HOLIVAR2006 Abstracts
Stable isotope compositions of speleothems from Hungary: climate conditions and local variations.
Z. Siklosy1,2, A. Demeny1, T.W. Vennemann3, J. Kramers4 and Sz. Leel-Ossy2
1Institute for Geochemical Research, Hungarian Academy of Sciences, Budapest, Budaorsi u.45, H-1112, Hungary
2Eotvos University, Budapest, Pazmany P. stny 1/C, H-1117, Hungary
3Institute of Mineralogy and Geochemistry, University of Lausanne, BFSH2, Humense, CH-1015, Switzerland
4Institute of Geological Sciences, University of Bern, Erlachstrasse 9A, CH-3012, Switzerland
Contact: S. Ziklosy (siklosy@geochem.hu)
Download Poster (359KB) | 
View JPG (737KB)
In the past decade an increasing number of cave-related paleoclimatological studies have been published that use mostly stalagmites as excellent continental climate records. Well studied speleothem occurrences from Central Europe are scarce and very rare in Hungary. However, in recent years new projects have begun to cover and compare this region. Climate conditions in the studied area are in a special position between the Atlantic-Mediterranean-sub-Arctic influences.
In the present work we report on isotopic profiles for some Hungarian, mostly contemporaneously deposited Holocene stalagmites. The U-Th analysis revealed that the samples studied were deposited mostly during or before the Early Holocene. All Hungarian samples collected in this work are younger than the cold and dry Younger Dryas period - that has left traces all over the world - except one (Leany cave, North-Central Hungary) which started growing 12,500 years ago. This stalagmite shows no abrupt oxygen isotope shift at the oldest part spanning the major climate change during the termination of the Younger Dryas and reveals only slight cyclical variation along the growth axis.
Another stalagmite sample collected from the same cave closer to the surface exhibits higher variability in carbon and oxygen isotope compositions. Besides isotopic pattern similarities in the contemporaneously grown sections (dated with MC-ICP-MS), the measured carbon isotope values are significantly higher in the case of the stalagmite formed at a higher level. This feature may be related to different infiltration pathways of the seepage water within the karst aquifer, or to considerable 13C/12C fractionation due to the escape of dissolved CO2 along migration pathways.
Trace element (e.g. Mg, Sr, Ba, U) contents and stable C and O isotope compositions were determined across two active, syngenetic soda straw stalagtites from the Beke Cave (NE Hungary) representing the last seven years to investigate the nature of these geochemical cycles and their potential for better understanding of past changes. The cold seasons are represented by low &delta18O values. The positive covariation of P concentration and &delta13C values of the soda straw suggest the presence of reduced activity in the soil zone during wintertime. Environment seasonality is clearly shown by the Sr and Ba concentrations: higher values represent cold periods, suggesting that restricted infiltration caused higher salinity.
The observed variations call attention to the calibration of recent speleothems with well known local meteorological records which is essential in trace element related palaeoclimatological studies.