A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history

Abstract

Abstract.A new detailed pollen and oxygen isotope record of the penultimate interglacial-glacial cycle, corresponding to the marine isotope stage (MIS) 7-6, has been generated from the Ahlat Ridge (AR) sediment core at Lake Van, Turkey. The presented Lake Van pollen record (ca. 250.2-128.8 ka) displays the highest temporal resolution in this region with a mean sampling interval of ∼ 540 years.The integration of all available proxies shows three temperate intervals of high effective soil moisture availability. This is evidenced by the predominance of steppe-forested landscapes (oak steppe-forest) similar to the present interglacial vegetation in this sensitive semiarid region between the Black Sea, the Caspian Sea, and the Mediterranean Sea.The wettest and warmest stage, as indicated by highest temperate tree percentages, can be broadly correlated with MIS 7c, while the amplitude of the tree population maximum during the oldest penultimate interglacial (MIS 7e) appears to be reduced due to warm but drier climatic conditions. The detailed comparison of 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 in the successive climatic cycles. Intervening periods of treeless vegetation can be correlated with MIS 7d and 7a, in which open landscapes favor local erosion and detrital sedimentation. The predominance of steppe elements (e.g., Artemisia, Chenopodiaceae) during MIS 7d indicates very dry and cold climatic conditions. In contrast, the occurrence of higher temperate tree percentages (mainly deciduous Quercus) throughout MIS 7b points to relatively humid and mild conditions, which is in agreement with other pollen sequences in southern Europe.Despite the general dominance of dry and cold desertsteppe vegetation during the penultimate glacial (broadly equivalent to MIS 6), this period can be divided into two parts: an early stage (ca. 193-157 ka) with higher oscillations in tree percentages and a later stage (ca. 157-131 ka) with lower tree percentages and subdued oscillations. This subdivision of the penultimate glacial is also seen in other pollen records from southern Europe (e.g., MD01-2444 and I-284;Margari et al., 2010;Roucoux et al., 2011). The occurring vegetation pattern is analogous to the division of MIS 3 and MIS 2 during the last glacial in the same sediment sequence. Furthermore, we are able to identify the MIS 6e event (ca. 179-159 ka) as described in marine pollen records, which reveals clear climate variability due to rapid alternation in the vegetation cover.In comparison with long European pollen archives, speleothem isotope records from the Near East, and global climate parameters (e.g., insolation, atmospheric CO 2 content), the new high-resolution Lake Van record presents an improved insight into regional vegetation dynamics and climate variability in the eastern Mediterranean region.

First Calibration and Application of Leaf Wax n-Alkane Biomarkers in Loess-Paleosol Sequences and Modern Plants and Soils in Armenia

“…Some pollen studies that have been conducted on Early to Middle Quaternary deposits (e.g., Shamb section-paleo-lake sediments in southern Armenia: [3]; North Caucasus and Kazakhstan: [65]) have suggested that the Pleistocene climate was characterized by an alternation of wet conditions during glacial periods and dry conditions during interglacial periods. Other, more modern pollen studies based on precise chronologies (Shamb section in southern Armenia: [5]; Dmanisi (Georgia): [66]; Lake Urmia (NW-Iran): [67]; Lake Van (Eastern Turkey): [68,69]) contradict this interpretation and suggest that glacial periods have been dry and cold and predominantly linked to a vegetation cover composed of grasses and herbs. In view of the high heterogeneity of hydrological conditions during glacial-interglacial cycles that must be expected for the mountainous Caucasus region, a comparison with these faraway paleoenvironmental archives will probably not lead to reliable statements.…”

Controls on Cyclic Formation of Quaternary Early Diagenetic Dolomite

“…Instead, it provides a unique opportunity for testing the envelope of environmental conditions assumed essential for dolomite formation. If juxtaposed with environmental proxies reflecting regional and local hydrological conditions (Kwiecien et al, ; Litt et al, ; North et al, ; Pickarski, Kwiecien, Djamali, et al, ; Pickarski, Kwiecien, Langgut, et al, ; Pickarski & Litt, ; Randlett et al, ; Stockhecke, Sturm, et al, ; Tomonaga et al, ) (Figure ), the dolomite occurrence is incompatible with the commonly accepted hypothesis of evaporitic conditions driving its formation. Our high‐resolution dolomite concentration data (Figure ), presented on the common Lake Van age model (Stockhecke, Kwiecien, et al, ), suggest that most of the dolomite‐rich intervals coincide with sediments deposited during a high lake level and generally wetter conditions.…”

Supplementary material to "Enhanced western Mediterranean rainfall during past interglacials driven by North Atlantic pressure changes"

“…(15) Lake Van in Turkey (Pickarski and Litt, 2017). The Mg/Ca-SSTs closely follow the runoff proxy, Ba/Ca values.…”