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About 50 samples of retail Czech wines from the South of Moravia (vintage years 2008 to 2015) were measured for δ18O values in wine water together with more than 60 European wines. The aim of the study was to compare Moravian wines (not measured for δ18O up to date) with regional European wines and published data from the European wine databanks. The observed variability of δ18O values with vintage year corresponds to the variability of German wines from the Rhine region. We did not observe any significant admixture of must from other regions. The method of 18O measurement appears to be very sensitive to small differences in the climate of the region (comparison of South Moravia and the near Malé Karpaty region). [ABSTRACT FROM AUTHOR]

The Miocene Kaiserstuhl volcanic complex in the Rhine graben rift is known for simultaneously exposing both intrusive and erupted (pyroclastic) calciocarbonatites. This makes Kaiserstuhl a promising candidate for studying the field and genetic relations between intrusive calciocarbonatite and its eruptive equivalent, and the processes enabling eruption of the calciocarbonatite at the surface in particular. Eruptive calciocarbonatites in Kaiserstuhl are represented by carbonatite tuff and lapillistone beds covering a debrite fan on the western flank of the volcano. The debrites are interpreted as lahar (debris flow) and possibly also debris-avalanche deposits. Based on the observed textures, the debris flows were most likely derived by water dilution from debris avalanches resulting from edifice failure, which occurred in the central part of the Kaiserstuhl volcanic complex. The edifice failure ultimately exposed the intrusive system, and the carbonatite pyroclasts (lapilli and ash) were ejected from narrow vents represented by open-framework tuff-breccias aligned along the detachment scarp. Since the Ca-carbonates break down rapidly at high temperatures and low pressures, calciocarbonatites are unlikely to form surface lavas. On the other hand, the presence of the calciocarbonatite pyroclastic deposits suggests that some geological process faster than the high-temperature breakdown of Ca-carbonate may facilitate calciocarbonatite eruption. We suggest that the sudden exposure and decompression of a suprasolidus high-level carbonatite intrusion by edifice collapse may be a suitable scenario enabling calciocarbonatite eruption. The absence of edifice failures on alkaline volcanoes, where carbonatite intrusion is either supposed or exposed, may explain the overall scarcity of erupted calciocarbonatites. [ABSTRACT FROM AUTHOR]

Four carbonatite bodies (Sukulu and Tororo - Uganda, Lemitar Mts. and Iron Hill - USA) from two intracontinental rift systems containing a prominent silicocarbonatite-carbonatite association were studied in detail in terms of petrography, major-/trace-element chemistry, and Sr-Nd-C-O isotope systematics to provide constraints on their petrogenesis and mutual relationship. The Sukulu and Tororo carbonatites (< 30 Ma) within the East African Rift System are characterized by the wide range of SiO2 contents and presence of phlogopite ± olivine and aegirine-augite + K-feldspar, respectively. These different mineral parageneses correspond to the Mg-K-rich nature of the former and Na-Fe-K-rich composition of the latter. Overall, these signatures can be best explained by progressive fractionation of parental carbonated silicate melts and liquid immiscibility documented by the chemical variation of clinopyroxene and the presence of silicate-carbonate pockets. However, at Tororo, this process was likely accompanied by assimilation of local crustal lithologies to account for its different Sr-Nd isotopic signatures and Na-rich nature of carbonatites. Despite their spatial and temporal difference, the Lemitar Mts. and Iron Hill from the Cambro-Ordovician North American Rift resemble similar petrography and mineralogy as Sukulu and Tororo bodies, expressed by the presence of phlogopite and clinopyroxene + K-feldspar. We present a general model explaining the origin of silicocarbonatite-carbonatite association involving segregation of silicate and carbonate melts from parental carbonated silicate melts through a process of liquid immiscibility. Subsequent distinct evolutionary paths are related to differences in Si-Na-K-Fe-Mg and H2O-F contents, oxygen fugacity, and melt ascent efficiency, perhaps related to crustal assimilation. Therefore, we emphasize that relatively silica-rich carbonatites represent a crucial linkage between silicate and carbonate melts. [ABSTRACT FROM AUTHOR]