Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-24T05:50:51.260Z Has data issue: false hasContentIssue false
  • English
  • Français

Timing of volcanism and evolution of the northern Kenya Rift

Published online by Cambridge University Press:  19 September 2008

IAN McDOUGALL  and
FRANCIS H. BROWN
IAN McDOUGALL*
Affiliation:
Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia
FRANCIS H. BROWN
Affiliation:
Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112-0112, USA
*
*Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The northern Kenya Rift is bounded on the west by uplands of Turkana which comprise horst-like blocks that include metamorphic basement rocks, locally overlain unconformably by the Cretaceous Lubur Sandstone, in turn overlain by predominantly volcanic sequences in which relatively thin sedimentary packages occur. Amphibolite facies crystalline rocks of the basement yield Early Palaeozoic K–Ar cooling ages reflecting the Pan-African Orogeny. Volcanism in Turkana was initiated through voluminous eruptions of transitional tholeiitic basalts commencing about 36 Ma ago in the Late Eocene, with some evidence for concomitant rhyolitic volcanism. Volcanism became dominantly rhyolitic in the interval from about 27 to 23 Ma ago, but remained bimodal as basaltic lavas are also known from this period. From about 19 to 15 Ma or younger, basaltic volcanism again dominated, often alkaline in nature, with thin but significant sedimentary sequences interleaved that have yielded important vertebrate faunal assemblages. Parallels exist between the volcanic history recorded in Turkana and that found in the Nabwal Hills east of Lake Turkana. In the southern Turkana region, oil exploration by seismic methods and deep drill holes has shown the existence of northerly-trending half-graben with up to 7 km of fill, and that these developed from at least Oligocene and possibly Late Eocene times. This suggests that the widespread basaltic volcanism at about 36 Ma ago (Late Eocene) heralds an earlier initiation of the Kenya Rift in northern Kenya than most workers have previously suggested.

