but must have evolved separately in the crust from the point of immiscibility. When these magmas interact beneath the volcano, a hybrid silicate magma forms (where clinopyroxene is no longer stable) and the composition of this hybrid causes the overall solubility of CO2 in the system to decrease drastically. This results in rapid exsolution of CO2 (g) which is allowed to expand during ascent, and we conclude that this is most likely the reason behind the unexpected vigor in the explosive eruptions of Oldoinyo Lengai. This massive release of CO2 during ascent may also explain the petrographic features of the pyroclasts as these are dominated by

  1. Mineralogical and geochemical characterization of ashes from an early phase of the explosive September 2007 eruption of Oldoinyo Lengai (Tanzania)

    NASA Astrophysics Data System (ADS)

    Mattsson, Hannes B.; Reusser, Eric

    2010-12-01

    Ashes from Oldoinyo Lengai were collected four days after the onset of the recent explosive episode (i.e., on September 7th 2007). The ash is composed of poorly-vesicular natrocarbonatite droplets, vesicular microcrystalline nephelinite shards, and a mixed variety containing both silicate and carbonate minerals in variable proportions. Simple mixing calculations show that the whole-rock composition of the ashes can be explained by mixing natrocarbonatite and nephelinite magmas with a ratio of 4:1. The dominant silicate minerals are clinopyroxene, nepheline, Ti-andradite, wollastonite and alumoåkermanite. Ti-magnetite is the most common oxide mineral. This mineral assemblage is similar to that present in the 1966 eruption products. In contrast to the 1966-1967 explosive eruption where clinopyroxene is resorbed and corroded, the ashfall from September 7th contains a large amount of euhedral clinopyroxene crystals, suggesting that magma mixing was heterogeneous and incomplete in this initial stage of the eruption. This is also supported by the petrography of the ashes. The composition of the dominant carbonate minerals (i.e., gregoryite and nyerereite) and the fluidal textures of the natrocarbonatite droplets suggest mixing of higher-viscosity nephelinite and low-viscosity natrocarbonatite magmas. Characteristic carbonate minerals produced by alteration cannot be found in the ashes. This suggests limited interaction with the older, pre-existing, natrocarbonatites inside the summit crater of the volcano. The carbonate minerals show textural evidence of being partially resorbed into the hotter nephelinitic magma. At least part of this decomposition of carbonate phases (releasing CO 2 and contributing to increased explosivity) must have occurred within the volcanic edifice such that the released gas is allowed to expand during decompression.

  2. Salt-bearing fumarole deposits in the summit crater of Oldoinyo Lengai, Northern Tanzania: interactions between natrocarbonatite lava and meteoric water

    NASA Astrophysics Data System (ADS)

    Genge, M. J.; Balme, M.; Jones, A. P.

    2001-04-01

    Oldoinyo Lengai in the Northern Tanzania rift is the only active nephelinite-carbonatite stratovolcano. We report the discovery of thermonatrite, aphthitalite, halite and sylvite fumarole deposits on recent natrocarbonatite lava flows erupted in the summit crater during the wet season. These salt deposits occur as delicate, concave fringes or tubes that line the cooling cracks in the lava flows and consist of intergrowths of euhedral crystals. The presence of a dark altered zone, depleted in halides and alkalies, adjacent to cooling cracks and observations of steam fumaroles emanating from the fractures suggest that the salts are formed by sublimation from saturated vapours generated by the extrusion of lavas over meteoric water. The crystallisation sequence recorded in the salts suggests that mixing between meteoric steam and magmatic CO 2 and H 2S occurs at high temperatures resulting in the sublimation of carbonates and sulphates. At lower temperatures the vapours are dominated by meteoric steam and sublimate halides. The high solubility of the fumarole salts within meteoric water and their formation only during the wet season implies that these are ephemeral deposits that are unlikely to be preserved in the geological record.

  3. Upper-mantle volatile chemistry at Oldoinyo Lengai volcano and the origin of carbonatites.

    PubMed

    Fischer, T P; Burnard, P; Marty, B; Hilton, D R; Füri, E; Palhol, F; Sharp, Z D; Mangasini, F

    2009-05-01

    Carbonatite lavas are highly unusual in that they contain almost no SiO(2) and are >50 per cent carbonate minerals. Although carbonatite magmatism has occurred throughout Earth's history, Oldoinyo Lengai, in Tanzania, is the only currently active volcano producing these exotic rocks. Here we show that volcanic gases captured during an eruptive episode at Oldoinyo Lengai are indistinguishable from those emitted along mid-ocean ridges, despite the fact that Oldoinyo Lengai carbonatites occur in a setting far removed from oceanic spreading centres. In contrast to lithophile trace elements, which are highly fractionated by the immiscible phase separation that produces these carbonatites, volatiles (CO(2), He, N(2) and Ar) are little affected by this process. Our results demonstrate that a globally homogenous reservoir exists in the upper mantle and supplies volatiles to both mid-ocean ridges and continental rifts. This argues against an unusually C-rich mantle being responsible for the genesis of Na-rich carbonatite and its nephelinite source magma at Oldoinyo Lengai. Rather, these carbonatites are formed in the shallow crust by immiscibility from silicate magmas (nephelinite), and are stable under eruption conditions as a result of their high Na contents. PMID:19424154

  4. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania. II. Eruptive behaviour during the 2007-2008 explosive eruptions

    NASA Astrophysics Data System (ADS)

    Kervyn, Matthieu; Ernst, Gerald G. J.; Keller, Jörg; Vaughan, R. Greg; Klaudius, Jurgis; Pradal, Evelyne; Belton, Frederic; Mattsson, Hannes B.; Mbede, Evelyne; Jacobs, Patric

    2010-10-01

    On September 4, 2007, after 25 years of effusive natrocarbonatite eruptions, the eruptive activity of Oldoinyo Lengai (OL), N Tanzania, changed abruptly to episodic explosive eruptions. This transition was preceded by a voluminous lava eruption in March 2006, a year of quiescence, resumption of natrocarbonatite eruptions in June 2007, and a volcano-tectonic earthquake swarm in July 2007. Despite the lack of ground-based monitoring, the evolution in OL eruption dynamics is documented based on the available field observations, ASTER and MODIS satellite images, and almost-daily photos provided by local pilots. Satellite data enabled identification of a phase of voluminous lava effusion in the 2 weeks prior to the onset of explosive eruptions. After the onset, the activity varied from 100 m high ash jets to 2-15 km high violent, steady or unsteady, eruption columns dispersing ash to 100 km distance. The explosive eruptions built up a ˜400 m wide, ˜75 m high intra-crater pyroclastic cone. Time series data for eruption column height show distinct peaks at the end of September 2007 and February 2008, the latter being associated with the first pyroclastic flows to be documented at OL. Chemical analyses of the erupted products, presented in a companion paper (Keller et al. 2010), show that the 2007-2008 explosive eruptions are associated with an undersaturated carbonated silicate melt. This new phase of explosive eruptions provides constraints on the factors causing the transition from natrocarbonatite effusive eruptions to explosive eruptions of carbonated nephelinite magma, observed repetitively in the last 100 years at OL.

  5. Trace- and rare-earth-element geochemistry of the June 1993 natrocarbonatite lavas, Oldoinyo Lengai (Tanzania): Implications for the origin of carbonatite magmas

    NASA Astrophysics Data System (ADS)

    Simonetti, Antonio; Bell, Keith; Shrady, Catherine

    1997-01-01

    Major-, trace- and rare-earth-element data from ten natrocarbonatite lavas collected during the June 1993 extrusive activity define two distinct groups. Although both groups are characterized by low Nb and Zr contents, and low Th/U (~1.0); Ba/Sr>1.0; (La/Sm) N>40; high Ba, Mo, Sr, W contents; and LREE contents ~1000 to 2000×chondrite, one group has much higher Al 2O 3, Fe 2O 3, Nb, Pb, SiO 2, Zr and total REEs contents. These differences are attributed to the presence of silicate spheroids in natrocarbonatites that form within the latter group. Similarity in trace- and rare-earth-element-normalized patterns for both groups of natrocarbonatite lavas suggest either a common source or generation from a common parental melt. Models proposed for the origin of natrocarbonatites include immiscible separation from a peralkaline, silicate magma, or late-stage fractionation from a parent olivine sövite magma. Although natrocarbonatite melt formation may be controlled by either of these differentiation processes, certain trace-element ratios for the 1993 lavas, such as Ce/Pb (~9), and Th/Nb (~0.1) are similar to those estimated for primitive mantle, and their Sm/Nd ratios (~0.07) are quite different to the average value of 0.15 for most carbonatites world-wide. The similarity in element ratios in many of the older silicate lavas at Oldoinyo Lengai (e.g., Zr/Nb, La/Nb, Ba/Nb, Rb/Nb, and Ba/La) to those estimated for HIMU and EM I suggest that source characteristics can be reflected in such melts. Even if the natrocarbonatites are formed by liquid immiscibility, recent experiments have shown that partition coefficients for trace elements (e.g., Ba, Ce, Mo, Nb, Pb, Th, U) between conjugate carbonate and silicate melts approach unity with increasing temperature. Alternatively, the similarity in trace-element ratios between those for the silicate lavas from Oldoinyo Lengai and mantle components are simply fortuitous.

  6. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania. I. New magma composition during the 2007-2008 explosive eruptions

    NASA Astrophysics Data System (ADS)

    Keller, Jörg; Klaudius, Jurgis; Kervyn, Matthieu; Ernst, Gerald G. J.; Mattsson, Hannes B.

    2010-10-01

    With a paroxysmal ash eruption on 4 September 2007 and the highly explosive activity continuing in 2008, Oldoinyo Lengai (OL) has dramatically changed its behavior, crater morphology, and magma composition after 25 years of quiet extrusion of fluid natrocarbonatite lava. This explosive activity resembles the explosive phases of 1917, 1940-1941, and 1966-1967, which were characterized by mixed ashes with dominantly nephelinitic and natrocarbonatitic components. Ash and lapilli from the 2007-2008 explosive phase were collected on the slopes of OL as well as on the active cinder cone, which now occupies the entire north crater having buried completely all earlier natrocarbonatite features. The lapilli and ash samples comprise nepheline, wollastonite, combeite, Na-åkermanite, Ti-andradite, resorbed pyroxene and Fe-Ti oxides, and a Na-Ca carbonate phase with high but varying phosphorus contents which is similar, but not identical, to the common gregoryite phenocrysts in natrocarbonatite. Lapilli from the active cone best characterize the erupted material as carbonated combeite-wollastonite-melilite nephelinite. The juvenile components represent a fundamentally new magma composition for OL, containing 25-30 wt.% SiO2, with 7-11 wt.% CO2, high alkalies (Na2O 15-19%, K2O 4-5%), and trace-element signatures reminiscent of natrocarbonatite enrichments. These data define an intermediate composition between natrocarbonatite and nephelinite, with about one third natrocarbonatite and two thirds nephelinite component. The data are consistent with a model in which the carbonated silicate magma has evolved from the common combeite-wollastonite nephelinite (CWN) of OL by enrichment of CO2 and alkalies and is close to the liquid immiscible separation of natrocarbonatite from carbonated nephelinite. Material ejected in April/May 2008 indicates reversion to a more common CWN composition.

  7. Changes in the crater of Oldoinyo Lengai: June 1993 - February 1997

    NASA Astrophysics Data System (ADS)

    Nyamweru, Celia

    1997-07-01

    The summit crater of the volcano Oldoinyo Lengai in the Rift Valley of northern Tanzania has been the site of numerous minor eruptions of highly fluid carbonatite lava since activity resumed in early 1983. In June 1993 the nature of the activity appeared to change, in that (1) explosive activity produced ash fall on the outer slopes of the cone, (2) eruptive vents formed on the southern part of the summit crater floor, rather than on its northern or central sectors as had previously been the case, and (3) large, highly viscous flows were formed. These changes gave rise to expectations that the volcano was entering a new phase in its activity, and that major explosive activity might be anticipated in the near future. To date, major explosive activity has not taken place. On numerous occasions since June 1993, liquid lava has been observed in the summit crater, and the activity appears to have resumed its former characteristics. Eye-witness reports and photographs are used to illustrate the activity that has occurred in the summit crater between June 1993 and early 1997.

  8. Peralkaline nephelinites. I. Comparative petrology of Shombole and Oldoinyo L'engai, East Africa

    NASA Astrophysics Data System (ADS)

    Peterson, Tony D.

    1989-04-01

    Shombole, a nephelinite-carbonatite volcano in south Kenya, erupted silicate lavas, carbonatite dikes and tuffs, and pyroclastic rocks similar to those at other East African alkaline centres. Shombole lavas containing cpx + nepheline + accessory minerals range from perovskite-bearing nephelinites (43% SiO2, volatile-free) to sphene-bearing and phonolitic nephelinites (46 49% SiO2) and phonolites (49 56% SiO2) and have low peralkalinity ([Na+K]/Al ≈ 1.15) which does not correlate with SiO2. Early fractionation of olivine and clinopyroxene strongly depleted Ni and Cr concentrations (≈10 ppm); fractionation of perovskite, melanite, sphene, and apatite produced negative correlations of all REE with SiO2. Many lavas contain cognate intrusive xenoliths and xenocrysts and oscillatory zoning is a common feature of clinopyroxene, nepheline, and melanite crystals, indicating recycling of intrusive material. Irregular calcite-rich bodies in many samples are interpreted as quenched immiscible Ca-carbonatite liquid, and [Ca-carbonate]-silicate liquid immiscibility is observed in experiments with one nephelinite. Chemical variation in the Shombole suite can be modeled as a combination of crystal fractionation (clinopyroxene and heavy minor phases) and retention of neutral density nepheline derived from disaggregated xenoliths entrained during emplacement of dike swarms. Six newly analyzed lavas from Oldoinyo L'engai, northern Tanzania, are geochemically similar to Shombole nephelinites except that they have relatively high Na2O+K2O (average 18% vs 12%) and Zr (average 680 ppm vs 400 ppm). They are extremely peralkaline and are not typical of nephelinites from other centres. Three with [Na+K]/Al≈1.5 contain euhedral wollastonite phenocrysts; three with [Na+K]/Al≈2.0 contain combeite (Na2Ca2Si3O9) phenocrysts and pseudomorphs after wollastonite. Both types contain abundant sodalite phenocrysts (+nepheline+clinopyroxene+melanite+sphene). Seven other wollastonite nephelinite

  9. Vapour transport of rare earth elements (REE) in volcanic gas: Evidence from encrustations at Oldoinyo Lengai

    NASA Astrophysics Data System (ADS)

    Gilbert, C. D.; Williams-Jones, A. E.

    2008-10-01

    Fumarolic encrustations and natrocarbonatite lava from the active crater of Oldoinyo Lengai volcano, Tanzania, were sampled and analysed. Two types of encrustation were distinguished on the basis of their REE content, enriched (~ 2800-5600 × [REE chondrite]) and depleted (~ 100-200 × [REE chondrite]) relative to natrocarbonatite (1700-1900 × [REE chondrite]. REE-enriched encrustations line the walls of actively degassing fumaroles, whereas REE-depleted encrustations occur mainly along cracks in and as crusts on cooling natrocarbonatite lava flows; one of the low REE encrustation samples was a stalactite from the wall of a possible fumarole. The encrustations are interpreted to have different origins, the former precipitating from volcanic gas and the latter from meteoric/ground water converted to steam by the heat of the overlying lava flow(s). REE-profiles of encrustations and natrocarbonatite are parallel, suggesting that there was no preferential mobilization of specific REE by either volcanic vapour or meteoric water vapour. The elevated REE-content of the first group of encrustations suggests that direct REE-transport from natrocarbonatite to volcanic vapour is possible. The REE trends observed in samples precipitating directly from the volcanic vapour cannot be explained by dry volatility based on the available data as there is no evidence in the encrustation compositions of the greatly enhanced volatility predicted for Yb and Eu. The observed extreme REE-fractionation with steep La/Sm slopes parallel to those of the natrocarbonatite reflects solvation and complexation reactions in the vapour phase that did not discriminate amongst the different REE or similar transport of REE in both the natrocarbonatite magma and its exsolving vapour. The low concentrations of REE in the encrustations produced by meteoric vapour suggest that the temperature was too low or that this vapour did not contain the ligands necessary to permit significant mobilization of the REE.

  10. Volatile Chemistry of the 2007 to Present Explosive Eruption of Oldoinyo Lengai Volcano, East African Rift

    NASA Astrophysics Data System (ADS)

    de Moor, J.; Fischer, T. P.; King, P. L.; Sharp, Z.; Shaw, A. M.; Mangasini, F.

    2008-12-01

    We characterize the volatile chemistry of the ongoing explosive eruption at Oldoinyo Lengai (OL) in the Gregory Rift Valley of N Tanzania. Fieldwork was conducted from 4-8 April 2008, during which time OL exhibited Strombolian to ash plume-producing activity. Eight distinct ash lapilli layers were sampled 900m from the crater. Mini-DOAS SO2 flux measurements were conducted on 6, 7, and 8 April. Despite moderate eruptive activity, SO2 concentrations were very low, from ~ 20ppm.m to below detection. A low concentration plume was detected on 7 April, allowing a SO2 flux estimate of 0.2-0.4 tons/day. SIMS analyses of carbonatite lavas erupted in 2005 show very high S concentrations (0.62wt %), suggesting that the low SO2 flux is due to partitioning of S into the melt. Ash leachates were analyzed as a proxy for plume chemistry and to assess health risks associated with mobile elements in the ashes. The solutions had high pH of 10.6 to 11.1. This has implications for pH fluctuations of Lake Natron (pH ~10; located 20km N of the crater), which may correlate with lacustrine ash deposition during passed explosive activity at OL. In the uppermost ash layer (deposited on 4/5/2008; not influenced by rain) dominant mobile ions are Cl (18120mg/kg), SO4 (26616mg/kg), PO4 (2393mg/kg), and F (534mg/kg), Na (101679mg/kg), K (22544mg/kg), Ca (721mg/kg), and Si (189mg/kg). Leachate S/Cl from this pristine ash is 0.49, compared to 0.29 measured by SIMS in lavas from 2005. Using the SO2 flux and the S/Cl in the leachates, the Cl flux was 0.5-0.8 tons/day. High concentrations of leachable ions, particularly F, on ash presents health hazards (F poisoning; water source contamination) to local communities. Concentrations in the underlying ashes are lower (40-129 mg/kg Cl, 965-3223 mg/kg SO4 , 66-104 mg/kg F, 40-335 mg/kg PO4 ) than those in the upper deposit due to leaching by rain prior to deposition of the uppermost ash layer. FTIR spectroscopy of ashes shows at least two carbonate

  11. Rift initiation in cratonic lithosphere: Seismicity patterns in the Manyara-Natron-Magadi basins and Oldoinyo Lengai volcano

    NASA Astrophysics Data System (ADS)

    Lambert, C.; Rodzianko, A.; Rasendra, N.; Msabi, M.; Muirhead, J.; Ebinger, C. J.; Tiberi, C.; Roecker, S. W.; Ferdinand, R. W.; Mtelela, K.; Muzuka, A.

    2013-12-01

    The CRAFTI project consists of a 2-year seismic acquisition program to quantify the partitioning of strain between faulting and magmatism during the early stages of continental rifting in Archaean and Proterozoic lithosphere. The <7 My Eastern Rift System in northern Tanzania and southern Kenya provides an ideal study system, as it comprises several rift segments at different stages of the rifting cycle. We present preliminary results from 38 broadband seismometers deployed in Tanzania in January 2013, and 4 stations in Kenya deployed in July 2013. The network includes a rift-perpendicular transect, and spans parts of 3 discrete rift basins in different stages of development: Manyara, Natron, Magadi. Initial analyses indicate relatively low noise levels at all stations deployed in Maasai bomas and rural schools, and good to excellent transmission, except near Quaternary Gelai, Oldoinyo Lengai, and Kitumbeine volcanoes. We present time-space relations of seismicity for the first 6 months' of data, and focal mechanisms for the largest events during that time period. Hypocentral locations are compared with the locations of eruptive centers, dike intrusions, and sub-surface projections of faults mapped in a complementary part of the CRAFTI project. The spatial and temporal distribution of earthquake activity will help identify the contributions of faulting and magmatism in each basin, and in the identification of subsurface magma reservoirs in this youthful rift system.

  12. Voluminous lava flows at Oldoinyo Lengai in 2006: chronology of events and insights into the shallow magmatic system

    NASA Astrophysics Data System (ADS)

    Kervyn, Matthieu; Ernst, Gerald G. J.; Klaudius, Jurgis; Keller, Jörg; Kervyn, François; Mattsson, Hannes B.; Belton, Frederic; Mbede, Evelyne; Jacobs, Patric

    2008-09-01

    The largest natrocarbonatite lava flow eruption ever documented at Oldoinyo Lengai, NW Tanzania, occurred from March 25 to April 5, 2006, in two main phases. It was associated with hornito collapse, rapid extrusion of lava covering a third of the crater and emplacement of a 3-km long compound rubbly pahoehoe to blocky aa-like flow on the W flank. The eruption was followed by rapid enlargement of a pit crater. The erupted natrocarbonatite lava has high silica content (3% SiO2). The eruption chronology is reconstructed from eyewitness and news media reports and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data, which provide the most reliable evidence to constrain the eruption’s onset and variations in activity. The eruption products were mapped in the field and the total erupted lava volume estimated at 9.2 ± 3.0 × 105 m3. The event chronology and field evidence are consistent with vent construct instability causing magma mixing and rapid extrusion from shallow reservoirs. It provides new insights into and highlights the evolution of the shallow magmatic system at this unique natrocarbonatite volcano.

  13. The Li isotopic composition of Oldoinyo Lengai: Nature of the mantle sources and lack of isotopic fractionation during carbonatite petrogenesis

    NASA Astrophysics Data System (ADS)

    Halama, Ralf; McDonough, William F.; Rudnick, Roberta L.; Keller, Jörg; Klaudius, Jurgis

    2007-02-01

    Lithium concentrations and Li isotope compositions are reported for natrocarbonatites and silicate lavas from Oldoinyo Lengai, Tanzania. Natrocarbonatites are characterized by very high Li contents (211-294 ppm) and a narrow range of δ7Li values between + 3.3 and + 5.1. These Li isotope compositions overlap with those reported for MORB and OIB and suggest that the natrocarbonatites reflect the Li isotopic composition of their mantle source. Co-genetic silicate lavas, covering a wide compositional spectrum, show no obvious isotopic fractionation as a function of igneous differentiation or liquid immiscibility. Primitive olivine melilitites (Mg# = 58-70), considered to be parental magmas, contain 14-23 ppm Li and have δ7Li values of + 2.4 to + 4.4. A highly differentiated, peralkaline nephelinite (Mg# = 12), likely to be related to the natrocarbonatites by liquid immiscibility, has about twice as much Li as the melilitite (57 ppm), but a similar isotopic composition (δ7Li = + 3). In contrast, a phonolite with 15 ppm Li has a lighter Li isotope composition (δ7Li = - 0.4), which may reflect assimilation of isotopically light lower crustal mafic granulites, a conclusion supported by radiogenic isotope data. Clinopyroxene and olivine separates from the silicate lavas have uniformly lower Li concentrations (3-15 ppm) and lower δ7Li values (δ7Li = - 2.9 to - 0.5) than the respective whole-rocks, with Δ7Liwhole-rock-mineral between 1.4 and 6.3. This difference between whole-rock and mineral data is interpreted to reflect diffusion-driven isotopic fractionation.

  14. Evolution of a magma-driven earthquake swarm and triggering of the nearby Oldoinyo Lengai eruption, as resolved by InSAR, ground observations and elastic modeling, East African Rift, 2007

    NASA Astrophysics Data System (ADS)

    Baer, G.; Hamiel, Y.; Shamir, G.; Nof, R.

    2008-07-01

    An earthquake swarm struck the North Tanzania Divergence, East African Rift over a 2 month period between July and September 2007. It produced approximately 70 M > 4 earthquakes (peak magnitude Mw 5.9), and extensive surface deformation, concurrent with eruptions at the nearby Oldoinyo Lengai volcano. The spatial and temporal evolution of the entire deformation event was resolved by Interferometric Synthetic Aperture Radar (InSAR) observations, owing to a particularly favorable acquisition programming of the Envisat and ALOS satellites, and was verified by detailed ground observations. Elastic modeling based on the InSAR measurements clearly distinguishes between normal faulting, which dominated during the first week of the event, and intermittent episodes of dike propagation, oblique dike opening and dike-induced faulting during the following month. A gradual decline in the intensity of deformation occurred over the final weeks. Our observations and modeling suggest that the sequence of events was initiated by pressurization of a deep-seated magma chamber below Oldoinyo Lengai which opened the way to lateral dike injection, and dike-induced faulting and seismicity. As dike intrusion terminated, silicate magma ascended the volcano conduit, reacted with the carbonatitic magma, and set off a major episode of explosive ash eruptions producing mixed silicate-carbonatitic ejecta. The rise of the silicate magma within the volcano conduit is attributed to bubble growth and buoyancy increase in the magma chamber either due to a temporary pressure drop after the termination of the diking event, or due to the dynamic effects of seismic wave passage from the earthquake swarm. Similar temporal associations between earthquake swarms and major explosive ash eruptions were observed at Oldoinyo Lengai over the past half century.

  15. Oldoinyo Lengai gas chemistry from 2005 to 2009: Insights to carbonatite-nephelinite volcanism

    NASA Astrophysics Data System (ADS)

    Fischer, T. P.; Burnard, P.; Marty, B.; de Moor, J.; Hilton, D. R.; Shaw, A. M.; Barry, P. H.; Ramirez, C.; Mangasini, F.

    2009-12-01

    The African Rift valleys are sites of carbonatite-nephelinite volcanic complexes. Oldoinyo Lengai (OL), the cone that rises to nearly 3000 m above Tanzania’s Rift Valley, is the world’s only active carbonatite volcano. Explosive eruptions have occurred at OL in 1966, 1983 [1] and 1993 [2] producing ash, cones and natrocarbonatite tephra. From Sept. 2007 to Nov. 2008, OL erupted explosively forming a ~60 m high ash cone. The magma composition of these eruptions is nephelinite mixed with carbonatite [3]. In June 2009, we observed a carbonatite lava lake at the bottom of the ~100m deep crater. Volcanic products at OL have therefore transitioned from carbonatite erupted in 2005/06 to nephelinite back to carbonatite in three years; a tribute to the highly dynamic nature of the volcano. We collected samples from crater fumaroles in July 2005, May 2006 and June 2009, spanning the volcanoes recent cycle of activity. The gas composition of all samples is dominated by H2O (meteoric) and CO2. S, HCl, and HF contents are < 1 mol%. Hydrogen and CO contents of 0.1 - 0.2 mol% and 0.0015 - 0.025 mol% respectively show the reduced nature of the gases consistent with H2S being the dominant S species. The CO2/S and CO2/HCl ratios of gases are lower than those of carbonatite magmas which contain up to 8000 ppm S and Cl suggesting that carbonatite acts as a condensor for S and Cl (see also [3]). Isotopic compositions of He, N2, Ar, C show that the mantle below OL is characterized by volatiles indistinguishable from those of MORB sources [4]. H2-H2O redox conditions indicate equilibrium with the ‘rock-buffer’ commonly controlling gases associated with silicic magmas [5]. Gas equilibrium temperatures from ~ 400C to 600C are similar to carbonatite magmas (540C). The 2009 gases have CO2/S ratios that are higher by factor of 10 than those collected in the 2005 and 2006, suggesting efficient condensation of S into the erupting carbonatite ~ 100 m below the sampling locality

  16. Multi-phase saturation experiments on the Oldoinyo Lengai natrocarbonatite lavas: derived from a sodic-potassic calciocarbonatite through fractionation

    NASA Astrophysics Data System (ADS)

    Weidendorfer, D.; Schmidt, M. W.; Mattsson, H. B.

    2015-12-01

    Typical natrocarbonatite eruption temperatures are 490-595°C and are at least 200-300°C lower than temperatures for any suitable silicic liquid that could be conjugate across a miscibility gap. In particular, the 2007 Oldoinyo Lengai (OL) eruption delivered a mix of nephelinitic and carbonatite melts, supporting the commonly accepted supposition that carbonatites are conjugate to spatially associated peralkaline nephelinites. We constrain possible parental melt compositions of the natrocarbonatites by saturation with calcite, apatite, cpx, wollastonite, nepheline, combeite or nyerereite (at 1 kbar, 650-1200°C, fast-quench cold-seal vessels); all occurring in the silicate or carbonatite rocks of OL The results show that the natrocarbonatite is highly undersaturated in calcite and apatite. At 1200°C, calcite saturation results in decreasing Na2O+K2O from initially 41.5 to 10.3 wt% while the CaCO3-component is increased to 80 wt%. In the complex system, there is no thermal (nyerereite-fairchildite) maximum, hence fractionation of calcite+apatite may proceed from a parent melt with 15 wt% alkali and 70% Ca-component to the observed OL natrocarbonatites. The observed melt inclusions in phenocrysts in the nephelinites at Keramasi (Guzmics et al. 2012, CMP) would serve as ideal parents, these melt compositions correspond to 1050oC. The modelled liquid line of descent along the calcite surface requires a total fractionation of ~48% calcite and ~9 wt% apatite. SiO2 solubility only increases from 0.2-2.9 wt% at 750-1200°C, leaving little leeway for reaction with silicates. A peritectic reaction among the above silicates conserving the Si-content in the carbonatite could not be identified. At >950°C cpx yields, through peritectic melting, an immiscible peralkaline silicate melt + extensive wollastonite (as observed in OL cumulates). This experimental silicate melt resembles the unusual silicate ash compositions from the 2007 eruption. The natrocarbonatite lavas from OL

  17. Crystallization, Fluid Exsolution, and Eruption of Extremely Volatile-rich Silicate Magma at Oldoinyo Lengai Volcano, East African Rift

    NASA Astrophysics Data System (ADS)

    de Moor, J.; Fischer, T. P.; King, P. L.; Hervig, R. L.; Hilton, D. R.

