Late Glacial to mid Holocene lacustrine ostracods from southern Anatolia, Turkey:A palaeoenvironmental study with pollen and stable isotopes

This study investigates the ostracod assemblages obtained from a sediment core from a paleolake in the Sağlık plain in south-central Anatolia (Turkey). In addition to ostracods, oxygen and. carbon stable isotopes of ostracod shells were analysed and pollen analysis of the core undertaken. The sediments comprise the Late Glacial and early Holocene interval with an approximate 14C age from 18,000 to 6700 14C years ago, after applying a correction for reservoir effects. Eight podocopid ostracod species were recorded, among them Cyprideis torosa and Candona sp. which were used for stable oxygen and carbon isotope analyses. C. torosa dominated during the Late Glacial while Candona sp. dominated most of the early Holocene assemblages. Both forms of C. torosa disappear abruptly close to the onset of the Holocene. Around this time, ostracod preservation was dominated by many black coloured valves and carapaces. Based on ostracod assemblage data and isotope analyses, relatively wet phases were identified for the Older Dryas, Younger Dryas, and during the mid-Holocene at around 7500 14C years ago. Relatively dry phases were identified during the Allerød interstadial, at the end of YD, and at about 6700 14C years ago. An oligotrophic and brackish lake persisted until shortly before the end of the YD, when, according to the δ 13C values, conditions gradually became more eutrophic. The sudden disappearance of C. torosa at the end of the YD seems the consequence of anoxic bottom water conditions and/or eutrophication. Alternating wet and dry phases characterize the early Holocene, with a longer period of wet and oligotrophic conditions around 7500 14C years ago (ca. 8300 calBP). Ostracod assemblages and isotope records indicate a dry and more productive lake around 6700 14C years ago (ca. 7550 calBP)

Geochronology of Betula extensions in pollen diagrams of Alpine Late-glacial lake deposits:A case study of the Late-glacial deposits of the Gasserplatz soil archives (Vorarlberg, Austria)

<p>Pollen diagrams of Alpine Late-glacial calcareous lake deposits show several extensions of Betula. The geochronology of these extensions cannot be based on radiocarbon dating due to reservoir effects of such lakes on the radiocarbon ages. A robust geochronology can be based on the oxygen isotope stratigraphy. Additionally, recognition of 12,920 calBP LST in the sediment cores provides a secure time marker. The combined results of pollen, macro-remains and stable isotope analyses of the Gasserplatz cores point to a correlation of the Betula extensions with the oscillations in the oxygen isotope curve and are related to global climatic oscillations. This is sustained by the correlation of the Gasserplatz isotope oscillations with the oscillations as registered in the Greenland ice cores. Comparison of the results of the Gasserplatz cores with the results of similar Alpine lake deposits makes clear that the fluctuations in the Betula curve are not a local but a regional phenomenon. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.</p>