Assessment of natural radioactivity of the rocks of Motur and Bijori Formation (Permian) using HPGe, around Imlikheda area, Betul District, Madhya Pradesh.

Thick siliciclastic sedimentary sequences belonging to Motur and Bijori Formations of lower Gondwana Supergroup are exposed around Imlikheda, Betul district, Madhya Pradesh is in the central part of fault bounded Satpura Basin. These sequences have been studied since last several decades from the point of understanding possible prospects of radioactivity within them by the earlier workers. The field radiometric survey has resulted in the identification of locations where the rocks of Motur (n = 1) and Bijori (n = 16) Formations show unusual high gamma radiation within the study area. The present study is aimed to assess these rocks using advance gamma spectroscopy technique by high resolution HPGe (high purity Germanium) detector in order to thorough identification of radioactivity generating elements and its quantifications. The identification of each of the radio nuclei present in the sample is confirmed by the characteristic gamma energies in the gamma spectrum and the quantification of the U, Th and K were made using peaks at 1765 keV, 2614 keV and 1460 keV energies respectively by two different methods. The results obtained indicate the presence of naturally occurring mixed U-Th anomalies wherein Uranium concentration ranges from 10 ppm to 0.01% whereas Thorium ranges between 57 ppm and 0.06% with an acceptable margin of error.