Journal of Petrology Volume 42 Number 5 Pages 877-900 2001
© Oxford University Press 2001
Plume–Lithosphere Interactions in the Generation of the Basalts of the Kenya Rift, East Africa
1ENVIRONMENTAL SCIENCE DIVISION, IENS, LANCASTER UNIVERSITY, LANCASTER LA1 4YQ, UK
2DEPARTMENT OF EARTH SCIENCES, THE OPEN UNIVERSITY, MILTON KEYNES MK7 6AA, UK
3DEPARTMENT OF GEOLOGY AND GEOPHYSICS, UNIVERSITY OF EDINBURGH, WEST MAINS ROAD, EDINBURGH EH9 3JW, UK
4PRIS, UNIVERSITY OF READING, WHITEKNIGHTS, READING RG6 2AB, UK
5BRITISH GEOLOGICAL SURVEY, MURCHISON HOUSE, WEST MAINS ROAD, EDINBURGH EH9 3LA, UK
Major and trace element and Sr–Nd–Pb isotopic data for mafic volcanic rocks are used to assess the number of mantle plumes contributing to the Tertiary–Holocene magmatism of the Kenya Rift Valley, current estimates of which vary from none to three. Rocks ranging in composition from nephelinite to hypersthene-normative basalt have been sampled from three lithospheric zones: the Tanzanian craton, the craton margin reworked during the late Proterozoic, and the Mozambique mobile belt. The magmas are interpreted as the products of variable degrees of partial melting within the spinel–garnet peridotite transition zone. Trace element and isotopic compositions from all three zones are broadly similar to those of oceanic island basalts, but there is considerable compositional variation, which is related to a strong overprint from the lithosphere on plume-derived melts. Sr and Nd isotopic ratios provide the only clear distinction between magmatic rocks from the three lithospheric domains. Within each setting, mafic magmatism has tended to become less silica undersaturated with time, and at any one locality magmatism has migrated towards the centre of the rift. Magmas may have formed as a result of the infiltration of plume-derived melts into the base of the lithosphere. The extent of interaction of inferred plume melts with the lithosphere has not varied systematically in time or space. The plume component appears to be similar to the source of oceanic island basalts.
KEY WORDS: Kenya Rift Valley; mantle plumes; geochemistry; metasomatism
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  R. Macdonald, H. E. Belkin, J. G. Fitton, N. W. Rogers, K. Nejbert, A. G. Tindle, and A. S. Marshall The Roles of Fractional Crystallization, Magma Mixing, Crystal Mush Remobilization and Volatile-Melt Interactions in the Genesis of a Young Basalt-Peralkaline Rhyolite Suite, the Greater Olkaria Volcanic Complex, Kenya Rift Valley J. Petrology, August 1, 2008; 49(8): 1515 - 1547. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Kaeser, A. Kalt, and T. Pettke Crystallization and Breakdown of Metasomatic Phases in Graphite-bearing Peridotite Xenoliths from Marsabit (Kenya) J. Petrology, September 1, 2007; 48(9): 1725 - 1760. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. KAESER, A. KALT, and T. PETTKE Evolution of the Lithospheric Mantle beneath the Marsabit Volcanic Field (Northern Kenya): Constraints from Textural, P-T and Geochemical Studies on Xenoliths J. Petrology, November 1, 2006; 47(11): 2149 - 2184. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. FURMAN, K. M. KALETA, J. G. BRYCE, and B. B. HANAN Tertiary Mafic Lavas of Turkana, Kenya: Constraints on East African Plume Structure and the Occurrence of High-{micro} Volcanism in Africa J. Petrology, June 1, 2006; 47(6): 1221 - 1244. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N.W. Rogers Basaltic magmatism and the geodynamics of the East African Rift System Geological Society, London, Special Publications, January 1, 2006; 259(1): 77 - 93. [Abstract] [PDF]
|
|
|
|
 |
|
 I. McDOUGALL and R. T. WATKINS Geochronology of the Nabwal Hills: a record of earliest magmatism in the northern Kenyan Rift Valley Geological Magazine, January 1, 2006; 143(1): 25 - 39. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. W. ROGERS, P. J. EVANS, S. BLAKE, S. C. SCOTT, and C. J. HAWKESWORTH Rates and Timescales of Fractional Crystallization from 238U-230Th-226Ra Disequilibria in Trachyte Lavas from Longonot Volcano, Kenya J. Petrology, September 1, 2004; 45(9): 1747 - 1776. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. FURMAN, J. G. BRYCE, J. KARSON, and A. IOTTI East African Rift System (EARS) Plume Structure: Insights from Quaternary Mafic Lavas of Turkana, Kenya J. Petrology, May 1, 2004; 45(5): 1069 - 1088. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. KIEFFER, N. ARNDT, H. LAPIERRE, F. BASTIEN, D. BOSCH, A. PECHER, G. YIRGU, D. AYALEW, D. WEIS, D. A. JERRAM, et al. Flood and Shield Basalts from Ethiopia: Magmas from the African Superswell J. Petrology, April 1, 2004; 45(4): 793 - 834. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L.-Q. Xia, X.-Y. Xu, Z.-C. Xia, X.-M. Li, Z.-P. Ma, and L.-S. Wang Petrogenesis of Carboniferous rift-related volcanic rocks in the Tianshan, northwestern China GSA Bulletin, March 1, 2004; 116(3-4): 419 - 433. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. PECCERILLO, M. R. BARBERIO, G. YIRGU, D. AYALEW, M. BARBIERI, and T. W. WU Relationships between Mafic and Peralkaline Silicic Magmatism in Continental Rift Settings: a Petrological, Geochemical and Isotopic Study of the Gedemsa Volcano, Central Ethiopian Rift J. Petrology, November 1, 2003; 44(11): 2003 - 2032. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. M. Goodenough, K.M. Goodenough, B.G.J. Upton, and R.M. Ellam Long-term memory of subduction processes in the lithospheric mantle: evidence from the geochemistry of basic dykes in the Gardar Province of South Greenland Journal of the Geological Society, December 1, 2002; 159(6): 705 - 714. [Abstract] [Full Text] [PDF]
|
|