Airborne gamma-ray spectrometry method is a powerful tool for geological mapping, mineral exploration and environmental monitoring. Qualitative and quantitative interpretations were performed on the airborne spectrometric data of G.Abu Had-G.Umm Qaraf area, South Eastern Desert, Egypt. Special attention is focused in this paper to discuss the distribution of k, eTh, eU and TC maps. Also there are statistical analyses for the radioactive content for the rock units of the studied area. Anomalies of high radioactive content were calculated and studied by field ground follow-up. The younger granites, Natach volcanic, gneissose granites and pegmatite rocks are the highly content of uranium in the studied area.
The present study aimed to assess the radiological hazards associated with applying the investigated granite in the building materials and the infrastructures applications. The investigated granites are classified into four categories: El-Urf, barren, colourful and opaque. El Urf monzogranite intrudes metagabbro diorite complex with sharp contacts. Based on the activity concentrations, the environmental parameters such as absorbed dose rate (Dair), annual effective dose (AED), radium equivalent activity (Raeq), external (Hex) and internal (Hin) hazard indices were measured. The mineralized pegmatite is located in the southwestern foothill of the Gabal El Urf younger granite. It displays well-defined zonation of three zones: outer, middle and inner zones represented by potash feldspar, quartz and mica, respectively. The isorad map showed that El Urf monzogranite is barren (Up to 100 cps) surrounding an excavation of the studied pegmatite that exhibits moderate colorful mineralization (phase-I = 500–1500 cps) and anomalous opaque mineralization (phase-II = 1500–3500 cps) pegmatites. The obtained results of radionuclides activity concentrations illustrated that the Opaque granites have the highest values of 238U (561 ± 127 Bq kg−1), 232Th (4289 ± 891 Bq kg−1) and 40K (3002 ± 446 Bq kg−1) in the granites, which are higher than the recommended worldwide average. Many of the radiological hazard parameters were lesser than the international limits in the younger granites and barren pegmatites. All of these parameters were higher in the colorful and opaque mineralized pegmatites. The high activity and the elevated radiological hazard parameters in the mineralized pegmatites are revised to the presence of radioactive and radioelements bearing minerals, such as thorite, meta-autunite, kasolite, phurcalite, columbite, fergusonite, Xenotime and fluorapatite. Other instances of mineralization were also recorded as cassiterite, atacamite, galena, pyrite and iron oxide minerals. Thus, the granites with high radioactivity concentration cannot be applied in the different applications of building materials and ornamental stones.
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.
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