Geochemical features and radiological risk assessment of Wadi El-Regeita granites, South Central Sinai, Egypt

The exposed rocks in the Wadi El-Regeita area are quartz monzonite, granodiorite and monzogranite intruded by andesite and diorite dikes. The monzogranites studied show a marked enrichment in Rb, Ba and Sr (large ion lithophile elements, LILE) and Zr, Nb and Y (high field strength elements, HFSE), but depletion in P and Ti. The genetic characteristics of the granites revealed calc-alkaline affinity, metaluminous and/or peraluminous characteristics. The studied quartz monzonite, granodiorite, and diorite rocks represent I-type granites that were emplaced in a volcanic arc tectonic environment. The monzogranite falls into post-collisional A-type granite that was emplaced within a plate environment under extensional regime. The calculated isovalents LREE/HREE, La/Yb, La/Sm and Tb/Yb show a relative enrichment of the lighter ones in the monzogranite. The quantities of 238U, 232Th and 40K in diorite samples have been investigated by gamma-ray spectroscopy. The measured radioisotope activity concentrations in Wadi El-Regeita varied from 100 to 1604 Bq.kg−1, with a mean of 370 ± 341 Bq.kg−1 for 238U. For 232Th, the range was from 35 to 140 Bq.kg−1, with a mean of 68 ± 27 Bq.kg−1. Finally, for 40K, the range was 501–3067 Bq.kg−1, with a mean of 1355 ± 570 Bq.kg−1. The levels of 238U, 232Th, and 40K detected in the diorite samples examined were found to exceed the worldwide limits of 35, 45, and 412 Bq.kg−1, respectively. The primary radiological hazards associated with these diorite dikes were attributed to the gamma rays emitted by the radioactive elements. Estimates of the radiological hazards in the granites were made and statistical methods were used to demonstrate the relationships between radionuclides and radiological factors. The statistical evaluation confirmed that uranium and its associated minerals in the diorite dikes were the main factors contributing to the radiological risks. Consequently, the study concluded that the diorite dikes found in the study area were unsuitable for construction purposes due to their elevated levels of radioactivity. •Granitesrepresents an economic strategy to apply in various building materials in Egypt.•A calibrated gamma-ray spectrometer is used to measure radioactivity in trachyte samples.•The radioactive hazard parameters are calculated, and the hazard's risk is evaluated.•The granites released radiation in the studies area poses a serious health concern.