Mineral chemistry and radiological characteristics of syenogranite bearing rare metals mineralization: environmental implications for radiation safety
摘要
The investigated syenogranite is predominantly enriched in rare metals mineralization. Thorite contains rare earth elements (REEs), and monazite has low Th- concentrations, while Th and Y are found in zircon crystals. These may be attributed to the effect of hydrothermal alteration. Fe2O3 and MnO are identified in the studied columbite, with a significant concentration of Fe2O3 indicating ferocolumbite. REE minerals are prominently included in the investigated syenogranite including (i) REE fluorocarbonates and fluoride (synchysite and fluorite); (ii) REE phosphates (monazite and xenotime). The total rare earth elements (TREE2O3) exhibit significant variability in their concentrations, particularly in monazite, synchysite, xenotime, fergusonite and columbite with average values of 64.16, 56.05, 22.58, 14.19 and 11.63 wt%. Ce is the most prevalent REEs in the analyzed monazite and synchysite, with average concentrations 32.27 and 25.57 wt%, respectively. This study also evaluates the radiological hazards and statistical relationships of radionuclides 238U, 232Th and 40K in syenogranite samples collected from a specific geological area. Gamma-ray spectrometry revealed that the activity concentrations of 238U, 232Th and 40K exhibited mean values of 153 ± 37, 171 ± 35, and 1390 ± 252 Bq kg−1, respectively. The calculated radiological hazard indices, including radium equivalent content (Raeq), external and internal hazard indices (Hex and Hin), absorbed dose rate (ADR), annual effective doses (Eout and Ein), and excess lifetime cancer risk (ELCR), generally exceeded international safety limits, suggesting potential health risks in the study area. Statistical analyses, including Kolmogorov–Smirnov tests, confirmed the normal distribution of radionuclide concentrations, while multivariate methods such as Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) provided insights into the relationships among variables. These results highlight the significance of recognizing the mineralogical and radiological characteristics of syenogranite, underscoring their relevance in geological research and ensuring its safe use in construction and various other applications.