Speleothem Stable Isotope Records from Eastern Europe & Turkey

Abstract

The region of Eastern Europe & Turkey contributed to the SISAL (Speleothem Isotopes Synthesis and AnaLysis) global database with stable carbon- and oxygen isotope time-series from 18 entities from 14 cave systems. The currently available oldest record from this region is the ABA-2 flowstone record (Abaliget Cave; Hungary) reaching back to MIS 6. The temporal distribution of the compiled 18 entities points out a ~20-kyr-long period, centering around 100 ka, lacking speleothem stable isotope record in the region. The regional subset of SISAL_v1 records displays a continuous coverage for the past ~90 kyr for both δ18O and δ13C, with a mean temporal resolution of ~12 yr for the Holocene, and >50 yr for the pre-Holocene period. The highest temporal resolution both for the Holocene and the pre-Holocene was achieved in the So-1 record (Sofular Cave; Turkey). Assessing the data, an important split was found regarding the climatic interpretation of speleothem δ18O. While the oxygen isotope composition of more continental formations is thought to reflect mainly temperature variations and changes in moisture transport trajectories, it may strongly reflect fluctuations of precipitation amount in the southern part of the region. Variations of δ13C primarily interpreted as humidity changes reflecting dry/wet periods across the region. Elevation gradients from three non-overlapping time periods from the region - for the last 5kyr - indicated systematically prevailing elevational gradients around -0.26‰ 100m-1 in δ18O. The regional comparison of SISAL_v1 speleothem δ18O and the temporal distribution of coarsely crystalline cryogenic cave carbonate occurrences back to 45ka does not appear to confirm the finding that occurrence of the latter coincides with the warming from stadial to interstadial conditions.

The Potential of Speleothems from Western Europe as Recorders of Regional Climate: A Critical Assessment of the SISAL Database

“…On the whole, the spatial trend in δ 18 O is very similar for precipitation and speleothems ( Figure 5), and reflects increasing rainout away from the Atlantic (continental effect, [24]). Smaller-scale trends, such as the high δ 18 O values found in the circum-Mediterranean region, and the altitude effect apparent in the Alpine region, are mirrored by the SISAL data.…”

“…We use the SISAL database to detect whether present-day regional trends in δ 18 O spel values exist, and how they compare to trends in precipitation δ 18 O, taking advantage of the dense network of GNIP stations with long-term measurement records (up to 50 years). All analyses were referenced to the period 1958-2015.…”

“…A latitudinal gradient is also present between the temperate-humid climate of Northern Europe and the seasonally arid climate of the Mediterranean region. These spatial gradients are reflected in the regional patterns of precipitation δ 18 O, and are predominantly related to the continental effect, with lower δ 18 O due to progressive rainout and Rayleigh distillation with increasing distance from the Atlantic coast [4,24]. Deviations from this trend are found in Southern Europe, where the influence of water vapour from the Mediterranean Sea can lead to higher δ 18 O values [25], and the Alpine region, where the altitude effect lowers precipitation δ 18 O [24,26].…”

Speleothems from the Middle East: An Example of Water Limited Environments in the SISAL Database

“…The distinct imprint of Greenland interstadials on the MIS2 50-kyr record suggests that SO-1 records decadal to centennial-scale events, however, on glacial time-scales the δ 18 Occ records Black Sea surface water composition rather than Mediterranean source which determines most of the EM coastline records [56]. Additional discussion on Sofular cave, including the Holocene cycle documented in the speleothem δ 13 C time-series, can be found in the review of Eastern European records in SISAL_v1 [37].…”

“…Additional 6 sites from Eastern Europe and northern Turkey (see Kern et al. [37,38]), are included as these sites are along the dominant EM storm tracks, the major climate patterns controlling precipitation in the region (Figures 1 and 2; Table 1). The aim of this work is to highlight the applicability of speleothems from the ME currently logged in the SISAL_v1 database to resolve regional-scale consistencies and inconsistencies and to test for spatial coherency between speleothems and additional climate recorders (i.e.…”