In situ radiation measurement and estimation of U/Th ratio to reflect on the uranium bearing potential zone in metamorphic rocks of Mahendragarh district, Haryana

Abstract

Gross gamma radiation survey was carried out using Nal(Tl) scintillator based portable gamma ray spectrometer (PGRS) around areas of Gaonri, Dholera, Pachnota and Meghot in Mahendragarh district, Haryana. Geologically the area forms part of north Delhi fold belt comprising calc-silicate, quartz biotite schist, impure marble, quartzite and pegmatite rocks. Equivalent uranium (eU₃O₈) concentration in ppm was estimated in situ on a regular grid pattern of 500 m (E-W) × 1000 m (N-S) and grab samples were collected at grid locations for analyzing in the laboratory for estimating the contents of eU₃O_s Ra_eq, ThO₂ and %K. A comparison with the laboratory analysed grab samples for eU₃0₈ data and in situ radiation measurements shows a good match of the two sets of data. The in situ measurements indicate higher concentration of eU₃O₈ in Chapra Bibipur in northeastern most corners, Maghot area in central part, Gaonri in western part and Pachnota in southwestern part of the study area.

As index to uranium favorability, U(Ra_eq)-Th contour map (prepared using Surfer software with Krieging interpolation method for this grid size) based on the data on grab samples was generated which show three major clusters of relatively high U-Th ratio. The blocks delineated are enriched in sodic mineral albite which support albite hosted uranium mineralization potential in metamorphic rocks in Haryana.