A comparative study of trace elements geochemistry and mineralogy of some uranium deposits of Labrador, and evaluation of some uranium exploration techniques in a glacial terrain

Abstract

The Aillik Group of Aphebian metavolcanic and metasedimentary rocks is situated in the Makkovik subprovince of Labrador, north of the Grenville Front. -- The Kaipokok volcanic and the Walker Lake-White Bear Mountain belts consist of flow-banded and porphyritic rhyolite lavas, quartzites, minor interbedded basalt lavas and volcanic tuff. -- Metamorphism has remained in the greenschist and amphibolite facies throughout tectonism. -- One hundred and seventy rock samples were collected from eight uranium showings in the map area and were analysed for 10 trace elements, namely Zr, Sr, Rb, Zn, Cu, Ba, Ni, Cr, U and Th. One hundred and ten thin sections were examined and autoradiographed. Uranium in these showings is present possibly in the following forms: -- 1) In uranium minerals of davidite composition. -- 2) In lenses of dark bituminous material. -- 3) As ions dispersed in such minerals as hornblende, quartz, feldspar and in part in some other minerals. -- 4) As ions adsorbed on to hematite. -- 5) As an isomorphous admixture in the minerals biotite, epidote, zircon and sphene. -- 6) As independant compounds within magnetite. -- 7) As submicroscopic inclusions of uranium minerals of unknown compositions within garnets, sodic amphiboles and feldspar porphyroblasts. -- Results obtained from different uranium exploration techniques in a glaciated terrain, e.g. radon detection, nearshore lake sediment geochemistry, lake water and air-borne surveys, should be interpreted in conjunction with glacial geology and other physiographic factors affecting their applicability.