Keywords

K–Ar datingKenya RiftTurkanaCenozoic volcanism
Type
Original Article
Information
Geological Magazine , Volume 146 , Issue 1 , January 2009 , pp. 34 - 47
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anyonge, W. 1991. Fauna from a new Lower Miocene locality west of Lake Turkana, Kenya. Journal of Vertebrate Paleontology 11, 378–90.CrossRefGoogle Scholar
Arambourg, C. 1935. Mission scientifique de l'Omo, 1932–1933, 1 (Géologie–Anthropologie). Bulletin Museum Nationale d'Histoire Naturelle. Paris.Google Scholar
Arambourg, C. & Wolff, R. G. 1969. Nouvelles données paléontologique sur l'âge des “grès du Lubur” (Turkana grits) à l'Ouest du lac Rodolphe. Compte Rendus Sommaire des Séances de la Société Géologique de France 6, 190–2.Google Scholar
Bellieni, G., Justin Visentin, E., Zanettin, B., Piccirillo, E. M., Radicati di Brozolo, F. & Rita, F. 1981. Oligocene transitional tholeiitic magmatism in northern Kenya: Comparison with the coeval Ethiopian volcanism. Bulletin Volcanologique 44, 411–27.CrossRefGoogle Scholar
Bonini, M., Corti, G., Innocenti, F., Manetti, P., Mazzarini, F., Abebe, T. & Pecksay, Z. 2005. Evolution of the Main Ethiopian Rift in the frame of Afar and Kenya rifts propagation. Tectonics 24, TC1007, doi:10.1029/2004TC001680 (21 pp.).CrossRefGoogle Scholar
Boschetto, H. B., Brown, F. H. & McDougall, I. 1992. Stratigraphy of the Lothidok Range, northern Kenya, and K/Ar ages of its Miocene primates. Journal of Human Evolution 22, 47–71.CrossRefGoogle Scholar
Brown, F. H. & Nash, W. P. 1976. Radiometric dating and tuff mineralogy of Omo Group deposits. In Earliest Man and Environments in the Lake Rudolf Basin (eds Coppens, Y., Howell, F. C., Isaac, G. Ll. & Leakey, R. E. F.), pp. 50–63. Chicago: University of Chicago Press.Google Scholar
Cahen, L., Snelling, N. J., Delhal, J. & Vail, J. R. 1984. The Geochronology and Evolution of Africa. Oxford: Clarendon Press, 512 pp.Google Scholar
Calais, E., Ebinger, C., Hartnady, C. & Nocquet, J. M. 2006. Kinematics of the East African Rift from GPS and earthquake slip data. In The Afar Volcanic Province within the East African Rift System (eds Yirgu, G., Ebinger, C. J. & Maguire, P. K. H.), pp. 9–22. Geological Society of London, Special Publication no. 259.Google Scholar
Davidson, A. 1983. The Omo River Project. Reconnaissance geology and geochemistry of parts of Ilubabor, Kefa, Gemu Gofa and Sidamo, Ethiopia. Ethiopian Institute of Geological Surveys, Bulletin 2, 89 pp.Google Scholar
Davidson, A. & Rex, D. C. 1980. Age of volcanism and rifting in southwestern Ethiopia. Nature 283, 657–8.CrossRefGoogle Scholar
Dodson, R. G. 1971. Geology of the area south of Lodwar, Degree Sheet 18, N.E. Quarter. Geological Survey of Kenya, Report no. 87, 36 pp.Google Scholar
Dunkelman, T. J., Rosendahl, B. R. & Karson, J. A. 1989. Structure and stratigraphy of the Turkana Rift from seismic reflection data. Journal of African Earth Sciences 8, 489–510.CrossRefGoogle Scholar
Ebinger, C. J., Bechtel, T. D., Forsyth, D. W. & Bowin, C. O. 1989. Effective elastic plate thickness beneath the East African and Afar Plateaus and dynamic compensation of the uplifts. Journal of Geophysical Research 94, 2883–901.CrossRefGoogle Scholar
Ebinger, C. J., Yemane, T., WoldeGabriel, G., Aronson, J. L. & Walter, R. C. 1993. Late Eocene–Recent volcanism and faulting in the southern main Ethiopian rift. Journal of the Geological Society, London 150, 99–108.CrossRefGoogle Scholar
Ebinger, C. J., Yemane, T., Harding, D. J., Tesfaye, S., Kelley, S. & Rex, D. C. 2000. Rift deflection, migration, and propagation: Linkage of the Ethiopian and Eastern rifts, Africa. Geological Society of America Bulletin 112, 163–76.2.0.CO;2>CrossRefGoogle Scholar
Fairburn, W. A. & Mathieson, F. J. 1970. Geology of the Loiya–Lorugumu Area, Degree Sheets 17, N.E. Quarter and 18, N.W. Quarter. Geological Survey of Kenya, Report no. 85, 52 pp.Google Scholar
Fernandes, R. M. S., Ambrosius, B. A. C., Noomen, R., Bastos, L., Combrinck, L., Miranda, J. M. & Spakman, W. 2004. Angular velocities of Nubia and Somalia from continuous GPS data: implications on present-day relative kinematics. Earth and Planetary Science Letters 222, 197–208.CrossRefGoogle Scholar
Furman, T., Kaleta, K. M., Bryce, J. G. & Hanan, B. B. 2006. Tertiary mafic lavas of Turkana, Kenya: Constraints on East African plume structure and the occurrence of high-μ volcanism in Africa. Journal of Petrology 47, 1221–44.CrossRefGoogle Scholar
George, R., Rogers, N. & Kelley, S. 1998. Earliest magmatism in Ethiopia: Evidence for two mantle plumes in one flood basalt province. Geology 26, 923–6.2.3.CO;2>CrossRefGoogle Scholar
Gradstein, F., Ogg, J. & Smith, A. 2005. A Geologic Time Scale 2004. Cambridge: Cambridge University Press, 589 pp.CrossRefGoogle Scholar
Haileab, B., Brown, F. H., McDougall, I. & Gathogo, P. N. 2004. Gombe Group basalts and initiation of Pliocene deposition in the Turkana depression, northern Kenya and southern Ethiopia. Geological Magazine 141, 41–53.CrossRefGoogle Scholar
Hendrie, D. B., Kusznir, N. J., Morley, C. K. & Ebinger, C. J. 1994. Cenozoic extension in northern Kenya: a quantitative model of rift basin development in the Turkana region. Tectonophysics 236, 409–38.CrossRefGoogle Scholar
Joubert, P. 1966. Geology of the Loperot Area, Degree Sheet 18, S.E. Quarter. Geological Survey of Kenya, Report no. 74, 52 pp.Google Scholar
