GEOLOGY AND DISTRIBUTION OF RADIOELEMENTS AS WELL AS ENVIRONMENTAL IMPACT AT ABU MARW YOUNGER GRANITES, SOUTH EASTERN DESERT, EGYPT

Abstract

This work discusses the geologic setting of Abu Marwarea, and the distribution of the natural radionuclides and assess the radiological hazard resulting from the granites in the area. The environmental background levels of natural radiation, human exposure and dose rates as well as possible environmental impacts of radiation were investigated. The field investigation of the different rock units, with references to their mode of occurrence, mutual relationships, petrography and regional structure resulted that the area is covered by Late Proterozoic igneous and metamorphic rocks. These rocks are nonconformably overlain by Cretaceous Nubian sandstone in the western and northern parts of the area and they arranged from the oldest to the youngest rocks by Metagabbros, Metavolcanics, Older granites (tonalities and granodiorites) and Younger granites (monzogranites, syenogranites and Alkali-feldspar granites). The younger granitic rocks at Abu Marw area have low uranium and thorium contents, where the average contents of uranium are 1.14ppm, 5.7ppm and 2.1ppm and thorium are15.2ppm, 22.5ppm and 13.8ppm for monzogranites, syenogranites and alkali feldspar granites. The excess values of uranium and thorium contents in syenogranites are due to the high contents of uranium and thorium bearing minerals in these rocks. The environmental impacts of the monzogranires, syenogranites and alkali feldspar granites at Abu Marw area are studied. The radium equivalent activity (Raeq), gamma activity index (I), alpha activity index (Iα), external hazard index (Hex), internal hazard index (Hin), external absorbed dose rate in outdoor (Dout) and indoor (Din), annual effective dose (AEDE), annual gondal dose equivalent (AGDE) and excess lifetime cancar risk (ELCR) are calculated. The studies concluded that all the environmental impacts dose rates values in the younger granitic rocks (monzogranites, syenogranites and alkali feldspar granites) rocks are lower than the publicpermissible values in these rocks and they are within the safety range for the public and workers. So, these rocks are safety for the building and ornamental materials.