Investigation of radiological parameters and their relationship with rock type from Hifan area, Yemen

Twenty rock samples (Marble, Biotite gneiss, Migmatite gneiss, Granite gneiss and Mylonites granite) were analyzed to determine the activity concentrations of 226Ra, 232Th and 40K in Bq kg−1 and their radiological parameters using gamma-ray spectrometer consisting of NaI (Tl) detector. 226Ra activity varied in the range from 7.45 ± 1.3 to 148.4 ± 15 Bq kg−1. The activity concentrations of 232Th ranged from 9.8 ± 1.6 to 432 ± 29 Bq kg−1, whereas activity concentration of 40K ranged from 519 ± 24 to 4491 ± 95 Bq kg−1. The highest average values concentration of 226Ra, 232Th and 40K were 112.1, 301 and 3875.9 Bq kg−1, respectively, which was observed in mylonites granite samples. The radiological parameters as radium-equivalent (Raeq) and external and internal hazard index (Hex, Hin) were determined. Raeq varied between 65.7 and 1147.5 Bq kg−1, which exceeded the permitted value (370 Bq kg−1) and the internal hazard index (Hin) (0.2–3.8), which is higher than 1. The total absorbed dose rates in air were calculated from the concentrations of the three radionuclides ranged from 33.2 to 521.1 nGy h−1, and the external annual effective dose rates were determined to be between 40.8 and 639.1 μSv y−1. The radiological maps of study area were obtained. The calculated average value of the radiological parameters in mylonites granite, granite gneisses and migmatite gneisses rocks samples were higher than the safe limit recommended by the Organization for Economic Cooperation and Development (OECD). •226Ra, 232Th and 40K in some rocks from Hifan area in Yemen were measured.•The radiological parameters have also been determined.•Major minerals and major elements for some rocks under study were investigated.•The absorbed dose and radiological parameters for Granite, granite gneisses rocks samples exceeding the safe limit recommended by (OECD).•The radiological maps for study area were drawn.