Differences in natural gamma radiation characteristics of Erinpura and Malani granites in NW India

In NW India, large volumes of exposed Neoproterozoic basement rocks are formed by two magmatic suites, Erinpura granites as a late thermal event with respect to the ∼ 1 Ga Delhi Orogeny and the younger Malani igneous suite (770–750 Ma). Average uranium and thorium equivalent concentrations (in ppm)...

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Bibliographic Details
Published in:	Journal of Earth System Science Vol. 128; no. 5; p. 137
Main Authors:	Scharfenberg, Lars, Jandausch, Sebastian, Anetzberger, Lina, Regelous, Anette, Sharma, Kamal K, De Wall, Helga
Format:	Journal Article
Language:	English
Published:	New Delhi Springer India 01-07-2019 Springer Nature B.V
Subjects:	Basement rock Earth and Environmental Science Earth Sciences Fractionation Gamma radiation Gamma rays Geology Granite In situ measurement Inductively coupled plasma mass spectrometry Lava Magma Mass spectrometry Mass spectroscopy Orogeny Radiation Rocks Space Exploration and Astronautics Space Sciences (including Extraterrestrial Physics Surveys Thorium Uranium γ Radiation India Natural gamma radiation uranium granitoids NW India thorium
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Summary:	In NW India, large volumes of exposed Neoproterozoic basement rocks are formed by two magmatic suites, Erinpura granites as a late thermal event with respect to the ∼ 1 Ga Delhi Orogeny and the younger Malani igneous suite (770–750 Ma). Average uranium and thorium equivalent concentrations (in ppm) inferred from spectroscopic gamma radiation survey are higher in Malani rocks (Th 47.33 ppm and U 6.95 ppm) as compared to the Erinpura granites (Th 33.55 ppm and U 4.77 ppm). These values are considerably above the granite world average (Th 14.8 ± 13.2 ppm; U 3.93 ± 3.27 ppm). High U (up to 19 ppm) and Th (up to 88 ppm) in some Malani granites and a constant Th–U ratio of 7 points to a high degree of fractionation of the felsic magma. Higher radioelement concentration in the east (Mirpur granite) as compared to the west (Jaswantpura granite) is substantiated by geochemical data. Areas to the west and east of the Sirohi frontal thrust show differences, most likely a consequence of anatexis in the eastern sector. A high linear correlation between inductively coupled plasma mass spectrometry and gamma-ray data underlines the suitability of in-situ measurements for the determination of U and Th concentrations during a field survey providing basic information for future petrogenetic and risk-hazard studies in this granitic terrain.
ISSN:	2347-4327 0253-4126 0973-774X
DOI:	10.1007/s12040-019-1166-x