    2011-12-01

    Oldoinyo Lengai volcano (OL) is famous for producing natrocarbonatite (NC) lava flows, yet its magmatic products are volumetrically dominated by silicate pyroclastic deposits [1]. After ~25 years of NC effusion, OL erupted explosively in 2007-2008 to produce nephelinite ash. NC effusion resumed in 2009, completing the typical historical eruptive cycle observed at OL [2]. Here we investigate the processes of magma differentiation and volatile exsolution resulting in this behavior through the study of major, trace, and volatile element compositions of nepheline-hosted melt inclusions (MI) and matrix glass (MG) in nephelinite scoria erupted in 2007-2008. The nephelinite scoria are extremely crystal rich, with nepheline and clinopyroxene dominating the phenocryst assemblage. Other phenocryst and accessory minerals include garnet, wollastonite, combeite, melilite, and sulfides. The glasses span a wide range in composition and define a cohesive evolutionary trend of decreasing SiO2 from ~46 wt% in the MI to ~38 wt% in the MG. The decrease in SiO2 is accompanied by strong enrichment in alkalis and depletion in Al2O3, resulting in extremely peralkaline MG. Rare earth elements and other incompatible elements are also strongly enriched in the MG relative to the MI. For example, the least evolved MI contain ~55 ppm Ce whereas the MG attains concentrations of >1000 ppm. Fractional crystallization modeling indicates that the evolutionary trends observed in the major element data are consistent with ~90% crystallization of the melt between the time of MI entrapment and eruption. The MI are exceptionally rich in volatiles and contain the highest CO2 concentrations (up to 2.5 wt%) ever measured in natural silicate glass, high H2O (up to 6 wt%), and high S (0.3-1.3 wt%). Immiscible NC coexists with nephelinite glass in many MI, providing clear evidence that the NC lavas and nephelinitic pyroclastics at OL are derived from a common magma [3]. The silicate MI are extremely CO2-rich

  18. New geologic map and radiometric ages, Oldonyo Lengai volcano and vicinity, United Republic of Tanzania

    NASA Astrophysics Data System (ADS)

    Sherrod, D. R.; Huard, J.; Magigita, M.; Kwelwa, S.

    2012-12-01

    A new 1:50,000-scale geologic map of Oldonyo Lengai volcano and its basin northward 20 km to Lake Natron encompasses 570 sq km in the Arusha district of Tanzania. Field work spanned a six-week period during February-March 2010. Stratigraphic units, ranging in age from Pliocene to Holocene, are chiefly volcanogenic, including interlayered lava flows, tuff, and sedimentary deposits in adjacent fault blocks and the full extent of debris-avalanche deposits spawned by Oldonyo Lengai itself. The essential geologic story could have been gleaned from existing published literature, but no map was available previously as a useful compilation and guide for exploration across the basin. New 40Ar/39Ar plateau ages (and 2σ analytical error) indicate the that Oldonyo Lengai's edifice has been part of the landscape for more than 500,000 years. Alkali feldspar and phlogopite from a phonolite lava flow (lat -2.7718°, long 35.9497° WGS84) and tuff cone (-2.7578°, 35.9501°), respectively, on the lower east flank of Oldonyo Lengai, yielded ages of 338±23 and 353±65 ka. These two units are at similar altitude and, presumably, stratigraphic position. An age of 340±85 ka was obtained from the glassy groundmass in a lava flow in the Natron-Engaruka volcanic field, sampled 8 km east-northeast of Oldonyo Lengai near Sidan Ndare stream (-2.7283°, 35.9829°). Stratigraphically incorrect ages, older than 1 Ma, came from efforts to date nepheline and groundmass from a nephelinite lava flow high on the Oldonyo Lengai cone, within the Eastern Chasm. Six Oldonyo Lengai-sourced debris-avalanche deposits were mapped, including a previously unrecognized sequence that was emplaced during a much higher stand of nearby Lake Natron. Phlogopite from tuff blocks within this oldest debris-avalanche deposit yielded an age of 793±63 ka (-2.6373°, 35.9837°). An age of 460±75 ka from the stratigraphically younger, most widely exposed, of the Oldonyo Lengai debris avalanche deposits also came from

  19. Olivine-mica pyroxenite xenoliths from northern Tanzania: metasomatic products of upper-mantle peridotite

    NASA Astrophysics Data System (ADS)

    Dawson, J. B.; Smith, J. V.

    1992-04-01

    Olivine-mica-pyroxene blocks in Neogene pyroclastics from Oldoinyo Lengai and Loluni, Tanzania, result from K, Ca, Fe, Ti, Al, REE, Cl, F and OH metasomatism of upper-mantle peridotite. Deformed olivine relicts and high Cr and Ni in bulk-rock analyses indicate a peridotite precursor.

  20. Preferential Weathering of Carbonatite Lava at Ol Doinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Robertson, C. H.; Harpp, K. S.; Geist, D.; Bosselait, M.

    2014-12-01

    Although carbonatites have been produced since the Archean and are preserved in the geologic record, the East African Rift is home to the only active carbonatite volcano, at Ol Doinyo Lengai. It has long been known that the natrocarbonatites become strongly weathered the first time they are exposed to rain. We studied the weathering patterns in the field and have determined the mineralogical transformations via petrography and XRD. Mass transport is assessed by XRF and ICP-MS analyses. Water preferentially dissolves specific minerals in the pristine lava, permeating through earlier layers of flow to form stalactites, which have differing mineralogical composition. These hang both from the host flow and from the bottom of underlying earlier flows. The weathering product is characterized by trona, a hydrated carbonate mineral, as well as the sodium sulfate mineral aphthitalite. Data from XRD analysis of the carbonatite lava confirm transformation of its original minerals, nyerereite and gregoryite, into secondary hydrated carbonate minerals gaylussite and pirssonite (e.g., Zaitsev and Keller, 2006). This transformation is attributed to the instability of the erupted minerals at atmospheric conditions. Data from XRF analysis indicate a 4-fold increase in the amount of sodium present in the stalactite as well as a 8-fold increase in potassium. Trace element analysis by ICP-MS indicates significantly elevated levels of vanadium, copper, and rubidium in the weathering product, whereas strontium, barium, lanthanum, and cesium are left behind in high concentrations in the carbonatite lava. Our results provide further evidence supporting the proposal by Dawson et al. (1987) that calcium carbonate dominated lava flows result from extensive weathering of sodic carbonatite flows.

  1. Natrocarbonatite tephra of Kerimasi volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Hay, Richard L.

    1983-10-01

    Carbonatite tephra was discharged in the final eruptive phase of Kerimasi, an extinct nephelinite volcano in the eastern rift valley of northern Tanzania. The tephra was dominantly of alkali carbonatite composition, thus providing the first well-documented example of premodern natrocarbonatite volcanism. The principal carbonate mineral was nyerereite, which is the dominant mineral in modern natrocarbonatite lava flows of the adjacent volcano Oldoinyo Lengai. The nyerereite of Kerimasi was leached of its alkalis by meteoric water and is now represented by calcite pseudomorphs. Natrocarbonatite tephra of Kerimasi shows that the alkali-rich eruptive rocks of Oldoinyo Lengai are not unique, thus supporting the hypothesis that carbonatite magmas associated with nephelinite volcanism were originally alkaline and that the subvolcanic calcitic carbonatites are a residuum from which the alkalis have been removed, either by volcanism or fenetizing fluids. A hypothesis to be tested is that eruptive carbonatite magma is, worldwide, commonly and perhaps dominantly of natrocarbonatite composition.

  2. Comment on Ra-Th disequilibria systematics: Timescale of carbonatite magma formation at Oldoinyo Lengai volcano, Tanzania

    SciTech Connect

    Gittins, J. )

    1988-04-01

    This paper discusses potential flaws in study by Williams, Gill, and bruland (1986) dealing with the extreme disequilibria between uranium and thorium series nuclides in alkalic carbonatite lava specimens. It discusses the apparent discrepencies between chemical compositions of lava which were reported from the same eruption. Clarification is made on the actual timing of eruptions in this volcanic region and the effects this would have on the petrogenesis interpretation of these rocks.

  3. The compressibility of CaCO3-Li2CO3-Na2CO3-K2CO3 liquids: application to natrocarbonatite and CO2-bearing nephelinite liquids from Oldoinyo Lengai

    NASA Astrophysics Data System (ADS)

    O'Leary, Mary Catherine; Lange, Rebecca A.; Ai, Yuhui

    2015-07-01

    To constrain the compressibility of natrocarbonate liquids, sound-speed measurements were made on 11 liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system from 808 to 1323 K at 1 bar with a frequency-sweep acoustic interferometer. CaCO3 concentrations range from 15 to 50 mol% in four of the experimental liquids. The sound-speed data for all liquids were converted to isothermal compressibility ( β T ), which were fit to an ideal mixing model with respect to composition; the average residual is 1.2 %. Fitted values (±1 σ) of the partial molar compressibility (10-2 GPa-1) at 1100 K were derived for CaCO3 (5.36 ± 0.13), Li2CO3 (8.09 ± 0.06), Na2CO3 (10.62 ± 0.07), and K2CO3 (14.09 ± 0.06); these values translate to bulk modulus values of 18.7, 12.4, 9.4, and 7.1 GPa, respectively, reflecting the relatively large compressibility of carbonate liquids. The data are additionally used to estimate the partial molar volume and compressibility of the CO2 component dissolved as carbonate in nephelinite liquids; the density of this dissolved component at 1423 K and 1 GPa ranges from 1.62, 1.71 to 1.83 g/cm3 when it is complexed with K+, Na+, and Ca2+, respectively, and is estimated to be ~2.05 and 2.14 g/cm3 when complexed with Fe2+ and Mg2+, respectively. The results from this study can be applied to natrocarbonate liquids, such as those erupted from Oldoinyo Lengai volcano in Africa, and indicate a melt density of ~2.19 g/cm3 at 1150 °C and 1 GPa, which is ~18 % less dense than the average melt density (~2.67 g/cm3) calculated for associated Mg-poor nephelinite liquids at the same conditions and volatile-free. However, the dissolution of 10.1 wt% H2O and 8.7 wt% CO2 in the average nephelinite melt (based on volatile contents reported in the literature for these magmas) reduces its density to ~2.14 g/cm3 at 1150 °C and 1 GPa, eliminating the buoyancy contrast with the natrocarbonate melt. In turn, it is highly likely that the natrocarbonatite melts contained

  4. Noble Gases in Carbonatite Magmatism: Oldonyo Lengai

    NASA Astrophysics Data System (ADS)

    Burnard, P.; Marty, B.; Fischer, T.; Hilton, D.; Mangasini, F.; Makene, C.

    2006-12-01

    Oldonyo Lengai,Tanzania, is the only volcano on Earth that is actively erupting carbonatitic lavas. In order to further constrain the origin of the Oldonyo Lengai magmas, an expedition to Oldonyo Lengai in July 2005 sampled to volcanic gases. Two fumaroles were sampled, one with a discharging temperature of 124 °C, the other more than 168 °C. The chemical composition of discharging gases is dominated by H2O (approx77 mol%) and CO2 (approx 22 mol%), SO2, H2S and HCl make up less than 1 mol%, combined. The inert gases (N2, He, He/Ne) show that these samples contain virtually no air. He/Ne ratios are between 2000 and 6500 and He/Ar ratios are up to 0.3 [Fischer et al, 2006, this volume]. The 3He/4He ratio of 6.7 - 6.8 Ra is consistent with an upper mantle origin of these gases. We have also measured Ne and Xe isotopic compositions of several aliquots of the sampled gases using a multicollector noble gas mass spectrometer (HELIX-MC). The additional precision afforded by multicollection allows us to identify noble gas isotopic anomalies at the sub 5 per mil level. Despite the excellent purity (low atmospheric content) of the gases, as evidenced by extremely high He/Ne ratios, the isotopic compositions of both Ne and Xe are very close to those of the atmosphere: a 2 per mil excess in 129Xe/130Xe ratio was observed (the remaining Xe isotope ratios being indistinguishable from air) and 20Ne/22Ne up to 10.3 was measured (50 per mil higher than air) in a split of the sample that has He/Ne = 6500. Although isotolically anomalous Ne was observed, it is not possible to determine if this is indeed mantle - derived Ne or if the 20Ne excesses result from kinetic fractionationed air entrained within the volcano's plumbing system: the composition of the three Ne isotopes (20Ne, 21Ne and 22Ne) are consistent with mass fractionation processes. Our results are most readily interpreted as atmospheric entrainment prior to sampling. However, further measurements of the remaining noble

  5. Evidence for Significant Aseismic Strike Slip During the 2007 Dike Intrusion Episode in Tanzania

    NASA Astrophysics Data System (ADS)

    Himematsu, Y.; Furuya, M.

    2014-12-01

    In July 2007, an earthquake swarm initiated Northern Tanzania near Lake Natron and lasted for about two months. Mt. Oldoinyo Lengai, which located near the seismicity, began to erupt effusively before about a month later, and increased eruption intensity on September when the swarm almost ceased. The explosive eruption continued until April 2008. Calais et al. (2008), Baer et al. (2008), and Biggs et al. (2009) have already reported the deformation associated with the swarm using InSAR. However, they mainly used ENVISAT/ASAR(C-band) images and only used images acquired from descending pass. We use both ascending and descending passes of ALOS/PALSAR (L-band) images. In addition to InSAR data, we also employ the offset-tracking technique to detect the signals along the azimuth direction. Using InSAR and offset-tracking, we could obtain the full 3D displacement field associated with the swarm. The inferred full 3D displacement indicates that the graben-like-subsiding zone was horizontally moving by ~48cm toward SSW. To our knowledge, the horizontal movement at the subsidence zone has never been identified. To explain the displacement, we performed the fault source modeling. The fault slip distribution indicates that the ratio of strike slip component is about 30% of total moment release. Aseismic strike-slip creep motion might have also been responsible for the horizontal motion area and the swarm activity.

  6. Distribution of fault activity in the early stages of continental breakup: an analysis of faults and volcanic products of the Natron Basin, East African Rift, Tanzania

    NASA Astrophysics Data System (ADS)

    Muirhead, J. D.; Kattenhorn, S. A.

    2012-12-01

    Recent magmatic-tectonic crises in Ethiopia (e.g. 2005 Dabbahu rifting episode, Afar) have informed our understanding of the spatial and temporal distribution of strain in magmatic rifts transitioning to sea-floor spreading. However, the evolving contributions of magmatic and tectonic processes during the initial stages of rifting, is a subject of ongoing debate. The <5 Ma northern Tanzania and southern Kenya sectors of the East Africa Rift provide ideal locations to address this problem. We present preliminary findings from an investigation of fault structures utilizing aerial photography and satellite imagery of the ~35 km wide Natron rift-basin in northern Tanzania. Broad-scale structural mapping will be supplemented by field observations and 40Ar-39Ar dating of lava flows cut by faults to address three major aspects of magma-assisted rifting: (1) the relative timing of activity between the border fault and smaller faults distributed across the width of the rift; (2) time-averaged slip rates along rift-zone faults; and (3) the spatial distribution of faults and volcanic products, and their relative contributions to strain accommodation. Preliminary field observations suggest that the ~500 m high border fault system along the western edge of the Natron basin is either inactive or has experienced a reduced slip rate and higher recurrence interval between surface-breaking events, as evidence by a lack of recent surface-rupture along the main fault escarpments. An exception is an isolated, ~2 km-long segment of the Natron border fault, which is located in close proximity (< 5km) to the active Oldoinyo Lengai volcano. Here, ~10 m of seemingly recent throw is observed in volcaniclastic deposits. The proximity of the fault segment to Oldoinyo Lengai volcano and the localized distribution of fault-slip are consistent with magma-assisted faulting. Faults observed within the Natron basin and on the flanks of Gelai volcano, located on the eastern side of the rift, have

  7. Volcanic activities in the Southern part of East African rift initiation: Melilitites and nephelinites from the Manyara Basin (North Tanzania rift axis)

    NASA Astrophysics Data System (ADS)

    Baudouin, Celine; Parat, Fleurice; Tiberi, Christel; Gautier, Stéphanie; Peyrat, Sophie

    2016-04-01

    The East African Rift exposes different stages of plate boundary extension, from the initiation of the rift (North (N) Tanzania) to oceanic accretion (Afar). The N Tanzania rift-axis (north-south (S) trend) is divided into 2 different volcanic and seismic activities: (1) the Natron basin (N) with shallow seismicity and intense volcanism and (2) the Manyara basin (S) with deep crustal earthquakes and sparse volcanism. The Natron basin is characterized by extinct volcanoes (2 Ma-0.75 Ma) and active volcano (Oldoinyo Lengai) and a link between seismicity and volcanism has been observed during the Oldoinyo Lengai crisis in 2007. In the S part of the N Tanzanian rift, volcanoes erupted in the Manyara basin between 0.4 and 0.9 Ma. In this study, we used geochemical signature of magmas and deep fluids that percolate into the lithosphere beneath Manyara basin, to define the compositions of magmas and fluids at depth beneath the S part of the N Tanzania rift, compare to the Natron basin and place constrain on the volcanic and seismic activities. The Manyara basin has distinct volcanic activities with mafic magmas as melilitites (Labait) and Mg-nephelinites (carbonatite, Kwaraha), and more differentiated magmas as Mg-poor nephelinites (Hanang). Melilitites and Mg-nephelinites are primary magmas with olivine, clinopyroxene (cpx), and phlogopite recording high-pressure crystallization environment, (melilitites >4 GPa and Mg-nephelinites>1 GPa) with high volatile contents (whole rock: 0.7-4.6 wt% CO2, 0.1-0.3 wt% F and 0.1 wt% Cl). FTIR analyses of olivine constrained the water content of Labait and Kwaraha magmas at 0.1 and 0.4 wt% H2O, respectively. Geochemical modelling suggests that mafic magmas result from a low degree of partial melting (1-2%) of a peridotitic source with garnet and phlogopite (high Tb/Yb (>0.6) and Rb/Sr (0.03-0.12) ratio). Mg-poor nephelinites from Hanang volcano crystallized cpx, Ti-garnet, and nepheline as phenocrysts. Magmas result from fractional

  8. Field-mapping and petrographic analysis of volcanoes surrounding the Lake Natron Homo sapiens footprint site, northern Tanzania

    NASA Astrophysics Data System (ADS)

    Hewitt, S. M.; Zimmer, B.; Liutkus, C.; Carmichael, S. K.; McGinnis, K.

    2010-12-01

    The Lake Natron Homo sapiens footprint site is located in northern Tanzania along the East African Rift escarpment. The site is positioned south of Lake Natron within an ephemeral channel of the Engare Sero River. The hominid footprints are preserved in a tuff, which originated from one of the volcanic centers surrounding the site. Two large volcanoes in the surrounding region, including the active carbonatite producing Oldoinyo L’engai and the now extinct Kerimasi are possible sources. This area also contains over 30 smaller tuff cones and tuff rings that have been poorly mapped and not analyzed in detail. The site is significant as it is the oldest modern human trackway in East Africa and one of the largest collections of hominid footprints in the world. Determining the source of the footprinted volcanic ash requires detailed field mapping, and both petrographic and geochemical analyses. Extensive field-mapping of the region revealed multiple regional beds that stratigraphically overlay the footprinted layer. Age dating as well as geochemical analysis is being conducted to relate these beds to the footprinted layer. Field-mapping showed that the footprinted tuff is over 35 cm thick, suggesting a large, sustained eruption. The bulk of the tuff cones examined in the field visibly varied in composition to the footprinted tuff and, based on proximity to the footprint site, are too small to produce the requisite volume of ash. Field analysis of samples collected from Oldoinyo L’engai reveal the most similar mineral assemblages to the footprinted layer, and the large volcano provides a source substantial enough to create a thick ash bed 10 km north of the summit. Preliminary research reveals that the footprinted tuff is a phonolite, characterized by silica depletion and the presence of sanidine, augite, and annite with interstitial calcite. XRD analysis of samples collected from Oldoinyo L’engai reveal a nepheline-rich phonolite with zeolites (ie. phillipsite

  9. Carbonatite tuffs in the Laetolil Beds of Tanzania and the Kaiserstuhl in Germany

    USGS Publications Warehouse

    Hay, R.L.; O'Neil, J.R.

    1983-01-01

    Carbonatite lava and tephra are now well known. The only modern eruptive carbonatites, from Oldoinyo Lengai, Tanzania, are of alkali carbonatite, whereas all of the pre-modern examples are of calcite or dolomite. Chemical and stable isotope analyses were made of separate phases of Pliocene carbonatite tuffs of the Laetolil Beds in Tanzania and of Miocene carbonatite tuffs of the Kaiserstuhl in Germany in order to understand the reasons for this major difference. The Laetolil Beds contain numerous carbonatite and melilitite-carbonatite tuffs. It is proposed that the carbonatite ash was originally of alkali carbonate composition and that the alkali component was dissolved, leaving a residuum of calcium carbonate. The least recrystallized melilitite-carbonatite tuff contains early-deposited calcite cement and calcite pseudomorphs after nyerereite (?) that have contents of strontium and barium and ??18O and ??13C values suggestive of incomplete chemical and isotopic exchange during alteration and replacement of alkali carbonatite ash. Carbonatite tuffs of the Kaiserstuhl contain globules composed of calcite phenocrysts and microphenocrysts in a groundmass of calcite with a small amount of clay, apatite, and magnetite. The SrO contents of phenocrysts, microphenocrysts, and groundmass calcite average 0.90, 1.42, and 0.59 percent, respectively. The average ??18O and ??13C values of globules (+14.3 and -9.0, respectively) fall between those of coarse-grained intrusive Kaiserstuhl carbonatite (avg. +6.6, -5.8) and those of low-temperature calcite cement in the carbonatite tuffs (+21.8, -14.9). The phenocrysts and microphenocrysts are primary magmatic calcite, but several features indicate that the groundmass has been recrystallized and altered in contact with meteoric water, resulting in weathering of silicate to clay, leaching of strontium, and isotopic exchange. The weight of evidence favors an original high content of alkali carbonatite in the groundmass, with

  10. Tanzania.

    PubMed

    1986-07-01

    In 1985, Tanzania's population was 21.7 million in the Mainland and 600,000 in Zanzibar, with an annual growth rate of 3.2%. The infant mortality rate was 110/1000 and life expectancy was 52 years. 85% of the labor force is engaged in agriculture, while the remaining 15% work in industry, commerce, or government. The gross domestic product (GDP) was estimated at US$4.1 billion in 1984, with an annual growth rate of 2.5% and a per capita income of $200. Tanzania is a single-party state with a strong central executive. The Government pursues a policy of socialism and self-reliance. Many manufacturing enterprises are state controlled. Although agriculture provides 1/3 of the GDP, the Government has focused on industrial development. Broad-based development plans stress providing food, shelter, drinking water, education, and health care at the village level. Government recognition of the domestic factors influencing allocation of scarce resources has led to an increasing emphasis on agriculture in macroeconomic policies. PMID:12177914

  11. Helium and carbon isotope systematics of Rungwe geothermal gases and fluids; southern Tanzania

    NASA Astrophysics Data System (ADS)

    Barry, P. H.

    2009-12-01

    observed latitudinal isotopic trends in He-CO2. However, the two localities with MORB-like 3He/4He ratios ~6 to 7 RA, δ13C ~ -4 to -5 ‰ and CO2/3He ~ 4 x10^9 are both cold temperature (~ 15°C) CO2 gas vents. The MORB-like characteristics of these cold vents are comparable to MORB-like values observed at Oldoinyo Lengai in northern Tanzania [4], suggesting that both Rungwe region and Oldoinyo Lengai may derive their volatile compositions from a homogeneous (MORB-like) mantle source common to the entire segment of the southern EAR. [1] Furman (2007) Journal of African Earth Sciences 48, 147-160. [2] Ebinger et al. (1989) Journal of Geophysical Research 94, 15,785-15,803. [3] Pik et al. (2006) Chemical Geology 226, 100-114. [4] Fisher et al. (2009) Nature 459, 77-80.

  12. Tanzania.

    PubMed

    1992-05-01

    Background notes on Tanzania present a profile of nationality, population count of 26 million, growth rate of 3.5%, ethnic groups (130), religions (33% Muslim, 33% animist, 33% Christian), languages, education (86% primary), literacy (79%), health (infant mortality of 106/1000), and work force (90% agriculture). Geographic data are given for the area, cities, terrain, and climate. The Tanzanian government is a republic with executive, legislative, and judicial branches of government. There is 1 political party and everyone 18 years is eligible to vote. 4% of the gross domestic product (GDP) ($5.9 billion) is devoted to defense. Economic growth is 4.3%/year and person income is $240/capita. Natural resources, agriculture, industry, and trade are identified. $400 million has been received between 1970-92 in US economic aid. The 1992 official exchange rate is 300 Tanzanian shillings to the US dollar. Descriptive text is given for the population, the history of Tanganyika and Zanzibar, the government, principal government officials (President, 1st Vice President [VP], 2nd VP and President of Zanzibar, Prime Minister, Foreign Affairs Minister, Ambassador to the US, Ambassador to the UN, and US embassy address and phone number), political conditions, the economy, the defense, foreign relations, and US-Tanzanian relations. Principal US officials are identified for the Ambassador, Deputy Chief of Mission, USAID Director, and Public Affairs Officer; the US embassy address is given also. The population is 80% rural with a density of 1/sq km in arid areas, 51/sq km on the mainland, and 134/sq km on Zanzibar. The new capital will be Dodoma in central Tanzania. Most residents are of Bantu stock; nomadic groups are the Masai and the Luo. 1% are non-Africans. Government has a strong central executive. The current President is Ali Hassan Mwinyi. The Revolutionary Party is in the primary policymaking body and provides all government leaders. The government seeks to foster the

  13. Mineralogy, geochemistry and petrology of the phonolitic to nephelinitic Sadiman volcano, Crater Highlands, Tanzania

    NASA Astrophysics Data System (ADS)

    Zaitsev, A. N.; Marks, M. A. W.; Wenzel, T.; Spratt, J.; Sharygin, V. V.; Strekopytov, S.; Markl, G.

    2012-11-01

    Sadiman volcano is located in the Crater Highlands area of northern Tanzania, which lies next to the western escarpment of the Gregory rift—a part of the eastern branch of the East African Rift system. It consists of interlayered phonolitic tuffs, tuff breccias (with blocks of nephelinites) and nephelinitic lava flows. Rare xenoliths of phonolite lava and ijolite were observed within the nephelinite lavas with ijolite blocks occurring in phonolitic tuffs. No evidence for the presence of melilite-bearing and/or carbonatitic rocks was found during this study. On the basis of petrography, mineralogy and geochemistry the nephelinites are divided into highly porphyritic nephelinite, wollastonite nephelinite and phonolitic nephelinite, the latter of which is the dominant variety at Sadiman. Nepheline + clinopyroxene + titanite ± perovskite ± andradite-schorlomite ± wollastonite ± sanidine ± sodalite are the principle pheno- and microphenocryst phases. The nephelinites are highly evolved (Mg# = 0.17-0.26) alkaline to peralkaline (AI = 0.88-1.21) rocks enriched in incompatible elements such as Rb, Ba, Th, U, Nb, Pb, Ta, Sr and light REEs, and strongly depleted in P and Ti. This suggests derivation from an enriched mantle source and fractionation of apatite and Ti-rich mineral(s). Primary melt inclusions in nepheline phenocrysts (Thomogenization = 860-1100 °C) indicate enrichment of volatile components in the melts, particularly of fluorine (up to 1.8 wt.% in silicate glass) resulting in the formation of daughter fluorite in partly and complete crystallized inclusions. The Sadiman nephelinites crystallized under relatively oxidizing conditions (above the FMQ buffer), which differ from the reducing conditions reported for trachytic and pantelleritic rocks from other parts of the Gregory rift. Similar rock types and relatively oxidizing conditions are known from Oldoinyo Lengai and other localities, all of which are closely associated with carbonatites. By analogy, we

  14. Aseismic strike-slip associated with the 2007 dike intrusion episode in Tanzania

    NASA Astrophysics Data System (ADS)

    Himematsu, Yuji; Furuya, Masato

    2015-08-01

    In July 2007, an earthquake swarm initiated in northern Tanzania near Lake Natron and lasted for about two months. Mt. Oldoinyo Lengai, located to the southwest of the swarm, began to erupt effusively about a month prior to the swarm, and increased its eruption intensity on September when the swarm almost ceased. Several previous studies have already reported the crustal deformation signals associated with the swarm using Interferometric Synthetic Aperture Radar (InSAR). However, nearly all the published data are based on the C-band ENVISAT/ASAR images acquired only from the descending path. We use the L-band ALOS/PALSAR images acquired from both ascending and descending paths, which allow us to examine the deformation signals in more detail. In addition to the InSAR data, we employ the offset-tracking technique to detect the signals along the azimuth direction. Using InSAR and offset-tracking data, we obtain the full 3D displacement fields associated with the episode. Besides the horizontal extension and subsidence signals due to the dike intrusion as already reported, the inferred full 3D displacements further indicate that the subsiding zone was horizontally moving by ~ 48 cm toward SSW. To explain the displacements, we performed fault source modeling, assuming an elastic half space. The fault slip distribution indicates that the contribution of the strike-slip component is about 20% of total moment release. Because almost all the focal mechanisms of earthquakes during the 2007 event indicate nearly pure normal faulting, aseismic strike-slip must have been responsible for the horizontal movement of the subsiding zone. The strike-slip at the shallowest depths suggests the presence of transtensive stress, which seems to be reasonable to generate the relay zones that are widely observed in the East African Rift. We also confirmed that the stress changes due to the dike intrusion were consistent with the inferred fault slip distributions.

  15. Surface deformation and stress interactions during the 2007-2010 sequence of earthquake, dyke intrusion and eruption in northern Tanzania

    NASA Astrophysics Data System (ADS)

    Biggs, Juliet; Chivers, Michael; Hutchinson, Michael C.