Key, R. M. & Watkins, R. T. 1988. Geology of the Sabarei area. Mines and Geology Department, Ministry of Environment and Natural Resources, Nairobi, Kenya, Report no. 111, 57 pp.Google Scholar
Leakey, M. G. & Harris, J. M. 2003. Lothagam: The Dawn of Humanity in Eastern Africa. New York: Columbia University Press, 678 pp.CrossRefGoogle Scholar
Leakey, M. G., Ungar, P. S. & Walker, A. 1995. A new genus of large primate from the Late Oligocene of Lothidok, Turkana District, Kenya. Journal of Human Evolution 28, 519–31.CrossRefGoogle Scholar
Leakey, R. E. & Leakey, M. G. 1986. A second new Miocene hominoid from Kenya. Nature 324, 146–8.CrossRefGoogle Scholar
Leakey, R. E. & Leakey, M. G. 1987. A new small-bodied Miocene ape from Kenya. Journal of Human Evolution 16, 369–87.CrossRefGoogle Scholar
Leakey, R. E. F. & Walker, A. 1985. New higher primates from the early Miocene of Buluk, Kenya. Nature 318, 173–5.CrossRefGoogle Scholar
McDougall, I. & Feibel, C. S. 1999. Numerical age control for the Miocene–Pliocene succession at Lothagam, a hominoid-bearing sequence in the northern Kenya Rift. Journal of the Geological Society, London 156, 731–45.CrossRefGoogle Scholar
McDougall, I. & Watkins, R. T. 1985. Age of hominoid-bearing sequence at Buluk, northern Kenya. Nature 318, 175–8.CrossRefGoogle Scholar
McDougall, I. & Watkins, R. T. 1988. Potassium–argon ages of volcanic rocks from northeast of Lake Turkana, northern Kenya. Geological Magazine 125, 15–23.CrossRefGoogle Scholar
McDougall, I. & Watkins, R. T. 2006. Geochronology of the Nabwal Hills: a record of earliest magmatism in the northern Kenya Rift Valley. Geological Magazine 143, 25–39.CrossRefGoogle Scholar
Mohr, P. 1983. Ethiopian flood basalt province. Nature 303, 577–84.CrossRefGoogle Scholar
Morley, C. K. (ed.) 1999. Geoscience of Rift Systems – Evolution of East Africa. American Association of Petroleum Geologists (AAPG), Studies in Geology no. 44, 242 pp.CrossRefGoogle Scholar
Morley, C. K., Ngenoh, D. K. & Ego, J. K. 1999. Introduction to the East African Rift System. In Geoscience of Rift Systems – Evolution of East Africa (ed. Morley, C. K.), pp. 1–18. Association of Petroleum Geologists (AAPG), Studies in Geology no. 44.CrossRefGoogle Scholar
Morley, C. K., Wescott, W. A., Stone, D. M., Harper, R. M., Wigger, S. T. & Karanja, F. M. 1992. Tectonic evolution of the northern Kenya Rift. Journal of the Geological Society, London 149, 333–48.CrossRefGoogle Scholar
Morley, C. K., Wescott, W. A., Stone, D. M., Harper, R. M., Wigger, S. T., Day, R. A. & Karanja, F. M. 1999. Geology and geophysics of the western Turkana basins, Kenya. In Geoscience of Rift Systems – Evolution of East Africa (ed. Morley, C. K.), pp. 19–54. Association of Petroleum Geologists (AAPG), Studies in Geology no. 44.CrossRefGoogle Scholar
Pik, R., Marty, B., Carignan, J., Yirgu, G. & Ayalew, T. 2008. Timing of East African Rift development in southern Ethiopia: Implication for mantle plume activity and evolution of topography. Geology 36, 167–70.CrossRefGoogle Scholar
Raja, P. K. S., Reilly, T. A. & Mussett, A. E. 1966. The paleomagnetism of the Turkana lavas. Journal of Geophysical Research 71, 1217–22.CrossRefGoogle Scholar
Reilly, T. A., Mussett, A. E., Raja, P. K. S., Grasty, R. L. & Walsh, J. 1966. Age and polarity of the Turkana lavas, north-west Kenya. Nature 210, 1145–6.CrossRefGoogle Scholar
Rogers, N. W. 2006. Basaltic magmatism and the geodynamics of the East African Rift System. In The Afar Volcanic Province within the East African Rift System (eds Yirgu, G., Ebinger, C. J. & Maguire, P. K. H.), pp. 77–93. Geological Society of London, Special Publication no. 259.Google Scholar
Steiger, R. H. & Jäger, E. 1977. Subcommission on Geochronology: Convention on the use of decay constants in geo- and cosmochronology. Earth and Planetary Science Letters 36, 359–62.CrossRefGoogle Scholar
Vetel, W. & Le Gall, B. 2006. Dynamics of prolonged continental extension in magmatic rifts: the Turkana Rift case study (North Kenya). In The Afar Volcanic Province within the East African Rift System (eds Yirgu, G., Ebinger, C. J. & Maguire, P. K. H.), pp. 209–33. Geological Society of London, Special Publication no. 259.Google Scholar
Walsh, J. & Dodson, R. G. 1969. Geology of Northern Turkana: Degree Sheets 1, 2, 9 and 10. Geological Survey of Kenya, Report no. 82, 42 pp.Google Scholar
Watkins, R. T. 1986. Volcano-tectonic control on sedimentation in the Koobi Fora sedimentary basin, Lake Turkana. In Sedimentation in the African Rifts (eds Frosdick, L. E., Renaut, R. W., Read, I. & Tiercelin, J. J.), pp. 85–94. Geological Society of London, Special Publication no. 25. Oxford: Blackwell Scientific Publications.Google Scholar
Williamson, P. G. & Savage, R. J. G. 1986. Early rift sedimentation in the Turkana basin, northern Kenya. In Sedimentation in the African Rifts (eds Fostick, L. E., Renaut, R. W., Reid, I. & Tiercelin, J. J.), pp. 267–83. Geological Society of London, Special Publication no. 25. Oxford: Blackwell Scientific Publications.Google Scholar
WoldeGabriel, G., Yemane, T., Suwa, G., White, T. & Asfaw, B. 1991. Age of volcanism and rifting in the Burgi–Soyoma area, Amaro Horst, southern Main Ethiopian Rift: geo- and biochronologic data. Journal of African Earth Sciences 13, 437–47.CrossRefGoogle Scholar
Zanettin, B., Justin Visentin, E., Bellieni, G., Piccirillo, A. M. & Rita, F. 1983. Le volcanisme du basin du Nord-Turkana (Kenya): Age succession et evolution structurale. Bulletin des Centre de Recherches Exploration-Production Elf-Aquitaine 7, 249–55.Google Scholar