Yazar "Kaya, Hakan" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Environmental changes based on multi-proxy analysis of core sediments in Lake Aktas, Turkey: Preliminary results
    (Pergamon-Elsevier Science LTD, 2018) Kılıç, Nurgül Karlıoğlu; Caner, Hülya; Erginal, Ahmet Evren; Ersin, Sinem; Selim, H. Haluk; Kaya, Hakan
    A sediment core covering the last millennium from Lake Aktas, a shallow alkaline soda lake in the northeast Anatolian highland of Turkey, was studied for pollen and physical and chemical proxies to reconstruct past climate change. The sediments were dated by AMS radiocarbon dating of bulk organic carbon. Among arboreal pollen (AP) from around 930 years ago, dominant trees were Pinus sylvestris, Picea orientalis, Abies, Betula, Fagus, and Quercus. AP exceeded NAP (non-arboreal pollen) in this time, whereas the opposite is the case in a pollen trap in the same region collecting the pollen for one year in 2015-2016. The comparison of modern and fossil pollen influx indicates that in that period trees were more widely distributed around the lake than today, where steppe vegetation now prevails. Inferred causes for the disappearance of trees are anthropogenic impacts and climatic change towards more continental conditions. The results also identify the onset of the Little Ice Age in the NE Anatolian highland of Turkey. (C) 2018 Elsevier Ltd and INQUA. All rights reserved.
  • Küçük Resim Yok
    Öğe
    MULTI-PROXY SEDIMENTARY RECORDS OF DRY-WET CLIMATE CYCLES DURING THE LAST 2 KA FROM LAKE CILDIR, EAST ANATOLIAN PLATEAU, TURKEY
    (Comitato Glaciologico Italiano, 2019) Erginal, Ahmet Evren; Cağatay, M. Namık; Selim, H. Haluk; Karabıyıkoğlu, Mustafa; Çakır, Cağlar; Yakupoğlu, Nurettin; Kaya, Hakan
    Multi-proxy analyses together with AMS radiocarbon dating of sedimentary organic carbon of a sediment core from Lake Cildir, NE Turkey was carried out to study temporal changes in climate over the last two millennia. The lake is characterized by very fine to coarse silt-sized, carbonate-free sediments deposited at a relatively low sedimentation rate of less than 0.31 mm/yr. Results from element geochemistry, total organic carbon (C-org), and physical properties (gamma density and magnetic susceptibility results testified the occurrence of alternating cycles of drier and wetter climatic periods since about 2.2 ka cal BP. The period from 2166 +/- 112 cal BP to the onset of Little Ice Age, including the Medieval Climatic Anomaly, is represented by alternation of warm and wet conditions with intervening relatively low-magnitude dry periods. The cold Little Ice Age period, on the other hand, was dry, with upward decreasing trends of Zr and Ti and C-org as well as relatively low values of Rb/Sr, indicating decreasing chemical weathering intensity in the drainage basin and low organic productivity in the lake.