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内容記述 |
Mylonitic rocks in north Abu Rusheid, Eastern Desert of Egypt, are naturally rich with naturally occurring radioactive materials (NORMs). Uranium (U) and thorium (Th) decay series are widely considered as NORM, with more abundance in the Earth's crust. NORMs may become concentrated through industrial processes such as niobium (Nb) and tantalum (Ta) extraction, zircon and zirconia, metal production, and mining of uranium ore. This study investigated the distribution and mineralogical hosts of NORMs in mylonitic rocks from North Abu Rusheid, located in Egypt’s mineral-rich Arabian-Nubian Shield. Thirty samples were collected from three trenches (TA, TB, and TC) to measure trace element concentrations using inductively coupled plasma mass spectrometry (ICP-MS). Mineralogical studies were conducted using heavy liquid separation and environmental scanning electron microscopy (ESEM) with EDX to identify minerals. Results indicated significantly elevated concentrations of refractory elements such as Nb (up to 1322 µg g-1), Ta (up to 252 µg g-1), Zr (up to 1901 µg g-1), U (up to 171 µg g-1), and Th (up to 454 µg g-1) were higher than upper continental crust values. Metal concentrations such as Sn were (up to 136 µg g-1), Zn (up to 574 µg g-1), and Pb (up to 771 µg g-1). The minerals identified in this study include columbite (host to Nb, Ta, and U), zircon (Zr-rich), cassiterite (Sn-rich), and uranothorite (a radioactive mineral containing both U and Th). The spatial distribution and mineralogical associations suggest a common origin for U and Th, with notable implications for radiological protection in potential mining activities. This research highlights the need for risk assessment and management strategies for radiation exposure in future resource exploitation in the North Abu Rusheid area. These findings will support safe practices in mineral extraction industries. |