    2013-10-01

    Magma movement and fault slip alter the magnitude and orientation of the stress in the surrounding crust. Observations of a sequence of events clustered in space and time provide information about the triggering mechanism and stress interactions between magma intrusion, earthquakes and eruptions. We investigate the syn- and post-intrusion stress changes associated with the 2007 Gelei dyke intrusion episode and subsequent eruption of nearby Oldonyo Lengai. Previous studies produced a kinematic model of the 2007 June-August sequence involving ˜1 m slip on a normal fault followed by the intrusion of the 7-10-km long Gelei dyke, collapse of a shallow graben and the deflation of the Gelei magma chamber. Immediately following this, the volcano Oldoinyo Lengai (<10 km away) experienced a new phase of explosive activity lasting for several months. Here, we present new geodetic observations covering Gelei and Oldoinyo Lengai in 2008 September-2010. We show continued slip on graben-bounding faults above the Gelei dyke. The eruption of Oldoinyo Lengai was accompanied by the intrusion of a 4 km-long E-W-trending dyke followed by deflation of a shallow source directly below the summit of the volcano. Next, we use stress calculations to investigate a number of hypotheses linking these events. (1) Before the onset of surface deformation, a dyke sufficiently deep and narrow to be geodetically undetectable could still have produced sufficient stress changes to trigger slip on the normal fault (i.e. the sequence could have been magmatically driven). (2) Stresses at the dyke tip would have been sufficient to overcome the effect of continued slip on the normal fault, allowing the dyke to propagate upwards into a region of clamping. (3) The Gelei sequence would have produced a significant stress change on the chamber beneath Oldoinyo Lengai. These static stress calculations allow us to discuss the roles played by dynamic stress, deeper magmatic changes and background stresses

  16. Is natrocarbonatite a cognate fluid condensate?

    NASA Astrophysics Data System (ADS)

    Nielsen, Troels; Veksler, Ilya

    2001-10-01

    Natrocarbonatite flows in the crater of the volcano Oldoinyo Lengai (Tanzania) are the only carbonatite magmas observed to erupt and have provided strong arguments in favor of a magmatic origin for carbonatite. The currently favored explanation for the genesis of these carbonatites by liquid immiscibility between a silicate and a carbonatite melt is questioned based on the extremely low eruption temperatures of 544-593 °C and compositional and mineralogical characteristics not in agreement with experimental constraints. Experimental investigations of the relationship between Oldoinyo Lengai natrocarbonatite and related silicate rock compositions do indicate that alkali-bearing peralkaline carbonatite with liquidus calcite can form by liquid immiscibility. At the same time, these experiments result in evidence which speaks against a liquid immiscibility origin for the highly alkaline and peralkaline Oldoinyo Lengai natrocarbonatite. On the carbonatite side of the miscibility gap, fractional crystallization cannot account for a liquid evolution from alkali-bearing peralkaline carbonatite to highly alkaline natrocarbonatite. Such an evolution does not seem to be compatible with the liquidus mineral assemblages and the chemistry of Oldoinyo Lengai natrocarbonatite. No natural silicate magma is known to produce natrocarbonatite compositions by liquid immiscibility. The best interpretation of the Oldoinyo Lengai natrocarbonatite flows involves expulsion of a cognate, mobile, alkaline, and CO2-rich fluid condensate. This conclusion is supported by recent studies of silicate and carbonatite melt inclusions in minerals of ultramafic alkaline complexes, trace element partitioning, isotopic constraints, and by experimental data on major element partitioning between coexisting H2O-CO2-rich fluid and carbonatitic melt. In contrast to all other suggested modes of formation, an origin of Oldoinyo Lengai natrocarbonatite from cognate fluid appears best to be in agreement with the

  17. Is natrocarbonatite a cognate fluid condensate?

    NASA Astrophysics Data System (ADS)

    Nielsen, Troels; Veksler, Ilya

    Natrocarbonatite flows in the crater of the volcano Oldoinyo Lengai (Tanzania) are the only carbonatite magmas observed to erupt and have provided strong arguments in favor of a magmatic origin for carbonatite. The currently favored explanation for the genesis of these carbonatites by liquid immiscibility between a silicate and a carbonatite melt is questioned based on the extremely low eruption temperatures of 544-593 °C and compositional and mineralogical characteristics not in agreement with experimental constraints. Experimental investigations of the relationship between Oldoinyo Lengai natrocarbonatite and related silicate rock compositions do indicate that alkali-bearing peralkaline carbonatite with liquidus calcite can form by liquid immiscibility. At the same time, these experiments result in evidence which speaks against a liquid immiscibility origin for the highly alkaline and peralkaline Oldoinyo Lengai natrocarbonatite. On the carbonatite side of the miscibility gap, fractional crystallization cannot account for a liquid evolution from alkali-bearing peralkaline carbonatite to highly alkaline natrocarbonatite. Such an evolution does not seem to be compatible with the liquidus mineral assemblages and the chemistry of Oldoinyo Lengai natrocarbonatite. No natural silicate magma is known to produce natrocarbonatite compositions by liquid immiscibility. The best interpretation of the Oldoinyo Lengai natrocarbonatite flows involves expulsion of a cognate, mobile, alkaline, and CO2-rich fluid condensate. This conclusion is supported by recent studies of silicate and carbonatite melt inclusions in minerals of ultramafic alkaline complexes, trace element partitioning, isotopic constraints, and by experimental data on major element partitioning between coexisting H2O-CO2-rich fluid and carbonatitic melt. In contrast to all other suggested modes of formation, an origin of Oldoinyo Lengai natrocarbonatite from cognate fluid appears best to be in agreement with the

  18. A melt evolution model for Kerimasi volcano, Tanzania: Evidence from carbonate melt inclusions in jacupirangite

    NASA Astrophysics Data System (ADS)

    Káldos, Réka; Guzmics, Tibor; Mitchell, Roger H.; Dawson, John Barry; Milke, Ralf; Szabó, Csaba

    2015-12-01

    This study presents compositional data for a statistically significant number (n = 180) of heated and quenched (recreated) carbonate melt inclusions trapped in magnetite and clinopyroxene in jacupirangite from Kerimasi volcano (Tanzania). On the basis of homogenization experiments for clinopyroxene-hosted melt inclusions and forsterite-monticellite-calcite phase relations, a range of 1000 to 900 °C is estimated for their crystallization temperatures. Petrographic observations and geochemical data show that during jacupirangite crystallization, a CaO-rich and alkali-"poor" carbonate melt (relative to Oldoinyo Lengai natrocarbonatite) existed and was entrapped in the precipitating magnetite, forming primary melt inclusions, and was also enclosed in previously crystallized clinopyroxene as secondary melt inclusions. The composition of the trapped carbonate melts in magnetite and clinopyroxene is very similar to the parental melt of Kerimasi calciocarbonatite; i.e., enriched in Na2O, K2O, F, Cl and S, but depleted in SiO2 and P2O5 relative to carbonate melts entrapped at an earlier stage and higher temperature (1050-1100 °C) during the formation of Kerimasi afrikandite. Significant compositional variation is shown by the major minerals of Kerimasi plutonic rocks (afrikandite, jacupirangite and calciocarbonatite). Magnetite and clinopyroxene in the jacupirangite are typically transitional in composition between those of afrikandite and calciocarbonatite. These data suggest that the jacupirangite represents an intermediate stage between the formation of afrikandite and calciocarbonatite. Jacupirangite most probably formed when immiscible silicate and carbonate melts separated from the afrikandite body, although the carbonate melt was not separated completely from the silicate melt fraction. In general, during the evolution of the carbonate melt at Kerimasi, concentrations of P2O5 and SiO2 decreased, whereas volatile content (alkalis, S, F, Cl and H2O) increased

  19. Ultramafic xenoliths and megacrysts from a melilitite tuff cone, Deeti, northern Tanzania

    NASA Astrophysics Data System (ADS)

    Johnson, L. H.; Jones, A. P.; Church, A. A.; Taylor, W. R.

    1997-07-01

    Deeti, a ˜50 m high 'ubehebe' tuff ring is situated in a small field of similar tuff cones of Quaternary age, next to the two nephelinite-carbonatite volcanoes of Kerimasi and Oldoinyo Lengai, south of Lake Natron. The tuff cones, lying on small parallel faults, may have been closely associated and possibly triggered by the same events that have given rise to the volcanic activity at Oldoinyo Lengai and Kerimasi. The host extrusive at Deeti is a melilitite (SiO 2 37.20%, MgO 15.0%, TiO 2 3.93%, CaO 9.26%, K 2O 2.76% and Mg66.4); it is mica porphyritic and contains ijolitic xenolith fragments. The upper part of the cone is formed of spectacular carbonate-cemented, coarse bedded deposits of cored, golf ball size lapilli. A distinctive megacryst suite is composed of phlogopitic mica (FeO 0.5%, TiO 2 4.8%, Mg80), pargasitic amphibole ( Mg71) and diopsidic clinopyroxene ( Mg80). Numerous ultramafic xenoliths dominated by amphibole-mica peridotites and pyroxenites, form the cores of larger lapilli and exist as bombs up to 30 cm across. This amphibole is chromian-pargasite, with very rare relics of richterite ( Mg88). The xenoliths show abundant evidence of multiple veining, overgrowths and substantial fabric modification. On the basis of electron microprobe data, we show that these petrographic textures probably developed as a result of metasomatism by alkaline silicate, and possibly carbonatite melts. The original protoliths include more primitive spinel peridotites (Fo >88) that have been significantly Fe-enriched. The lava has sampled upper mantle wall rock to depths of origin of the melilitite (> 60 km) and these xenoliths may constrain possible mantle source compositions for the adjacent larger carbonatite volcanoes.

  20. Peralkaline nephelinites

    NASA Astrophysics Data System (ADS)

    Peterson, Tony D.

    1989-07-01

    Two fractionation trends in sodic alkaline ultramafic liquids have been predicted from experiments in subsystems of the join Di-Ak-Ne-Lc-Qz. The products of these trends are equated with contrasting suites of peralkaline nephelinites from two nephelinite-carbonatite volcanos of the south Gregory Rift, Shombole (southern Kenya) and Oldoinyo L'engai (northern Tanzania). In both trends, peralkalinity is interpreted to result from fractional crystallization of aluminous clinopyroxene. The “Shombole trend” has olivine nephelinite as its parental magma, and the differentiation products are mildly peralkaline [(Na+K)/Al≈1.15] nephelinites. It is the most common lineage observed in nephelinite-carbonatite centres. The “Oldoinyo L'engai trend” has melilitite or olivine-melilite nephelinite as its parental magma, and produces extremely peralkaline [(Na+K)/Al=1.4 2.3] wollastonite- and combeite- (Na2 Ca2Si3O9) bearing nephelinites. The presence of a reaction relation between wollastonite and liquid to produce combeite, indicated by corroded wollastonite phenocrysts armoured by combeite in some nephelinites from Oldoinyo L'engai, is confirmed by melting experiments. Combeite nephelinites from Oldoinyo L'engai were erupted simultaneously with natrocarbonatite ash, and are very similar in composition to silicate liquids that have been shown by experiment to be immiscible with natrocarbonatite. Because the L'engai trend is rarely expressed at extrusive centres (combeite has been recorded at only three localities), and combeite nephelinites are highly evolved magmas, it is unlikely that natrocarbonatite is primary to other carbonatite types. It is proposed that carbonatite liquid is exsolved at crustal pressures from a wide range of nephelinitic liquids: Mg-rich carbonatite from primitive, olivine-bearing alkaline ultramafic liquids, Ca-rich carbonatite from olivine-free nephelinites of low peralkalinity, and natrocarbonatite from strongly peralkaline combeite

  1. The 2005 and 2006 eruptions of Ol Doinyo Lengai: assessing deep and shallow processes at an active carbonatite volcano using volatile chemistry and fluxes

    NASA Astrophysics Data System (ADS)

    Fischer, T.; Burnard, P.; Marty, B.; Palhol, F.; Mangasini, F.; Shaw, A. M.

    2006-12-01

    The African Rift valleys are sites of classical carbonatite volcano complexes. Ol Doinyo Lengai, the spectacular cone that rises to nearly 3000 m above Tanzania's Eastern Rift Valley, is the world's only active carbonatite volcano. High-alkali carbonatite lavas from this volcano were first recognized in the 1960's and the oldest natrocarbonatite tuffs have been dated to 1250 years B.P.. Earlier eruptions produced phonolitic and nephelinitc lavas [1]. Since the 1960's the volcano has erupted frequently producing carbonatite lava flows. Explosive eruptions are much less frequent but have occurred in 1966, 1983 [1] and 1993 [3] producing ash, cones and natrocarbonatite tephra. In July 2005, we launched an expedition to the crater to collect gas and rock samples. On July 4, the volcano began erupting low viscosity, low T (540C) high velocity (2 m/sec) lava flows at a rate of about 0.3 m3/sec. By afternoon, the lava was flowing over the eastern crater rim. During the eruption we sampled gases from nearby hornitos at 120 and 168C, yielding pristine magmatic gases characterized by 75 mol% H2O, 22% CO2, < 1% SO2, H2S, HCl and traces of H2, He, Ar, N2, CH4 and CO. CO2-CH4-CO gas equilibrium temperatures are 580C consistent with lava flow temperatures. N2-He-Ar abundances indicate an upper mantle origin of volatiles, confirmed by isotopes [4]. SO2 flux measured by mini DOAS was low (10 t/day). CO2 fluxes calculated using CO2/SO2 are 3000 to 4000 t/day. Volatiles measured in the carbonatite lavas by SIMS show low H2O (< 0.7 wt%), high S (0.2 to 1 wt%) and Cl (0.6 to 1.4 wt%) and variable F (0.06 to 0.7 wt%). CO2 contents are 30 wt% with major and trace elements typical of natrocarbonatite lavas previously reported in [1]. The release of all CO2 (30 wt% or 20 t/day) from eruption lavas would only produce a small fraction of the measured CO2. In March 2006 eyewitnesses [3] reported the occurrence of an explosive eruption and some of us returned to the volcano on May 12. The

  2. Huntington's disease in Tanzania.

    PubMed Central

    Scrimgeour, E M

    1981-01-01

    Huntington's disease was studied in a Bantu community in northern Tanzania. Although there is evidence to suggest that the disease has been present here for over one hundred years, this is the first report of the condition in Tanzania. A survey of published reports indicates that the disease is infrequently reported in persons of Negro ancestry. PMID:6453998

  3. Carbonatite melt inclusions in coexisting magnetite, apatite and monticellite in Kerimasi calciocarbonatite, Tanzania: melt evolution and petrogenesis

    NASA Astrophysics Data System (ADS)

    Guzmics, Tibor; Mitchell, Roger H.; Szabó, Csaba; Berkesi, Márta; Milke, Ralf; Abart, Rainer

    2011-02-01

    Kerimasi calciocarbonatite consists principally of calcite together with lesser apatite, magnetite, and monticellite. Calcite hosts fluid and S-bearing Na-K-Ca-carbonate inclusions. Carbonatite melt and fluid inclusions occur in apatite and magnetite, and silicate melt inclusions in magnetite. This study presents statistically significant compositional data for quenched S- and P-bearing, Ca-alkali-rich carbonatite melt inclusions in magnetite and apatite. Magnetite-hosted silicate melts are peralkaline with normative sodium-metasilicate. On the basis of our microthermometric results on apatite-hosted melt inclusions and forsterite-monticellite phase relationships, temperatures of the early stage of magma evolution are estimated to be 900-1,000°C. At this time three immiscible liquid phases coexisted: (1) a Ca-rich, P-, S- and alkali-bearing carbonatite melt, (2) a Mg- and Fe-rich, peralkaline silicate melt, and (3) a C-O-H-S-alkali fluid. During the development of coexisting carbonatite and silicate melts, the Si/Al and Mg/Fe ratio of the silicate melt decreased with contemporaneous increase in alkalis due to olivine fractionation, whereas the alkali content of the carbonatite melt increased with concomitant decrease in CaO resulting from calcite fractionation. Overall the peralkalinity of the bulk composition of the immiscible melts increased, resulting in a decrease in the size of the miscibility gap in the pseudoquaternary system studied. Inclusion data indicate the formation of a carbonatite magma that is extremely enriched in alkalis with a composition similar to that of Oldoinyo Lengai natrocarbonatite. In contrast to the bulk compositions of calciocarbonatite rocks, the melt inclusions investigated contain significant amount of alkalis (Na2O + K2O) that is at least 5-10 wt%. The compositions of carbonatite melt inclusions are considered as being better representatives of parental magma composition than those of any bulk rock.

  4. The last ~1 million years of carbonatite volcanism in northern Tanzania; last gasp of a decaying rift?

    NASA Astrophysics Data System (ADS)

    Jones, A.

    2003-04-01

    Continued monitoring of volcanic activity at Oldoinyo Lengai for the last ~35 years suggests that this central volcano has become a highly evolved low temperature/low volume carbonatite-nephelinite system. The sustained intermingling of silicate and carbonatitic eruptions for most of this volcano's history contrasts sharply with the two-stage sequential development of neighbouring Kerimasi (nephelinite then carbonatite). The footprint of the older Kerimasi volcano is effected by active faulting of earlier flood lavas along the west rift wall. The mineralogy, petrology and geochemistry of both volcanos generally conform with the LeBas model of carbonatite-nephelinite volcanism for the eastern arm of the EAR. However, their overall differences in bulk chemistry suggest that their ~15 km horizontal separation at the surface, reflects compositional heterogeneity of the mantle source over a similar length scale. This is consistent with primary melt segregation at relatively shallow mantle depths, and crustal delivery along pipe-like conduits with minimal lateral transport. The surrounding rift valley floor is pock-marked with numerous small volcanic structures, such as tuff cones, craters and minor lava flows. The ages of these minor volcanos are bracketed by the two larger central volcanos, and also contain both carbonatite and alkaline silicate magmas; they extend the compositional range and suggest deeper sources for periodic small volume primary melilitite magmas. Their xenolith populations are consistent with an extended history of metasomatised mantle peridotites characterised by increasing amphibole, mica, and clinopyroxene at the expense of orthopyroxene. Megacrysts and cumulate-textured xenoliths are also consistent with repeated occupation of vertical conduits and local sidewall crystallisation at depths close to the Moho. Overall, the recent volcanic activity represents highly evolved small volume batches of mantle melts with high carbonate and CO2, and

  5. Solar Power for Tanzania

    SciTech Connect

    Chen, Christine; Gerace, Jay; Mehner, Nicole; Mohamed, Sharif; Reiss, Kelly

    1999-12-06

    Condensed list of products and activities: 8 educational posters and 1 informational brochure (all original illustrations and text); a business plan with micro-agreements; corporation created called Tanzanian Power, LLC; business feasibility study developed with the University of Albany; Hampshire College collaborated in project development; research conducted seeking similar projects in underdeveloped countries; Citibank proposal submitted (but rejected); cleaned and sent PV panels to Tanzania; community center built in Tanzania; research and list provided to Robinson for educational TV videos and product catalogs; networked with Chase Manhattan Bank for new solar panels; maintained flow of information among many people (stateside and Tanzania); wrote and sent press releases and other outreach information. Several families purchased panels.

  6. Tanzania: Country Status Report.

    ERIC Educational Resources Information Center

    Robson, Barbara

    A survey of the status of language usage in Tanzania begins with an overview of the three levels of language use: (1) Swahili, the national and official language, used in public life; (2) English, used in international affairs and in technical and intellectual matters; and (3) the over 120 vernacular languages used in family and religious life,…

  7. Corporal Punishment in Tanzania's Schools

    ERIC Educational Resources Information Center

    Feinstein, Sheryl; Mwahombela, Lucas

    2010-01-01

    The purpose of this survey was to acquire descriptive information regarding corporal punishment in Tanzania's O-level secondary schools. 448 individuals participated in the study: 254 teachers and 194 students, all from government or private secondary schools in the Iringa Region of Tanzania. In addition, 14 students and 14 teachers were…

  8. Adult Students go to Tanzania

    ERIC Educational Resources Information Center

    Harvey, Brian

    1976-01-01

    A preparatory course and a three-week study safari to Tanzania were conducted jointly by the University of Southampton and Nottingham University. The course sought to increase the participants' understanding of Tanzania's geography, economy, politics, education, and social systems. The actual visit is also described. (Author/EC)

  9. Malaria control in Tanzania

    SciTech Connect

    Yhdego, M.; Majura, P. )

    1988-01-01

    A review of the malaria control programs and the problem encountered in the United Republic of Tanzania since 1945 to the year 1986 is discussed. Buguruni, one of the squatter areas in the city of Dar es Salaam, is chosen as a case study in order to evaluate the economic advantage of engineering methods for the control of malaria infection. Although the initial capital cost of engineering methods may be high, the cost effectiveness requires a much lower financial burden of only about Tshs. 3 million compared with the conventional methods of larviciding and insecticiding which requires more than Tshs. 10 million. Finally, recommendations for the adoption of engineering methods are made concerning the upgrading of existing roads and footpaths in general with particular emphasis on drainage of large pools of water which serve as breeding sites for mosquitoes.

  10. Country watch: Tanzania.

    PubMed

    Kishe, F; Mtweve, S P

    1995-01-01

    This article describes the approach of the KIWAKKUKI women's group in helping to change sex behavior among youth and to inform community women's groups in Moshi, Tanzania. The group concluded after four years of experience that people change risky sexual behavior most when participatory methods based on local culture are used in educational programs. KIWAKKUKI established discussion groups for primary and secondary school students in the schools. The approach included use of videos, clothboards, chalkboards, and sometimes role plays. The mothers engaged in discussions with children other than their own, which reduced some embarrassment. Sex education discussion groups were also conducted among church youth and community women's groups. Monthly meetings drew a membership of about 356 persons, of whom 30-50 were trainers and advocates. Some of the topics of conversation were knowledge about physical bodies and personalities, assertiveness and the ability to say "no," laws and regulations relating to marriage, inheritance, sexual harassment, abuse, and AIDS. Other topics focused on the cultural understanding of circumcision, teeth extraction, wife inheritance, and women's income generation. The basic premise of their operation is empowerment of women and the belief that women can make a difference in changing culture. Men, who indicated an interest in forming a group, were redirected to their own group formation. PMID:12346873

  11. Reforming Teacher Education in Tanzania

    ERIC Educational Resources Information Center

    Hardman, Frank; Abd-Kadir, Jan; Tibuhinda, Audax

    2012-01-01

    It is widely acknowledged that in order to improve the quality of education in primary schools in developing countries there is a need to place pedagogy and its training implications at the centre of teacher education reform. Like many countries in Eastern and Southern Africa, Tanzania has introduced various initiatives and reforms to improve the…

  12. Conventialization of Numerals in Tanzania

    ERIC Educational Resources Information Center

    Kajoro, Peter

    2012-01-01

    The supposed pre-eminence of an external examination can exert a disproportionate influence on a curriculum and the associated learning and teaching. Teaching can easily subordinate learning and understanding to curriculum coverage if the society develops a culture that appears to make such demands. This study focuses on Tanzania and provides the…

  13. Crater Highlands, Tanzania

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Shuttle Radar Topography Mission (SRTM), flown aboard Space Shuttle Endeavour in February 2000, acquired elevation measurements for nearly all of Earth's landmass between 60oN and 56oS latitudes. For many areas of the world SRTM data provide the first detailed three-dimensional observation of landforms at regional scales. SRTM data were used to generate this view of the Crater Highlands along the East African Rift in Tanzania. Landforms are depicted with colored height and shaded relief, using a vertical exaggeration of 2X and a southwestwardly look direction.

    Lake Eyasi is depicted in blue at the top of the image, and a smaller lake occurs in Ngorongoro Crater. Near the image center, elevations peak at 3648 meters (11,968 feet) at Mount Loolmalasin, which is south of Ela Naibori Crater. Kitumbeine (left) and Gelai (right) are the two broad mountains rising from the rift lowlands. Mount Longido is seen in the lower left, and the Meto Hills are in the right foreground.

    Tectonics, volcanism, landslides, erosion and deposition -- and their interactions -- are all very evident in this view. The East African Rift is a zone of spreading between the African (on the west) and Somali (on the east) crustal plates. Two branches of the rift intersect here in Tanzania, resulting in distinctive and prominent landforms. One branch trends nearly parallel the view and includes Lake Eyasi and the very wide Ngorongoro Crater. The other branch is well defined by the lowlands that trend left-right across the image (below center, in green). Volcanoes are often associated with spreading zones where magma, rising to fill the gaps, reaches the surface and builds cones. Craters form if a volcano explodes or collapses. Later spreading can fracture the volcanoes, which is especially evident on Kitumbeine and Gelai Mountains (left and right, respectively, lower center).

    The Crater Highlands rise far above the adjacent savannas, capture moisture from passing air masses

  14. [AIDS in Tanzania].

    PubMed

    Barstad, S

    1993-04-20

    The World Health Organization has announced that within 3 years 10% of Tanzania's population of 26 million will be infected with the human immunodeficiency virus (HIV). But there is some faint hope in the research of Tanzanian traditional medicine. An almost 90-year-man, Waziri Mrisho, is credited with having treated AIDS patients successfully with herbs that strengthen the immune system. Margaret Nakamya was stricken by the symptoms of AIDs in March 1990. She was referred to Waziri and started using his herbs. 3 years later she weighs 49 kg compared to 40 kg before. The old man's son set up a little factory where he pulverizes herbs and sells them at the price he can command The 3 types of trees that the herbal medicine is taken from grow in the wild, but some have also been planted around the factory. Even if these herbs are effective, it will take years before the AIDS epidemic is over, when people have changed their lifestyles. The means of communication (TV, cinema, radio, telephone) are missing or inadequate. In the Kagera region, with 1.2 million inhabitants, 25% of pregnant women are HIV-infected and 65,000 children lost their parents to AIDS. There are 2000 children in Dar Es Salaam living in the streets. The Anglican St. Albans Church runs a center for street kids where they get meals 3 times a week. The nurse Ruth Nesje enlisted a Norwegian physician and homeopath in a research project involving 30 AIDS patients in Norway. The University in Bergen will do in vitro testing. One group of patients will receive both AZT and the herbs, another group will get only AZT, and the 3rd group will obtain only the herbs. The Norwegian Nursing Association, NORAD, and DANIDA also plan various projects in the Tanga region. PMID:8499187

  15. Marine fisheries in Tanzania.

    PubMed

    Jiddawi, Narriman S; Ohman, Marcus C

    2002-12-01

    Fishery resources are a vital source of food and make valuable economic contributions to the local communities involved in fishery activities along the 850 km stretch of the Tanzania coastline and numerous islands. Small-scale artisanal fishery accounts for the majority of fish catch produced by more than 43 000 fishermen in the country, mainly operating in shallow waters within the continental shelf, using traditional fishing vessels including small boats, dhows, canoes, outrigger canoes and dinghys. Various fishing techniques are applied using uncomplicated passive fishing gears such as basket traps, fence traps, nets as well as different hook and line techniques. Species composition and size of the fish varies with gear type and location. More than 500 species of fish are utilized for food with reef fishes being the most important category including emperors, snappers, sweetlips, parrotfish, surgeonfish, rabbitfish, groupers and goatfish. Most of the fish products are used for subsistence purposes. However, some are exported. Destructive fishing methods such as drag nets and dynamite fishing pose a serious problem as they destroy important habitats for fish and other organisms, and there is a long-term trend of overharvested fishery resources. However, fishing pressure varies within the country as fishery resources are utilized in a sustainable manner in some areas. For this report more than 340 references about Tanzanian fishery and fish ecology were covered. There are many gaps in terms of information needed for successful fishery management regarding both basic and applied research. Most research results have been presented as grey literature (57%) with limited distribution; only one-fifth were scientific publications in international journals. PMID:12572817

  16. Corporal punishment in Tanzania's schools

    NASA Astrophysics Data System (ADS)

    Feinstein, Sheryl; Mwahombela, Lucas

    2010-10-01

    The purpose of this survey was to acquire descriptive information regarding corporal punishment in Tanzania's O-level secondary schools. 448 individuals participated in the study: 254 teachers and 194 students, all from government or private secondary schools in the Iringa Region of Tanzania. In addition, 14 students and 14 teachers were interviewed. It was found that corporal punishment was the most common form of punishment in secondary schools. The majority of teachers supported its continued use, but believed in moderation. The majority of students and teachers were unaware of national laws to restrict corporal punishment. There was agreement between students and teachers that corporal punishment was used for major and minor student offences such as misbehaviour and tardiness. Students reported disliking the practice and believed it was ineffective and resulted in emotional, as well as physical, distress.

  17. Child Sexual Abuse in Tanzania and Kenya

    ERIC Educational Resources Information Center

    Lalor, Kevin

    2004-01-01

    Objective: Most research on child abuse in Tanzania and Kenya is unpublished in the international literature. The purpose of this paper is to examine the various commentaries and reports extant, toward an overview of the nature and frequency of child sexual abuse in Tanzania and Kenya. Methods: Contacts were made with academics, government…

  18. Partitioning of elements between silicate melt and immiscible fluoride, chloride, carbonate, phosphate and sulfate melts, with implications to the origin of natrocarbonatite

    NASA Astrophysics Data System (ADS)

    Veksler, Ilya V.; Dorfman, Alexander M.; Dulski, Peter; Kamenetsky, Vadim S.; Danyushevsky, Leonid V.; Jeffries, Teresa; Dingwell, Donald B.

    2012-02-01

    Liquid-liquid partitioning of 42 elements between synthetic silicate melts and immiscible fluoride, chloride, carbonate, phosphate and sulfate liquids was studied at temperatures of 650-1100 °C, pressures 72-100 MPa, with 0-11 wt.% H2O. One series of experiments was performed in a rotating internally-heated autoclave where separation of the immiscible liquids was assisted by centrifugal forces. An analogous series of experiments was done in static rapid-quench cold-seal pressure vessels. The experimentally determined liquid-liquid distribution coefficients (D's) vary over several orders of magnitude, as a result of variable Coulombic interactions between cations and anions. For alkaline, alkaline earth and rare earth elements ther is a strong and systematic dependence of the liquid/liquid D values on the ionic potential Z/r for all the examined systems. In contrast, highly charged cations (e.g., HFSE) show no systematic relationships between the D's and Z/r. New experimental constraints on the carbonate/silicate liquid-liquid D values presented here confirm that rare metals such as Nb, Zr, REE, Th and U concentrate in silicate liquids, and therefore carbonatites that carry economical rare metal mineralization are not likely to have formed by liquid immiscibility. The comparison between experimentally-determined carbonate-silicate liquid-liquid D values and bulk-rock natrocarbonatite vs. nephelinite compositions at the Oldoinyo Lengai in Tanzania reveals significant discrepancies for Cs, Rb, Ba, Be, Zn, heavy REE, Ti, Mo and W, thus rendering a simple, one-stage immiscibility model for Oldoinyo Lengai questionable.

