Shield making in Western Kenya

Abstract

The Precambrian Kisii Series in Western Kenya is unmetamorphosed and contains andesites, rhyolites, quartzites and basalts. The basalts, for which a minimum K-Ar age of 930 My is cited, were sampled at 15 sites, and after A.F. treatment nine sites yielded a stable palaeomagnetic direction which is believed to be primary. The mean direction (N= 9) after tilt correction is D= 99°, I=−59°, α= 10°, and the corresponding palaeomagnetic south pole is at 6° N, 12° W with A95= 14°. This pole lies close to several other poles for Africa but it is of a very different age and it cannot be correlated with them. Instead it is suggested that the Kisii pole must form part of a previously undefined polar wander path for the Late Precambrian of Africa proposed in an accompanying paper by Brock and Piper.