Paper No. 6
Presentation Time: 2:50 PM
CARBON AND OXYGEN STABLE ISOTOPES OF THE MIDDLE MIOCENE BADENIAN GYPSUM-ASSOCIATED LIMESTONES (KUDRYNTSI QUARRY SECTION, WEST UKRAINE): IMPLICATIONS FOR PALEOENVIRONMENTS IN THE CENTRAL PARATETHYS
The Middle Miocene Badenian evaporite deposits in the marginal part of the
are usually overlain by the Late Badenian transgressive deposits (mixed-fossil lithoclastic packstones/grainstones with intercalations of marls, and then coralline algal limestones). At the Kudryntsi Quarry ( Carpathian Foredeep Basin West Ukraine), siliciclastic series ( 4 m thick) occurs between the gypsum and the transgressive deposits. The siliciclastic series contains limestone intercalations which are first sparitic and -microsparitic, and then become pelletal. They are barren of marine fauna. The pelletal depositional textures are interpreted as originated in restricted environments. Limestones show a wide range of δ13C values (from -1.6‰ to -18.2‰) and δ18O values (from -0.2‰ to -9.4‰) indicating that the cementation and some recrystallization took place in meteoric-water-dominated fluid but the restriction-controlled trend can be recognized. In turn, the transgressive calcareous deposits contain rich marine fauna. They also show negative carbon and oxygen isotope values (from -4.6‰ to -15.4‰ and from -2.7‰ to -6.5‰, respectively) suggesting the presence of isotopically light, meteoric water rather than only seawater or concentrated, 18O-rich seawater-derived brines. The average δ18O values in limestones of Kudryntsi follow restriction-controlled trend, similar to that assumed for the Upper Badenian from . Much wide ranges of δ13C and δ18O values in Kudryntsi are probably result of considerably more complex recystallization owing to many episodes of dissolution and reprecipitation.