K/Ar and Rb/Sr age determinations on Precambrian crystalline rocks in the Inglefield Land – Inglefield Bredning region, Thule district, western North Greenland

Abstract

FolIowing field investigations in North Greenland in 1971 by one of us (P.R.D.) a selection of rocks was made available for age dating work. The first results - K/Ar whole-rock ages on dolerites - suggest that the basal part of the unmetamorphosed Thule Group is at least 1200 m.y. old (Dawes et al., 1973). This note reports the first results of adating programme carried out by O. L. at the Institute for Petrology, Vniversity of Copenhagen and is concerned with the age of the underlying and older crystalline basement complex. Further work is continuing particularly on a Rb/Sr whole-rock isochron. Supplementary sample collecting is scheduled to take place in the summer of 1974.