Drainage sampling for uranium in the Torrington district, New South Wales, Australia

A brief orientation study has been conducted to evaluate the use of drainage geochemical sampling for U in the granitic and forested terrain of the Torrington district of northeastern New South Wales. Anomalous U levels are present in both stream sediments and waters draining a known W prospect containing accessory U. The U dispersion is affected by interrelated environmental factors such as catchment physiography and the organic content of the stream sediments. The influence of organic content on U level in stream sediments is most significant. Variation in sediment organic content is related to accumulation of vegetal organic debris and charcoal in stream channels by sheetwashing of sparsely covered forest floors particularly in catchments of high topographic relief. The U is apparently absorbed onto the organic material from ephemerally flowing stream waters. Temporal variations in U content of stream sediment are indicated which necessitate careful consideration in planning and interpreting the results of a survey in this environment.