Geochronology of the Nabwal Hills: A record of earliest magmatism in the northern Kenyan Rift Valley

Geological Magazine

Volumn 143, Issue 1, 2006, Pages 25-39

  McDougall, Ian ^a   Watkins, Ronald T ^b  

^a AUSTRALIAN NATIONAL UNIVERSITY   (Australia)

^b CURTIN UNIVERSITY   (Australia)

Author keywords

Basalts; Geochronology; Ignimbrites; Kenya; Tectonics

Indexed keywords

BASALT; BUILDINGS; FELDSPAR; GEOCHRONOLOGY; GEOLOGIC MODELS; MICA; TECTONICS;

ALKALI FELDSPAR; BASALTIC LAVA FLOW; CRUSTAL EXTENSION; EAST AFRICAN RIFT; IGNIMBRITES; KENYA; METAMORPHIC BASEMENTS; VERTEBRATE FOSSILS;

POTASSIUM COMPOUNDS;

BASALT; IGNIMBRITE; MAGMATISM; MIOCENE;

AFRICA; EAST AFRICA; EAST AFRICAN RIFT; KENYA; KENYA RIFT; SUB-SAHARAN AFRICA;

PAN; PRIMATES; VERTEBRATA;

EID: 33644889052     PISSN: 00167568     EISSN: 14695081     Source Type: Journal    
DOI: 10.1017/S0016756805001184     Document Type: Article

References (50)

