Browsing by Author "Basu, N. K."

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    The Geochemistry of Mafic and Ultramafic Rocks in the Wami River Granulite Complex, Central Coastal Tanzania
    (1987) Maboko, Makenya A. H.; Basu, N. K.
    The geochemistry of mafic and ultramafic rocks in the Wami River granulite complex of the central part of the coastal region, Tanzania, suggests that their protolith consisted of basaltic rocks with a calc-alkaline differentiation trend. Some of the ultramafic rocks show primitive chemical characteristics including high (Mg/Mg + Fetot) ratios and high Ni contents. These primary magmas later evolved mainly by olivine fractionation to yield the parent magmas which cooled to form the protolith of the bulk of the mafic granulites. The effect of the granulite facies metamorphism on the geochemistry of the rocks is restricted to depletion of Nb and Rb and possibly the enrichment of Ba.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Petrology of the Talc-Kyanite-Yoderite-Quartz Schist and Associated Rocks of Mautia Hill, Mpwapwa District, Tanzania
    (Elsevier, 1987) Mruma, Abdulkarim H.; Basu, N. K.
    Talc-kyanite-yoderite-quartz schist and associated rocks belonging to the Proterozoic Usagaran System occurring along the western edge of the Mozambique Orogenic Belt (450–600 Ma) were studied using petrographic, X-ray diffraction, electron-microprobe and fluid inclusion methods. The main rock types studied in the area include talc-kyanite-yoderite-quartz schist, piemontite quartzite, epidote-phogopite quartzite, kyanite-quartz-biotite schist and biotite gneiss. Fluid inclusion studies on the selected rock types indicate the presence of usually two-phased H2O-rich and CO2-rich fluids with a range of filling from 0.6 to 0.95. Some CO2-rich fluids may be one-phased (liquid) at room temperature with their degree of filling ranging from 0.4 to 1.0. Most of the CO2-rich inclusions show negative crystal shapes. Fluid inclusions trapped in kyanite in the talc-kyanite-yoderite-quartz schist with isolated negative crystal shapes are considered primary. The presence of CO2-rich fluids indicates low water fugacity during the formation of the talc-kyanite assemblage, and so pressure was probably lower. Primary fluid inclusions could be trapped at pressures between 5.2 and 5.6 kb and temperatures ranging from 540 to 570°C; this gives the possible P-T range of the peak of the first phase of progressive metamorphism.
  • Thumbnail Image
    Item
    Petrology of the Talc-Kyanite-Yoderite-Quartz Sschist and Asociated Rocks of Mautia Hill, Mpwapwa District, Tanzania
    (2003) Mruma, Abdulkarim H.; Basu, N. K.
    alc-kyanite-yoderite-quartz schist and associated rocks belonging to the Proterozoic Usagaran System occurring along the western edge of the Mozambique Orogenic Belt (450–600 Ma) were studied using petrographic, X-ray diffraction, electron-microprobe and fluid inclusion methods. The main rock types studied in the area include talc-kyanite-yoderite-quartz schist, piemontite quartzite, epidote-phogopite quartzite, kyanite-quartz-biotite schist and biotite gneiss. Fluid inclusion studies on the selected rock types indicate the presence of usually two-phased H2O-rich and CO2-rich fluids with a range of filling from 0.6 to 0.95. Some CO2-rich fluids may be one-phased (liquid) at room temperature with their degree of filling ranging from 0.4 to 1.0. Most of the CO2-rich inclusions show negative crystal shapes. Fluid inclusions trapped in kyanite in the talc-kyanite-yoderite-quartz schist with isolated negative crystal shapes are considered primary. The presence of CO2-rich fluids indicates low water fugacity during the formation of the talc-kyanite assemblage, and so pressure was probably lower. Primary fluid inclusions could be trapped at pressures between 5.2 and 5.6 kb and temperatures ranging from 540 to 570°C; this gives the possible P-T range of the peak of the first phase of progressive metamorphism.
  • Thumbnail Image
    Item
    Structural Evolution of the Ubendian Belt: Preliminary Results of a Traverse Between Karema and Mpanda (Tanzania).
    (1981) Nanyaro, J. T.; Basu, N. K.; Muhongo, S. M.; Mruma, Abdulkarim H.; Djare, S. A.; Mwakalukwa, G. L.; Nduma, I.; Mudiguza, K. M.; Van Straaten, P.; Klerkx, J.; Theunissen, K.