DOI: 10.25921/1wmp-d039
title: NOAA/WDS Paleoclimatology - Savi Cave Geochemical Data from 15300 to 9300 Cal Yr BP

description: Geochemical and physical changes along the growth axis of speleothems are controlled by climate as well as the dynamics of the host karst system. Discriminating between the two is one of the major challenges in assembling robust cave palaeoclimate records. Overcoming this dilemma may be achieved by investigating multiple properties from two or more speleothems from the same cave, spanning the same time interval. In this study, we use high-resolution stable oxygen and carbon isotope (δ13C and δ18O), morphological and petrographic data from two calcite stalagmites (SV1 and SV7) from Grotta Savi, Italy, to help constraining the regional climate conditions during the Younger Dryas. The new SV1 record, spanning 15.3–9.4 ka, builds on a previously published low-resolution stable isotope time series. It is anchored by 22 new U–Th ages and lamina-counting, yielding a refined age model that supersedes the previous one. The SV7 record is anchored by 8 U–Th ages and spans 13.1–10.5 ka, partially overlapping the SV1 record. Together, the morphological and geochemical characteristics of SV1 and SV7 allow us to identify site-specific processes driving the isotopic variations. This enables us to explore the degree of complacency in speleothems whereby, periodically, a speleothem is insensitive to recording a climate signal, due to aquifer hydrology and network evolution. The model suggests that δ18O is a proxy for the infiltration amount that reaches the site of deposition, which, in the case of SV7, was buffered by the aquifer hydrology. The interpretation of δ13C in both stalagmites is more complex, being influenced by both temperature and hydrology. Only a comparison of the two stalagmite records allows us to recognise a decoupling between the effects of hydrology and temperature. According to our interpretation, the most distinctive climate information of the Younger Dryas was the high hydrological variability, with phases dominated by seasonal infiltration within an overall cooling trend. Our record also reveals a significant Early Holocene climate anomaly – centred at 10.4 ka – whose magnitude was possibly amplified by local synoptic conditions. Our research demonstrates the importance of investigating several complementary proxies, particularly from morphologically diverse stalagmites. When monitoring data are not available, fabric and lamina thickness can be fundamental to unravelling the dominant control of hydrology or temperature on stable isotopes.
description: Data contributed as part of SISAL v3 Global Speleothem Isotope and Trace Element Database (https://doi.org/10.25921/jajq-qg60). Notes from the SISAL database: The final age model of SV7 (SISAL entity_id = 895) has been tuned to the SV1 (entity_id = 894) age model using the stable isotope series. Three transects spaced 1 mm apart were measured and stacked following the approach of Treble et al. (2003). Trace element profiles of the three transects were aligned using both specific features along the Sr and Ba concentration and petrographic observation. Master profiles for each element were constructed by averaging data from the three scans, resulting in uncertainties in element/Ca ratios of 7% [cf. Belli et al., 2017]