Geology and Environmental Impact Assessment of Psammitic Gneiss and Lamprophyre Dykes at Wadi Sikait, South Eastern Desert, Egypt

Abstract

The present study was carried out on promising lamprophyre dykes at Wadi Sikait, through the mineralogical and petrography studies with emphasis on the radiological hazard’s indices along Wadi Sikait. So, the radioelement contents in the studied rocks were measured radiometrically by using gamma-spectrometry (NaI-detector). The psammitic gneisses formed an elongated zone striking NNE-SSW and are silicified, banded, jointed, sheared, mylonitized, and hematized. The lamprophyre dykes strike NNW-SSE varies in thickness from 0.5 m to 1.5 m, and extend more than one kilometer. The averages of the eU/eTh ratio are 2.02, indicating uranium accumulation, which confirmed positive disequilibrium (P-factor). Many of the radiological hazard parameters in both psammitic gneisses and lamprophyre dykes are higher than the international limits, suggesting probable hazard. 40K plays the main and most important role in dose rate contribution. The high activity and the elevated radiological hazard parameters in the lamprophyre are related to the presence of radioactive and radioelements bearing minerals like kasolite, thorite, uranothorite, xenotime, cheralite and baddeleyite. Other mineralization was also recorded as gold and base metal minerals.