  19. Type 1 diabetes care updates: Tanzania.

    PubMed

    Muze, Kandi Catherine; Majaliwa, Edna Siima

    2015-04-01

    Tanzania is located in east Africa with a population of 45 million. The country's population is growing at 2.5% annually. The International Diabetes Federation Child Sponsorship Program was launched in Tanzania in 2005. The number of type 1 diabetes mellitus children enrolled in the changing diabetes in children program in Tanzania has augmented from almost below 50 in 2005 to over 1200 in 2014. The country had an overall trend of HbA1c value of 14% in 2005 while the same has reduced over the years to 10% in 2012-13. The program has been able to reduce the proportion of patients with HbA1c values of 11-14%; from 71.9% in 2008 to 49.8% in 2012-13. The challenges, which CDiC faces are misdiagnosis, low public awareness, and stigma especially in the reproductive age/adolescent groups. PMID:25941637

  20. The integrated project in Tanzania.

    PubMed

    1989-03-01

    The 1st Integrated Project (IP) in Africa was started in Tanzania in 1983 by the International Planned Parenthood (IPPF) Africa Bureau. It was to be done by the Family Planning Association of Tanzania (UMATI). 2 pilot areas are in the Kilimanjaro region. 1 covers Modio and Roo villages in rural Masama; the other is a sugar cane plantation run by Tanganyika Planting Company Ltd. (TPC). The IP National Steering Committee (NSC) was formed in 1983 with representatives from the Ministry of Health and a parasitologist. No nutritionist was included. In 1983 a survey of population, health care activities, and demographic characteristics was undertaken. In 1984 house-to-house visits were made. Information was gathered on family planning knowledge, practice, and sanitary conditions. Mass stool examinations and blanket treatment for both children and adults began in August, 1984. Family planning information is fully integrated with education about sanitation and nutrition. 11 films were shown at TPC to about 500 children and adults and almost 20,000 children and adults received some form of health education. Health educators and laboratory technicians moved to accommodations in TPC and Modio village to live among the people they were serving. At the end of 1986, the number of family planning acceptors had risen quite a bit. It continued to do so in 1987. At TPC mass stool tests and deworming were done in 1985. This was completed in Masama in May, 1987. For follow-up selective treatments twice a year was done. The focus of environmental sanitation activity, especially in Masama, was the search for a cheap, well-built latrine. The IP staff in Masama trained 43 of the 90 traditional birth attendants (TBAs). UMATI has realized in 1984 that thought IP they can more effectively involve the community in family planning. By working on parasite infection, the IP staff aroused community interest in family planning. The NSC has set the tone of this project because it understood the

  1. Geographical Aspects of Cancer in Tanzania

    PubMed Central

    Alexander, George A.

    1983-01-01

    Cancer is an important cause of morbidity and mortality in Tanzania. According to the Tanzanian Cancer Registry, which records all histologically confirmed malignant tumors, the number of reported cancer cases has increased significantly over the past three decades. The most commonly diagnosed tumors are cervix cancer, skin cancer, primary liver cancer, Kaposi's sarcoma, and Burkitt's lymphoma. Geographical and tribal variations exist in disease frequency. Environmental factors appear to have a major role in the distribution. Through elimination of these factors, cancer in Tanzania could be reduced if not totally prevented. ImagesFigure 3Figure 4Figure 5Figure 6Figure 7Figure 8 PMID:6631988

  2. Fires in Tanzania and Mozambique

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Like many countries, the southeastern African country of Malawi faces the challenge of balancing a growing population's need for food and energy with preservation of natural resources. This MODIS image from November 8, 2001, shows Malawi surrounded by (starting from top and moving clockwise) Tanzania, Mozambique, and northern Zambia. Lake Malawi runs north-south through the eastern part of the country, and is the southern-most of Africa's Great Rift Lakes, a series of deep lakes that run roughly north-south along the Great Rift Valley in eastern Africa, formed when the Earth buckled and then sank after the collision of Africa and Eurasia millions of years ago. Most of the land around the lake and throughout the country has been cleared of its natural vegetation and converted to agricultural land. This causes soil erosion problems and sedimentation in the lake, which affects the sustainability of fishing in the lake. In this image, greenish swirls in the water around the shores could indicate a mixture of sediment and phytoplankton or algae. Deforestation is also a major issue, especially since wood for fuel is the primary source of the country's energy. The difference between the lands protected by parks and preserves stand out dramatically. The largest protected area is halfway down the western border of the country-Kasungu National Park. Several smaller preserves also exist, and where they do, they stand out in green against the paler landscape. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  3. Curriculum Unit: Kenya and Tanzania, Tourist Economies.

    ERIC Educational Resources Information Center

    Lynn, Karen

    This curriculum guide is designed to enable teachers and ninth grade students to develop a clearer understanding of the countries of Kenya and Tanzania and the economic needs of their citizens. A pretest-posttest examination with 20 true or false questions, 2 essay questions, and a list of 50 vocabulary words is provided. Brief descriptions of the…

  4. Education and Poverty Reduction in Tanzania

    ERIC Educational Resources Information Center

    Wedgwood, Ruth

    2007-01-01

    This paper reviews research on the returns to education in Tanzania, both financial and non-financial, and considers whether these returns translate into poverty reduction. It looks at reasons why achievement of high primary enrolment rates in the past did not lead to the realisation of the associated developmental outcomes, considering factors…

  5. Evolution of Elections Management in Tanzania

    ERIC Educational Resources Information Center

    Norman, A. S.; Mdegella, O. M.; Lubawa, R. M.

    2011-01-01

    This paper provides a discussion on the evolution of elections management in Tanzania with a focus on technological advancement in administering registration of voters. The paper provides the merits that permanent voters register has brought over the thumb practice. It traces the management of elections during colonialism, after independence…

  6. Modeling solutions to Tanzania's physician workforce challenge

    PubMed Central

    Goodell, Alex J.; Kahn, James G.; Ndeki, Sidney S.; Kaale, Eliangiringa; Kaaya, Ephata E.; Macfarlane, Sarah B. J.

    2016-01-01

    Background There is a great need for physicians in Tanzania. In 2012, there were approximately 0.31 physicians per 10,000 individuals nationwide, with a lower ratio in the rural areas, where the majority of the population resides. In response, universities across Tanzania have greatly increased the enrollment of medical students. Yet evidence suggests high attrition of medical graduates to other professions and emigration from rural areas where they are most needed. Objective To estimate the future number of physicians practicing in Tanzania and the potential impact of interventions to improve retention, we built a model that tracks medical students from enrollment through clinical practice, from 1990 to 2025. Design We designed a Markov process with 92 potential states capturing the movement of 25,000 medical students and physicians from medical training through employment. Work possibilities included clinical practice (divided into rural or urban, public or private), non-clinical work, and emigration. We populated and calibrated the model using a national 2005/2006 physician mapping survey, as well as graduation records, graduate tracking surveys, and other available data. Results The model projects massive losses to clinical practice between 2016 and 2025, especially in rural areas. Approximately 56% of all medical school students enrolled between 2011 and 2020 will not be practicing medicine in Tanzania in 2025. Even with these losses, the model forecasts an increase in the physician-to-population ratio to 1.4 per 10,000 by 2025. Increasing the absorption of recent graduates into the public sector and/or developing a rural training track would ameliorate physician attrition in the most underserved areas. Conclusions Tanzania is making significant investments in the training of physicians. Without linking these doctors to employment and ensuring their retention, the majority of this investment in medical education will be jeopardized. PMID:27357075

  7. The economics of pharmaceutical supply in Tanzania.

    PubMed

    Yudkin, J S

    1980-01-01

    This paper analyzes the patterns of purchasing, distribution, and utilization of pharmaceuticals currently found in Tanzania, an underdeveloped country in Africa. Like other nations in the Third World, Tanzania offers the prospect of a rapidly expanding market for the multinational pharmaceutical industry. However, this market has been to a large extent developed by the intense promotional activities of the drug companies themselves. In addition to normal marketing methods, these companies indulge in techniques which would be neither acceptable nor legal in developed countries. As a result, expensive proprietary drugs are overpurchased and overprescribed, mainly in the large urban hospitals, with consequent deprivation of other health care facilities, particularly those for the rural peasants who form the majority of the population. The activities of the multinational pharmaceutical companies in the Third World are therefore an important component in the continuing underdevelopment of health in these nations. PMID:7419314

  8. Wildlife and wildlife management in Tanzania.

    PubMed

    Caro, Tim; Davenport, Tim R B

    2016-08-01

    Tanzania, arguably mainland Africa's most important nation for conservation, is losing habitat and natural resources rapidly. Moving away from a charcoal energy base and developing sustainable finance mechanisms for natural forests are critical to slowing persistent deforestation. Addressing governance and capacity deficits, including law enforcement, technical skills, and funding, across parts of the wildlife sector are key to effective wildlife protection. These changes could occur in tandem with bringing new models of natural resource management into play that include capacity building, corporate payment for ecosystem services, empowering nongovernmental organizations in law enforcement, greater private-sector involvement, and novel community conservation strategies. The future of Tanzania's wildlife looks uncertain-as epitomized by the current elephant crisis-unless the country confronts issues of governance, embraces innovation, and fosters greater collaboration with the international community. PMID:26681228

  9. Cutaneous squamous cell carcinoma in Tanzania.

    PubMed

    Amir, H; Mbonde, M P; Kitinya, J N

    1992-11-01

    The Tanzania Cancer Registry at Muhimbili Medical Centre, Dar es Salaam, Tanzania was reviewed for squamous cell carcinoma of the skin in non-albino African subjects. The data was analysed for age, sex, site and predisposing factors. Our results were then compared with studies previously carried out in Tanzania, elsewhere in Africa and also on Blacks in America. Squamous cell carcinoma of the skin was found to be a common malignancy, and the commonest skin cancer. Its peak was in the 40-49 years age group though it could occur in children under five years of age. The most affected site was the lower limb, followed by the head and the neck. The penis in the male and the vulva in the female were the third most affected sites. The scalp and the lip were more affected in females than males. Chronic trauma, chronic ulcers, and scars were the main predisposing risk factors to the lower limb and the scalp, while ultra violet radiation to the head and neck, and smegma of the uncircumcised penis were thought to be predisposing risk factors. PMID:1308840

  10. A review of pig pathology in Tanzania.

    PubMed

    Wilson, Richard Trevor; Swai, Emmanuel

    2013-08-01

    The approximately 1.58 million pigs in Tanzania represent 3.7% of the national population of quadruped meat-producing animals. Pigs are kept mainly by small producers who own 99.5% of the national stock in units that average 3.04 animals (range 2-48). Government policy has had little practical application. African swine fever, foot-and-mouth disease and Cysticercosis are important diseases. The first two are notifiable diseases under Tanzania legislation; the last has widespread distribution and relevance as a major zoonosis. Ascariasis (Ascaris suum), hydatidosis (Echinococcus granulosus), leptospirosis (Leptospira interrogans) and thermophilic Campylobacter are other zoonoses associated with pigs. Gastrointestinal helminths and external parasites, especially Sarcoptes scabiei, are common. Risk factors associated with cysticercosis for humans working with pigs or eating their meat include the free-range or semi-confined management systems, the use of rivers or ponds as a source of water, lack of household sanitation, informal home slaughter, pork not being inspected at slaughter slabs and undercooked and barbecued meat. Pigs are a minor component of Tanzania's livestock sector but there is potential for increasing their contribution to human welfare. Prospects are enhanced by the shorter life cycle, greater number of young produced per year and the possibility of producing high-quality animal protein at a lower cost than meat produced by cattle and small ruminants. PMID:23733144

  11. Science Education in Tanzania: Challenges and Policy Responses

    ERIC Educational Resources Information Center

    Semali, Ladislaus M.; Mehta, Khanjan

    2012-01-01

    Students in rural and urban areas in Tanzania, and elsewhere in Africa, continue to have limited or lack access to culturally and employment-relevant science education. The current case study, a 2007-2009 examination of barriers to the reform movement of science education in Tanzania, uses data from interviews, classroom observations, document…

  12. "Finding a Life" among Undocumented Congolese Refugee Children in Tanzania

    ERIC Educational Resources Information Center

    Mann, Gillian

    2010-01-01

    The majority of undocumented Congolese refugee children living in Dar es Salaam, Tanzania, experience extreme poverty and social exclusion, harassment and discrimination. Their fear of deportation, forcible removal to refugee camps and imprisonment is coupled with a strong feeling that they are unwelcome in Tanzania. These realities require that…

  13. Seismic experiment reveals rifting of craton in Tanzania

    NASA Astrophysics Data System (ADS)

    Nyblade, Andrew A.; Langston, Charles A.; Last, Robert J.; Birt, Christopher; Owens, Thomas J.

    A research project in Tanzania, East Africa, is being conducted to examine seismic velocities within the crust and upper mantle in an area where cratonic lithosphere is experiencing extensional tectonism. The results will be used to evaluate models of cratonic structure. Waveforms from several hundred teleseismic earthquakes and over 10,000 regional and local earthquakes recorded in 1994 and 1995 by the Tanzania Broadband Seismic Experiment are not only yielding new insights into deep continental structure, but are also helping to determine the tectonic stability of cratons by identifying the locus of rifting within northeastern Tanzania.

  14. Use of Modern Technologies in Improving Astronomy Education in Tanzania

    NASA Astrophysics Data System (ADS)

    Jiwaji, N. T.

    2006-08-01

    With only the most basic astronomy content officially included in the Physics syllabus of Secondary Schools in Tanzania and a one semester Astrophysics option course offered in the Physics Department of one University, the reasons for apathy towards astronomy education in Tanzania are discussed. Using the current focus on introducing ICT into Primary and Secondary schools in Tanzania, the potential for advancing astronomy education per se and natural sciences in general is presented. Limiting factors such as teachers in general and science and astronomy literate teachers in particular, infrastructure and running costs of providing ICT based education, cultural impediments need to be overcome.

  15. Contagious bovine pleuropneumonia in Tanzania: current status.

    PubMed

    Msami, H M; Ponela-Mlelwa, T; Mtei, B J; Kapaga, A M

    2001-02-01

    CBPP reappeared in Arusha, Northern Tanzania in 1990, having been introduced from Kenya. The disease spread rapidly to Mara region through rustling of sick or infected animals. In November 1992, an unrelated outbreak occurred in Kagera, having spread from Southern Uganda. Up to the end of December 1994, the disease appeared to be confined to Kagera and Arusha. In January 1995, CBPP was observed in Morogoro region, south of the central railway line. Thereafter, the disease spread through western Tanzania. More recently, further disease has occurred in the Southern Highlands and Central regions. The contaminated area now stretches roughly between latitudes 1 degree and 9 degrees S and longitudes 30 degrees and 37 degrees E, with a cattle population of about 10 million. The direct losses incurred as a result of animal mortality, and vaccination campaign and disease surveillance costs have been assessed at over US$11 million. Indirect losses resulting from chronic disease are much more difficult to assess but are believed to be even higher. Control of the disease has been through restricting animal movements and a mass vaccination campaign. Uncontrolled animal movement during transhumance, trade, cattle thefts and vaccination breakthroughs facilitated the spread of the disease. PMID:11234189

  16. Maritime and Underwater Cultural Heritage Initiatives in Tanzania and Mozambique

    NASA Astrophysics Data System (ADS)

    Jeffery, Bill; Parthesius, Robert

    2013-06-01

    The aim of this paper is provide an overview of the capacity building programmes in maritime and underwater cultural heritage (MUCH) conducted by the authors in Tanzania and Mozambique. Tanzania and Mozambique have long histories of indigenous cultures, foreign contacts and influences and African adaptations beginning in the late Greco-Roman period, when the coastal populations exploited the peoples and riches of the interior. Today the coastline contains numerous examples of indigenous tangible and intangible heritage and many sites and histories related to the Swahili culture. Some exploratory research and training has been conducted in Tanzania and Mozambique, but the implementation by local residents of their own MUCH programme is still at an early stage. Under a UNESCO agreement framework, Tanzania in particular has started to develop a MUCH programme, which can assist in highlighting their extensive histories, cultural landscapes and cultural identity.

  17. Maternal mortality and morbidity. Women's reproductive health in Tanzania.

    PubMed

    Alloo, F

    1994-01-01

    Sexuality is a taboo for women in a patriarchal society. Tanzania has inadequate reproductive health care. Aspects of reproductive health are dealt with in safe motherhood or maternal and child health programs. Tanzania's health policy is based on women as mothers; it does not refer to women's right. For women in Tanzania, reproductive health is the right to live. Thousands of Tanzanian women die every year due to maternal complications. In an effort to contribute to the improvement of the conditions in health institutions and the advancement of women's status in the country, the Tanzania Media Women's Association (TAMWA) and the Medical Women's Association of Tanzania (MEWATA) joined in the organization of a Reproductive Health Meeting in Dar es Salaam. At the conference, major factors causing maternal mortality and morbidity, such as complications of abortion, anaemia in pregnancy, hypertensive disorders in pregnancy and puerperal sepsis, were discussed. A World Health Organization (WHO) report indicated that maternal mortality in Tanzania was 200-400/100,000 live births, while a survey conducted by MEWATA showed that maternal deaths at the Muhimbili Medical Center in the capital were 754/100,000 live births in 1991. Many maternal deaths could be prevented if hospitals were be properly equipped. Tanzanian women's poor health results in large part from their low socioeconomic status, poor nutrition, lack of income and employment. TAMWA chairperson Fatma Alloo and Dr. Kimambo (Ministry of Health) endorsed a national women's health movement to demand a government commitment to a holistic reproductive health policy. PMID:12288398

  18. Non-traumatic paraplegia in northern Tanzania.

    PubMed Central

    Scrimgeour, E M

    1981-01-01

    A retrospective study of all 100 cases of non-traumatic (medical) paraplegia admitted to a large hospital in northern Tanzania over an eight-year period was undertaken; 15 of the patients were examined. Patients' ages ranged from 2 to 80 years (mean 31), and 67 were male. Seventy-one lived under 85 km (53 miles) from the hospital, and the average period from onset of symptoms of paraplegia to admission to the referral hospital was ten weeks. Tuberculosis was the most frequent cause of paraplegia (54%), followed by neoplasia (13%) and schistosomiasis, (6%). No cases of nutritional myelopathy were diagnosed. In 12 cases a diagnosis could not be established. The average period spent in hospital was 11 weeks, and 35 patients made a good recovery and were ambulant at discharge. PMID:6793199

  19. Plague and the Human Flea, Tanzania

    PubMed Central

    Leirs, Herwig; Makundi, Rhodes H.; Van Dongen, Stefan; Davis, Stephen; Neerinckx, Simon; Deckers, Jozef; Libois, Roland

    2007-01-01

    Domestic fleas were collected in 12 villages in the western Usambara Mountains in Tanzania. Of these, 7 are considered villages with high plague frequency, where human plague was recorded during at least 6 of the 17 plague seasons between 1986 and 2004. In the remaining 5 villages with low plague frequency, plague was either rare or unrecorded. Pulex irritans, known as the human flea, was the predominant flea species (72.4%) in houses. The density of P. irritans, but not of other domestic fleas, was significantly higher in villages with a higher plague frequency or incidence. Moreover, the P. irritans index was strongly positively correlated with plague frequency and with the logarithmically transformed plague incidence. These observations suggest that in Lushoto District human fleas may play a role in plague epidemiology. These findings are of immediate public health relevance because they provide an indicator that can be surveyed to assess the risk for plague. PMID:17553245

  20. Geospatial Resource Access Analysis In Hedaru, Tanzania

    NASA Astrophysics Data System (ADS)

    Clark, Dylan G.; Premkumar, Deepak; Mazur, Robert; Kisimbo, Elibariki

    2013-12-01

    Populations around the world are facing increased impacts of anthropogenic-induced environmental changes and rapid population movements. These environmental and social shifts are having an elevated impact on the livelihoods of agriculturalists and pastoralists in developing countries. This appraisal integrates various tools—usually used independently— to gain a comprehensive understanding of the regional livelihood constraints in the rural Hedaru Valley of northeastern Tanzania. Conducted in three villages with different natural resources, using three primary methods: 1) participatory mapping of infrastructures; 2) administration of quantitative, spatially-tied surveys (n=80) and focus groups (n=14) that examined land use, household health, education, and demographics; 3) conducting quantitative time series analysis of Landsat- based Normalized Difference Vegetation Index images. Through various geospatial and multivariate linear regression analyses, significant geospatial trends emerged. This research added to the academic understanding of the region while establishing pathways for climate change adaptation strategies.

  1. Spectroscopy of red dravite from northern Tanzania

    NASA Astrophysics Data System (ADS)

    Taran, Michail N.; Dyar, M. Darby; Naumenko, Ievgen V.; Vyshnevsky, Olexij A.

    2015-07-01

    Low-Fe dravite with a formula of Na0.66Ca0.16Mg2.62Fe0.33Mn0.02Ti0.02Al5.95B3Si6.04O27(OH)4 is described from Engusero Sambu, northern Tanzania (On maps, Engusero Sambu may be found to be marked as belonging to Kenya, but in reality, it is located near the border in northern Tanzania). The sample has an unusual red color that is distinctly different from the red dravite from the Osarara, Narok district, in Kenya that was formerly studied by Mattson and Rossman (Phys Chem Miner 14:225-234, 1984) and Taran and Rossman (Am Mineral 87:1148-1153, 2002). This unique sample has been characterized by optical and Mössbauer spectral measurements to investigate underlying cause of the intense bands in absorption spectra that give rise to the red color. These features are shown to be caused by exchange-coupled Fe3+-Fe3+ interactions. Thermal annealing of the samples causes an increase in Fe3+ contents due to oxidation of [Y]Fe2+. However, heat treatment does not change the high-energy absorption edge, which is probably caused by intense ligand-to-Fe3+ charge-transfer UV bands. In fact, Mössbauer results show that high-temperature annealing initiates breakdown of the tourmaline into an Fe oxide and causes accompanying redistribution of Fe3+ within the structure. Because of the popularity of tourmaline as a gemstone, this work has implications for understanding the causes of color in tourmaline, facilitating recognition of the distinctions between naturally occurring and treated tourmalines in the gem industry and enabling heat treatments for color enhancement.

  2. Nutrition Transition in Rural Tanzania and Kenya.

    PubMed

    Keding, Gudrun

    2016-01-01

    All three types of malnutrition - underweight, overweight and micronutrient deficiency - are experienced in countries undergoing a nutrition transition, and they can occur in parallel in one community or even one household. To combat this triple burden of malnutrition, a combination of different strategies will be necessary, including a focus on food-based strategies that promote the consumption of a wide range of foods across nutritionally distinct food groups. In addition to a literature review, data from our own nutrition studies in both Tanzania and Kenya are presented in this paper. The literature review revealed an average of 10% of children in urban areas of Kenya and Tanzania with overweight and obesity, which is an alarming trend, and it is suggested that interventions need to start not only at school but also with adolescent girls and pregnant women to target the '1,000-day window'. From own study data, dietary patterns were generated that included a 'purchase' pattern dominated by bought and processed foods, indicating a possible nutrition transition even in the rural areas of both countries. Vegetable and especially fruit consumption was low in both countries. In addition, in Kenya, study participants exceeded the suggested maximum level of sugar consumption per day, which will most likely contribute to increasing levels in overweight and obesity prevalence and other noncommunicable diseases in general. As sugar was mainly consumed in combination with black tea, next to eating habits, changing drinking habits is also an important part of the nutrition transition and needs to receive more attention. A 'healthy eating at school and at home strategy' is suggested, which needs the support of both schools and parents/caregivers. In general, to take countermeasures against the negative trends of nutrition transition, joint efforts from all players in the field - not only those in nutrition, health and medicine, but also those in education and agriculture

  3. Structure of carbonate melts at high pressure

    NASA Astrophysics Data System (ADS)

    Hudspeth, J.; Sanloup, C.; Cochain, B.; Konopkova, Z.; Afonina, V.; Morgenroth, W.

    2015-12-01

    Carbonate melts are rare magmas with only a single active volcano (Oldoinyo Lengai,Tanzania [1]). They are of fundamental interest for their role in the Earth's deep carbon cycle and are of immense economic importance due to their affinity for REE strategic metals (niobium, uranium, tantalum, etc). They have remarkable physical properties such as very low viscosity [2] and magmatic temperatures for alkaline carbonate lavas [3] and it has been predicted that their compressibility could be significantly higher than that of silicate melts [4,5]. Despite the atomic structure of carbonate melts being fundamental for controlling their physical and chemical behavior in natural systems, very few structural studies have been reported and these have been largely computational. Here we present initial structural investigations of carbonate melts at mantle pressures using in situ x-ray diffraction in diamond anvil cells. The structure factor S(Q) is transformed to obtain the real space pair distribution function G(R) which describes the local and intermediate range atomic ordering allowing bond length and coordination number changes with pressure to be determined. [1] Krafft and Keller, Science 245:168-170, 1989 [2] Yono et al., Nat. Commun. 5:5091, 2014 [3] Dobson et al., Earth Planet. Sci. Lett. 143:207-215, 1996 [4] Genge et al., Earth Planet. Sci. Lett. 131:225-238, 1995 [5] Jones et al., Rev. Mineral. Geochem. 75:289-322, 2013

  4. Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Kamenetsky, Vadim S.; Simonetti, Antonio

    2013-10-01

    The Earth’s sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na2Ca(CO3)2] and gregoryite [(Na2,K2,Ca)CO3]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic carbonates. Consequently, this leads to the conundrum as to the composition of primary, mantle-derived carbonatite liquids. Here we report a detailed chemical investigation of melt inclusions associated with intrusive (plutonic) calcite-rich carbonatites from the ~120 Ma carbonatite complex of Oka (Canada). Melt inclusions are hosted by magnetite (Fe3O4), which crystallizes through a significant period of carbonatite melt solidification. Our results indicate mineral assemblages within the melt inclusions that are consistent with those documented in natrocarbonatite lavas. We propose therefore that derivation of alkali-enriched parental carbonatite melts has been more prevalent than that preserved in the geological record.

  5. Norman L. Bowen Award to John Barry Dawson

    NASA Astrophysics Data System (ADS)

    Smith, Joseph V.; Dawson, J. B.

    Barry Dawson is just right for th e first Norman L. Bowen Award in Volcanology, Geochemistry, and Petrology. Like Norman L. Bowen, he has the inspiration to combine ideas from different disciplines to obtain a higher synthesis. Consider his brilliant talk of yesterday morning (Eos 69, p. 502, abstract V11C-06, Veined and metasomatised upper mantle beneath the Eastern African Rift: Evidence from N. Tanzania xenoliths). Barry rapidly reviewed the tectonic setting of east Africa, showed some nice photographs of the volcanic cones of Pello and Oldoinyo Lengai, focused on the upper-mantle xenoliths in scoria at Pello, moved in on the microscopy and mineral chemistry of the metasomatic veins in the peridotites, snowed how the lower density of a metasomatized peridotite would fit the middle of a geophysical profile from seismic surveys, and brought off a grand finale in which the Kenya dome was interpreted to result from inflation related to metasomatization of underlying peridotite. Undoubtedly, this will lead to many further studies of doming adjacent to rift systems around the world.

  6. An analogue experimental model of depth fluctuations in lava lakes

    NASA Astrophysics Data System (ADS)

    Witham, Fred; Woods, Andrew W.; Gladstone, Charlotte

    2006-07-01

    Lava lakes, consisting of molten degassing lava in summit craters of active basaltic volcanoes, sometimes exhibit complex cycles of filling and emptying on time-scales of hours to weeks such as recorded at Pu’u’O’o in Hawaii and Oldoinyo Lengai in Tanzania. Here we report on a new series of analogue laboratory experiments of two-phase flow in a reservoir-conduit-lava lake system which spontaneously generates oscillations in the depth of liquid within the lake. During the recharge phase, gas supplied from a subsurface reservoir of degassing magma drives liquid magma up the conduit, causing the lake to fill. As the magmastatic pressure in the lake increases, the upward supply of magma, driven by the gas bubbles, falls. Eventually the upflow becomes unstable, and liquid drains downwards from the lake, driven by the magmastatic pressure of the overlying lake, suppressing the ascent of any more bubbles from the chamber. At a later stage, once the lake has drained sufficiently, the descent speed of liquid through the conduit decreases below the ascent speed of the bubbles, and the recharge cycle resumes. Application of a quantitative model of the experiments to the natural system is broadly consistent with field data.

  7. Shallow and deep earthquake sequences captured in the North Tanzanian Divergence, East Africa: Inferences on seismogenic processes and rheology

    NASA Astrophysics Data System (ADS)

    Albaric, J.; Perrot, J.; Déverchère, J.; Deschamps, A.; Ferdinand, R. W.; Le Gall, B.

    2009-12-01

    Using a temporary local seismic network of 35 stations deployed in North Tanzania (SEISMOTANZ'07 experiment) during 6 months in 2007, we captured two earthquake sequences (Gelai and Manyara) occurring respectively in the southern end of the Kenya rift and in the North Tanzanian Divergence (NTD). None of the sequences depicts typical swarm or mainshock-aftershock patterns. Although distant of only ~150 km, their triggering mechanisms appear to be different. They highlight a major change in the magmatic/tectonic nature of the rift where the eastern branch of the Est African Rift enters the Tanzanian craton. Both depict similar shape and long-axis, emphasizing the preferred locus of active strain release along NE-SW discontinuities which probably root at depth into steep Proterozoic shear zones. At Gelai, the deformation is dominated by aseismic processes involving slow slip on a normal fault and dyke intrusion within the upper crust, and an interaction with the eruption of the nearby Oldoinyo Lengai volcano. At Manyara, the sequence reveals a long-lasting seismic activity deeply rooted (~20-35 km depth), possibly indicative of stress loading transmitted laterally. Focal solutions demonstrate a mixture of normal and strike slip faulting on sub-vertical inherited structures striking N60°E. The yield stress envelope modelled from the depth frequency distribution of earthquakes in Manyara is consistent with the presence of a mafic lower crust and further supports the strength increase of the rifted crust from south Kenya to the NTD.

  8. Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada.

