Rubidium and Strontium age determination of some Pre-Cambrian granitic rocks, S.E. Uganda

Abstract

SummaryWhole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.