1. Asfaw, B., Beyene, Y., Semaw, S., Suwa, G., White, T. & WoldeGabriel, G. 1991. Fejej: A new paleoanthropological research area in Ethiopia. Journal of Human Evolution 21, 137-43.
2. Berggren, W. A., Kent, D. V., Swisher III, C. C. & Aubry M.-P. 1995. A revised Cenozoic geochronology and chronostratigraphy. In Geochronology, Time Scales and Stratigraphic Correlation (eds W. A. Berggren, D. V. Kent, D.-V. Aubry and J. Hardenbol), pp. 129-212. Tulsa: Society for Sedimentary Geology (SEPM), Special Publication no. 54.
3. Cahen, L. & Snelling, N. J. 1966. The Geochronology of Equatorial Africa. Amsterdam: North-Holland, 195 pp.
4. Chu, D. & Gordon, R. G. 1999. Evidence for motion between Nubia and Somalia along the Southwest Indian ridge. Nature 398, 64-7.
5. 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.
6. Davidson, A. & Rex, D. C. 1980. Age of volcanism and rifting in southwestern Ethiopia. Nature 283, 657-8.
7. DeMets, C., Gordon, R. G., Argus, D. F. & Stein, S. 1990. Current plate motions. Geophysical Journal International 101, 425-78.
8. DeMets, C., Gordon, R. G., Argus, D. F. & Stein, S. 1994. Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophysical Research Letters 21, 2191-4.
9. 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.
10. 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.
11. 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.
12. 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.
13. Fitch, F. J., Hooker, P. J., Miller, J. A., Mitchell, T. G. & Watkins, R. T. 1985. Reconnaissance potassium-argon geochronology of the Suregei-Asille district, northern Kenya. Geological Magazine 122, 609-22.
14. Fleagle, J. G., Bown, T. M., Harris, J. M., Watkins, R. T. & Leakey M. G. 1997. Fossil monkeys from Northern Kenya. (Abstract). American Journal of Physical Anthropology, Supplement 24, 111.
15. Fleagle, J. G., Harris, J. M., Watkins, R. T. & Miller, E. R. 2000. Early Miocene mammalian faunas from northern Kenya and southern Ethiopia. (Abstract). Journal of Vertebrate Paleontology 20, Supplement no. 3, Abstract of Papers, p. 41A.
16. Furman, T., Bryce, J. G., Karson, J. & Iotti, A. 2004. East African Rift System (EARS) plume structure: Insights from Quaternary mafic lavas of Turkana, Kenya. Journal of Petrology 45, 1069-88.
17. George, R. M. & Rogers, N. W. 2002. Plume dynamics beneath the African plate inferred from the geochemistry of the Tertiary basalts of southern Ethiopia. Contributions to Mineralogy and Petrology 144, 286-304.
18. 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.
19. 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.
20. Harris, J. M. & Watkins, R. T. 1974. New Early Miocene vertebrate locality near Lake Rudolf, Kenya. Nature 252, 576-7.
21. 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.
22. 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 111, 57 pp.
23. KRISP Working Party. 1991. Large-scale variation in lithospheric structure along and across the Kenya rift. Nature 354, 223-7.
24. Latin, D., Norry, M. J. & Tarzey, R. J. E. 1993. Magmatism in the Gregory Rift, East Africa: Evidence for melt generation by a plume. Journal of Petrology 34, 1007-27.
25. Leakey, M. G., Feibel, C. S., McDougall, I., Ward, C. & Walker, A. 1998. New specimens and confirmation of an early age for Australopithecus anamensis. Nature 393, 62-6.
26. Leakey R. E. F. & Walker, A. 1985. New higher primates from the early Miocene of Buluk, Kenya. Nature 318, 173-5.
27. Macdonald, R., Rogers, N. W., Fitton, J. G., Black, S. & Smith, M. 2001. Plume-lithosphere interactions in the generation of the basalts of the Kenya Rift, East Africa. Journal of Petrology 42, 877-900.
28. Macdonald, R., Williams, L. A. J. & Gass, I. G. 1994. Tectonomagmatic evolution of the Kenya rift valley: Some geological perspectives. Journal of the Geological Society, London 151, 879-88.
29. 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, 731-115.
30. 39Ar Method. 2nd ed. New York: Oxford University Press, 269 pp.
31. McDougall, I. & Watkins, R. T. 1985. Age of hominoid-bearing sequence at Buluk, northern Kenya. Nature 318, 175-8.
32. McDougall, I. & Watkins, R. T. 1988. Potassium-argon ages of volcanic rocks from northeast of Lake Turkana, northern Kenya. Geological Magazine 125, 15-23.
33. McKenzie, D. P. & Bickle, M. J. 1988. The volume and composition of melt generated by extension of the lithosphere. Journal of Petrology 29, 625-79.
34. Mechie, J., Keller, G. R., Prodehl, C., Gaciri, S., Braile, L. W., Mooney, W. D., Gajewski, D. & Sandmeier, K.-J. 1994. Crustal structure beneath the Kenya Rift from axial profile data. Tectonophysics 236, 179-200.
35. Mohr, P. 1983. Ethiopian flood basalt province. Nature 303, 577-84.
36. Moore, J. M. & Davidson, A. 1978. Rift structure of southern Ethiopia. Tectonophysics 46, 159-73.
37. Morley C. K. (ed.) 1999. Geoscience of Rift Systems - Evolution of East Africa. American Association of Petroleum Geologists (AAPG), Studies in Geology vol. 44, 242 pp.
38. 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. C. K. Morley), pp. 1-18. AAPG Studies in Geology no. 44.
39. 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. C. K. Morley), pp. 19-54. AAPG Studies in Geology, no. 44.
40. 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.
41. Richmond, B. G., Fleagle, J. G., Kappelman, J. & Swisher III, C. C. 1998. First hominoid from the Miocene of Ethiopia and the evolution of the catarrhine elbow. American Journal of Physical Anthropology 105, 257-77.
42. Rogers, N., MacDonald, R., Fitton, J. G., George, R., Smith, M. & Barreiro, B. 2000. Two mantle plumes beneath the East African rift system; Sr, Nd and Pb isotope evidence from Kenya Rift basalts. Earth and Planetary Science Letters 176, 387-400.
43. 39Ar dating standards. Chemical Geology 198, 189-211.
44. 39Ar geochronology of eruptions between two caldera-forming events. Geological Society of America Bulletin 108, 1549-66.
45. 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.
46. Stewart, K. & Rogers, N. 1996. Mantle plume and lithosphere contributions to basalts from southern Ethiopia. Earth and Planetary Science Letters 139, 195-211.
47. Tiffney B. H., Fleagle, J. G. & Bown, T. M. 1994. Early to Middle Miocene angiosperm fruits and seeds from Fejej, Ethiopia. Tertiary Research 15, 25-42.
48. Watkins, R. T. 1986. Volcano-tectonic control on sedimentation in the Koobi Fora sedimentary basin, Lake Turkana. In Sedimentation in the African Rifts (eds L. E. Frosdick, R. W. Renaut, I. Read and J. J. Tiercelin), pp. 85-94. Geological Society of London, Special Publication no. 25. Oxford: Blackwell Scientific Publications.
49. Watkins, R. T. 1989. The Buluk Member, a fossil hominoid-bearing sedimentary sequence of Miocene age from northern Kenya. Journal of African Earth Sciences 8, 107-12.
50. 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.