    PubMed

    Chen, Wei; Kamenetsky, Vadim S; Simonetti, Antonio

    2013-01-01

    The Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na2Ca(CO3)2] and gregoryite [(Na2,K2,Ca)CO3]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic carbonates. Consequently, this leads to the conundrum as to the composition of primary, mantle-derived carbonatite liquids. Here we report a detailed chemical investigation of melt inclusions associated with intrusive (plutonic) calcite-rich carbonatites from the ~120 Ma carbonatite complex of Oka (Canada). Melt inclusions are hosted by magnetite (Fe3O4), which crystallizes through a significant period of carbonatite melt solidification. Our results indicate mineral assemblages within the melt inclusions that are consistent with those documented in natrocarbonatite lavas. We propose therefore that derivation of alkali-enriched parental carbonatite melts has been more prevalent than that preserved in the geological record. PMID:24173270

  9. Observation-centered approach to ASD assessment in Tanzania.

    PubMed

    Harrison, Ashley J; Zimak, Eric H; Sheinkopf, Stephen J; Manji, Karim P; Morrow, Eric M

    2014-10-01

    Abstract In many lower-income countries, there is a paucity of assessment services for autism spectrum disorders (ASD)., Guidelines will be provided for conducting cross-cultural assessments in the context of limited validated resources in Tanzania. By examining behavioral, social, and adaptive differences we were able to provide differential diagnostic evaluations aligning with best practice standards for 41 children in Tanzania age 2-21 years. We describe the utility of a flexible, behavioral observation instrument, the Childhood Autism Rating Scales, Second Edition (CARS2), to gather diagnostic information in a culturally sensitive manner. We observed that the ASD group was characterized by significantly higher scores on the CARS2, F  =  21.09, p < .001, η(2)  =  .37, than the general delay comparison group. Additional recommendations are provided for making cultural adaptations to current assessment instruments for use in a country without normed instruments, such as Tanzania. PMID:25247726

  10. The current status of women in physics in Tanzania

    NASA Astrophysics Data System (ADS)

    Mohammed, Najat K.; Kazmili, Brenda

    2015-12-01

    Women's representation in physics in Tanzania is generally low. Various studies have shown that Tanzanian girls face obstacles to realizing their educational and intellectual capabilities. The situation is even worse in the field of physics because of the perception that the subject is too difficult. The number of women in physics at the university level is highly associated with their number in secondary school level as well as their performance. This paper analyzes the current status of women engaged in physics in Tanzania in the academic and research institutions.

  11. Maternal deaths in Tanzania -- a challenge.

    PubMed

    1994-08-01

    A reproductive health approach to health care has many consequences for women in Tanzania. Conditions are currently such that in one hospital in Amana there were 30 to 40 deliveries daily, but only 2 beds. The consequence was patients were treated while lying on the floor. The main city hospital did not have a vacuum aspirator, resuscitation equipment for newborns, or a sterilizer. A Dar es Salaam study shows a hospital maternal mortality rate of 754/100,000 live births, which is much higher than the 200-400/100,000 live births estimated by the WHO. The barriers to women's health are low socioeconomic status, poor nutrition, lack of income, lack of employment opportunities, and limited access to basic sanitation. There is discrimination against women in food, education, and economic independence, and social custom that denies decision making about marriage and reproduction. Access to information is limited to mother and child clinics. Men tend not to be involved in family planning or in treatment for sexually transmitted diseases. Strategies have been narrowly focused on maternal mortality, rather than on reproductive health and the right to live. Pregnancy threatens the right to life. PMID:12222520

  12. The sedimentary basins of Tanzania - reviewed

    NASA Astrophysics Data System (ADS)

    Mbede, E. I.

    The sedimentary basins of Tanzania have been classified into four morphotectonic groups: the coastal basin, the Karoo rift basins, basins found within the present East African rift valley and the cratonic sag basins. Except for the cratonic sag basins, each of these basin group has been affected by rifting at one time or another. The geology of each basin is discussed, structural evolution is evaluated and the prospectivity is thence looked into. Coal is exploited at Songwe-Kiwira coalfield and is found in potentially economic quantities in other Karoo basins. Prospecting for hydrocarbon resources has been going on since the 50s. Gas has been discovered in Songosongo and Mnazi bay fields, uneconomical quantities of oil have also been reported in Songosongo. Being basically rift basins which have reached different stages of development, source rocks normally associated with Initial-rifting, synrifting as well as post-rifting processes are probably well developed. Reservoir rocks, traps and cap rocks are normally not rare in such tectonic environments. Thermal gradients associated with the rifting stage are normaly high to effect maturation of source rocks even at low sedimentary thicknesses. Studies done so far are still inconclusive, because while testing has mainly been focused on structural traps stratigraphic traps seems to be more promising.

  13. Contextualized IT Education in Tanzania: Beyond Standard IT Curricula

    ERIC Educational Resources Information Center

    Tedre, Matti; Bangu, Nicholas; Nyagava, Seth I.

    2009-01-01

    Tumaini University at Iringa, Tanzania, started a new B.Sc. program in IT in 2007. In the course of planning and implementation of the program, we found out that standard ACM/IEEE IT curricula are not adequate for an IT program in a poor, developing country. The standard curricula describe, in detail, the competences that IT specialists in…

  14. Evaluating a School-Based Trachoma Curriculum in Tanzania

    ERIC Educational Resources Information Center

    Lewallen, Susan; Massae, Patrick; Tharaney, Manisha; Somba, Margareth; Geneau, Robert; MacArthur, Chad; Courtright, Paul

    2008-01-01

    Trachoma remains a public health problem in a number of sub-Saharan Africa countries; behavioral change and environmental improvements are cornerstones of prevention efforts. Evidence of successful health education are few in Africa. Health education efforts through primary schools have recently been developed and adopted in Tanzania. We evaluated…

  15. Did Tanzania Achieve the Second Millennium Development Goal? Statistical Analysis

    ERIC Educational Resources Information Center

    Magoti, Edwin

    2016-01-01

    Development Goal "Achieve universal primary education", the challenges faced, along with the way forward towards achieving the fourth Sustainable Development Goal "Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all". Statistics show that Tanzania has made very promising steps…

  16. Women's Access to Higher Education in Tanzania: A Qualitative Study

    ERIC Educational Resources Information Center

    Johnson, Megan Patricia

    2011-01-01

    The purpose of this study was to reveal the ways in which first-generation women in Tanzania explained their success in pursuing a university education despite cultural and social obstacles. Such obstacles include social policies, socio-cultural factors, and academic factors. A review of the literature revealed that issues such as patriarchy,…

  17. Investigating Motivations for Women's Skin Bleaching in Tanzania

    ERIC Educational Resources Information Center

    Lewis, Kelly M.; Robkin, Navit; Gaska, Karie; Njoki, Lillian Carol

    2011-01-01

    Why do many African women continue to use damaging skin-bleaching cosmetics that contain dangerous chemicals (e.g., mercury) that may increase their rates of infertility, skin cancer, and serious skin/brain/kidney disease? To address this question, our study investigated motivations driving the preservation of skin-bleaching practices in Tanzania.…

  18. Childhood Sexual Abuse among University Students in Tanzania

    ERIC Educational Resources Information Center

    McCrann, Denis; Lalor, Kevin; Katabaro, Joviter Kamugisha

    2006-01-01

    Objectives: There are no prevalence data for childhood sexual abuse among Tanzanian university students. This investigation addressed this paucity. The nature of sexual abuse was also investigated. Method: Participants (N=487) from a university in Tanzania completed a questionnaire which assessed abusive childhood sexual experiences, gathering…

  19. School Proximity and Child Labor: Evidence from Rural Tanzania

    ERIC Educational Resources Information Center

    Kondylis, Florence; Manacorda, Marco

    2012-01-01

    Is improved school accessibility an effective policy tool for reducing child labor in developing countries? We address this question using microdata from rural Tanzania and a regression strategy that attempts to control for nonrandom location of households around schools as well as classical and nonclassical measurement error in self-reported…

  20. High Seroprevalence for Typhus Group Rickettsiae, Southwestern Tanzania

    PubMed Central

    Dill, Tatjana; Dobler, Gerhard; Saathoff, Elmar; Clowes, Petra; Kroidl, Inge; Ntinginya, Elias; Machibya, Harun; Maboko, Leonard; Löscher, Thomas; Hoelscher, Michael

    2013-01-01

    Rickettsioses caused by typhus group rickettsiae have been reported in various African regions. We conducted a cross-sectional survey of 1,227 participants from 9 different sites in the Mbeya region, Tanzania; overall seroprevalence of typhus group rickettsiae was 9.3%. Risk factors identified in multivariable analysis included low vegetation density and highway proximity. PMID:23347529

  1. Schooling, Child Labor, and the Returns to Healthcare in Tanzania

    ERIC Educational Resources Information Center

    Adhvaryu, Achyuta R.; Nyshadham, Anant

    2012-01-01

    We study the effects of accessing better healthcare on the schooling and labor supply decisions of sick children in Tanzania. Using variation in the cost of formal-sector healthcare to predict treatment choice, we show that accessing better healthcare decreases length of illness and changes children's allocation of time to school and work.…

  2. Engaged Learning and Peace Corps Service in Tanzania: An Autoethnography

    ERIC Educational Resources Information Center

    Darling, Brianna; Thorp, Laurie; Chung, Kimberly

    2014-01-01

    The Peace Corps Masters International program offers students the opportunity to combine their Peace Corps service with their master's education. This article demonstrates how classroom learning strengthened the author's Peace Corps service in Tanzania, which in turn strengthened her master's thesis. Peace Corps supports an approach…

  3. Child Sexual Abuse: Community Concerns in Urban Tanzania

    ERIC Educational Resources Information Center

    Kisanga, Felix; Nystrom, Lennarth; Hogan, Nora; Emmelin, Maria

    2011-01-01

    The aim of this study was to explore community perceptions about child sexual abuse in Tanzania. Thirteen focus group discussions were conducted with adult community members. The core category, "children's rights challenged by lack of agency", was supported by eight categories. "Aware but distressed" portrayed feelings of hopelessness, "lack of…

  4. Etiologies of Autism in a Case-Series from Tanzania

    ERIC Educational Resources Information Center

    Mankoski, Raymond E.; Collins, Martha; Ndosi, Noah K.; Mgalla, Ella H.; Sarwatt, Veronica V.; Folstein, Susan E.

    2006-01-01

    Most autism has a genetic cause although post-encephalitis cases are reported. In a case-series (N = 20) from Tanzania, 14 met research criteria for autism. Three (M:F = 1:2) had normal development to age 22, 35, and 42 months, with onset of autism upon recovery from severe malaria, attended by prolonged high fever, convulsions, and in one case…

  5. Special Education in Tanzania: Project Findings and Recommendations. Terminal Report.

    ERIC Educational Resources Information Center

    United Nations Educational, Scientific, and Cultural Organization, Paris (France).

    The report describes a UNESCO (United Nations Educational, Scientific, and Cultural Organization) project in Tanzania which has the following objectives: establishment of seven educational assessment and resource centers for handicapped children; establishment of four units for deaf children in ordinary schools; implementation of three training…

  6. Higher Education System and Jobless Graduates in Tanzania

    ERIC Educational Resources Information Center

    Ndyali, Lyata

    2016-01-01

    The Tanzania's higher education institutions haven't raised much of expectations the graduates lack the skills required by the labor market and this trend results in mass graduate unemployment, otherwise this would have assisted them to be more self-reliant. The study explores the importance of higher-level business education human resources…

  7. Tanzania Higher Education--Fifty Years after Independence

    ERIC Educational Resources Information Center

    Mnubi, Godfrey M.

    2013-01-01

    As Tanzania celebrates fifty years of independence at the crossroads of globalization, the country has experienced a changing landscape and a major transformation in higher learning education with spectacular expansion in student enrollment rates. This requires its higher education institutions, particularly universities, to function effectively…

  8. Greenhouse gases mitigation options and strategies for Tanzania

    SciTech Connect

    Mwandosya, M.J.; Meena, H.E.

    1996-12-31

    Tanzania became a party to the United Nations Framework on Climate Change (UN FCCC) when she ratified the Convention in March, 1996. Now that Tanzania and other developing countries are Parties to the UN FCCC, compliance with its provisions is mandatory. The legal requirements therefore provide a basis for their participation in climate change studies and policy formulation. All parties to the Convention are required by Article 4.1 of the United Nations Convention on Climate Change (UN FCCC) to develop, periodically update, publish, and make available national inventories of anthropogenic emissions and removal of greenhouse gases that are not controlled by the Montreal Protocol. This study on possible options for the mitigation of greenhouse gases in Tanzania is a preliminary effort towards the fulfilment of the obligation. In order to fulfil their obligations under the UN FCCC and have a meaningful mitigation assessment, identification and quantification of anthropogenic sources of atmospheric emissions of greenhouse gases in the country was undertaken. In this respect, the study of anthropogenic emissions by source and removals by sink of GHGs in Tanzania was done with the main objective of increasing the quantity and quality of base-line data available in order to further scientific understanding of the relationship of greenhouse gas emissions to climate change. Furthermore, the study facilitated identification of national policy and technological options that could reduce the level of emissions in the country.

  9. Resistance to Information Technology in Public Procurement in Tanzania

    ERIC Educational Resources Information Center

    Nditi, Christopher

    2010-01-01

    Organizations have become more dependent on information technology (IT) in the 21st century. But IT implementation and use is resisted in certain sectors of Tanzania, particularly in government-run enterprises. The purpose of this study was to investigate the causes and consequences of resistance to IT development and implementation in the…

  10. Literacy and Power--The Cases of Tanzania and Rwanda

    ERIC Educational Resources Information Center

    Wedin, Asa

    2008-01-01

    In this paper it is claimed that the relation between literacy and power is complex. What people do with literacy has effects on power relations but literacy is not democratic "per se". Drawing from two cases from Tanzania and Rwanda it is argued that plans for adult education and literacy education should consider the perspectives of target…

  11. Successful Community Nutrition Programming: Lessons from Kenya, Tanzania, and Uganda.

    ERIC Educational Resources Information Center

    Iannotti, Lora; Gillespie, Stuart

    This report on the key findings from a series of assessments of successful community nutrition programming conducted in Kenya, Tanzania, and Uganda between 1999 and 2000. The aim of the assessments was to identify key lessons learned from the successful processes and outcomes in these programs. The report is divided into eight chapters: (1)…

  12. Clinical and epidemiologic variations of esophageal cancer in Tanzania

    PubMed Central

    Gabel, Jaime V; Chamberlain, Robert M; Ngoma, Twalib; Mwaiselage, Julius; Schmid, Kendra K; Kahesa, Crispin; Soliman, Amr S

    2016-01-01

    AIM: To estimate the incidence of esophageal cancer (EC) in Kilimanjaro in comparison to other regions in Tanzania. METHODS: We also examined the clinical, epidemiologic, and geographic distribution of the 1332 EC patients diagnosed and/or treated at Ocean Road Cancer Institute (ORCI) during the period 2006-2013. Medical records were used to abstract patient information on age, sex, residence, smoking status, alcohol consumption, tumor site, histopathologic type of tumor, date and place of diagnosis, and type and date of treatment at ORCI. Regional variation of EC patients was investigated at the level of the 26 administrative regions of Tanzania. Total, age- and sex-specific incidence rates were calculated. RESULTS: Male patients 55 years and older had higher incidence of EC than female and younger patients. Of histopathologically-confirmed cases, squamous-cell carcinoma represented 90.9% of histopathologic types of tumors. The administrative regions in the central and eastern parts of Tanzania had higher incidence rates than western regions, specifically administrative regions of Kilimanjaro, Dar es Salaam, and Tanga had the highest rates. CONCLUSION: Further research should focus on investigating possible etiologic factors for EC in regions with high incidence in Tanzania. PMID:26989467

  13. Hydrogeochemical features of Lake Ngozi (SW Tanzania)

    NASA Astrophysics Data System (ADS)

    Delalande-Le Mouëllic, Manuëlla; Gherardi, Fabrizio; Williamson, David; Kajula, Stephen; Kraml, Michael; Noret, Aurélie; Abdallah, Issah; Mwandapile, Ezekiel; Massault, Marc; Majule, Amos; Bergonzini, Laurent

    2015-03-01

    Located on the triple rift junction hosting the Karonga-Usungu depression in Tanzania, Lake Ngozi is the second largest crater lake of the East African Rift. The lake has a number of peculiar features: it has a near constant water level, no permanent surface inlets and outlets, it is vertically well-mixed, with homogeneous distribution of temperature and chemical composition, and it is characterised by near neutral to slightly acid Na-Cl waters of comparatively high salinity and high P-CO2. Based on the different chemical signature of surface and ground waters (low-Cl type) from lake waters, mass balance methods have been applied to investigate lake dynamics. Water enters the lake mainly by precipitation and groundwater inflow, and leaves by groundwater outflow and evaporation. A large groundwater outflow of 2.4 m yr-1 has been estimated. The high salinity, Na-Cl signature of Lake Ngozi waters, together with 3He/4He ratios measured on dissolved gases (between 7 and 8.3 Ra) and high-PCO2 values estimated all along the water vertical column indicate the inflow of deep-seated fluids, likely magmatic in origin, into the lake. The existence of a hydrothermal system possibly at 250 °C in the root of the volcanic edifice is also hypothesised on the basis of solute geothermometry. Despite the current lack of vertical stratification, the lake is suspected to act as condenser for CO2 and other gases of deep magmatic origin, and should be then further monitored for the risk of limnic eruptions as well as for environmental and climatic concerns.

  14. Rift initiation with volatiles and magma

    NASA Astrophysics Data System (ADS)

    Ebinger, Cynthia; Muirhead, James; Roecker, Steve; Tiberi, Christel; Muzuka, Alfred; Ferdinand, Rrichard; Mulibo, Gabrile; Kianji, Gladys

    2015-04-01

    Rift initiation in cratonic lithosphere remains an outstanding problem in continental tectonics, but strain and magmatism patterns in youthful sectors of the East African rift provide new insights. Few teleseisms occur in the Eastern rift arm of the East African rift system, except the southernmost sector in northern Tanzania where extension occurs in Archaean lithosphere. The change in seismic energy release occurs over a narrow along-axis zone, and between sectors with and without volcanoes in the central rift valley. Are these differences in strain behavior indicative of along-strike variations in a) rheology; b) strain transfer from border faults to magma intrusion zones; c) dike vs fault slip; and/or d) shallow vs deep magma chambers? We present time-space relations of seismicity recorded on a 38-station array spanning the Kenya-Tanzania border, focal mechanisms for the largest events during those time periods, and compare these to longer-term strain patterns. Lower crustal seismicity occurs along the rift length, including sectors on and off craton, and those with and without central rift valley volcanoes, and we see no clear along-strike variation in seismogenic layer thickness. One explanation for widespread lower crustal seismicity is high gas pressures and volatile migration from active metasomatism of upper mantle and magma degassing, consistent with very high volatile flux along fault zones, and widespread metasomatism of xenoliths. Volatile release and migration may be critical to strength reduction of initially cold, strong cratonic lithosphere. Seismicity patterns indicate strain (and fluid?) transfer from the Manyara border fault to Gelai shield volcano (faulting, diking) via Oldoinyo Lengai volcano. Our focal mechanisms and Global CMTs from an intense fault-dike episode (2007) show a local, temporally stable, rotation from ~E-W extension to NE-SE extension in this linkage zone, consistent with longer term patterns recorded in vent and eruptive

  15. Lower Crustal Seismicity, Volatiles, and Evolving Strain Fields During the Initial Stages of Cratonic Rifting

    NASA Astrophysics Data System (ADS)

    Lambert, C.; Muirhead, J.; Ebinger, C. J.; Tiberi, C.; Roecker, S. W.; Ferdinand-Wambura, R.; Kianji, G.; Mulibo, G. D.

    2014-12-01

    The volcanically active East African rift system in southern Kenya and northern Tanzania transects thick cratonic lithosphere, and comprises several basins characterized by deep crustal seismicity. The US-French-Tanzania-Kenya CRAFTI project aims to understand the role of magma and volatile movement during the initiation and evolution of rifting in cratonic lithosphere. Our 38-station broadband network spans all or parts of fault-bounded rift segments, enabling comparison of lithospheric structure, fault kinematics, and seismogenic layer thickness with age and proximity to the deeply rooted Archaen craton. Seismicity levels are high in all basins, but we find profound differences in seismogenic layer thickness along the length of the rift. Seismicity in the Manyara basin occurs almost exclusively within the lower crust, and in spatial clusters that have been active since 1990. In contrast, seismicity in the ~ 5 My older Magadi basin is localized in the upper crust, and the long border fault bounding the west side of the basin is seismically inactive. Between these two basins lies the Natron rift segment, which shows seismicity between ~ 20 and ~2 km depth, and high concentrations at Oldoinyo Lengai and Gelai volcanoes. Older volcanoes on the uplifted western flank (e.g., Ngorongoro) experience swarms of activity, suggesting that active magmatism and degassing are widespread. Focal mechanisms of the frequent earthquakes recorded across the array are spatially variable, and indicate a stress field strongly influenced by (1) Holocene volcanoes, (2) mechanical interactions between adjacent rift basins, and (3) a far-field ESE-WNW extensional stress regime. We explore the spatial correlation between zones of intense degassing along fault systems and seismicity, and examine the influence of high gas pressures on lower and upper crustal seismicity in this youthful cratonic rift zone.

  16. Assessment of maternal mortality in Tanzania.

    PubMed

    Walraven, G E; Mkanje, R J; van Roosmalen, J; van Dongen, P W; Dolmans, W M

    1994-05-01

    The results from a prospective community survey, a sisterhood method survey, and a hospital survey were compared in order to ascertain a reliable and inexpensive method for estimating direct deaths from obstetric complications of pregnancy. The maternal mortality ratio was used to express risk of dying during pregnancy. The surveys were conducted in Kwimba District in Mwanza region of northwestern Tanzania: in August 1989 to March 1991 in the community study within the primary health care area of Sumve Hospital, which supplied data on maternal mortality between 1986 and 1990. The sisterhood survey was conducted in 2 villages in 1990, of which 1 village was included in the community survey. The village study included 447 women, of whom 421 remained in the survey and delivered 427 infants (415 live born); there was 1 maternal death. The sisterhood method engaged 2865 respondents and the lifetime risk of maternal death was estimated at 297 and the proportional maternal mortality rate was 13.9%. There were 82 maternal deaths and 589 deaths from all causes among sisters aged 15 years and older. 7526 women were included in the hospital survey, of which 7335 births were represented; there were 62 maternal deaths. The maternal mortality risk was 845 among hospital admissions. 69% of all maternal deaths were accounted for by direct causes. Most deaths were attributed to the top 5 worldwide causes: obstructed labor, puerperal sepsis, postpartum hemorrhage, complications of abortion, and preeclampsia. There were few reports of abortions and abortion-related mortality. Relapsing fever or Borrelia infection was an indirect cause of death common to the region and particularly hazardous to pregnant women. Many hospital deaths were emergency admissions. The conclusion was that the sisterhood method provided a better indication of the extent of maternal mortality within the community. Other advantages were the small sample and the speed, quickness, and low cost. Hospital data

  17. Wetland plant waxes from Olduvai Gorge, Tanzania

    NASA Astrophysics Data System (ADS)

    Tamalavage, A.; Magill, C. R.; Barboni, D.; Ashley, G. M.; Freeman, K. H.

    2013-12-01

    Olduvai Gorge, northern Tanzania, exposes a Plio-Pleistocene sedimentary record that includes lake and lake-margin sediments and fossil remains of ancient plants and early humans. There are rich paleontological and cultural records at Olduvai Gorge that include thousands of vertebrate fossils and stone tools. Previous studies of plant biomarkers in lake sediments from Olduvai Gorge reveal repeated, abrupt changes in landscape dominance by woodland or grassland vegetation during the early Pleistocene, about 1.8 million years ago. However, the reconstruction of wetland vegetation in the past is limited by a dearth of published lipid signatures for modern wetland species. Here, we present lipid and isotopic data for leaf tissues from eight modern plants (i.e., sedge and Typha species) living in wetlands near Olduvai Gorge. Trends in values for molecular and leaf δ13C and average chain length (ACL) of n-alkanes in plant tissues are similar to values for underlying soils. Compound-specific δ13C values for n-alkanes C25 to C33 range between -36.4 to -23.1‰ for C3 plants and -22.3 to -19.5‰ for C4 plants. Fractionation factors between leaf and lipids, ɛ29 and ɛ33, fall within the range reported in the literature, but they differ more widely within a single plant. For C3 plants, the average difference between ɛ29 and ɛ33 is 6.5 ‰, and the difference between ɛ29 and ɛ33 for C4 plants is less than 2‰. Both plant types show a parabolic relationship between chain length and δ13C values, in which C29 typically has the most depleted value, and typically shift by 3-5‰ between alkane homologs. This pattern has not been previously reported, and could be unique for sedge lipids. If so, these data help constrain the application of plant wax biomarkers from sedges for paleo-vegetation reconstruction in paleoclimate studies and at archaeological sites.

  18. Epidemiology and control of human schistosomiasis in Tanzania

    PubMed Central

    2012-01-01

    In Tanzania, the first cases of schistosomiasis were reported in the early 19th century. Since then, various studies have reported prevalences of up to 100% in some areas. However, for many years, there have been no sustainable control programmes and systematic data from observational and control studies are very limited in the public domain. To cover that gap, the present article reviews the epidemiology, malacology, morbidity, and the milestones the country has made in efforts to control schistosomiasis and discusses future control approaches. The available evidence indicates that, both urinary and intestinal schistosomiasis are still highly endemic in Tanzania and cause significant morbidity.Mass drug administration using praziquantel, currently used as a key intervention measure, has not been successful in decreasing prevalence of infection. There is therefore an urgent need to revise the current approach for the successful control of the disease. Clearly, these need to be integrated control measures. PMID:23192005

  19. Workplace prevention programs promote behavior change in Tanzania.

    PubMed

    Henry, K

    1995-02-01

    An estimated 800,000 Tanzanians had been infected with HIV by the end of 1992. Since working-age people spend 75% of their time at work, the African Medical and Research Foundation (AMREF), the Tanzanian Council for Social Development, and the Organization of Tanzanian Trade Unions organize and implement workplace-based HIV/AIDS prevention programs. For example, anonymous HIV screening conducted by AMREF at Tanzania Breweries Limited in September 1993 found 11.4% of the brewery's truck drivers to be HIV-seropositive. The men subsequently participated in an informal AIDS education session conducted by peer educators with help from the brewery's STD/AIDS coordinator. These sessions are a regular part of workplace AIDS prevention programs supported by the US Agency of International Development's Tanzania AIDS Program implemented by the AIDS Control and Prevention Project (AIDSCAP). The author considers motivating managers, peer education, condoms, behavior change, and expansion and sustainability. PMID:12347575

  20. Factors associated with road traffic injuries in Tanzania

    PubMed Central

    Boniface, Respicious; Museru, Lawrence; Kiloloma, Othman; Munthali, Victoria

    2016-01-01

    Introduction Injuries represent a significant cause of morbidity and mortality worldwide and road traffic crashes accounts for a significant proportion of these injuries. Tanzania is among the countries with high rates of road traffic crashes. The aim of this study was to determine the pattern, associated factors and management of road traffic injury patients in Tanzania. Methods A cross-sectional study of patients involved in motor traffic crashes and attended in six public hospitals of Tanzania mainland between April 2014 and September 2014. Results A total of 4675 road traffic injury patients were seen in studied hospitals, 76.6% were males. Majority (70.2%) were between 18 - 45 years age group. Motorcycles were the leading cause of road traffic crashes (53.4%), and drivers (38.3%) accounted for majority of victims. Fractures accounted for 34.1%, and injuries were severe in 2.2% as determined by the Kampala trauma score II (KTS II). Majorities 57.4% were admitted and 2.2% died at the casualty. Factors associated with mortality were; using police vehicles to hospital (P = 0.000), receiving medical attention within 2 to 10 hours after injury (P = 0.000), 18 - 45 years age group (P = 0.019), not using helmet (P = 0.007), severe injuries (P = 0.000) and sustaining multiple injury (P = 0.000). Conclusion Road traffic Injuries in Tanzania are an important public health problem, predominantly in adult males, mostly due to motorcycle crashes. It is therefore important to reinforce preventive measures and pre-hospital emergency service is urgently needed. PMID:27217872

  1. Patient satisfaction with emergency oral health care in rural Tanzania.

    PubMed

    Ntabaye, M K; Scheutz, F; Poulsen, S

    1998-10-01

    Emergency oral health care, as conceived in Tanzania, is an on-demand service provided at a rural health center or dispensary by a Rural Medical Aide. The service includes: simple tooth extraction under local anesthesia, draining of abscesses, control of acute oral infection with appropriate drug therapy, first aid for maxillo-facial trauma, and recognition of oral conditions requiring patient referral for further care at the district or regional hospital dental clinic. The objective of the present study was to describe patient satisfaction with emergency oral health care services in rural Tanzania and determine the relative importance of factors influencing patient satisfaction. The study was carried out as a cross-sectional interview survey between April 1993 and May 1994 using a patient satisfaction questionnaire in rural villages in the Rungwe district of Tanzania. It included 206 patients aged 18 years or more who had received emergency oral health care between April 1993 and March 1994. Overall, 92.7% of the respondents reported that they were satisfied with the service. Patients who were married, had no formal education and lived more than 3 km from the dispensary were more likely to be satisfied with treatment. In a logistic regression model, a good working atmosphere at the dispensary, a good relationship between care provider and patients (art of care) and absence of post-treatment complications significantly influenced patient satisfaction with odds ratios of 10.3, 17.4 and 6.2, respectively. PMID:9792119

  2. The past, present and future of domestic equines in Tanzania.

    PubMed

    Wilson, R Trevor

    2013-01-01

    Equines are minor species in Tanzania's array of domestic livestock. Attempts to use them for transport by early explorers from the mid-nineteenth century usually failed. Donkeys were used extensively as pack animals to complement human porters by both British and German forces in the First World War, but their advantages were often outweighed by slow progress and competition with troops and porters for water, and they died in huge numbers. The British had regular cavalry troops in their campaign and mules found limited use as individual mounts for officers. In modern times, there are very few horses in Tanzania but they find several uses. Exotic safaris are made on horseback, they are used as stock horses on ranches, there is a polo club in northern Tanzania and there are leisure riding activities around the capital city. Official census records for donkeys estimate numbers at under 300,000 with concentrations in the northern pastoral and agropastoral areas where they are used as pack animals with water being the main commodity transported. Elsewhere donkeys are used to a limited extent in transport and traction work. There is little interest in equines by the central and local governments or the general public and the status quo can be expected to continue. PMID:24834000

  3. Early Child Development and Care in Tanzania: Challenges for the Future

    ERIC Educational Resources Information Center

    Mtahabwa, Lyabwene

    2009-01-01

    Much remains unknown about the status of early child development and care in Tanzania. The little information available has never been put together to provide a holistic picture of the progress so far made in this important area. This paper intends to synchronise the information available in Tanzania for the purpose of depicting the country's…

  4. Angular leaf spot disease status and characterization of the causative pathgen (P. Griseola) in Tanzania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Angular leaf spot caused by the fungus Pseudocercospora griseola is one of the most important disease of common bean in Tanzania. Breeding for resistance to this disease is complicated by the variable nature of the pathogen. In Tanzania no thorough attempt has been completed to evaluate the variabil...

