Metasomatism of the carbonate rocks of the contact zone with the basalt

The influence of low-grade contact metamorphism – metasomatism on carbonate rocks from the contiguous zone with Paleogene-Neogene basalt on the isotopic composition and geochemical properties of limestones from this zone was presented. The limestone and basalt samples were collected in the contiguous zone between Triassic limestones and Paleogene-Neogene basalts in the area of St. Anne Mountain (Opole Silesia region). The limestones from the contact zone are macroscopically different in colour from other limestones from the Opole Silesia region. They are enriched in Al, Si, Fe, K, Na, Ti, Cr, V, Cr, Mn, Zr, Co, Ni, Cu, Zn, Pb and Cl, i.e. elements typical of non-carbonate phases. The δ¹³C and δ¹⁸O values of the high-Mg calcite of the contact zone samples differ from those of the other areas. The δ¹³C_VPDB values are only negative, whereas the δ¹³C_VPDB values of the other limestones are sometimes positive. δ¹⁸O values below 0‰ and elevated high-Mg calcite crystallisation temperatures above 25 °C, higher than those prevailing in the sea basin where the carbonates were formed and that typical for diagenetic processes, indicate that metasomatism may have altered the original oxygen isotopic composition and geochemistry of the limestone.