Coeval dry events in the central and eastern Mediterranean basin at 5.2 and 5.6ka recorded in Corchia (Italy) and Soreq caves (Israel) speleothems

Abstract

Soreq (Israel) and Corchia (central Italy) Caves are located 2500 km far apart along the Mediterranean winterstormtrack and are ideally suited for investigating past variations of winter rainfall in the Mediterranean region. Analyses of speleothem δ18O records from both caves for the period between ca. 7 to 4 ka BP show some striking similarities for the ca. 6 and 4 ka interval, but lack agreement between ca. 7 to 6 ka BP. Two prominent isotopic excursions, argued to reflect relatively drier conditions, are centred at ca. 5.6 and ca. 5.2 ka. The 5.2 ka event lasts less than a century, whereas the 5.6 ka event extends fromca. 5.7 to 5.4 ka. A period of progressive drying is also apparent fromca. 5 to 4 ka. Another prominent event, reflecting wetter conditions, is recorded in both records at ca. 5.8 ka and seems to last several decades. The 5.6 and 5.2 ka events occurred within a period of higher deposition of haematite-stained grains in cores of the sub-polar North Atlantic, and correlationwith the wind strength proxy record fromHólmsá loess profile in Iceland suggests that rainfall reductionwas related to a reduced vapour advection from Atlantic towards the Mediterranean connected to northward shift in the Westerlies. A comparisonwith Alpine records, including the Spannagel Cave isotope record, suggests that dry events recorded at Soreq and Corchia caves may correspond to wetter (lake high stands) and cooler (glacier expansion) conditions in the Alpine region, indicating complex regional climate re-organization.