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Rb-Sr isochron from Gboko and Ikyuen rhyolites and its implications for the age and evolution of the Benue Trough, Nigeria

Published online by Cambridge University Press:  01 May 2009

A. C. Umeji  and
M. Caen-Vachette
A. C. Umeji
Affiliation:
Department of Geology, University of Nigeria Nsukka, Nigeria.
M. Caen-Vachette
Affiliation:
Laboratoire Associe No. 10, C.N.R.S. et Université, ‘Chronologie des Terrains cristallins et Volcanologie’, 5, rue Kessler, 63038 Clermont-Ferrand Cedex., France.
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Abstract

Summary. Rhyolites overlying the basement granitic gneisses and granites adjacent to the selimentfilled Benue Trough were studied. Rb-Sr isochron age of 113 ± 3 Ma and initial 87Sr/86Sr rato of 0.7067 were obtained from two extrusive bodies which form Gboko and Ikyuen hills. It is shown that their eruption has some relation to crustal doming at the onset of the Benue rifting. The published age of the oldest exposed sedimentary infill of the trough is Albian. As a result of the investigation of these volcanic rocks from the basement margin, however, an earlier and absolute age for the initiation of the rift is implied and a late Barremian to early Aptian age is proposed for the formation of this continental rift.

Type
Articles
Information
Geological Magazine , Volume 120 , Issue 6 , December 1983 , pp. 529 - 533
Copyright
Copyright © Cambridge University Press 1983

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References

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