Radiogenic heavy minerals in Chhatrapur beach placer deposit of Orissa, southeastern coast of India

The beach placer deposit at Chhatrapur coast of Orissa state, southeastern coast of India, has a significant concentration of radiogenic heavy minerals. The average activity concentrations of radioactive elements such as 232Th, 238U and 40K were measured by gamma ray spectrometry using a HPGe detector, and found to be 2650 ± 50, 400 ± 30 and 120 ± 30 Bq/kg, respectively, for the bulk sand samples. The activity concentrations in monazite and zircon sands are found to be 305,000 ± 2000 and 2000 ± 150 Bq/kg for the 232Th and 21,500 ± 300 and 3450 ± 250 Bq/kg for the 238U. Electron probe microanalysis results of monazite sands show the average ThO2 and UO3 concentrations to be 10.42 wt.%, and 0.32 wt.%, respectively. The major contributors for the enhanced level of radioactivity are monazite and zircon sands. These heavy mineral sands were derived from the nearby source areas such as Eastern Ghats Group of rocks. (author)