Natural Radioactivity of Intrusive-Metamorphic and Sedimentary Rocks of the Balkan Mountain Range (Serbia, Stara Planina)

Abstract

Stara Planina (also known as the Balkan mountain range) is known for numerous occurrences and deposits of uranium and associated radionuclides. It is also famous for its geodiversity. The geologic framework is highly complex. The mountain is situated between the latitudes of 43 • and 44 • N and the longitudes from 22 • 16 to 23 • 00 E. Uranium exploration and radioactivity testing on Stara Planina began back in 1948. Uranium has also been mined in the zone of Kalna, within the Janja granite intrusive. The naturally radioactive geologic units of Stara Planina are presented in detail in this paper. The main sources of radioactivity on Stara Planina can be classified as: 1. Granitic endogenous-syngenetic-epigenetic deposits and occurrences; 2. Metamorphogenic-syngenetic; and 3. Sedimentary, including occurrences of uranium deposition and fluctuation caused by water in different types of sedimentary rocks formed in a continental setting, which could be classified under epigenetic types. The area of Stara Planina with increased radioactivity (higher than 200 cps), measured by airborne gamma spectrometry, is about 380 square kilometers. The highest values of measured radioactivity and uranium grade were obtained from a sample taken from the Mezdreja uranium mine tailing dump, where 226 Ra measures 2600 ± 100 Bq/kg and the uranium grade is from 76.54 to 77.65 ppm U. The highest uranium (and lead) concentration, among all samples, is measured in graphitic schist with high concentrations of organic (graphitic) material from the Inovska Series-99.47 ppm U and 107.69 ppm Pb. Thorium related radioactivity is the highest in granite samples from the Janja granite in the vicinity of the Mezdreja granite mine and the Gabrovnica granite mine tailing dump, and it is the same-250 ± 10 Bq/kg for 232 Th, while the thorium grade varies from 30.82 to 60.27 ppm Th. In gray siltstones with a small amount of organic material, the highest radioactivity is related to potassium-2080 ± 90 Bq/kg for 40 K.

Distribution of natural radioactivity in different geological formations and their environmental risk assessment in Malaysia

“…However, the p XRF and XRD result for pyrite-graphite-quartz schist does not show a significantly higher percentage of radioactive minerals and radionuclides than mudstone, which is probably due to the heterogeneity of accessory minerals and radioactive isotopes. Abdulqader et al ( 2018 ) also observed that the schist sample with higher graphitic content also contains more uranium. However, quartz in metamorphic rocks can show insignificant radioactivity (Manjunatha et al 2013 ).…”

Natural Radioactivity of Laterite and Volcanic Rock Sample for Radioactive Mineral Exploration in Mamuju, Indonesia

“…According to the HPGe measurement result, Mamuju is an anomalous area because it has high contents of 238 (Figure 6) [21]. This shows that Mamuju has potential as an exploration area for radioactive minerals if we compare these values with other studies [22][23][24]. According to the HPGe measurement result, Mamuju is an anomalous area because it has high contents of 238 (Figure 6) [21].…”