REMOBILIZATION OF URANIUM AND ASSOCIATED METALS THROUGH KARSTIFICATION PROCESSES - A CASE-STUDY FROM THE TIMNA FORMATION (CAMBRIAN), SOUTHERN ISRAEL

Uranium enrichment (up to 4000 ppm) occurs in phosphatic and manganese minerals of the Sasgon Member of the Lower/Middle Cambrian Timna Formation, particularly in the sandy lithofacies. The host rocks are epigenetic sandstones, which are the insoluble residue of sandy dolomites that underwent dissolution of the carbonate constituent by karstification processes during the Neogene(?). The uranium, originally slightly enriched (up to 31 ppm) in the dolomites, was leached, mobilized and chemically entrapped by apatite and Mn-oxides associated with the insoluble residue. Mass-balance calculation for uranium, as well as for other associated metals within the Sasgon Member points to a semi-closed intraformational system.