Radioactivity and geochemistry of calc-alkaline neovolcanites of the West Carpathians

Abstract

The distribution of radioactive elements(Th, U, K) and selected trace elements(Rb, Sr, Ba, Y, Zr, V, Cr, Ni) in a set of 29 volcanic rocks of the West Carpathians was studied. The rock types follow the typical calc-alkaline sequence from basaltic andesites to rhyolites with average contents of SiO2, K2O, Th, U, Rb, Ba and Zr increasing, and with average contents of TiO2, Al2O3, FeOt, MnO, MgO, CaO, P2O5, Sr, V, Cr and Ni decreasing from less to more acid rocks. Statistically significant differences in the contents of Th, U, Rb, Sr, Ba, Zr, K2O, CaO and P2O5, found between the pyroxene andesites of Central and Eastern Slovakia, may indicate that the volcanism in both regions took place under different conditions. The andesites of Central Slovakia are characterized by relatively high contents of Th, U and Rb as opposed to the andesites from other volcanic areas, e.g., from the intraoceanic island arcs, the Andes or the Mexican volcanic belt.