Browsing by Author "John, George"

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    Stratigraphy and structural evolution of the southern Musoma Mara greenstone belt in the Suguti area, Northern Tanzania
    (University of Dar es Salaam, 2008) John, George
    This study presents the lithostratigraphy and structural characteristics of the southern Musorna-Mara Greenstone Belt in an area of about 726 km2 around Suguti in northern Tanzania based on satellite imagery, aerial photography and airborne geophysical investigations supplemented by detailed field work and petrographic investigations. The area consists of supracrustal rocks of the upper Nyanzian Supergroup, which have been intruded by granitic rocks which have been metamorphosed into the greenschist facies. High-resolution satellite imagery data and airborne magnetic data show a dominant NW-SE macro-structural pattern which cross cut earlier E-W lineaments resulting in open symmetrical folds. A regional dextral sense of deformation is inferred from deformation patterns in xenoliths, megaphenocrysts and C-C' relationships in shear zones. Apart from the shear zones, sub-vertical thrusts in cherts also cause folds and repetition of strata The sub-vertical shear planes indicate curvilinear listric thrusts with drag folds and listric back-thrusts. Likewise, ridges display distinct listric type of thrust patterns dipping NNW forming duplex thrust piles indicative of SSE thrust tectonics. The local stratigraphic sequence in the area is, from older to younger as follows; basic metavolcanics (greenschists), acidic (felsic) metavolcanics and the upper metasedimentary group.