Diatom oxygen isotope records of Northern Eurasia as indicators of environmental, hydrological and climate changes in the regions
Keywords:stable oxygen isotopes, hydrological fluctuations, diatoms, climate change, lake sediments
The environmental, hydrological and climate dynamics were assessed in Northern Eurasia during the Holocene. The reconstructions are based on oxygen isotope composition of acustrine diatom silica (δ18Odiatom) preserved in sediment cores from Ladoga, Bolshoye Shchuchye and Emanda lakes. Interpretation of the δ18Odiatom data is supported by a comprehensive study of modern isotope hydrology and analysis of local and regional proxies. The Northern Eurasia δ18Odiatom records are characterized by pronounced short term variations (1.5–5‰), pointing to the unstable climatic and hydrological conditions in the study regions. All records have clearly demonstrated a gradual depletion over the Holocene in their δ18Odiatom values by ~3–4‰, which follows the trend of decreasing summer insolation, as well as the temperature history of the Northern Hemisphere (NH), indicating a positive response of diatom oxygen isotope signal to large-scale climate changes.
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