A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history
A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history
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DOI：
10.5194/cp-13-689-2017
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发表时间：
2016-12
影响因子：
4.3
通讯作者：
N. Pickarski;T. Litt
中科院分区：
文献类型：
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作者：
N. Pickarski;T. Litt
抽象的。土耳其货车湖的阿赫拉特海岭（AR）沉积物岩芯记录了倒数第二次间冰期-冰期旋回（对应于海洋同位素阶段（MIS）7-6）的新的详细花粉和氧同位素记录。货车湖的花粉记录（约1000年）。250.2- 128.8ka），平均采样间隔为1.540万年，显示了该地区最高的时间分辨率。所有可用的代理集成显示三个温带区间的高有效土壤水分的可用性。这是证明了草原森林景观（橡树草原森林）的优势，类似于目前的间冰期植被在这个敏感的半干旱地区之间的黑海，里海和地中海。最潮湿和最温暖的阶段，所示的最高温带树木的百分比，可以广泛地与MIS 7 C，而最古老的倒数第二次间冰期（MIS 7 E）的树木种群最大幅度似乎减少，由于温暖，但干燥的气候条件。对倒数第二次间冰期复合体（MIS 7）与末次间冰期（Eemian，MIS 5e）和当前间冰期（全新世，MIS 1）的详细比较，生动地说明了连续气候循环中可能存在的差异。无树植被的干预时期可以与MIS 7 d和7a相关，其中开放的景观有利于局部侵蚀和碎屑沉积。草原元素的优势（例如，蒿属，藜科）在MIS 7 d表示非常干燥和寒冷的气候条件。与此相反，整个MIS 7 B的温带树木（主要是落叶栎）的百分比较高的发生点相对潮湿和温和的条件下，这是在南欧的其他花粉序列的协议。尽管在倒数第二次冰期（大致相当于MIS 6）期间，干旱和寒冷的荒漠草原植被占主导地位，但这一时期可以分为两个部分：早期阶段（约2000年）。193-157 ka），树木百分比和后期阶段（约。157-131 ka），树木比例较低，振荡减弱。倒数第二个冰川的这种细分也见于南欧的其他花粉记录中（例如，MD 01 -2444和I-284; Margari等人，2010; Roucoux等人，2011年）。其植被格局类似于末次冰期同一沉积序列中MIS 3和MIS 2的划分。此外，我们能够识别MIS 6 e事件（约。179-159 ka），如海洋花粉记录所述，这揭示了由于植被覆盖的快速变化而导致的明显的气候变化。与欧洲长期花粉档案、近东洞穴沉积物同位素记录和全球气候参数（例如，日照、大气CO2含量），新的高分辨率Lake Van货车记录提供了对东地中海地区区域植被动态和气候变率的更深入了解。
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 desert-steppe 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 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.