Variation in U-238 and Th-232 enrichment in U-mineralized zone and geological controls on their spatial distribution,Singhbhum Shear Zone of India |
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| Authors: | K S Banerjee R Guin J L Gutierrez-Villanueva M E Charro D Sengupta |
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| Institution: | (1) Department of Geology and Geophysics, I.I.T, Kharagpur, 721302, India;(2) Radiochemistry Division, Variable Energy Cyclotron Centre, BARC, Kolkata, West Bengal, 700 064, India;(3) Grupo Radon, Departamento de Ciencias Medicas y Quirurgicas Universidad de Cantabria, 39005 Santander, Spain;(4) Area of Soil Science and Soil Chemistry, Universidad de Valladolid, 34004 Palencia, Spain;(5) Laboratorio LIBRA, Universidad de Valladolid, 47011 Valladolid, Spain |
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| Abstract: | The determination of the natural radioactivity has been carried out, by means of gamma-ray spectrometry, in exposed rock samples
collected from various geological formations across the Singhbhum Shear Zone of India. The spatial variation in the concentration
of primordial radionuclides reflects, in general, the geochemical variance among the analyzed rocks and affirms the earlier
views on genesis of uranium mineralization. This study further speculates new possibilities of thorium depletion during shearing
and metamorphism. All the obtained U-values were more than the worldwide average U-concentration (which is about 40 Bq/kg).
Interestingly, U-concentration in mica schists from Singhbhum group of rocks and in slates and argillaceous quartzites from
Iron Ore group of rocks was five to seven times higher than the global values. In contrast, the granites in study area showed
comparatively lower U-concentration. The overall results suggest the control of complex metamorphism and shearing on U-distribution
in the terrane. The contribution of 238U, 232Th and 40K to the total radiation dose in the study area was found to be significant ranging from 110 to 310 nGy/h in comparison with
the lower global, as well as Indian average values. |
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