A 4000-year long Late Holocene climate record from Hermes Cave (Peloponnese, Greece)

Abstract. The societal and cultural development during the Bronze Age and the subsequent Iron Age was enormous in Greece, however interrupted by two significant transformations around 4200 years b2k (Early Helladic II/III; b2k refers to years before 2000 CE) and 3200 years b2k (end of Late Helladic III). Artefacts and building remains provide some insights into the cultural evolution, but only little is known about environmental and climatic changes on a detailed temporal and spatial scale. Here we present a 4000-year long stalagmite record (GH17-05) from Hermes Cave, Greece, located on Mount Ziria in the close vicinity of the Late Bronze Age citadel of Mycenae and the Classical-Hellenistic polis of Corinth. The cave was used in ancient times, as indicated by ceramic fragments in the entrance area and a pronounced soot layer in the stalagmite.

²³⁰Th-U dating provides age constraints for the growth of the stalagmite (continuous between ~ 800 and ~ 5300 years b2k) and the formation of a soot layer (2.5_+0.5-0.65 ka b2k). Speleothem δ¹⁸O and δ¹³C values together with clumped isotopes and elemental ratios provide a detailed paleoclimate record of the Northern Peloponnese. The proxy data suggest significant centennial scale climate variability (i.e., wet vs. dry). Furthermore, carbonate δ¹⁸O values, calculated drip water δ¹⁸O values, ²³⁴U/²³⁸U activity ratios and elemental ratios suggest a long-term trend towards drier conditions from ca 3.7 to ~ 2.0 ka b2k. From 2.0 ka b2k towards growth stop of the stalagmite, a trend towards wetter conditions is observed. A high degree of correlation was found for isotope trends of different speleothems from the Peloponnese and partially with climate records from the Eastern Mediterranean, whereas speleothems and lake records with a larger distance to the Peloponnese show little correlation or even opposing trends.