Evolution of Th and U whole-rock contents in the Ilímaussaq intrusion

Abstract

A great variety of investigations have been made on the distribution of Tb and U in the Ilimaussaq alkaline intrusion, South Greenland. The major emphasis has been placed on economic assessment of the Kvanefjeld uranium deposit (Sørensen et al., 1974) but attention has also been given to the Tb and U contents of rocks and minerals outside the deposit (Buchwald & Sørensen, 1961; Sørensen, 1962; Hamilton, 1964; Gerasimovsky, 1969; Bohse et al., 1974; Steenfelt & Bohse, 1975). In the present study, we present Tb and U values largely obtained by laboratory gamma-ray spectrometric (GRS) analysis of a large collection of representative samples taken from all rock types of the intrusion. The results are discussed in relation to current knowledge and ideas on the petrologic evolution of the Ilimaussaq intrusion.