Age of fault movements in Tanzanian sector of East-African rift system

R.M. MacIntyre, J.G. Mitchell, J.B. Dawson, Macintyre R.M.

    Research output: Contribution to journalArticle

    55 Citations (Scopus)

    Abstract

    The Neogene volcanic province of northern Tanzania is a southerly extension of the more extensive volcanic areas of Ethiopia and Kenya. It stands astride the Eastern Rift Valley and represents a complex interplay of volcanic activity and widespread Earth movements with associated faulting. A general picture is that an older series of basaltic-trachytic shield volcanoes, together with smaller nephelinitic centres, erupted and grew up on the floor of a major late-Tertiary fault-bounded depression; this earlier series includes the basaltic volcanoes of the Crater Highlands, Oldoinyo Sambu, Gelai and Kitumbeine, and the nephelinitic volcanoes Mosonik and Essimingor (Fig. 1). This volcanic area was later disrupted by a major episode of faulting that created the present-day Rift Valley depression. The main manifestation of this faulting is the major Rift Escarpment that runs from Lake Natron in the north to well south of Lake Manyara, this escarpment being the surface expression of the major Manyara-Natron Fault. The Tanzania sector of the Rift Valley is not a classic graben, as in Kenya to the north, and is bounded on its eastern side only by minor faults or down-warping. The major faulting was followed by another phase of volcanic activity, the volcanoes being dominantly nephelinitic, with carbonatite present at some centres; the major volcanoes are Hanang, Ufiome, Meni, Burko, Kerimasi and Oldoinyo Lengai together with many smaller volcanoes1. Previous geochronological studies on volcanic rocks from the Tanzania province have outlined the ages of various volcanic centres2, and also of individual flows in connection with palaeomagnetic determinations3 or anthropological studies4. The work described here has been directed at dating the faulting episodes, particularly the main phase, with a view to setting a maximum age for the onset of the later nephelinite-carbonatite magmatism, and also for the comparison with dated volcanic areas in Kenya to the north5,6. Such basic age information is also necessary for examination of the suggested temporal and spatial association of swelling, rifting and volcanicity (pluming?) with carbonatite magmatism7.
    LanguageEnglish
    Pages354-356
    Number of pages2
    JournalNature Physics
    Volume247
    Issue number5440
    DOIs
    Publication statusPublished - 1974

    Fingerprint

    African rift system
    volcanology
    sectors
    volcanoes
    Tanzania
    Kenya
    valleys
    escarpments
    lakes
    Earth movements
    Ethiopia
    highlands
    bedrock
    dating
    craters
    swelling
    examination
    rocks

    Keywords

    • Tanzinian
    • East African
    • rift system
    • fault movements

    Cite this

    MacIntyre, R. M., Mitchell, J. G., Dawson, J. B., & Macintyre R.M. (1974). Age of fault movements in Tanzanian sector of East-African rift system. Nature Physics, 247(5440), 354-356. https://doi.org/10.1038/247354a0
    MacIntyre, R.M. ; Mitchell, J.G. ; Dawson, J.B. ; Macintyre R.M. / Age of fault movements in Tanzanian sector of East-African rift system. In: Nature Physics. 1974 ; Vol. 247, No. 5440. pp. 354-356.
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    MacIntyre, RM, Mitchell, JG, Dawson, JB & Macintyre R.M. 1974, 'Age of fault movements in Tanzanian sector of East-African rift system' Nature Physics, vol. 247, no. 5440, pp. 354-356. https://doi.org/10.1038/247354a0

    Age of fault movements in Tanzanian sector of East-African rift system. / MacIntyre, R.M.; Mitchell, J.G.; Dawson, J.B.; Macintyre R.M.

    In: Nature Physics, Vol. 247, No. 5440, 1974, p. 354-356.

    Research output: Contribution to journalArticle

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    MacIntyre RM, Mitchell JG, Dawson JB, Macintyre R.M. Age of fault movements in Tanzanian sector of East-African rift system. Nature Physics. 1974;247(5440):354-356. https://doi.org/10.1038/247354a0