Holocene wet episodes recorded by magnetic minerals in stalagmites from Soreq Cave, Israel

This study demonstrates the feasibility of speleothem magnetism as a paleo-hydrology proxy in speleothems growing in semi-arid conditions. Soil-derived magnetic particles in speleothems retain valuable information on the physicochemical conditions of the overlying soil, and changes in bedrock hydrology. Yet, the link between magnetic and isotopic proxies of speleothems has been only partly established. We reveal strong coupling between the inflow of magnetic particles (quantified using the magnetic flux index, IRM_flux) and δ¹³C in two Holocene speleothems from Soreq Cave (Israel). The stalagmite record spans from ca. 9.7 to ca. 5.4 ka, capturing the warm-humid conditions associated with the early Holocene and the transition to mid-Holocene wet-dry cycles. Extremely low IRM_flux during the early Holocene, indicating minimal contribution from the overlying soil, is accompanied by anomalously high δ¹³C (approaching bedrock values) hypothesized to be caused by high rainfall and soil erosion. By contrast, IRM_flux during the mid-Holocene covaries with the saw-tooth cyclicity of δ¹³C and δ¹⁸O, interpreted as rapid fluctuations in rainfall amount. The peaks in IRMflux precede the negative (wet) δ¹³C peaks by ~60–120 yr. The apparent lag is explained as a rapid physical translocation of overlying soil particles via groundwater (high IRM_flux) as a response to increasing rainfall, compared with slower soil organic matter turnover rates (10–102 yr).