  5. Nutritional Problems and Policy in Tanzania. Cornell International Nutrition Monograph Series, Number 7 (1980).

    ERIC Educational Resources Information Center

    Mgaza, Olyvia

    This monograph discusses policies designed to deal with food and nutrition problems in Tanzania. Available information on food supplies and nutritional conditions in Tanzania clearly shows that the country faces nutritional problems; protein energy malnutrition is the most serious and requires priority action. Iron deficiency anemia, goiter, and…

  6. The Role of Media Technology within the Proposed Open University of Tanzania.

    ERIC Educational Resources Information Center

    Cutting, Alan K.

    This report begins by briefly reviewing actions that have been taken since the idea of an Open University in Tanzania was first proposed in the late 1970s. The main body of the report begins with a discussion of the role of media technology in an open university with emphasis on delivery and support systems. The current situation in Tanzania is…

  7. Academia-Industry-Government Linkages in Tanzania: Trends, Challenges and Prospects

    ERIC Educational Resources Information Center

    Mpehongwa, Gasper

    2013-01-01

    This paper analyzed trends, challenges and prospects of academia-industry-government linkages in Tanzania. Using case study design, and documentary review to gather the required data, the study sought to answer three research questions: (1) what are the trends of academia-industry-government linkages in Tanzania?, (2) what are the challenges…

  8. Standards to Assure Quality in Tertiary Education: The Case of Tanzania

    ERIC Educational Resources Information Center

    Manyaga, Timothy

    2008-01-01

    Purpose: The purpose of this paper is to provide information on development of standards in Tanzania which may be of help to training providers in other countries as they seek to improve the quality and standards of their provision. Design/methodology/approach: The need to provide quality assured tertiary qualifications in Tanzania to win both…

  9. Provision of Pre-Primary Education as a Basic Right in Tanzania: Reflections from Policy Documents

    ERIC Educational Resources Information Center

    Mtahabwa, Lyabwene

    2010-01-01

    This study sought to assess provision of pre-primary education in Tanzania as a basic right through analyses of relevant policy documents. Documents which were published over the past decade were considered, including educational policies, action plans, national papers, the "Basic Education Statistics in Tanzania" documents, strategy documents,…

  10. UPE in Tanzania: SWAP-ing Quality for Quantity--Again?

    ERIC Educational Resources Information Center

    Kuder, Jeanette

    2005-01-01

    In 2002, Tanzania renewed its 1974 commitment to universal primary education. This paper explores differences in the current policy-formulation context, examining how development discourse and aid practice have shifted the space and scale of public governance in Tanzania, legitimising international agendas and the participation of non-Tanzanians…

  11. Performance of Andean common bean under low fertility stress in Tanzania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low soil fertility is a limiting factor for bean production in East Africa. In Tanzania low available N and P soils are widespread. Average bean yields in Tanzania are around 500 kg/ha although the potential yield under reliable rain-fed conditions is 1500–3000kg/ha, using improved varieties and pro...

  12. Walking in Unfamiliar Territory: Headteachers' Preparation and First-Year Experiences in Tanzania

    ERIC Educational Resources Information Center

    Onguko, Brown Bully; Abdalla, Mohamed; Webber, Charles F.

    2012-01-01

    Purpose: The purpose of this study is to describe the preappointment experiences of early-career headteachers in Tanzania and to discuss implications for postsecondary institutions and ministries of education in East Africa. Research Design: Seven novice headteachers in a suburb of Dar es Salaam, Tanzania, completed questionnaires and participated…

  13. Tanzania at the Turn of the Century: Background Papers and Statistics. A World Bank Country Study.

    ERIC Educational Resources Information Center

    World Bank, Washington, DC.

    This report presents lessons from Tanzania's development experience of the past four decades, with emphasis on the period since the last report (1996), and assesses the imperatives for higher sustained growth and better livelihood for its citizens in the future. The background papers review and assess Tanzania's actual growth and poverty reduction…

  14. The influence of climate change on Tanzania's hydropower sustainability

    NASA Astrophysics Data System (ADS)

    Sperna Weiland, Frederiek; Boehlert, Brent; Meijer, Karen; Schellekens, Jaap; Magnell, Jan-Petter; Helbrink, Jakob; Kassana, Leonard; Liden, Rikard

    2015-04-01

    Economic costs induced by current climate variability are large for Tanzania and may further increase due to future climate change. The Tanzanian National Climate Change Strategy addressed the need for stabilization of hydropower generation and strengthening of water resources management. Increased hydropower generation can contribute to sustainable use of energy resources and stabilization of the national electricity grid. To support Tanzania the World Bank financed this study in which the impact of climate change on the water resources and related hydropower generation capacity of Tanzania is assessed. To this end an ensemble of 78 GCM projections from both the CMIP3 and CMIP5 datasets was bias-corrected and down-scaled to 0.5 degrees resolution following the BCSD technique using the Princeton Global Meteorological Forcing Dataset as a reference. To quantify the hydrological impacts of climate change by 2035 the global hydrological model PCR-GLOBWB was set-up for Tanzania at a resolution of 3 minutes and run with all 78 GCM datasets. From the full set of projections a probable (median) and worst case scenario (95th percentile) were selected based upon (1) the country average Climate Moisture Index and (2) discharge statistics of relevance to hydropower generation. Although precipitation from the Princeton dataset shows deviations from local station measurements and the global hydrological model does not perfectly reproduce local scale hydrographs, the main discharge characteristics and precipitation patterns are represented well. The modeled natural river flows were adjusted for water demand and irrigation within the water resources model RIBASIM (both historical values and future scenarios). Potential hydropower capacity was assessed with the power market simulation model PoMo-C that considers both reservoir inflows obtained from RIBASIM and overall electricity generation costs. Results of the study show that climate change is unlikely to negatively affect the

  15. Educational, scientific, tourist and outreach potential of the September 1, 2016 Annular Solar Eclipse in Tanzania

    NASA Astrophysics Data System (ADS)

    Tayabali Jiwaji, Noorali

    2015-08-01

    Tanzania will witness a major astronomical spectacle of an annular eclipse on September 1, 2016. The central part of the eclipse will pass through southern Tanzania, crossing national parks and game reserves such as Katavi and the world famous Selous. For the rest of Tanzania and neighbouring countries it will be a memorable event with large of the proportion of the Sun being covered up. The climate in Tanzania during September is cool and dry which will provide ideal viewing conditions. Solar eclipse events attract "eclipse chasers" from around the globe.Scientific interest in measuring the properties of the Sun and the effects of the eclipse on the atmosphere will allow local scientists to partner with leading scientists to gain valuable experience and knowledge.Local population's wonder and interest in eclipses can be exploited through public-private partnerships by encouraging students and local people to travel to the central path or to observe from their backyards. Large number of eclipse glasses can be manufactured cheaply using safe solar filters for supplying to students and general population in Tanzania and neigbouring countries. This will raise science awareness about the wonders of our Universe.When combined with the attraction of Tanzania's treasures in the north and the 16 tonne Mbozi meteorite in southern Tanzania, the touristic potential of this event can be exploited through tour packages and worldwide advertisements during the coming year.

  16. Partial Genetic Characterization of Peste Des Petits Ruminants Virus from Goats in Northern and Eastern Tanzania

    PubMed Central

    Kgotlele, T; Macha, E S; Kasanga, C J; Kusiluka, L J M; Karimuribo, E D; Van Doorsselaere, J; Wensman, J J; Munir, M; Misinzo, G

    2014-01-01

    Peste des petits ruminants (PPR) is an acute viral disease of small ruminants. The disease was first reported in Tanzania in 2008 when it was confined to the Northern Zone districts bordering Kenya. The present study was carried out to confirm the presence of PPR virus (PPRV) in Tanzania and to establish their phylogenetic relationships. Samples (oculonasal swabs, tissues and whole blood) were obtained from live goats with clinical presentation suggestive of PPR and goats that died naturally in Ngorongoro (Northern Tanzania) and Mvomero (Eastern Tanzania) districts. The clinical signs observed in goats suspected with PPR included fever, dullness, diarrhea, lacrimation, matting of eye lids, purulent oculonasal discharges, cutaneous nodules, erosions on the soft palate and gums and labored breathing. Post mortem findings included pneumonia, congestion of the intestines, and hemorrhages in lymph nodes associated with the respiratory and gastrointestinal systems. PPRV was detected in 21 out of 71 tested animals using primers targeting the nucleoprotein (N) gene. Phylogenetic analysis, based on the N gene, indicated that PPRV obtained from Northern and Eastern Tanzania clustered with PPRV strains of Lineage III, together with PPRV from Sudan and Ethiopia. The findings of this study indicate that there are active PPRV infections in Northern and Eastern Tanzania, suggesting risks for potential spread of PPR in the rest of Tanzania. PMID:25135464

  17. Partial genetic characterization of peste des petits ruminants virus from goats in northern and eastern Tanzania.

    PubMed

    Kgotlele, T; Macha, E S; Kasanga, C J; Kusiluka, L J M; Karimuribo, E D; Van Doorsselaere, J; Wensman, J J; Munir, M; Misinzo, G

    2014-08-01

    Peste des petits ruminants (PPR) is an acute viral disease of small ruminants. The disease was first reported in Tanzania in 2008 when it was confined to the Northern Zone districts bordering Kenya. The present study was carried out to confirm the presence of PPR virus (PPRV) in Tanzania and to establish their phylogenetic relationships. Samples (oculonasal swabs, tissues and whole blood) were obtained from live goats with clinical presentation suggestive of PPR and goats that died naturally in Ngorongoro (Northern Tanzania) and Mvomero (Eastern Tanzania) districts. The clinical signs observed in goats suspected with PPR included fever, dullness, diarrhea, lacrimation, matting of eye lids, purulent oculonasal discharges, cutaneous nodules, erosions on the soft palate and gums and labored breathing. Post mortem findings included pneumonia, congestion of the intestines, and hemorrhages in lymph nodes associated with the respiratory and gastrointestinal systems. PPRV was detected in 21 out of 71 tested animals using primers targeting the nucleoprotein (N) gene. Phylogenetic analysis, based on the N gene, indicated that PPRV obtained from Northern and Eastern Tanzania clustered with PPRV strains of Lineage III, together with PPRV from Sudan and Ethiopia. The findings of this study indicate that there are active PPRV infections in Northern and Eastern Tanzania, suggesting risks for potential spread of PPR in the rest of Tanzania. PMID:25135464

  18. Response to Rift Valley Fever in Tanzania: Challenges and Opportunities.

    PubMed

    Fyumagwa, Robert D; Ezekiel, Mangi J; Nyaki, Athanas; Mdaki, Maulid L; Katale, Zablon B; Moshiro, Candida; Keyyu, Julius D

    2011-12-01

    Rift Valley Fever (RVF) is an arthropod borne viral disease affecting livestock (cattle, sheep, goats and camels), wildlife and humans caused by Phlebovirus. The disease occurs in periodic cycles of 4-15 years associated with flooding from unusually high precipitations in many flood-prone habitats. Aedes and Culex spp and other mosquito species are important epidemic vectors. Because of poor living conditions and lack of knowledge on the pathogenesis of RVF, nomadic pastoralists and agro-pastoralists are at high risk of contracting the disease during epidemics. RVF is a professional hazard for health and livestock workers because of poor biosafety measures in routine activities including lack of proper Personal Protective Equipment (PPE). Direct exposure to infected animals can occur during handling and slaughter or through veterinary and obstetric procedures or handling of specimens in laboratory. The episodic nature of the disease creates special challenges for its mitigation and control and many of the epidemics happen when the governments are not prepared and have limited resource to contain the disease at source. Since its first description in 1930s Tanzania has recorded six epidemics, three of which were after independence in 1961. However, the 2007 epidemic was the most notable and wide spread with fatal human cases among pastoralists and agro-pastoralists concurrent with high livestock mortality. Given all the knowledge that exist on the epidemiology of the disease, still the 2006/2007 epidemic occurred when the government of Tanzania was not prepared to contain the disease at source. This paper reviews the epidemiology, reporting and outbreak-investigation, public awareness, preparedness plans and policy as well as challenges for its control in Tanzania. PMID:26591988

  19. Tanzania wildcats to evaluate Jurassic Mandawa salt basin

    SciTech Connect

    Nagati, M.

    1996-10-07

    After 5 years of stagnant exploration in East Africa, Canadian independent Tanganyika Oil Co. of Vancouver, B.C., will drill two wildcats in Tanzania to evaluate the hydrocarbon potential of the coastal Jurassic Mandawa salt basin. Mita-1, spudded around Oct. 1, will be drilled to about 7,000 ft, East Lika-1 will be drilled in early December 1996 to approximately 6,000 ft. The two wells will test different structures and play concepts. The paper describes the exploration history, source rock potential, hydrocarbon shows, potential reservoir, and the prospects.

  20. The risk factors for human cysticercosis in Mbulu District, Tanzania.

    PubMed

    Mwang'onde, Beda J; Nkwengulila, Gamba; Chacha, Mwita

    2014-01-01

    The objective of this study was to explore the reasons for the persistence of human cysticercosis (HCC) transmission in Mbulu District, northern Tanzania. The study was carried out in 25 villages, whereby five major risks were identified. The risks were indiscriminate defaecation and improper use of toilets; a free-range system of keeping pigs; indiscriminate or unregulated slaughtering and inadequate meat hygiene and inspection; consumption of undercooked and porcine cysticerci infected pork; and social structure and roles. All of the identified risks were backed up by the immanent lifestyles of the community involved. These findings are important for the development of intervention strategies in the study area. PMID:25005750

  1. Income and Health in Tanzania. An Instrumental Variable Approach

    PubMed Central

    Fichera, Eleonora; Savage, David

    2015-01-01

    Summary There is a substantial debate over the direction of the causal relation between income and health. This is important for our understanding of the health production process and for the policy debate over improving healthcare. We instrument income with rainfall measurements by matching satellite information on timing and positioning of 21 rainfall stations to longitudinal data (1991–94) of over 4,000 individuals in 51 villages in Tanzania. A 10% increase in income reduces the number of illnesses by 0.02. We also find that a 10% increase in income implies an increase of about 0.1 vaccinations of children under six. PMID:25648157

  2. African Oral Traditions: Riddles Among The Haya of Northwestern Tanzania

    NASA Astrophysics Data System (ADS)

    Ishengoma, Johnson M.

    2005-05-01

    This study argues for the integration of African oral traditions and other elements of traditional learning into the modern school curriculum. It thus contributes to supporting the increased relevance of education to local communities. In particular, using the example of riddles collected from one of the main ethnic groups in Northwestern Tanzania, the Haya people, the present study challenges the views of those social and cultural anthropologists who hold that African riddles have no substantially meaningful educational value. Instead, it is maintained that riddles make an important contribution to children's full participation in the social, cultural, political, and economic life of African communities, especially by fostering critical thinking and transmitting indigenous knowledge.

  3. Schooling, Child Labor, and the Returns to Healthcare in Tanzania

    PubMed Central

    Adhvaryu, Achyuta R.; Nyshadham, Anant

    2013-01-01

    We study the effects of accessing better healthcare on the schooling and labor supply decisions of sick children in Tanzania. Using variation in the cost of formal-sector healthcare to predict treatment choice, we show that accessing better healthcare decreases length of illness and changes children’s allocation of time to school and work. Children attend school for more days per week—but not for more hours per day—as a result of accessing better healthcare. There are no significant effects on child labor, but the results suggest that time spent in physically strenuous activities such as farming and herding increases. PMID:24353348

  4. Volunteers who won't give up in Tanzania.

    PubMed

    2000-02-01

    The voluntary position of community-based distribution agent (CBDA) is not one to be taken lightly. There are many responsibilities and burdens, and the community looks to CBDAs for guidance. However, when support for their activities stop and funding runs dry, many volunteers give up. Consequently, the Family Planning Association of Tanzania (UMATI) has gone to great lengths to ensure the quality and success of those chosen to be CBDAs, nurturing them into "volunteers who won't give up". In Tanzania, CBDAs are tested and selected through the joint efforts of the community and UMATI, and they therefore become respected members of the community. UMATI ensures their success by regular supervision and community participation. The active participation of the community leaders creates a sense of responsibility and ownership for a project, and this helps to support the CBDAs as well. UMATI's CBD training includes management of income generating activities (IGA), since the volunteers have to earn a living in addition to working for the community. There is also a network of support of IGAs that CBDAs can draw on. In addition to this support, there are nonmonetary incentives, such as bicycles and uniforms, which give the CBDAs a visible social presence. In some areas, village authorities have exempted CBDAs from other community services, and some villages provide space or land for IGAs for CBDAs. All of these factors, especially community support, lead to a very low dropout rate for volunteers, and the high morale and commitment of the CBDAs. PMID:12295747

  5. Animal research ethics in Africa: is Tanzania making progress?

    PubMed

    Seth, Misago; Saguti, Fredy

    2013-12-01

    The significance of animals in research cannot be over-emphasized. The use of animals for research and training in research centres, hospitals and schools is progressively increasing. Advances in biotechnology to improve animal productivity require animal research. Drugs being developed and new interventions or therapies being invented for cure and palliation of all sorts of animal diseases and conditions need to be tested in animals for their safety and efficacy at some stages of their development. Drugs and interventions for human use pass through a similar development process and must be tested pre-clinically in laboratory animals before clinical trials in humans can be conducted. Therefore, animals are important players in research processes which directly and indirectly benefit animals and humans. However, questions remain as to whether these uses of animals consider the best interests of animals themselves. Various research and training institutions in Tanzania have established some guidelines on animal use, including establishing animal ethics committees. However, most institutions have not established oversight committees. In institutions where there may be guidelines and policies, there are no responsible committees or units to directly oversee if and how these guidelines and policies are enforced; thus, implementation becomes difficult or impossible. This paper endeavours to raise some issues associated with the responsible use of animals in research and training in Tanzania and highlights suggestions for improvement of deficiencies that exist in order to bridge the gap between what ought to be practised and what is practised. PMID:23006770

  6. Experience on healthcare utilization in seven administrative regions of Tanzania

    PubMed Central

    2012-01-01

    Health care utilization in many developing countries, Tanzania included, is mainly through the use of traditional medicine (TRM) and its practitioners despite the presence of the conventional medicine. This article presents findings on the study that aimed to get an experience of health care utilization from both urban and rural areas of seven administrative regions in Tanzania. A total of 33 health facility managers were interviewed on health care provision and availability of supplies including drugs, in their respective areas. The findings revealed that the health facilities were overburden with higher population to serve than it was planned. Consequently essential drugs and other health supplies were available only in the first two weeks of the month. Conventional health practitioners considered traditional health practitioners to be more competent in mental health management, and overall, they were considered to handle more HIV/AIDS cases knowingly or unknowingly due to shear need of healthcare by this group. In general conventional health practitioners were positive towards traditional medicine utilization; and some of them admitted using traditional medicines. Traditional medicines like other medical health systems worldwide have side effects and some contentious ethical issues that need serious consideration and policy direction. Since many people will continue using traditional/alternative medicine, there is an urgent need to collaborate with traditional/alternative health practitioners through the institutionalization of basic training including hygiene in order to improved healthcare in the community and attain the Millennium Development Goals by 2015. PMID:22284539

  7. Phenotypes including immunocompetence in scavenging local chicken ecotypes in Tanzania.

    PubMed

    Msoffe, P L; Minga, U M; Olsen, J E; Yongolo, M G; Juul-Madsen, H R; Gwakisa, P S; Mtambo, M M

    2001-07-01

    A study was conducted to determine the variations in physical characters and immunocompetence among scavenging local chicken ecotypes in Tanzania. Eighty-four adult scavenging local chickens from four eco-climatic regions of Tanzania were studied. Measurements of adult body weight, body length, shank length and egg weight and observations of plumage colour and pattern, earlobe colour, skin colour and the shape of the comb were conducted. The antibody response to sheep red blood cells, serum haemolytic complement and the cutaneous response to phytohaemagglutinin-P were assessed. Five ecotypes were identified and named Mbeya, Morogoro-medium, Ching'wekwe, Kuchi and Singamagazi. Singamagazi and Kuchi were significantly heavier, with longer shanks and heavier eggs than the other ecotypes. The average adult body weight for males ranged from 1621 g (Mbeya) to 2915 g (Singamagazi). Average female weights ranged from 1108 g (Morogoro-medium) to 2020 g (Singamagazi). Mean egg weights ranged from 37.65 g (Ching'wekwe) to 45.61 (Singamagazi). The Kuchi had mostly rose and walnut combs, while the other ecotypes were mostly single combed. In each ecotype there were chickens with a high or low antibody response to red blood cells, but there was a significant difference between the ecotypes. PMID:11474868

  8. Healthcare Cost of Smoking Induced Cardiovascular Disease in Tanzania

    PubMed Central

    Kidane, Asmerom; Hepelwa, Aloyce; Ngeh, Ernest Tingum; Hu, Teh-wei

    2016-01-01

    The study presented here estimates the total health care cost attributable to smoking induced cardiovascular disease in Tanzania. The study based on a survey conducted at a referral university hospital in Dar es Salaam in 2014. Assuming a 2% prevalence rate of cardiovascular disease and a population of 47.2 million, it was estimated that there are 943,800 cardiovascular patients in Tanzania. The proportion of ever smokers among the surveyed patients was found to be 25 percent yielding 240,400 patients who suffer from smoking induced cardiovascular diseases. Per capita annual expenditure per patient is estimated to be 566.6 US dollars and total annual expenditure for the country was estimated to be 136.1 million US dollars. On a per capita basis more direct and indirect cost is incurred on males compared to females; more is spent on the elderly (40 or more years) compared to the youth (less than 20 years). When compared with the mean annual household income of the surveyed population, the smoking induced per capita expenditure constitutes 35% of household income. PMID:27152318

  9. Music therapy in the context of palliative care in Tanzania.

    PubMed

    Hartwig, Rebecca

    2010-10-01

    There has been much written to support music therapy as an adjunct in managing pain and anxiety in palliative care patients in Western societies, but little written on its use in developing countries. In light of increasing numbers of terminally ill patients in Tanzania owing to HIV/AIDS and cancer, limited access to opioids, and a growing interest in palliative care support, this study looks at the application of music in this context. The study reviews the history and principles of therapeutic music and outlines its role in palliative care. A qualitative study was conducted by questionnaire of 17 professionals involved in home-based palliative care in Tanzania. Findings include beliefs about the power of music, how music is being used to bring comfort to the dying patient, and the most important aspects of helpful music to many Tanzanian palliative care patients. Music can powerfully affect body, mind and spirit. It is vocal music, which is an accepted therapeutic music tool used to bring comfort to the palliative care patient and their family members. Finally, music is an active and participatory activity in Tanzanian culture, even for the dying. PMID:20972382

  10. Brucellosis among Hospitalized Febrile Patients in Northern Tanzania

    PubMed Central

    Bouley, Andrew J.; Biggs, Holly M.; Stoddard, Robyn A.; Morrissey, Anne B.; Bartlett, John A.; Afwamba, Isaac A.; Maro, Venance P.; Kinabo, Grace D.; Saganda, Wilbrod; Cleaveland, Sarah; Crump, John A.

    2012-01-01

    Acute and convalescent serum samples were collected from febrile inpatients identified at two hospitals in Moshi, Tanzania. Confirmed brucellosis was defined as a positive blood culture or a ≥ 4-fold increase in microagglutination test titer, and probable brucellosis was defined as a single reciprocal titer ≥ 160. Among 870 participants enrolled in the study, 455 (52.3%) had paired sera available. Of these, 16 (3.5%) met criteria for confirmed brucellosis. Of 830 participants with ≥ 1 serum sample, 4 (0.5%) met criteria for probable brucellosis. Brucellosis was associated with increased median age (P = 0.024), leukopenia (odds ratio [OR] 7.8, P = 0.005), thrombocytopenia (OR 3.9, P = 0.018), and evidence of other zoonoses (OR 3.2, P = 0.026). Brucellosis was never diagnosed clinically, and although all participants with brucellosis received antibacterials or antimalarials in the hospital, no participant received standard brucellosis treatment. Brucellosis is an underdiagnosed and untreated cause of febrile disease among hospitalized adult and pediatric patients in northern Tanzania. PMID:23091197

  11. Brucellosis among hospitalized febrile patients in northern Tanzania.

    PubMed

    Bouley, Andrew J; Biggs, Holly M; Stoddard, Robyn A; Morrissey, Anne B; Bartlett, John A; Afwamba, Isaac A; Maro, Venance P; Kinabo, Grace D; Saganda, Wilbrod; Cleaveland, Sarah; Crump, John A

    2012-12-01

    Acute and convalescent serum samples were collected from febrile inpatients identified at two hospitals in Moshi, Tanzania. Confirmed brucellosis was defined as a positive blood culture or a ≥ 4-fold increase in microagglutination test titer, and probable brucellosis was defined as a single reciprocal titer ≥ 160. Among 870 participants enrolled in the study, 455 (52.3%) had paired sera available. Of these, 16 (3.5%) met criteria for confirmed brucellosis. Of 830 participants with ≥ 1 serum sample, 4 (0.5%) met criteria for probable brucellosis. Brucellosis was associated with increased median age (P = 0.024), leukopenia (odds ratio [OR] 7.8, P = 0.005), thrombocytopenia (OR 3.9, P = 0.018), and evidence of other zoonoses (OR 3.2, P = 0.026). Brucellosis was never diagnosed clinically, and although all participants with brucellosis received antibacterials or antimalarials in the hospital, no participant received standard brucellosis treatment. Brucellosis is an underdiagnosed and untreated cause of febrile disease among hospitalized adult and pediatric patients in northern Tanzania. PMID:23091197

  12. Human migration, protected areas, and conservation outreach in Tanzania.

    PubMed

    Salerno, Jonathan D; Borgerhoff Mulder, Monique; Kefauver, Shawn C

    2014-06-01

    A recent discussion debates the extent of human in-migration around protected areas (PAs) in the tropics. One proposed argument is that rural migrants move to bordering areas to access conservation outreach benefits. A counter proposal maintains that PAs have largely negative effects on local populations and that outreach initiatives even if successful present insufficient benefits to drive in-migration. Using data from Tanzania, we examined merits of statistical tests and spatial methods used previously to evaluate migration near PAs and applied hierarchical modeling with appropriate controls for demographic and geographic factors to advance the debate. Areas bordering national parks in Tanzania did not have elevated rates of in-migration. Low baseline population density and high vegetation productivity with low interannual variation rather than conservation outreach explained observed migration patterns. More generally we argue that to produce results of conservation policy significance, analyses must be conducted at appropriate scales, and we caution against use of demographic data without appropriate controls when drawing conclusions about migration dynamics. PMID:24476123

  13. High Malaria Prevalence among Schoolchildren on Kome Island, Tanzania.

    PubMed

    Kim, Min-Jae; Jung, Bong-Kwang; Chai, Jong-Yil; Eom, Keeseon S; Yong, Tai-Soon; Min, Duk-Young; Siza, Julius E; Kaatano, Godfrey M; Kuboza, Josephat; Mnyeshi, Peter; Changalucha, John M; Ko, Yunsuk; Chang, Su Young; Rim, Han-Jong

    2015-10-01

    In order to determine the status of malaria among schoolchildren on Kome Island (Lake Victoria), near Mwanza, Tanzania, a total of 244 schoolchildren in 10 primary schools were subjected to a blood survey using the fingerprick method. The subjected schoolchildren were 123 boys and 121 girls who were 6-8 years of age. Only 1 blood smear was prepared for each child. The overall prevalence of malaria was 38.1% (93 positives), and sex difference was not remarkable. However, the positive rate was the highest in Izindabo Primary School (51.4%) followed by Isenyi Primary School (48.3%) and Bugoro Primary School (46.7%). The lowest prevalence was found in Muungano Primary School (16.7%) and Nyamiswi Primary School (16.7%). These differences were highly correlated with the location of the school on the Island; those located in the peripheral area revealed higher prevalences while those located in the central area showed lower prevalences. Plasmodium falciparum was the predominant species (38.1%; 93/244), with a small proportion of them mixed-infected with Plasmodium vivax (1.6%; 4/244). The results revealed that malaria is highly prevalent among primary schoolchildren on Kome Island, Tanzania, and there is an urgent need to control malaria in this area. PMID:26537036

  14. Mycobacteria in Terrestrial Small Mammals on Cattle Farms in Tanzania

    PubMed Central

    Durnez, Lies; Katakweba, Abdul; Sadiki, Harrison; Katholi, Charles R.; Kazwala, Rudovick R.; Machang'u, Robert R.; Portaels, Françoise; Leirs, Herwig

    2011-01-01

    The control of bovine tuberculosis and atypical mycobacterioses in cattle in developing countries is important but difficult because of the existence of wildlife reservoirs. In cattle farms in Tanzania, mycobacteria were detected in 7.3% of 645 small mammals and in cow's milk. The cattle farms were divided into “reacting” and “nonreacting” farms, based on tuberculin tests, and more mycobacteria were present in insectivores collected in reacting farms as compared to nonreacting farms. More mycobacteria were also present in insectivores as compared to rodents. All mycobacteria detected by culture and PCR in the small mammals were atypical mycobacteria. Analysis of the presence of mycobacteria in relation to the reactor status of the cattle farms does not exclude transmission between small mammals and cattle but indicates that transmission to cattle from another source of infection is more likely. However, because of the high prevalence of mycobacteria in some small mammal species, these infected animals can pose a risk to humans, especially in areas with a high HIV-prevalence as is the case in Tanzania. PMID:21785686

  15. The Past, Present and Future of Domestic Equines in Tanzania

    PubMed Central

    WILSON, R. Trevor

    2013-01-01

    Equines are minor species in Tanzania’s array of domestic livestock. Attempts to use them for transport by early explorers from the mid-nineteenth century usually failed. Donkeys were used extensively as pack animals to complement human porters by both British and German forces in the First World War, but their advantages were often outweighed by slow progress and competition with troops and porters for water, and they died in huge numbers. The British had regular cavalry troops in their campaign and mules found limited use as individual mounts for officers. In modern times, there are very few horses in Tanzania but they find several uses. Exotic safaris are made on horseback, they are used as stock horses on ranches, there is a polo club in northern Tanzania and there are leisure riding activities around the capital city. Official census records for donkeys estimate numbers at under 300,000 with concentrations in the northern pastoral and agropastoral areas where they are used as pack animals with water being the main commodity transported. Elsewhere donkeys are used to a limited extent in transport and traction work. There is little interest in equines by the central and local governments or the general public and the status quo can be expected to continue. PMID:24834000

  16. Community-based advocacy opportunities for tobacco control: experience from Tanzania.

    PubMed

    Kagaruki, Lutgard K

    2010-06-01

    Tanzania is third in Africa in tobacco production after Malawi and Zimbabwe. In spite of increased production, Tanzania remains a poor country, with tobacco farmers getting poorer and the country losing more than 16,500 hectares of forests annually from tobacco curing alone. Tanzania grows fire-cured and air-cured tobacco. Regarding tobacco use, 35% of Tanzanians smoke tobacco regularly and about 32% of all cancers at Ocean Road Cancer Institute are attributed to tobacco use, with the country spending more than $30m annually to treat tobacco-related cancers. Unfortunately, knowledge on tobacco-related hazards is limited even among policy/decision makers. However, surveys indicate that more than 65% of resource-poor tobacco farmers favour alternative livelihoods when assured of sustainable markets. There is need of intensifying advocacy campaigns against tobacco, in order to improve the socio-economic status of tobacco farmers, enhance public health and sustain the environment in Tanzania. PMID:20595340

  17. Research Trends in Emerging Contaminants on the Aquatic Environments of Tanzania

    PubMed Central

    Miraji, H.; Othman, O. C.; Ngassapa, F. N.; Mureithi, E. W.

