Speleothem Records of the Hydroclimate Variability throughout the Last Glacial Cycle from Manita peć Cave (Velebit Mountain, Croatia)

• Published in: Geosciences
• Main Authors: Maša Surić, Petra Bajo, Robert Lončarić, Nina Lončar, Russell N. Drysdale, John C. Hellstrom, Quan Hua
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: speleothem; cave; hydroclimate; palaeoenvironmental changes; Croatia; Geology; QE1-996.5; Greenland; Carbonic acid; Greenland ice cores
• Online Access: https://doi.org/10.3390/geosciences11080347; https://doaj.org/article/3c750b5885e54395b9e980608dfa1a41

We present stable carbon (δ 13 C) and oxygen (δ 18 O) isotope records from two partially coeval speleothems from Manita peć Cave, Croatia. The cave is located close to the Adriatic coast (3.7 km) at an elevation of 570 m a.s.l. The site experienced competing Mediterranean and continental climate influences throughout the last glacial cycle and was situated close to the ice limit during the glacial phases. U-Th dating constrains the growth history from Marine Isotope Stage (MIS) 5 to MIS 3 and the transition from MIS 2 to MIS 1. 14 C dating was used to estimate the age of the youngest part of one stalagmite found to be rich in detrital thorium and thus undatable by U-Th. On a millennial scale, δ 18 O variations partly mimic the Dansgaard–Oeschger interstadials recorded in Greenland ice cores (Greenland Interstadials, GI) from GI 22 to GI 13. We interpret our δ 18 O record as a proxy for variations in precipitation amount and/or moisture sources, and the δ 13 C record is interpreted as a proxy for changes in soil bioproductivity. The latter indicates a generally reduced vegetation cover towards MIS 3–MIS 4, with shifts of ~8‰ and approaching values close to those of the host rock. However, even during the coldest phases, when a periglacial setting and enhanced aridity sustained long-residence-time groundwater, carbonic-acid dissolution remains the driving force of the karstification processes. Speleothem morphology follows changes in environmental conditions and complements regional results of submerged speleothems findings. Specifically, narrow sections of light porous spelaean calcite precipitated during the glacial/stadial sea-level lowstands, while the warmer and wetter conditions were marked with compact calcite and hiatuses in submerged speleothems due to sea-level highstands. Presumably, the transformation of this littoral site to a continental one with somewhat higher amounts of orographic precipitation was a site-specific effect that masked regional environmental changes.