Development and Testing of a Model for the Supergene Distribution of Uranium and Accompanying Elements around a Known Uranium Deposit Associated with an Alkaline Intrusion

摘要

This report deals with secondary geochemical dispersion in a subarctic environment (Ilimaussaq Complex, south Greenland) of uranium and accompanying elements around a U deposit in which the refractory mineral steenstrupine is the main U-bearing mineral. Weathering profiles, including soils, and sediments in rivers, lakes and fjords have been sampled and studied. Chemical weathering is not well developed. The coarse-grained agpaitic nepheline syenites of the Ilimaussaq Complex are covered by debris of crumbling material and practically without vegetation, but soil profiles and vegetation are developed on glacial deposits and on weathered basement granite. 480 samples have been analysed for 22 elements and the data treated by multivariable analyses with main emphasis on principal component analysis. It was found that U and the other elements have been dispersed during weathering. The sediments in rivers and fjords show low correlation of U with those elements that are associated with U Ilimaussaq. Principal component analysis of the total sample materia of soils and lake and river sediments based on 17 elements makes the identification of the area containing the U deposit possible in the first three dimentions. The elements used are those which correlate with Th in this type of deposit. The statistical significance is however low when single sample populations, as for instance the C-horizons of soils, are used. 41 refs. (ERA citation 13:021029)