1990 Annual report the Granites-Tanami Project

Abstract

The radioactive anomalies in Area 15 and Area 10 within the upper Browns Range Dome Beds were found to fall into one of several geochemical associations. These associations include; Uranium, Thorium, Zircon association analysis indicates that mineralisation is derived from the country rock by hydrothermal fluids which precipitated it into thin veins whilst mobilising more mobile elements up through the rock sequence; Uranium in clay-mineralisation correlates with Ca +--Mg and is inversely proportional to Cr, Ni and Zr. The source of mineralisation is uncertain, but due to its shape, association with excessive carbonate and correlation Ca and Mg suggests leaching and water table mobilisation of a low level carbonate related anomaly; Uranium associated with ferruginous quartz veining. The fault appears to have been a conduit for mineralising fluids during the Proterozoic. Surficial mobilisation-concentrator and saprolitic weathering causing the anomaly at Area 10; Uranium associated with the base of an albite rich vein in an amphibolite sequence. The albite appears to be of metasomatic origin. None of these styles of mineralisation are economically important as they are not generally associated with large scale mobilisation of uranium.