The relationship of soil 210Po and 210Pb geochemical dispersion patterns to uranium mineralization

Abstract

210Po and 210Pb measurements of soils delineated uranium anomalies at three out of four test sites in Ontario, Canada. Measurements were made of 210Po in solutions produced by both complete digestion and partial leaching of soil samples. Direct plating of 210Po onto metal plates was followed by measuring the alpha activity. Subsequent plating of 210Po in-grown from 210Pb in solution several months later confirmed the anomalies. The 210Po and 210Pb anomalies at three of the test sites coincided with 226Ra and 222Rn anomalies. Samples from the fourth uranium occurrence associated with a known 222Rn anomaly failed to show either a 226Ra anomaly on the one hand, or 210Po or 210Pb anomalies on the other. This suggests that the 210Po and 210Pb anomalies were probably produced by the decay of 226Ra contained within secondary dispersion haloes. Although anomalies due to the 210Po and 210Pb products of 222Rn have now been documented, prospecting methods based on their use as direct tracers of the migration paths of 222Rn require much further development.