Tephrochronological Synchronisation of the Dead Sea and Lake Van ICDP sediment records in the eastern Mediterranean for the last 130 kyrs (TephroMed)

该项目旨在精确同步来自死海和凡湖的ICDP沉积岩芯，以便为调查地中海东部假定的区域水文气候差异提供可靠的年代学基础。对于死海和凡湖沉积物记录，已经根据不同的相对和绝对测年技术建立了独立的年表，但这些年表存在相当大的不确定因素，特别是在放射性碳时间范围之外。这妨碍了对这些关键的古气候记录进行详细的比较和整合，以便调查区域气候差异。我们将利用在沉积物记录中寻找隐形火山玻璃碎片(宏观上看不见的火山玻璃碎片)的最新进展，这些记录已被证明是一种合适的区域同步工具，即使无法获得相关火山喷发的准确年代。我们的目标是在死海ICDP岩芯中寻找上一次冰期/间冰期循环期间主要气候转变周围的玻璃碎片，并通过常量和微量元素化学将这些玻璃碎片与凡湖记录中选定的主要可见Tephra层的玻璃碎片联系起来。在一项初步研究中，我们可以证明来自安纳托利亚的火山玻璃在死海沉积物中比预期的要丰富得多。到目前为止，Erciyes Dag(安纳托利亚中部)、Süphan和Nemrut(安纳托利亚东部)火山的早期全新世和晚期冰川喷发的强烈地球化学关联是成功的。这使得死海火山喷发与安纳托利亚火山喷发的相关性非常有希望，即使由于大量具有相似地球化学的安纳托利亚火山喷发，这可能不可能适用于死海的所有特弗拉地平线。我们将应用玻璃碎片形态以及常量元素和微量元素地球化学进行对比。除了死海和凡湖岩心之间的直接联系外，我们还试图通过与合作伙伴合作，通过与安纳托利亚近岸沉积物和其他湖泊沉积物记录的玻璃化学进行对比，确定火山中心，并在可能的情况下确定主要的特弗拉岩层的准确喷发。我们在英国的合作伙伴正在进行的Leverhulme项目中，进一步尝试与死海附近黎凡特考古遗址中发现的Tephra进行关联。即使来自意大利和希腊火山中心的隐翅虫在死海沉积物中相对罕见，我们也会调查与这些来源的可能关联。最终，基于Tephra的死海和Van ICDP岩心的同步将为测试两个岩心的独立年龄模型提供坚实的基础，并减少目前的测年不确定性。最后，这两个关键古气候记录的同步将允许在时间上量化和更好地了解地中海东部的区域水文气候差异。

This project aims at precise synchronisation of the long ICDP sediment cores from the Dead Sea and Lake Van in order to provide a robust chronological fundament to investigate the assumed regional hydroclimatic differences in the eastern Mediterranean. For both the Dead Sea and Lake Van sediment records independent chronologies based on different relative and absolute dating techniques have been established which, however, suffer from rather large dating uncertainties especially beyond the radiocarbon time scale. This prevents from a detailed comparison and integration of these key palaeoclimatic records in order to investigate regional climatic differences. We will make use of recent advances in the search for cryptotephra (macroscopically invisible volcanic glass shards) in sediment records that have been demonstrated as a suitable tool for regional synchronisation even if a precise dating of the correlating volcanic eruptions is not available. We aim at searching for glass shards in the Dead Sea ICDP core around major climatic transitions during the last glacial/interglacial cycle and correlate these through major and trace element chemistry with glass shards from selected major visible tephra layers in the Lake Van record. In a pilot study we could prove that volcanic glass from Anatolian sources is much more abundant in the Dead Sea sediments than expected. So far, a robust geochemical correlation with early Holocene and late Glacial eruptions of the Erciyes Dag (central Anatolia), Süphan and Nemrut (eastern Anatolia) volcanoes was successful. This makes correlations of Dead Sea tephra with Anatolian volcanic eruptions very promising, even if that presumably will not be possible for all tephra horizons in the Dead Sea due to the large number of Anatolian eruptions with similar geochemistry. We will apply glass shard morphology as well as major and trace element geochemistry for correlations. In addition to the direct link of the Dead Sae and Lake Van cores, we attempt to determine the volcanic centres and where possible the exact eruption of major tephra horizons through correlation with glass chemistry from proximal deposits and other lacustrine sediment records in Anatolia through collaboration with partners. We further attempt correlation with tephra found in archaeological sites in the Levant near the Dead Sea in an ongoing Leverhulme project by our partners in the UK. Even if cryptotephra from Italian and Hellenic volcanic centres is comparably rare in the Dead Sea sediments, we will investigate possible correlations with these sources. Ultimately, a tephra-based synchronisation of the Dead Sea and Lake Van ICDP cores will provide a solid base for testing the independent age models of both cores and reduce present dating uncertainties. Finally, the synchronisation of these two key palaeoclimatic records will allow to temporally quantify and better understand regional hydroclimatic differences in the eastern Mediterranean.