Preliminary geochemical work on the Ilímaussaq alkaline intrusion, South Greenland

Abstract

As part of the geological investigation of the Ilimaussaq intrusion (Sørensen, 1970; Ferguson, 1964; Andersen, et al., 1973; Sørensen et al., 1974), trace-element analyses have been performed on carefully chosen rock samples. Material was selected on the basis of detailed field mapping and with particular attention paid to its fresh and representative nature; in every case more than 15 kg was obtained by blasting. The samples have aiready been used for the separation of accessory ore minerals and for analysis of fluid inclusions. To date, the rocks have been analysed for trace elements by neutron activation (R.G.) and X-ray fluorescence (J.B.) analysis. Comparisons with earlier analyticai results indicate closest agreement with the work of Gerasimovsky (1969), except for the element Ga where his results are consistently higher. Experiments by Ib Sørensen (GGU Chemical Laboratory) indicate that fused samples yield low totals for many Ilimaussaq rocks; the absorption effects of heavy minor elements (Zr, Nb, REE) on the light major elements will be quantitatively corrected for. Analyses by isotope fluorescence, delayed neutron analysis, X-ray spectrometry and other techniques are in progress.