School Of Mines and Geoscience

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Browsing School Of Mines and Geoscience by Author "Boniface, Nelson"

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    Contact Metamorphism in the Supracrustal Rocks of the Sukumaland Greenstone Belt in the North West Tanzania
    (2011) Boniface, Nelson
    Biotite-granite intrusions in meta-ironstones at Geita Hills and the Bukoli alkali-granite intrusion in metabasites at Mawemeru area produced heat that baked the respective country rocks through epidote-amphibolite- to amphibolite-facies. Critical and informative mineral assemblages in the metairostones of Geita Hills are garnet-grunerite-epidote-quartz and garnetferrogedrite- biotite-quartz and in the metabasites of Mawemeru is ferrotschermakite-(Naplagioclase)- quartz. Peak temperatures ranging between 438°C and 544°C were calculated from the above mineral assemblages and a pressure not exceeding 3 kbar was inferred to from the composition of magnesium-iron amphiboles (grunerite with XFe ratio of 0.83, i.e. Gru83). Hornfels textures in the metaironstones are suggested by euhedral poikiloblastic garnet and quartz with grain boundaries intersecting at approximately 120° (granoblastic polygonal texture) and biotite aggregates forming an interlocking network of elongate grains aligned in all directions and bounded by rational crystal faces (decussate texture).
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    The First Master Program in Petroleum Geology at the University of Dar es Salaam: Lessons and Challenges
    (2015-11-17) Bertotti, G.; Boniface, Nelson; de Bresser, J. H. P.; Manya, Shukrani; Nkotagu, H.; van Ruitenbeek, F.
    The UDSM, supported by group of geoscientists from Universities of the Netherlands has been able to establish the first Master program in Petroleum Geology of the country. With the crucial financial support of BG-Group 13 students has enrolled for the program. Courses have been given in the first year covering a wide range of relevant disciplines. Students have demonstrated a remarkable dedication to the course and have all performed at high level. The second year of the program will be dedicated to research projects developed in close connection with Industry. Challenges for the future include the development of shared data bases and e-learning facilities, the strengthening of the training the trainers component of the project and the establishment of robust relations with Industry
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    Structural Analysis, Metamorphism, and Geochemistry of the Archean Granitoids-Greenstones of the Sukumaland Greenstone Belt Around Geita Hills, Northern Tanzania
    (2012) Boniface, Nelson; Mruma, Abdul H.
    Greenstone rocks, which include Banded Iron Formations (BIFs), tuffs, volcanic flows (basalt, andesite and rhyolite), and clastic sedimentary rocks (shale-mudstone, greywacke-sandstone and conglomerate), crop out around Geita Hills and are flanked by granites and granodiorites. BIFs and tuffs occupy larger area than other lithological units, which crop out as patches. Structural analysis indicates that layers of greenstone rocks are folded and display a regional fold axis with an attitude of 320˚/40˚. Low-grade metamorphic mineral assemblages (actinoliteepidote-chlorite in basalts and muscoviteepidote-chlorite in granitoids) are common in these rocks; this indicates a regional metamorphism at greenschist facies. However, BIFs and basalts are locally metamorphosed to epidoteamphibolite and amphibolite facies. Basalts belong to the tholeiite series whereas granites, diorites and rhyolites belong to the calc-alkaline series. Chondrite normalized rare earth element pattern of basalt is flat and plot slightly below the average N-MORB values suggesting the enrichment of the light rare earth elements, which means that mantle magma source was an EMORB. Granitoids and rhyolites have strong affinities to the continental arc source magma displaying strong enrichments in the LREEs with (La/Sm)N values ranging between 2.53 and 3.95 in rhyolites and between 4.08 and 5.40 in granitoids. The granitoids are classified as the I-type synorogenic metaluminous granites and granodiorites. Geochemical signatures suggest that the Geita Hills basalts erupted at the enriched mid ocean ridge setting of the back arc setting, and the granites, granodiorite and rhyolite formed in a volcanic arc setting particularly the continental arc.