    2016-01-01

    The continuity for discovery and production of new chemicals, allied products, and uses has currently resulted into generation of recent form of contaminants known as Emerging Contaminants (ECs). Once in the aquatic environment ECs are carcinogenic and cause other threats to both human's and animals' health. Due to their effects this study was aimed at investigating research trends of ECs in Tanzania. Findings revealed that USA and EU countries were leading in ECs researches, little followed by Asia, South Africa, and then Zambia. Only few guidelines from USA-EPA, WHO, Canada, and Australia existed. Neither published guidelines nor regulations for ECs existed in Tanzania; rather only the occurrence of some disinfection by-products and antibiotics was, respectively, reported in Arusha and Dar es Salaam, Tanzania. As these reports had a limited coverage of ECs, henceforth, these findings constitute the first-line reference materials for ECs research in Tanzania which shall be useful for future monitoring and regulation planning. PMID:26998381

  18. Focal mechanisms and the stress regime in NE and SW Tanzania, East Africa

    NASA Astrophysics Data System (ADS)

    Brazier, Richard A.; Nyblade, Andrew A.; Florentin, Juliette

    2005-07-01

    We report 12 new focal mechanisms from earthquakes in NE and SW Tanzania where the stress regime within the East African rift system is not well constrained. Focal mechanisms for events at the intersection of the Lake Tanganyika and Rukwa rifts in SW Tanzania indicate a complicated stress pattern with possible dextral strike-slip motion on some faults but oblique motion on others (either sinistral on NW striking faults or dextral on NE striking faults). Within the Rukwa rift, focal mechanisms indicate normal dip-slip motion with NE-SW opening. In NE Tanzania where the Eastern rift impinges on the margin of the Tanzania Craton, fault motions are consistent with a zone of distributed block faults and sub E-W extension. All twelve earthquakes likely nucleated within the crust.

  19. Modelling and mapping the topsoil organic carbon content for Tanzania

    NASA Astrophysics Data System (ADS)

    Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

    2014-05-01

    Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small

  20. Termite fishing by wild chimpanzees: new data from Ugalla, western Tanzania.

    PubMed

    Stewart, Fiona A; Piel, Alex K

    2014-01-01

    Chimpanzees manufacture flexible fishing probes to fish for termites in Issa, Ugalla, western Tanzania. These termite-fishing tools are similar in size and material to those used by long-studied communities of chimpanzees in western Tanzania (Pan troglodytes schweinfurthii) and in West Africa (P. t. verus), but not central African populations (P. t. troglodytes). This report adds to the patchwork of evidence of termite-fishing tool use behaviour by chimpanzees across Africa. PMID:23720026

  1. Lithium Isotope Systematics of Rift-related Alkaline Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Halama, R.; McDonough, W. F.; Rudnick, R. L.; Trumbull, R.; Klaudius, J.; Keller, J.; Taubald, H.

    2006-05-01

    Intracontinental alkaline igneous rocks from the Proterozoic Gardar Province (Greenland), the Cretaceous Damaraland Province (Namibia), the Tertiary Kaiserstuhl complex (Germany) and from the Holocene volcano Oldoinyo Lengai (Tanzania) were analyzed to characterize Li isotopic compositions of their mantle sources and to determine the processes affecting δ7Li in alkaline igneous rocks. The inferred mantle Li isotope signatures of the primitive alkaline rocks (δ7Li = +1 to +7) are similar to those of present- day MORB, OIB and carbonatites, and appear to be relatively constant in time and space. Gabbros from the Gardar Province define a relatively small field of Li isotope compositions (δ7Li = +4 to +7). Mineral separates (clinopyroxene, plagioclase) mostly overlap with the whole-rock values, which we interpret to reflect the δ7Li of the mantle sources of the gabbros. Mantle-like δ7Li values are also observed for primitive alkaline rocks from the other regions. Li isotope compositions in more differentiated rocks (syenites, phonolites and rhyolites) are highly variable (+11 to -22 per mil) and reflect a diversity of evolutionary processes that may vary from complex to complex. δ7Li values vary independently of Sr and Nd isotope values and indices of differentiation (e.g. MgO content) or weathering (e.g. LOI). Consistently light δ7Li values (+2 to -22) occur in Gardar syenites associated with a carbonatite. These may be explained by weathering and sub-solidus alteration, as indicated by petrographic observations. Alternatively, fluid-assisted diffusion processes, related to a fenitizing fluid from the carbonatite, may have led to extreme Li isotope fractionation. Whole-rock oxygen isotope analyses will be carried out to evaluate interaction with meteoric water, which would be reflected in a decrease in δ18O compared to magmatic values. The heaviest Li isotopic composition (+11 per mil) was obtained for a rhyolite, probably related to the presence of quartz

  2. Uranium and thorium decay series disequilibria in young volcanic rocks

    SciTech Connect

    Williams, R.W.

    1988-01-01

    Two of the central questions in igneous geochemistry that study of radioactive disequilibria can help to answer are: what are the rates of magma genesis; and what are the timescales of magma separation and transport. In addition to the temporal information that may be extracted from disequilibria data, the {sup 230}Th/{sup 232}Th of a young rock may be used as a tracer of the Th/U ratio of its source region. Measurements were made by isotope dilution alpha-spectrometry of {sup 238}U, {sup 234}U, {sup 230}Th, and {sup 232}Th in 20 subduction related, 3 oceanic intraplate, and 10 continental intraplate volcanics. {sup 210}Pb was measured in all, {sup 226}Ra was measured in about half, and {sup 228}Th was measured in 10 of the most recent samples. Disequilibrium between {sup 228}Th and {sup 232}Th was found only in the Nacarbonatite samples from Oldoinyo Lengai volcano in Tanzania, which is attributable to {sup 228}Ra/{sup 232}Th {approximately} 27 at the time of eruption. These rocks also have {sup 226}Ra/{sup 230}Th > 60. Three Ra-enrichment models are developed which constrain carbonatite magma formation at less than 20 years before eruption. The effects of different partial melting processes on the {sup 238}U decay series are investigated. If mid-ocean ridge basalts are formed by a dynamic melting process, the {sup 230}Th/{sup 232}Th of the basalts provides a minimum estimate of the Th/U ratio of the source region. The {sup 238}U enrichment in arc volcanics is probably the results of metasomatism of the source by fluids derived from the subducting slab, and the {sup 230}Th enrichment observed for other volcanics is probably due to the partial melting process in the absence of U-bearing fluids.

  3. Contrasted seismogenic and rheological behaviours from shallow and deep earthquake sequences in the North Tanzanian Divergence, East Africa

    NASA Astrophysics Data System (ADS)

    Albaric, J.; Perrot, J.; Déverchère, J.; Deschamps, A.; Le Gall, B.; Ferdinand, R. W.; Petit, C.; Tiberi, C.; Sue, C.; Songo, M.

    2010-12-01

    We report preliminary results of a seismological experiment, SEISMO-TANZ' 07, which consisted in the deployment of a local network (35 stations) in the East African Rift System (EARS), North Tanzania, during 6 months in 2007. We compare two earthquake sequences (Gelai and Manyara) occurring, respectively, in the southern end of the Kenya rift and in the North Tanzanian Divergence (NTD). Only distant of ˜150 km, their triggering mechanisms are different. None of the sequences depicts typical swarm or mainshock-aftershock patterns. They highlight the change in the magmatic/tectonic nature of the rift where the eastern branch of the EARS enters the Tanzanian craton. The similar shape and long-axis of the elongate sequences emphasize the preferred locus of active strain release along NE-SW discontinuities which probably root at depth into steep Proterozoic shear zones. At Gelai, the deformation is dominated by aseismic process involving slow slip on normal fault and dyke intrusion within the upper crust (Calais et al., 2008). The spatial and temporal earthquake distribution indicates a possible correlation between the Gelai crisis and the eruption of the nearby Oldoinyo Lengai volcano. At Manyara, the sequence is more uncommon, revealing a long-lasting seismic activity deeply rooted (˜20-35 km depth) possibly related to stress loading transmitted laterally. The yield strength envelope modelled from the depth frequency distribution of earthquakes in the NTD is consistent with the presence of a mafic lower crust and further supports the strength increase of the rifted crust from south Kenya to the NTD.

  4. Carbonatite diversity in the Central Andes: the Ayopaya alkaline province, Bolivia

    NASA Astrophysics Data System (ADS)

    Schultz, Frank; Lehmann, Bernd; Tawackoli, Sohrab; Rössling, Reinhard; Belyatsky, Boris; Dulski, Peter

    2004-12-01

    The Ayopaya province in the eastern Andes of Bolivia, 100 km NW of Cochabamba, hosts a Cretaceous alkaline rock series within a Palaeozoic sedimentary sequence. The alkaline rock association comprises nepheline-syenitic/foyaitic to ijolitic intrusions, carbonatite, kimberlite, melilititic, nephelinitic to basanitic dykes and diatremes, and a variety of alkaline dykes. The carbonatites display a wide petrographic and geochemical spectrum. The Cerro Sapo area hosts a small calciocarbonatite intrusion and a multitude of ferrocarbonatitic dykes and lenses in association with a nepheline-syenitic stock. The stock is crosscut by a spectacular REE-Sr-Th-rich sodalite-ankerite-baryte dyke system. The nearby Chiaracke complex represents a magnesiocarbonatite intrusion with no evidence for a relationship to igneous silicate rocks. The magnesiocarbonatite (Σ REE up to 1.3 wt%) shows strong HREE depletion, i.e. unusually high La/Yb ratios (520 1,500). Calciocarbonatites (Σ REE up to 0.5 wt%) have a flatter REE distribution pattern (La/Yb 95 160) and higher Nb and Zr contents. The sodalite-ankerite-baryte dyke system shows geochemical enrichment features, particularly in Na, Ba, Cl, Sr, REE, which are similar to the unusual natrocarbonatitic lavas of the recent volcano of Oldoinyo Lengai, Tanzania. The Cerro Sapo complex may be regarded as an intrusive equivalent of natrocarbonatitic volcanism, and provides an example for carbonatite genesis by late-stage crystal fractionation and liquid immiscibility. The magnesiocarbonatite intrusion of Chiaracke, on the other hand, appears to result from a primary carbonatitic mantle melt. Deep seated mantle magmatism/metasomatism is also expressed by the occurrence of a kimberlite dyke. Neodymium and strontium isotope data (ɛNd 1.4 5.4, 87Sr/86 Sr

  5. Auditory impairments in HIV-infected individuals in Tanzania

    PubMed Central

    Maro, Isaac I.; Moshi, Ndeserua; Clavier, Odile H.; MacKenzie, Todd A.; Kline-Schoder, Robert J.; Wilbur, Jed C.; Chambers, Robert D.; Fellows, Abigail M.; Jastrzembski, Benjamin G.; Mascari, John E.; Bakari, Muhammad; Matee, Mecky; Musiek, Frank E.; Waddell, Richard D.; von Reyn, C. Fordham; Buckey, Jay C.

    2014-01-01

    Objectives Abnormal hearing tests have been noted in HIV-infected patients in several studies, but the nature of the hearing deficit has not been clearly defined. We performed a cross-sectional study of both HIV+ and HIV− individuals in Tanzania using an audiological test battery. We hypothesized that HIV+ adults would have a higher prevalence of abnormal central and peripheral hearing test results compared to HIV− controls. Additionally, we anticipated that the prevalence of abnormal hearing assessments would increase with anti-retroviral therapy (ART) use, and treatment for tuberculosis (TB). Design Pure-tone thresholds, distortion product otoacoustic emissions (DPOAEs), tympanometry, and a gap detection test were performed using a laptop-based hearing testing system on 751 subjects (100 HIV− in the U.S., plus 651 in Dar es Salaam Tanzania including 449 HIV+ [130 ART− and 319 ART+], and 202 HIV−, subjects. No U.S. subjects had a history of TB treatment. In Tanzania, 204 of the HIV+, and 23 of the HIV−, subjects had a history of TB treatment. Subjects completed a video and audio questionnaire about their hearing as well as a health history questionnaire. Results HIV+ subjects had reduced DPOAE levels compared to HIV− subjects, but their hearing thresholds, tympanometry results, and gap detection thresholds were similar. Within the HIV+ group, those on ART reported significantly greater difficulties understanding speech-in-noise, and were significantly more likely to report that they had difficulty understanding speech than the ART− group. The ART+ group had a significantly higher mean gap detection threshold compared to the ART− group. No effects of TB treatment were seen. Conclusions The fact that the ART+/ART− groups did not differ in measures of peripheral hearing ability (DPOAEs, thresholds), or middle ear measures (tympanometry), but that the ART+ group had significantly more trouble understanding speech and higher gap detection thresholds

  6. Hydrograph separation using hydrochemical tracers in the Makanya catchment, Tanzania

    NASA Astrophysics Data System (ADS)

    Mul, Marloes L.; Mutiibwa, Robert K.; Uhlenbrook, Stefan; Savenije, Hubert H. G.

    Hydrochemical tracers were used to separate and quantify different runoff components in the semi-arid Makanya catchment in the South Pare Mountains of Tanzania. One flood event was investigated during the rainy season of October-December 2005 and analysed for electrical conductivity, dissolved silica and major anions and cations. The event on 9 November 2005 showed two peaks, each originating from one of two sub-catchments, upper-Vudee and Ndolwa, each with a distinct water quality signature. Hydrograph separation indicated that the two peaks in the hydrograph originated from a delay in response between the two catchments. The hydrograph separation indicated that, for this event, over 95% of the discharge could be attributed to sub-surface runoff, while the remainder was due to faster surface runoff processes. The dominance of sub-surface processes was also indicated by the lack of suspended sediments in the samples, which is a clear indication that no surface runoff took place.

  7. The evolutionary ecology of early weaning in Kilimanjaro, Tanzania.

    PubMed

    Wander, Katherine; Mattison, Siobhán M

    2013-10-01

    Public health recommendations promote prolonged breastfeeding of all children; however, parental investment (PI) theory predicts that breastfeeding will be allocated among a mothers' offspring to maximize her reproductive success. We evaluated PI in terms of risk for weaning before age two among 283 children in Kilimanjaro, Tanzania. Results demonstrate: (i) a Trivers-Willard effect--high socioeconomic status (SES) females and low SES males were more likely to be weaned early; (ii) later-born children were less likely to be weaned early; (iii) higher birthweight children were less likely to be weaned early, and (iv) no effect of cattle (a source of supplementary milk) ownership. These associations were largely independent and remained significant in models controlling for potential confounders; however, the inverse association between early weaning and birth order lost significance in the model containing birthweight. These patterns were observed despite public health recommendations encouraging breastfeeding for at least two years. PMID:23926151

  8. Creating a national culture of quality: the Tanzania experience.

    PubMed

    Mwidunda, Patrick E; Eliakimu, Eliudi

    2015-07-01

    Although quality improvement has been a priority for Tanzania's health sector since the 1970s, few effective quality improvement initiatives were implemented, due to limited expertise, political commitment and resources. More recently, as the HIV epidemic gained momentum within the country, an influx of funding and of international organizations with quality improvement expertise accelerated the implementation of quality improvement projects, as well as efforts to institutionalize quality improvement at the national level. The support of US President's Emergency Plan for AIDS Relief (PEPFAR) and other donors, and the increasing numbers of HIV-implementing partners focused on quality management, and quality improvement strategies catalysed the development of HIV-specific quality improvement initiatives first, and then of national quality improvement frameworks. The diversity of quality improvement approaches championed by various donors and partners also presented important challenges to harmonization and institutionalization of quality improvement programmes. PMID:26102628

  9. Childbearing Experiences Following an HIV Diagnosis in Iringa, Tanzania.

    PubMed

    Saleem, Haneefa T; Surkan, Pamela J; Kerrigan, Deanna; Kennedy, Caitlin E

    2016-09-01

    People living with HIV (PLHIV) continue to have children after being diagnosed with HIV, yet little research attention has been paid to actual lived childbearing experiences of PLHIV post-HIV diagnosis. We interviewed 10 HIV-positive women and 11 HIV-positive men in Iringa, Tanzania, about their experiences of conceiving and having children after being diagnosed with HIV. We adopted an approach to data analysis based on grounded theory and phenomenology. Participants' experiences were shaped by social and institutional factors. Some participants reported pressures to bear children by partners and relatives, whereas others reported negative reactions from others concerning their pregnancies. Most participants had not discussed having children with a provider before attempting to conceive. Some reported being reprimanded by health providers for getting pregnant without seeking their advice. Consideration of support systems and challenges surrounding the childbearing experiences of PLHIV can help inform reproductive health interventions for those who desire children. PMID:26443798

  10. Linking lake variability, climate, and human activity in Basotu, Tanzania.

    NASA Astrophysics Data System (ADS)

    Higgins, Lindsey; Westerberg, Lars-Ove; Risberg, Jan

    2016-04-01

    Lake Basotu (4.3697°S, 35.0728°E) is a crater lake in north-central Tanzania. This lake is an important source of freshwater for local people as no perennial rivers are present. Due to intensive agricultural methods and climatic factors, lake level has fluctuated greatly over time. A history of environmental variability of the past 1800 years was established using the diatom record, magnetic parameters, and carbon content from a three meter long sediment core. Fluctuations in modern lake extent (1973 - 2015) were calculated using archived Landsat images and compared to meteorological records and documents of activity around the lake to determine the greatest impacts and their consequences on this essential water resource. Variations in the paleo-record indicate that fluctuations in lake level are not abnormal, however human influence has likely increased the sensitivity of Lake Basotu to climatic fluctuations.

  11. Economic evaluation of rural woodlots in a developing country: Tanzania

    SciTech Connect

    Kihiyo, V.B.M.S.

    1996-03-01

    Rural areas in developing countries use wood as their main source of energy. Previously, wood has been obtained free from natural forests and woodlands. The pressure of increased demand through population growth, and the fact that natural trees take longer to grow, has made this resource scarce. Thus, raising trees in woodlots has been adopted as the solution to its shortage in the wild. However, growing trees in woodlots will inevitably require resources in terms of capital, land and manpower. Economic evaluation becomes necessary to ascertain that these resources are used economically. This paper dwells on some of the salient features of the economic evaluation of woodlots, such as interest rates, shadow prices of factors of production, social opportunity, cost of capital and sensitivity analysis of such woodlots in a developing country such as Tanzania. 19 refs., 5 tabs.

  12. The evolutionary ecology of early weaning in Kilimanjaro, Tanzania

    PubMed Central

    Wander, Katherine; Mattison, Siobhán M.

    2013-01-01

    Public health recommendations promote prolonged breastfeeding of all children; however, parental investment (PI) theory predicts that breastfeeding will be allocated among a mothers' offspring to maximize her reproductive success. We evaluated PI in terms of risk for weaning before age two among 283 children in Kilimanjaro, Tanzania. Results demonstrate: (i) a Trivers–Willard effect—high socioeconomic status (SES) females and low SES males were more likely to be weaned early; (ii) later-born children were less likely to be weaned early; (iii) higher birthweight children were less likely to be weaned early, and (iv) no effect of cattle (a source of supplementary milk) ownership. These associations were largely independent and remained significant in models controlling for potential confounders; however, the inverse association between early weaning and birth order lost significance in the model containing birthweight. These patterns were observed despite public health recommendations encouraging breastfeeding for at least two years. PMID:23926151

  13. East African and Kuunga Orogenies in Tanzania - South Kenya

    NASA Astrophysics Data System (ADS)

    Fritz, H.; Hauzenberger, C. A.; Tenczer, V.

    2012-04-01

    Tanzania and southern Kenya hold a key position for reconstructing Gondwana consolidation because here different orogen belts with different tectonic styles interfere. The older, ca. 650-620 Ma East African Orogeny resulted from the amalgamation of arc terranes in the northern Arabian-Nubian Shield (ANS) and continental collision between East African pieces and parts of the Azania terrane in the south (Collins and Pisarevsky, 2005). The change form arc suturing to continental collision settings is found in southern Kenya where southernmost arcs of the ANS conjoin with thickened continental margin suites of the Eastern Granulite Belt. The younger ca. 570-530 Ma Kuunga orogeny heads from the Damara - Zambesi - Irumide Belts (De Waele et al., 2006) over Tanzania - Mozambique to southern India and clashes with the East African orogen in southern-central Tanzania. Two transitional orogen settings may be defined, (1) that between island arcs and inverted passive continental margin within the East African Orogen and, (2) that between N-S trending East African and W-E trending Kuungan orogenies. The Neoproterozoic island arc suites of SE-Kenya are exposed as a narrow stripe between western Azania and the Eastern Granulite belt. This suture is a steep, NNW stretched belt that aligns roughly with the prominent southern ANS shear zones that converge at the southern tip of the ANS (Athi and Aswa shear zones). Oblique convergence resulted in low-vorticity sinstral shear during early phases of deformation. Syn-magmatic and syn-tectonic textures are compatible with deformation at granulite metamorphic conditions and rocks exhumed quickly during ongoing transcurrent motion. The belt is typified as wrench tectonic belt with horizontal northwards flow of rocks within deeper portions of an island arc. The adjacent Eastern Granulite Nappe experienced westward directed, subhorizontal, low-vorticity, high temperature flow at partly extreme metamorphic conditions (900°C, 1.2 to 1.4 GPa

  14. Storage Mixing Variability Across Seasons and Scales in Tanzania

    NASA Astrophysics Data System (ADS)

    Koutsouris, A. J.; Lyon, S. W.

    2015-12-01

    Our ability to accurately assess water residence times and storage volumes hinges on data availability. However, hydrological data is often limited or non-existing in most regions of the world. This study synthesizes hydrological tracer data with hydroclimatic information in order to disentangle storage volume dynamics and variability across data-limited African catchments. Specifically, we focus on the Kilombero Valley in Tanzania where there is a large potential to develop and expand the agricultural sector and thus increasing food security nationally. The lack hydrological data and subsequent limited process understanding hinders our capacity to assess the sustainability of such an increased and intensified agriculture landscape. We demonstrate how hydrological tracers constitute an exceptionally valuable piece of information for constraining model parameterizations, improving process understanding and representing storage volumes in data limited regions. Geochemical (e.g., Ca2+, Na+, K+, Mg2+, SO42-, Cl-) and stable water isotope (d18O and d2H) tracers were used to estimate recharge rates and seasonal shifts in hydrologic flow pathways. End member mixing analysis (EMMA) applied within the GLUE uncertainty framework was used to assess relative source contributions to streamflow and storage volume connectivity across scales. Strong variations in stable water isotopes between rainfall seasons in Tanzania and geological partitioning of storages allowed for clear characterization of seasonal variations in hydrologic flow pathway development. Wetlands dominated the wet season flows while variability in the connectivity of water storages could be seen during the dry season. Differences in the wetting up versus drying down storage mixing across the landscape highlights process shifts. This characterization improves our ability to utilize the limited data available in Kilombero Valley as it provides the basis for modelling surface-groundwater interactions regionally and

  15. Two treatments, one disease: childhood malaria management in Tanga, Tanzania

    PubMed Central

    2009-01-01

    Background In the Tanga District of coastal Tanzania, malaria is one of the primary causes of mortality for children under the age of five. While some children are treated with malaria medications in biomedical facilities, as the World Health Organization recommends, others receive home-care or treatment from traditional healers. Recognition of malaria is difficult because symptoms can range from fever with uncomplicated malaria to convulsions with severe malaria. This study explores why caregivers in the Tanga District of Tanzania pursue particular courses of action to deal with malaria in their children. Methods Qualitative data were collected through interviews with three samples: female caregivers of children under five (N = 61), medical practitioners (N = 28), and traditional healers (N = 18) in urban, peri-urban, and rural areas. The female caregiver sample is intentionally stratified to reflect the greater population of the Tanga District in level of education, marital status, gender of household head, religion, and tribal group affiliation. Qualitative data were counted, coded and analysed using NVivo7 software. Results Results indicate that a variety of factors influence treatment choice, including socio-cultural beliefs about malaria symptoms, associations with spiritual affliction requiring traditional healing, knowledge of malaria, and fear of certain anti-malaria treatment procedures. Most notably, some caregivers identified convulsions as a spiritual condition, unrelated to malaria. While nearly all caregivers reported attending biomedical facilities to treat children with fever (N = 60/61), many caregivers stated that convulsions are best treated by traditional healers (N = 26/61). Qualitative interviews with medical practitioners and traditional healers confirmed this belief. Conclusion Results offer insight into current trends in malaria management and have implications in healthcare policy, educational campaigns, and the importance of integrating

  16. Appropriate deflouridation technology for use in flourotic areas in Tanzania

    NASA Astrophysics Data System (ADS)

    Mjengera, H.; Mkongo, G.

    High fluoride in drinking water is a problem found in both ground and surface water in various parts of Tanzania. Several defluoridation methods have been tested and detailed studies have been carried on bone-char method, alum/lime method and the combination of the two methods. In bone char method, the bones are charred in special kilns fuelled by wood charcoal. Different sizes of the kiln have been fabricated and tested. Crushing and sieving devices have been developed. The effectiveness of bone char particles sizes in fluoride removal has been studied and the results favoured small particle sizes. However, experimental conditions discouraged the use of very fine particles sizes of bone char due easy clogging. Household and institutional levels bone char defluoridation systems have been developed and tested. Filter columns packed with heat-activated bones are found to be more effective than fill and draw bucket type defluoridator. The bone char media used has the capability of producing water with a residual fluoride concentration of less than 0.1 mg/l from an initial fluoride of 12.0 mg/l. Use of alum and lime in fluoride removal from waters with excessive fluoride has been experimented upon. A plant with an automatic chemical dosing and mixing system for use at institutional levels has been developed and tested. The method was able to treat water with an initial fluoride concentration of 12 mg/l to a residual fluoride concentration ranging from 2 to 3 mg/l. During the study it was established, that the bone char method is appropriate for use in rural areas of Tanzania due its simplicity, local availability of materials and the possibility of processing the material locally.

