The Valhalla uranium deposit, Qeensland, Australia

Abstract

As of March 2006, the Valhalla U deposit has a drilled indicated resource of 11.5 Mt at 0.144% U3O8 and contains 36.5 million pounds of U3O8 with an inferred resource of over 55 million pounds U3O8. The Valhalla uranium deposit is located 40 km north of Mount Isa, in the western succession of the Mt Isa basin. The Mt Isa basin is divided into three stratigraphic successions termed the Leichhardt, the Calvert and the Isa Superbasins. Valhalla and other U occurrences around Mt Isa are hosted in mafic volcanics and metasediments belonging to the Leichhardt Superbasin. The Leichhardt Superbasin comprises 1) poorly sorted and immature, coarse to fine grained sandstone, pebbly sandstone and conglomerate, 2) medium to fine grained, well sorted and locally mature sandstones and 3) metabasalts with interbedded metasediments that include calcareous siltstones, shales and tuffs. Poorly sorted proximal fluvial facies occur in the basal Bottletree Formation, the lower Mount Guide Quartzite and the Lena Quartzite, whereas more mature sandstones dominate the upper Mount Guide Quartzite, the Myally Subgroup and the Quilalar Formation. The metabasalts belong to the Eastern Creek Volcanics.