The late holocene climate and vegetation reconstruction using the Lake Gölcük (SW Anatolia) sedimentary and pollen records

The Late Holocene (the last 1600 years were considered as Late Holocene in this study) climate change comprises of some important climate perturbations in which the current climate change can be placed. The Late Holocene climate changes comprised of the Dark Ages Cold Period (DACP), Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), which may be related with some societal changes. This makes Late Holocene's paleoclimate reconstructions and climate mechanisms crucial to our understanding of current and future climate changes. In Anatolia, there are need for high-resolution well-dated multiproxy records of the Late Holocene. Therefore, this PhD thesis aims to contribute to the understanding of the DACP, MCA and LIA in Anatolia and the eastern Mediterranean basin at large by presenting high-resolution well dated sediment records. In order to achieve this aim, a piston core (GÖLCÜK18P01) and two gravity cores (GÖLCÜK18G02 and GÖLCÜK18G09) were drilled in a high-altitude crater Lake Gölcük. The cores were lithologically described and analyzed using magnetic susceptibility (hereafter MS) and μXRF. The μXRF were further investigated using factor analysis, after which Log(Ca/K) and Log(Sr/Ca) were selected for paleoclimate interpretation. The core P01 was further analyzed using pollen and stable isotope (δ13C and δ18O). A Bayesian age-depth model was reconstructed with the help of 14C, 210Pb and 137Cs dating techniques. The result of multiproxy data of, MS, Log(Ca/K), Log(Sr/Ca), pollen, δ13C- δ18O and lithology revealed various periods with wet (warm) and dry (cold) phases. The data suggest a generally mud lithology, reduced arboreal pollen, low MS, low (Ca/K) and high Sr/Ca indicating a dry (cold) DACP period (~AD 400-770). During the MCA (AD 900-1300) on the other hand, high-low-high arboreal pollen, generally sandy lithology, generally high MS, high-low-high (Ca/K), low-high-low Sr/Ca were recorded. These are interpreted as wet (warm) - dry (cold) - wet (warm) MCA. In contrast to the MCA, the LIA was a generally dry (cold) period as revealed by low arboreal pollen, mixed sand-clay-mud lithology, low MS, low Ca/K, high stable x isotopes (δ13C and δ18O), even though with short punctuation of wet (warm) episodes. Although timing of the Late Holocene climate events appeared to differ from region to region, the Lake Gölcük records appear to mostly agree with SW Anatolian and some eastern Mediterranean records in terms of wet (warm) and dry (cold) periods. The possible link of the Late Holocene climate changes observed in the Lake Gölcük to North Atlantic Oscillation (NAO), solar activity and volcanic forcing are discussed. Increase (decrease) in summer temperature is found to be related with high (low) solar activity. Solar activities such as the Oort Minimum, Medieval Maximum, Wolf Minimum, Spörer Minimum, Maunder Minimum and Dalton Minimum are related with changes in the multiproxy records of Lake Gölcük. Meteorological data of winter precipitation tends to be associated with negative winter NAO, which agrees with the comparison of the Lake Gölcük paleo records with a NAO reconstruction from tree rings. The North Sea Caspian Pattern (NCP) atmospheric teleconnection may also be partly related with the Late Holocene climate changes. Keywords: Late Holocene, Vegetation Change, Dark Ages Cold Period, Medieval Climate Anomaly, Little Ice Age.