Early to Mid-Holocene Lake level and temperature records from the terraces of Lake Sünnet in NW Turkey

Abstract

Lake Sünnet, a freshwater landslide-dammed lake in NW Anatolia, comprises a10m thick widespread of Early-to-mid Holocene deltaic sediments. Paleo-environmental interpretation of these deposits coupled with a high-resolution data (18yrs/sample) of stable O and C isotopes, magnetic susceptibility and total organic and carbonate contents, allows an understanding of the nature of the mid-Holocene climatic transition as well as the short duration extreme events in relatively humid NW Turkey. Detailed sedimentological logging showed that four phases of progradation of deltaic sand bodies over pro-delta muds occurred. It is suggested that they correspond to phases of increased precipitation. A sudden vertical transition from lacustrine muds to subaerial colluvial facies at 5.9kacal BP is considered to be due to lake level drop related to water deficit. Oxygen isotope data suggest that the Mid-Holocene transition with high mean summer temperatures initiated at 7.3kacal BP and continued until the end of the section, with an interruption by a humid event between 6.8 and 6.0kacal BP. Centennial extreme events characterized by sharp δ18O positive shifts (1–2 permil) are also encountered at 9.2, 8.9, 8.2, and 7.6kacal BP. A comparison of the Lake Sünnet record with previous Aegean and Sea of Marmara palynological and sea surface temperature data shows a good fit in terms of the timing and nature of mid-Holocene transition and Early Holocene cold events. The Lake Sünnet stable isotope record particularly suggests gradually increasing summer temperatures and hence continentality during the mid-Holocene cooling in the Mediterranean.