This study provides an integrated geochemical, petrographic, and
radiological assessment of the El Gara El Hamra and El Gara El Soda
granitoids in Egypt’s Southwestern Desert. Whole-rock major, trace, and REE
geochemistry, combined with tectonic discrimination diagrams, reveals that
the granitoids belong to ferroan A-type suites and comprise both
peraluminous and peralkaline varieties. These contrasting chemistries reflect
heterogenous crustal sources and within-plate magmatic processes associated with late Neoproterozoic post-collisional extension. Elemental
ratios (e.g., Nb/Yb, Ga/Al) and HFSE enrichments support an anhydrous,
oxidized, high-temperature melt regime consistent with the regional
evolution of the Arabian–Nubian Shield.
High-resolution gamma spectrometry was used to quantify primordial
radionuclides (238U, 232Th, 40K). Thorium and potassium show pronounced
enrichment in the peralkaline samples, whereas uranium displays moderate variability across the granitoid suites. Calculated radiological parameters—
including absorbed dose rate (Dγ), annual effective dose (E_annual), radium
equivalent activity (Raeq), and hazard indices—exceed global crustal averages
but remain within ranges typical of A-type granites worldwide. Radiogenic
heat production (RHP) varies significantly between the peraluminous and
ACCAERPTTICEDLE M IANN PURSECSRSIPT
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peralkaline groups, reaching up to 9.99 μW/m³, indicating favorable potential
for shallow-crust geothermal exploration.
Organ-specific dose modeling (ICRP‐based) identifies the bone marrow and
lungs as the most impacted tissues under hypothetical prolonged exposure scenarios. Although some samples exceed recommended limits for
unrestricted building use, actual public exposure would depend on rock
utilization and exposure geometry rather than intrinsic radionuclide
concentrations alone.
Overall, the El Gara granitoids represent a compositionally diverse A-type system with elevated heat-producing elements and moderate radiological
significance. These findings highlight the need for site-specific radiological
evaluation before large-scale quarrying or use as construction materials, and
underscore their potential relevance for geothermal energy assessments.