The uranium, thorium and molybdenum distribution in selected leucogranites of the Cape-granite-suite

Younger intrusions and hydrothermally altered rocks like alkali granite, alaskite, syenite and episyenite resembling uranium ore deposits in France and the Roessing ore body in SWA/Namibia are found within the Saldanha and Darling batholiths of the south-western Cape Province. Two areas were geologically mapped in detail and surveyed with a portable gamma spectrometer in order to establish the regional variation in U and Th concentration. A quantitative study of alpha particle tracks on autoradiographs of selected thin sections led to the determination of the contributions by various minerals to the U and Th content of each individual rock type. The rocks were also investigated petrologically and geochemically with special attention to secondary alteration processes that could have played a part in causing the distribution pattern of U and Th. Radioelement analyses of 45 mineral separates and 51 whole rock analyses were utilised