NEW FINDINGS OF THE TECTONIC CHARACTERISTICS OF THE EAST AFRICAN OROGENY IN THE KITUI – TAITA HILLS, S.E KENYA

Citation:
WASWA AARONK, Nyamai CM, MATHU ELIUDM, Ichang’i DW. "NEW FINDINGS OF THE TECTONIC CHARACTERISTICS OF THE EAST AFRICAN OROGENY IN THE KITUI – TAITA HILLS, S.E KENYA.". In: 35TH INTERNATIONAL GEOLOGICAL CONGRESS. CAPE TOWN, SOUTH AFRICA; 2016.

Date Presented:

August 2016

Abstract:

The research area occurs within the Neoproterozoic Mozambique belt (NMB) in the south-eastern part of Kenya. An enigmatic problem within the polyphase and highly deformed NMB, is the lack of better understanding of the geology and tectonic structures. In order to decipher the aforementioned problem, this study undertook a geological study with the aim of having a better understanding of the petrology and tectono-metamorphic setting, in the study area. The research was carried out using geological field mapping and remote sense investigation. Samples collected in the field were analysed using XRF (X- ray fluorescence) and AAS (Atomic absorption spectrophotometry). The petrological investigation was carried out using petrographic microscopy. An investigation using remotely sensed data established prevalent geological structures, lithology and mineral alteration zones. This study has provided a comprehensive understanding of the tectono-thermal scenario. One of the key findings of this study is the realization that Kitui – Taita gneisses and migmatites represent a thick sequence of meta-sedimentary rocks. The entire protolith sequence was marked by the alternation of thin pelitic, psammitic and limey layers, together with minor thin basic meta-volcanic rocks that were deposited under deep marine conditions. The entire paragneissic sequence was subsequently subjected to multiple phases of successive deformation and metamorphism, which was accompanied by shearing, faulting and folding. Petrochemistry has revealed that Kitui – Taita hills area has remnants of Island alkali tholeiite and calc – alkaline Metabasalts. It has also revealed that Ikutha (south of Kitui) has huge deposit of apatite – iron of Kiruna type. Petrological studies have shown that Mutomo–Ikutha area occurs in an ophiolitic suite and mimics similar lithological and geochemical signatures as those reported in other ophiolite suites occurring in Kenya like in Moyale, Sekerr in West Pokot and Voi, SE Kenya. The field occurrence of this suite has been documented by the lithological and stratigraphic sequence of serpentinite, sheeted dykes, gabbro, limestone, tectonic mélange and remnants of pillow lava found in the type area. The field occurrence of this suite is an indication of the remnants of the obducted oceanic crust during the closure of the paleo- Mozambique Ocean and collision of the East and West Gondwanaland

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