Elemental concentration of U, Th and K in tectonically active regions of Khari River basin, Kachchh, Western India

Elemental concentrations of U, Th and K were determined using alpha counter and gamma-ray spectrometer to study the natural environmental radiation over a wide tectonically active region of Khari river basin in Kachchh, western India. Activity concentrations of 238U, 232Th and 40K estimated in different types of sediments deposited/relocated in the Khari river cliff due to neotectonic activity near Bharasar (23deg11'36.5'N, 69deg35'22.6'E) and Kodki transverse fault (23deg14'37.37'N, 69deg34'59.99'E) near Bhuj in the Khari River basin. Distribution of these radioactive elements on the earth's surface is controlled by geological features like faults, shear zones, metamorphism etc. Mainland Kachchh has two E-W trending major faults viz. Kachchh Mainland Fault and Katrol Hill Fault, which exhibits evidences of active tectonics during Quaternary. Kodki transverse fault is one of several NNE-SSW and NNW-SSE trending transverse faults affecting the Katrol Hill Range. The River Khari flows from the Katrol Ridge and traverses through Cretaceous sediments of Bhuj Formation (fluvio-deltaic, comprised dominantly of sandstones) in its course. All the three tectonically relocated sediments in the Khari river cliff have similar 238U and much lower 232Th activity concentration values corresponding to the worldwide median values of 35 and 30 Bqkg-1, respectively, while 40K activity concentrations were quite lower for two sediments and almost similar for the scarp-derived colluvium compared to the worldwide median value of 400 Bqkg-1. Kodki transverse fault, however, has higher 238U and 232Th and almost half of 40K activity concentration values relative to the worldwide median value. (author)