  17. Economic cost of primary prevention of cardiovascular diseases in Tanzania.

    PubMed

    Ngalesoni, Frida; Ruhago, George; Norheim, Ole F; Robberstad, Bjarne

    2015-09-01

    Tanzania is facing a double burden of disease, with non-communicable diseases being an increasingly important contributor. Evidence-based preventive measures are important to limit the growing financial burden. This article aims to estimate the cost of providing medical primary prevention interventions for cardiovascular disease (CVD) among at-risk patients, reflecting actual resource use and if the World Health Organization (WHO)'s CVD medical preventive guidelines are implemented in Tanzania. In addition, we estimate and explore the cost to patients of receiving these services. Cost data were collected in four health facilities located in both urban and rural settings. Providers' costs were identified and measured using ingredients approach to costing and resource valuation followed the opportunity cost method. Unit costs were estimated using activity-based and step-down costing methodologies. The patient costs were obtained through a structured questionnaire. The unit cost of providing CVD medical primary prevention services ranged from US$30-41 to US$52-71 per patient per year at the health centre and hospital levels, respectively. Employing the WHO's absolute risk approach guidelines will substantially increase these costs. The annual patient cost of receiving these services as currently practised was estimated to be US$118 and US$127 for urban and rural patients, respectively. Providers' costs were estimated from two main viewpoints: 'what is', that is the current practice, and 'what if', reflecting a WHO guidelines scenario. The higher cost of implementing the WHO guidelines suggests the need for further evaluation of whether these added costs are reasonable relative to the added benefits. We also found considerably higher patient costs, implying that distributive and equity implications of access to care require more consideration. Facility location surfaced as the main explanatory variable for both direct and indirect patient costs in the regression

  18. Economic cost of primary prevention of cardiovascular diseases in Tanzania

    PubMed Central

    Ngalesoni, Frida; Ruhago, George; Norheim, Ole F; Robberstad, Bjarne

    2015-01-01

    Tanzania is facing a double burden of disease, with non-communicable diseases being an increasingly important contributor. Evidence-based preventive measures are important to limit the growing financial burden. This article aims to estimate the cost of providing medical primary prevention interventions for cardiovascular disease (CVD) among at-risk patients, reflecting actual resource use and if the World Health Organization (WHO)’s CVD medical preventive guidelines are implemented in Tanzania. In addition, we estimate and explore the cost to patients of receiving these services. Cost data were collected in four health facilities located in both urban and rural settings. Providers’ costs were identified and measured using ingredients approach to costing and resource valuation followed the opportunity cost method. Unit costs were estimated using activity-based and step-down costing methodologies. The patient costs were obtained through a structured questionnaire. The unit cost of providing CVD medical primary prevention services ranged from US$30–41 to US$52–71 per patient per year at the health centre and hospital levels, respectively. Employing the WHO’s absolute risk approach guidelines will substantially increase these costs. The annual patient cost of receiving these services as currently practised was estimated to be US$118 and US$127 for urban and rural patients, respectively. Providers’ costs were estimated from two main viewpoints: ‘what is’, that is the current practice, and ‘what if’, reflecting a WHO guidelines scenario. The higher cost of implementing the WHO guidelines suggests the need for further evaluation of whether these added costs are reasonable relative to the added benefits. We also found considerably higher patient costs, implying that distributive and equity implications of access to care require more consideration. Facility location surfaced as the main explanatory variable for both direct and indirect patient costs in

  19. Significance of Trends on Enrolment, Budget and Actual Expenditure in the Examination of Higher Education Financing in Tanzania

    ERIC Educational Resources Information Center

    Memba, Albert Zephaniah; Feng, Zhao Jun

    2016-01-01

    Financing of higher education in Tanzania is considered a crucial factor in realizing the country's development vision. It is for these reasons that Tanzania has been financing its higher education since its inception. Diminishing resource capacity and competing interests for government finance plunged the higher education into financial doldrums.…

  20. A Ghanaian Response to the Study on "Widening Participation in Higher Education in Ghana and Tanzania: Developing an Equity Scorecard"

    ERIC Educational Resources Information Center

    Effah, Paul

    2011-01-01

    The study on "Widening Participation in Higher Education in Ghana and Tanzania: developing an Equity Scorecard" is a contribution to making higher education more socially inclusive in sub-Saharan Africa. The findings reinforce some of the policy initiatives taken in Ghana and Tanzania, and underscore the importance of widening participation in…

  1. Characterization of the common bean host and Pseudocercospora griseola the causative agent of angular leaf spot disease in Tanzania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola is one of the most important diseases of common bean in Tanzania. Breeding for resistance to this disease is complicated by the variable nature of the pathogen. In Tanzania no thorough analysis of the variability of this pathogen...

  2. Smallholder Information Sources and Communication Pathways for Cashew Production and Marketing in Tanzania: An Ex-Post Study in Tandahimba and Lindi Rural Districts, Southern Tanzania

    ERIC Educational Resources Information Center

    Nyambo, Brigitte; Ligate, Elly

    2013-01-01

    Purpose: To identify and review production and marketing information sources and flows for smallholder cashew (Anacardium occidentale L.) growers in Tanzania and recommend systems improvements for better technology uptake. Design/methodology/approach: Two-stage purposive samples were drawn. First, two districts in the main cashew producing areas,…

  3. Foot-and-mouth disease in Tanzania from 2001 to 2006.

    PubMed

    Picado, A; Speybroeck, N; Kivaria, F; Mosha, R M; Sumaye, R D; Casal, J; Berkvens, D

    2011-02-01

    Foot-and-mouth disease (FMD) is endemic in Tanzania, with outbreaks occurring almost each year in different parts of the country. There is now a strong political desire to control animal diseases as part of national poverty alleviation strategies. However, FMD control requires improving the current knowledge on the disease dynamics and factors related to FMD occurrence so control measures can be implemented more efficiently. The objectives of this study were to describe the FMD dynamics in Tanzania from 2001 to 2006 and investigate the spatiotemporal patterns of transmission. Extraction maps, the space-time K-function and space-time permutation models based on scan statistics were calculated for each year to evaluate the spatial distribution, the spatiotemporal interaction and the spatiotemporal clustering of FMD-affected villages. From 2001 to 2006, 878 FMD outbreaks were reported in 605 different villages of 5815 populated places included in the database. The spatial distribution of FMD outbreaks was concentrated along the Tanzania-Kenya, Tanzania-Zambia borders, and the Kagera basin bordering Uganda, Rwanda and Tanzania. The spatiotemporal interaction among FMD-affected villages was statistically significant (P≤0.01) and 12 local spatiotemporal clusters were detected; however, the extent and intensity varied across the study period. Dividing the country in zones according to their epidemiological status will allow improving the control of FMD and delimiting potential FMD-free areas. PMID:21078082

  4. Preliminary investigation on presence of peste des petits ruminants in Dakawa, Mvomero district, Morogoro region, Tanzania.

    PubMed

    Kgotlele, Tebogo; Kasanga, Christopher J; Kusiluka, Lughano J M; Misinzo, Gerald

    2014-01-01

    Peste des petits ruminants (PPR) is an acute viral disease of small ruminants characterised by the sudden onset of depression, fever, oculonasal discharges, sores in the mouth, foul-smelling diarrhoea and death. For many years, in Africa, the disease was mainly confined to West and Central Africa but it has now spread southwards to previously PPR-free countries including Tanzania, Democratic Republic of Congo and Angola. The disease was first reported in Tanzania in 2008 when it was confined to the Northern Zone districts bordering Kenya. Presence of the disease has also been confirmed in southern Tanzania especially Mtwara region. Recently, a suspected outbreak of PPR in Dakawa area, Mvomero district, Morogoro region was reported. Clinical samples (lungs, intestines, lymph nodes, whole blood and sera) from suspected goats (n = 8) and sheep (n = 1) were submitted to Sokoine University of Agriculture for analysis. Molecular diagnosis by amplification of the nucleoprotein gene and the fusion gene of PPR virus (PPRV) using PPRV specific primers was done. Five goats and the sheep were positive for PPRV after performing RT-PCR. To our knowledge, this is the first report confirming the presence of PPR in the Mvomero district of the Morogoro region, Tanzania. Hence, more efforts should be put in place to prevent the spread of PPR in Tanzania. PMID:25134174

  5. The role of liquid immiscibility in the genesis of carbonatites — An experimental study

    NASA Astrophysics Data System (ADS)

    Freestone, I. C.; Hamilton, D. L.

    1980-07-01

    The two-liquid field between alkali-carbonate liquids and phonolite or nephelinite magmas from the Oldoinyo Lengai volcano has been determined between 0.7 and 7.6 kb and 900° 1,250° C. The miscibility gap expands with increase in P_{CO_2 } and decrease in temperature. Concomitantly there is a rotation of tie-lines so that the carbonate liquids become richer in CaO. The element distribution between the melts indicates that a carbonate liquid equivalent in composition to Oldoinyo Lengai natrocarbonatite lava would have separated from a phonolitic rather than a nephelinitic magma. CO2-saturated nephelinites coexist with carbonate liquids much richer in CaO than the Lengai carbonatites, but even so these liquids have high alkali concentrations. If the sövites of hypabyssal and plutonic ijolite-carbonatite complexes originated by liquid immiscibility, then large quantities of alkalis have been lost, as is suggested by fenitization and related phenomena. The miscibility gap closes away from Na2O-rich compositions, so that the tendency to exsolve a carbonatite melt is greater in salic than in mafic silicate magmas. The two-liquid field does not approach kimberlitic compositions over the range of pressures studied, suggesting that the globular textures observed in many kimberlite sills and dykes may be the result of processes other than liquid immiscibility at crustal pressures.

  6. Agricultural Development, Land Change, and Livelihoods in Tanzania's Kilombero Valley

    NASA Astrophysics Data System (ADS)

    Connors, John Patrick

    The Kilombero Valley lies at the intersection of a network of protected areas that cross Tanzania. The wetlands and woodlands of the Valley, as well as the forest of surrounding mountains are abundant in biodiversity and are considered to be critical areas for conservation. This area, however, is also the home to more than a half million people, primarily poor smallholder farmers. In an effort to support the livelihoods and food security of these farmers and the larger Tanzanian population, the country has recently targeted a series of programs to increase agricultural production in the Kilombero Valley and elsewhere in the country. Bridging concepts and methods from land change science, political ecology, and sustainable livelihoods, I present an integrated assessment of the linkages between development and conservation efforts in the Kilombero Valley and the implications for food security. This dissertation uses three empirical studies to understand the process of development in the Kilombero Valley and to link the priorities and perceptions of conservation and development efforts to the material outcomes in food security and land change. The first paper of this dissertation examines the changes in land use in the Kilombero Valley between 1997 and 2014 following the privatization of agriculture and the expansion of Tanzania's Kilimo Kwanza program. Remote sensing analysis reveals a two-fold increase in agricultural area during this short time, largely at the expense of forest. Protected areas in some parts of the Valley appear to be deterring deforestation, but rapid agricultural growth, particularly surrounding a commercial rice plantation, has led to loss of extant forest and sustained habitat fragmentation. The second paper focuses examines livelihood strategies in the Valley and claims regarding the role of agrobiodiversity in food security. The results of household survey reveal no difference or lower food security among households that diversify their

  7. Traditional healers in Tanzania: sociocultural profile and three short portraits.

    PubMed

    Gessler, M C; Msuya, D E; Nkunya, M H; Schär, A; Heinrich, M; Tanner, M

    1995-11-01

    Traditional healers are an important part of African societies, but unfortunately the knowledge of the extent and character of traditional healing and the people involved in the practice is limited and impressionistic. They are frequently ignored in studies of user/provider patterns, although they cover the health needs of a substantial proportion of the population. For future health planning it is necessary to know what the reasons are that even in big cities, where western health care services are available, traditional healers flourish, and even compete with each other for certain aspects. The aim of this study was to investigate certain aspects of the profession of traditional healing in general in different areas in Tanzania in order to get an idea about the kind of traditional medical services which are available, and about the people who provide such services. For this reason traditional healers were interviewed with a semi-structured questionnaire in different rural and urban places: in the Kilombero valley (Kilombero/Ulanga district), on the main island of Ukerewe (Ukerewe District), and in the region near Bukoba town (Bukoba District), and in the settlement of Dar es Salaam (largest city of Tanzania). The results of the study show that traditional healers are a very heterogeneous group of persons not having much in common relating to their religion, sex and level of education. The traditional practice is very often taken over from a family member, but also other reasons for becoming a healer, like initiation through ancestor spirits, are very frequently given. More than 50% of the respondents practice full time. These full time practitioners are mainly found among men and in the younger age group. Treatment of in-patients, who can stay in special patient-houses, is offered by half of the traditional healers. Divination used as a diagnostic tool was found mainly among men. Referral of patients to the hospital was mentioned by almost all respondents in

  8. Population growth, agrarian peasant economy and environmental degradation in Tanzania.

    PubMed

    Madulu, N F

    1995-03-01

    Population strategies to relieve the density pressures on land and resources in Tanzania have not considered the basic causes of population growth. Resettlement results in the same environmental degradation as in the original settlement. There should be a reduction in the population growth and planning of proper land use and resource exploitation before resettlement. Rural development must include a decline in the dependency on subsistence agriculture. Population in Tanzania increased by 213% during 1948-88. An absolute increase in population size during 1978-88 is recorded despite a slight decline in the rate of growth. Death rates declined, but birth rates were relatively stable at around 50 per 1000 population. Regions with the highest growth rates were Dar es Salaam (4.8%), Rukwa (4.3%), Arusha (3.8%), Mbeya (3.1%), and Ruvuma (3.2%). The regions with the lowest rates were Tanga and Kilimanjaro (2.1%), Coast (2.1%), Lindi (2%), and Mtwara (1.4%). Low growth rates are attributed to low fertility and high infertility. Other factors affecting high growth rates are culture, rates of natural increase, intensity of internal and international migration, climatic conditions, and availability of resources. In 1988 46% of the population was under 15 years old. Per capita land availability declined from 11.8 hectares in 1948 to 3.8 hectares in 1988. The number of landless peasants increased. Productivity declined, and distances to farms increased. The total fertility rate was 6.5 children per woman in 1988 and 6.1 during 1991-92. Slight declines were apparent in the crude birth rate also. High fertility was a response to universal marriage, low contraceptive use (7% using modern methods during 1991-92), declining lactation periods, high mortality rates, and old traditions favoring large families. Children were used extensively in time-consuming and labor-intensive activities, such as fetching water. The mean number of children ever born was higher among women with 1

  9. Gendered norms, sexual exploitation and adolescent pregnancy in rural Tanzania.

    PubMed

    McCleary-Sills, Jennifer; Douglas, Zayid; Rwehumbiza, Annagrace; Hamisi, Aziza; Mabala, Richard

    2013-05-01

    Adolescent pregnancy places girls at increased risk for poor health and educational outcomes that limit livelihood options, economic independence, and empowerment in adulthood. In Tanzania, adolescent pregnancy remains a significant concern, with over half of all first births occurring before women reach the age of 20. A participatory research and action project (Vitu Newala) conducted formative research in a rural district on the dynamics of sexual risk and agency among 82 girls aged 12-17. Four major risk factors undermined girls' ability to protect their own health and well-being: poverty that pushed them into having sex to meet basic needs, sexual expectations on the part of older men and boys their age, rape and coercive sex (including sexual abuse from an early age), and unintended pregnancy. Transactional sex with older men was one of the few available sources of income that allowed adolescent girls to meet their basic needs, making this a common choice for many girls, even though it increased the risk of unintended (early) pregnancy. Yet parents and adult community members blamed the girls alone for putting themselves at risk. These findings were used to inform a pilot project aimed to engage and empower adolescent girls and boys as agents of change to influence powerful gender norms that perpetuate girls' risk. PMID:23684192

  10. Occurrence of haemoparasites in cattle in Monduli district, northern Tanzania.

    PubMed

    Haji, Isihaka J; Malele, Imna; Namangala, Boniface

    2014-01-01

    Haemoparasite infections are among the most economically important cattle diseases in sub-Saharan Africa. The present study investigated the occurrence of haemoparasites in 295 indigenous cattle from five villages (Mswakini, Lake Manyara, Naitolia, Makuyuni and Nanja) of the Monduli district, a wildlife-domestic animal-human interface area in northern Tanzania. The data showed that the overall occurrence of haemoparasites in the sampled cattle was 12.5% (95% CI: 8.7% - 16.3%), involving single and mixed infections with Theileria parva, Anaplasma marginale, Babesia bovis, Trypanosoma vivax and Trypanosoma brucei. The highest haemoparasite occurrence was recorded in Lake Manyara (18.3%; 95% CI: 8.5% - 28.1%), and the lowest was recorded in Nanja (6.5%; 95% CI: 0.4% - 12.6%). This preliminary study, furthermore, provided evidence of the possible arthropod vectors (ticks and tsetse flies) that may be involved in the transmission of haemoparasites to cattle in the Monduli district. It is envisaged that this survey will stimulate more studies to determine the prevalence of haemoparasites in livestock by using more sensitive molecular techniques. PMID:25685864

  11. The Rungwe Volcanic Province, Tanzania - A volcanological review

    NASA Astrophysics Data System (ADS)

    Fontijn, Karen; Williamson, David; Mbede, Evelyne; Ernst, Gerald G. J.

    2012-02-01

    The Rungwe Volcanic Province in SW Tanzania is a densely populated area that is considered volcanically active. As part of the East African Rift System, a significant control of tectonic activity seems to exist on the location and also potential destabilization of volcanic edifices. Three large volcanoes, Ngozi, Rungwe, and Kyejo, dominate the landscape and all show contrasting eruptive behaviour in the recent geological past. Kyejo volcano is a flow-dominated volcano that had a historic lava flow eruption. Lake sediment cores, drilled in Lakes Malawi, Masoko, Rukwa, and Tanganyika, provide a record of frequent explosive eruptions in the last few tens of thousands of years. In combination with on-land stratigraphic observations, they constrain the minimum eruptive frequency of especially Rungwe and Ngozi volcanoes. Both volcanoes had Plinian-style eruptions in the Holocene. The most striking documented Rungwe eruption, the ca. 4 ka Rungwe Pumice, is a rare case of a Plinian eruption in near-wind-free conditions. Furthermore, the Rungwe Pumice, just like any other Rungwe tephra deposit, does not show any evidence of pyroclastic density current deposits. Apart from explosive eruptions at a range of scales happening every few hundred years at Rungwe, the volcano also experienced at least two sector collapse events generating debris avalanches. All existing evidence shows that the Rungwe Volcanic Province is prone to future significant explosive eruptions. To further assess, quantify and mitigate volcanic hazard risks, extensive and systematic multidisciplinary geological research, and both volcanic and tectonic monitoring are needed.

  12. Human and animal Campylobacteriosis in Tanzania: A review.

    PubMed

    Komba, Erick V G; Mdegela, Robinson H; Msoffe, Peter L M; Ingmer, Hanne

    2013-01-01

    The thermotolerant species of Campylobacter have become very important in public health, particularly as agents of infectious diarrhoea in human beings. Though the mechanism by which they cause disease is yet to be fully explained, they have been recognized as the leading cause of bacterial enteritis in both developed and developing countries. The organisms colonize different animal species without causing any symptoms of disease; and humans acquire infections through contact with or consumption of contaminated meat especially raw/undercooked poultry meat. The growing trend of antibiotic resistant Campylobacter isolates continues to pose significant public health challenges. In this review we present the available information generated in Tanzania about Campylobacter infections in humans and animals. We conducted a structured literature search of PUBMED and ScienceDirect electronic databases and identified 15 articles. Studies on humans reported Campylobacter infections in both symptomatic and asymptomatic subjects; with higher prevalence in children under the age of five years. Studies on animals found colonization of both domestic and wild species. Among isolates, some demonstrated antimicrobial resistance. The available information for both human and animal Campylobacteriosis in the country is sparse. It however provides an insight of the bacteriological and epidemiological aspects of Campylobacter infections in the country and eventually creates more awareness on the need to develop control strategies. Since the organism is zoonotic its control strategies should adopt the "One Health" approach involving collaborative efforts from veterinary and human medicine. PMID:26591672

  13. Suicide in the Dar es Salaam region, Tanzania, 2005.

    PubMed

    Mgaya, Edward; Kazaura, Method R; Outwater, Anne; Kinabo, Lina

    2008-04-01

    Suicide surveillance was launched at the Muhimbili National Hospital mortuary in Dar es Salaam Region, Tanzania from 1st January to 31st December, 2005 to determine its magnitude and characteristics. Following the WHO guidelines with minor modifications, information on sex, dates of birth and death, places of residence and death, occupation, reasons and means of suicide were collected. There were 65 (2.3 per 100,000 population) suicides recorded in 2005. The suicide rate for males was 3.4/100,000 and for females was 1.2/100,000 which maybe some of the lowest rates ever reported in the world. The mean age at suicide was 32.9 (SD=13.1) years. Males were about three times more likely to commit suicide as females. The main motive behind suicide was recorded for 26 (40%) victims as family-related and for 11 (17%) as health related. Although there was a wide range of ages at which people committed suicide, the average age seems to be very low. Since reasons for suicide are coated with family problems, strategies to improve awareness of psychological and mental health services and to provide alternative economic and social support networks are advocated. PMID:18313013

  14. Language promotion for educational purposes: The example of Tanzania

    NASA Astrophysics Data System (ADS)

    Rubagumya, Casmir M.

    1991-03-01

    Kiswahili is one of the most widely used languages in East and Central Africa. In Tanzania, where it is the national language, attempts have been made to develop it so that it can be used as an efficient tool of communication in all sectors of the society, including education. This paper shows that although Kiswahili has successfully been promoted as the medium of primary and adult education, at secondary and tertiary levels of education, its position is still precarious. The notion that English and Kiswahili are in complementary distribution is rejected. It is argued that the two languages are in conflict, and that those who are in a better socio-political/economic position have more control of, and better access to, English. In such a situation the right question to ask is not in which domains English is used, but why it is used in such domains and who uses it. The paper further argues that the present sociolinguistic environment makes the use of English as a viable medium unsustainable. For this reason, insistence on the use of English adversely affects the learning process. It is suggested that if Kiswahili became the medium of education at secondary school level and English was taught well as a foreign language, this would help to promote both languages without jeopardising the learning process.

  15. Magma supply rates inferred from cinder cone volumes

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Borgia, A.; Neri, M.; Kervyn, M.

    2010-12-01

    Revisiting the question of how cinder cones grow suggests the possibility of inferring magma supply rates from cinder cones sizes. We start with a conceptual model of cinder cone growth: (1) Eruption volume flux increases rapidly and then decreases exponentially. (2) Cinder cones get steeper during the initiation of the eruption and then maintain a constant steepness. (3) The initial basal diameter varies with volume flux into the cone. Based on these constraints, we propose a general form for the relationship between cinder cone volume and magma supply rate: V = Q(exp(-t/b)/b - exp(-t/a)/a), where V is volume (in m3), Q is the maximum potential magma flux (in m3/s), t is time (in s), a is a damping factor (in s) controlling the decline in volume flux, and b is a factor controlling the initial increase in volume flux. Then we use the data available on the growth of cinder cones from four modern eruptions to show the relevance of our model and to constrain the supply curves. All four modern cones (Paricutin, Mexico which erupted 1943-1974; Tolbachik, Kamchatka which erupted in 1975-1976; Cono del Laghetto, Mount Etna, Italy which formed in 2001; and a small cone on the summit of Oldoinyo Lengai, Tanzania, which formed during the 2007 eruption) show the basic growth pattern: initial rapid growth followed by declining growth (Figure 1). The regression results yeild the following magma supply rates: The southern Tolbachik cones have the largest predicted magma supply at ~100 m3/s. Paricutin and Laghetto are around 9 m3/s. The Oldoinyo Lengai cone has a magma supply of ~0.5 m3/s. The northern Tolbachik cone has the lowest magma supply of ~0.1 m3/s. In contrast, the damping factor a is generally on the order of 107 (it varies from 8 x 106 at southern Tolbachik to 4 x 107 at northern Tolbachik). The parameter b controlling the initial increase is generally small (<1). The predicted magma supply does not seem to be very sensitive to either parameter. Thus we suggest that

  16. Democratising Higher Education in Ghana and Tanzania: Opportunity Structures and Social Inequalities

    ERIC Educational Resources Information Center

    Morley, Louise; Leach, Fiona; Lugg, Rosemary

    2009-01-01

    This article is based on an ESRC/DFID funded research project on Widening Participation in Higher Education in Ghana and Tanzania: Developing an Equity Scorecard (http://www.sussex.ac.uk/education/wideningparticipation). There are questions about whether widening participation in higher education is a force for democratisation or differentiation.…

  17. Adolescent Hopefulness in Tanzania: Street Youth, Former Street Youth, and School Youth

    ERIC Educational Resources Information Center

    Nalkur, Priya G.

    2009-01-01

    This study compares hope in street youth, former street youth, and school youth (aged 12-18) in Tanzania. Responding to Snyder's hope theory, the author argues that not only personal agency but also the stability of living context (street, shelter, home) shapes hopefulness. Employing qualitative and quantitative analyses, the author presents a…

  18. The 1977 Universal Primary Education in Tanzania: A Historical Base for Quantitative Enquiry

    ERIC Educational Resources Information Center

    Sabates, Ricardo; Westbrook, Jo; Hernandez-Fernandez, Jimena

    2012-01-01

    This study focuses on the importance of increasing women's education as a result of Universal Primary Education (UPE) and its further impact on improving children's educational access in Tanzania. The study uses data from the 2007 Demographic Health Survey (DHS) for empirical analysis and it is informed by the historical accounts of the UPE reform…

  19. Innovations in Adult Education: The Changing Perspective of the Post-Literacy Curriculum in Tanzania.

    ERIC Educational Resources Information Center

    Mushi, Philemon A. K.

    1994-01-01

    Analyzes the context in which a postliteracy curriculum was perceived and developed in Tanzania in the late 1970s. Indicates that the first postliteracy curriculum sought to provide neoliterates with general knowledge in politics, history, geography, health, and agriculture. Analyzes factors that influenced changes in the curriculum's form and…

  20. Clinical, Virologic, and Epidemiologic Characteristics of Dengue Outbreak, Dar es Salaam, Tanzania, 2014

    PubMed Central

    Mboera, Leonard E.G.; De Nardo, Pasquale; Oriyo, Ndekya M.; Meschi, Silvia; Rumisha, Susan F.; Colavita, Francesca; Mhina, Athanas; Carletti, Fabrizio; Mwakapeje, Elibariki; Capobianchi, Maria Rosaria; Castilletti, Concetta; Di Caro, Antonino; Nicastri, Emanuele; Malecela, Mwelecele N.; Ippolito, Giuseppe

    2016-01-01

    We investigated a dengue outbreak in Dar es Salaam, Tanzania, in 2014, that was caused by dengue virus (DENV) serotype 2. DENV infection was present in 101 (20.9%) of 483 patients. Patient age and location of residence were associated with infection. Seven (4.0%) of 176 patients were co-infected with malaria and DENV. PMID:27088845

  1. Preparing Tanzania's Young Children for the Economic World: Possibilities for Collaboration with Other Countries.

    ERIC Educational Resources Information Center

    Mushi, Selina L. P.

    This paper is a critical analysis of the role of the Tanzanian education system in enhancing young children's awareness of economic aspects around them. The major factors the paper considers are: the poverty of the country; the prominence of the education system as a socializing agent for children; the aim of early education in Tanzania; and young…

  2. Predicting Participation in Environmental Education by Teachers in Coastal Regions of Tanzania

    ERIC Educational Resources Information Center

    Bruyere, Brett; Nash, Peter E.; Mbogella, Felix

    2011-01-01

    Theories of responsible environmental behavior (REB) have most often been applied in developed countries and to direct forms of REB such as recycling and conserving water. This study applied a model of REB to a developing country setting in Tanzania based in part on variables from a Hungerford and Volk (1990) model and targeting an indirect form…

  3. Girls' Education in Pastoral Communities: An Ethnographic Study of Monduli District, Tanzania. Research Report

    ERIC Educational Resources Information Center

    Raymond, Adella

    2014-01-01

    This research report notes that despite the focus on girls' education in the Millennium Development Goals, there remains a huge number of girls out of education, a situation which, although improving, is still a significant concern in Tanzania, Africa. Women and girls in pastoral communities are subject to a particularly challenging…

  4. Higher Education as an Instrument of Social Integration in Tanzania: Challenges and Prospects

    ERIC Educational Resources Information Center

    Mkude, Daniel

    2011-01-01

    In developing countries, higher education is a powerful instrument for social mobility and economic prosperity. An in-depth study of the relationship between higher education and certain equity issues has revealed that in Ghana and Tanzania there is inadequate effort to widen higher education participation to include traditionally disadvantaged…

  5. Clinical, Virologic, and Epidemiologic Characteristics of Dengue Outbreak, Dar es Salaam, Tanzania, 2014.

    PubMed

    Vairo, Francesco; Mboera, Leonard E G; De Nardo, Pasquale; Oriyo, Ndekya M; Meschi, Silvia; Rumisha, Susan F; Colavita, Francesca; Mhina, Athanas; Carletti, Fabrizio; Mwakapeje, Elibariki; Capobianchi, Maria Rosaria; Castilletti, Concetta; Di Caro, Antonino; Nicastri, Emanuele; Malecela, Mwelecele N; Ippolito, Giuseppe

    2016-05-01

    We investigated a dengue outbreak in Dar es Salaam, Tanzania, in 2014, that was caused by dengue virus (DENV) serotype 2. DENV infection was present in 101 (20.9%) of 483 patients. Patient age and location of residence were associated with infection. Seven (4.0%) of 176 patients were co-infected with malaria and DENV. PMID:27088845

  6. "Drugs, Religion and Chemistry in Tanzania": An Interactive Seminar for Chemistry Students

    ERIC Educational Resources Information Center

    Buchanan, Malcolm S.

    2015-01-01

    Most Tanzanian Higher Education Institutes do not have the materials and technology to give students a significant practical experience in the sciences. In 2013 Tanzania was rated 159th out of 187 countries for "human development" (United Nations Development Program 2014 Report). In order to supplement their current, limited practical…

  7. Peste des petits ruminants infection among cattle and wildlife in northern Tanzania.

    PubMed

    Lembo, Tiziana; Oura, Christopher; Parida, Satya; Hoare, Richard; Frost, Lorraine; Fyumagwa, Robert; Kivaria, Fredrick; Chubwa, Chobi; Kock, Richard; Cleaveland, Sarah; Batten, Carrie

    2013-12-01

    We investigated peste des petits ruminants (PPR) infection in cattle and wildlife in northern Tanzania. No wildlife from protected ecosystems were seropositive. However, cattle from villages where an outbreak had occurred among small ruminants showed high PPR seropositivity, indicating that spillover infection affects cattle. Thus, cattle could be of value for PPR serosurveillance. PMID:24274684

  8. First report of Phakopsora pachyrhizi on soybean causing rust in Tanzania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phakopsora pachyrhizi Syd. was reported on legume hosts other than soybean in Tanzania as early as 1979. Soybean rust (SBR), caused by P. pachyrhizi, was first reported on soybean in Africa in Uganda in 1996, and its introduction into Africa was proposed to occur through urediniospores blowing from ...

  9. Antecedents of Continued Usage Intentions of Web-Based Learning Management System in Tanzania

    ERIC Educational Resources Information Center

    Lwoga, Edda Tandi; Komba, Mercy

    2015-01-01

    Purpose: The purpose of this paper is to examine factors that predict students' continued usage intention of web-based learning management systems (LMS) in Tanzania, with a specific focus on the School of Business of Mzumbe University. Specifically, the study investigated major predictors of actual usage and continued usage intentions of…

  10. Building an Agricultural Extension Services System Supported by ICTs in Tanzania: Progress Made, Challenges Remain

    ERIC Educational Resources Information Center

    Sanga, C.; Kalungwizi, V. J.; Msuya, C. P.

    2013-01-01

    The conventional agricultural extension service in Tanzania is mainly provided by extension officers visiting farmers to provide agricultural advisory service. This system of extension service provision faces a number of challenges including the few number of extension officers and limited resources. This article assesses the effectiveness of an…