A new high-resolution pollen sequence at Lake Van, Turkey, during MIS 6-7
2017
Pickarski, Nadine | Litt, Thomas
A new detailed pollen and oxygen isotope record of the penultimate interglacial-glacial cycle, corresponding to the Marine Isotope Stage (MIS) 7–6 (c. 242.5–131.2 ka before present), has been generated from the "Ahlat Ridge" (AR) sediment core at Lake Van, Turkey. The presented record displays the highest temporal resolution for this interval with a mean sampling interval of ~540 years. Integration of all available proxies shows three intervals of effective moisture, evidenced by the predominance of forested landscapes (oak-pine steppe forest), which can be correlated with MIS 7e, 7c, and 7a. The warmest stage in terms of highest temperate tree percentages is MIS 7c, while the amplitude of MIS 7e appears to be truncated by a shift to colder/drier climatic conditions. The detailed comparison between the penultimate interglacial complex (MIS 7) to the last interglacial (Eemian, MIS 5e) and the current interglacial (Holocene, MIS 1) provides a vivid illustration of possible differences of successive climatic cycles. Intervening periods of open steppe landscape correlate with MIS 7d and 7a, favouring local erosion and detrital sedimentation. The predominance of steppe elements during MIS 7d indicates very cold/dry climatic conditions. In contrast, the occurrence of more temperate tree percentages throughout MIS 7b points to relatively mild conditions, in agreement with atmospheric CO2 concentration and oxygen isotope records. Despite the general dominance of dry/cold desert-steppe vegetation during the penultimate glacial (MIS 6), this period can be divided into two parts: an early stage (c. 193–157 ka BP) with pronounced oscillations in tree percentages, and a later stage (c. 157–131 ka BP) with lower tree percentages and subdued oscillations. The occurring vegetation pattern is analogous to the MIS 3 to MIS 2 division during the last glacial in the same sedi–159 ka BP) as described in marine pollen records, which indicates cooler but relatively wetter climate conditions during the penultimate glacial. In comparison with long European pollen records, speleothem isotope records from the Near East, and global climate parameters (e.g., insolation, atmospheric CO2 content), the new high-resolution Lake Van record presents an improved insight into regional vegetation dynamics and climate variability in the eastern Mediterranean region.
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Este registro bibliográfico ha sido proporcionado por Alfred Wegener Institute for Polar and Marine Research