Trans-European ash plumes from the largest explosive volcanic eruptions: A tephra record from the East European Plain

预测未来大喷发的先决条件之一是了解过去类似事件的规模和复发时间。然而，由于大多数估计仅基于近端沉积物，而没有考虑远端火山灰的大量面纱，因此对已知爆炸性喷发的规模往往限制得很差。许多火山灰柱被盛行的西风吹散，吹向东欧平原，那里到处都是火山灰的发现，而且常常与考古层有关。尽管这些发现对古火山学、古气候学和考古研究具有重要意义，但这些发现从未被现代分析工具研究过。只有来自俄罗斯顿河中段Kostenki-Borschevo旧石器时代遗址群的Tephra被地球化学表征，并与著名的~40 ka Campanian Ignimbrite火山喷发（意大利）相关联。从北部的奔萨和坦波夫市到南部的高加索山脉，散布在俄罗斯南部草原上的大约100个其他的火炬手遗址仍未被确认和确定日期。在考古发掘过程中，在洞穴中也发现了少量碲，但大部分碲产于数十米厚的黄土层中。这些火山喷发可能来自地中海、喀尔巴阡山脉、土耳其、北伊朗和高加索的火山喷发，一旦进行地球化学分析，就可以了解早期未知的火山事件、它们的规模和母岩浆的成分。此外，地球化学指纹和年代测定为不同古环境和考古档案的精确对比和年代测定提供了一个极好的工具。我们建议在俄罗斯南部开展一项区域合作研究，其中包括实地取样和沉积物取样，确定其沉积的古地理和古环境条件，以及随后的地球化学分析（EMPA、LA-ICP-MS、TIMS）和定年（Ar-Ar、U/Pb、(U- th)/He）。项目团队包括来自德国和俄罗斯的火山学家和地球化学家，他们在合作研究火山方面有丰富的经验，还有年轻的俄罗斯古地理学家和地貌学家，他们在俄罗斯南部的古环境研究方面具有专长。我们相信，共同努力将使我们能够(i)破译俄罗斯南部期待已久的麻风记录，（ii）描绘来自不同来源的麻风分布，以及（iii）估计母火山喷发的年龄和规模。确定的热毯层将被整合到欧洲热毯框架中，并有助于将俄罗斯的古环境数据整合到全欧洲背景中。

One of the prerequisites of predicting future giant eruptions is the understanding of sizes and recurrence times of past similar events. The size of known explosive eruptions, however, is often poorly constrained as the majority of estimates are based solely on proximal deposits and do not consider voluminous veils of distal ash. Many ash plumes were dispersed by prevailing westerly winds towards the East European plain where tephra findings are ubiquitous and often associated with archaeological layers. In spite of importance of these tephra findings for the paleovolcanological, paleoclimate and archaeological research, those have never been studied with modern analytical tools. Tephra from only one locality, a cluster of Paleolithic sites of Kostenki-Borschevo (Middle Don River, Russia), was geochemically characterized and linked to the famous ~40 ka Campanian Ignimbrite eruption (Italy). About a hundred of other tephra sites dispersed in south Russian steppe from Penza and Tambov cities in the north to the Caucasus Mountains in the south remain unidentified and undated. Most of the tephras occur in tens of meters thick loess sequences, while a few tephras were found also in caves in the course of archaeological excavations. These tephras are likely derived from Mediterranean, Carpathian, Turkish, North Iranian and Caucasian eruptions and - once geochemically analyzed - could inform about earlier unknown volcanic events, their magnitudes and compositions of parent magma. In addition, geochemically fingerprinted and dated tephra layers provide an excellent tool for precise correlation and dating of disparate paleoenvironmental and archaeological archives. We propose a collaborative regional study of visible tephra layers in south Russia, which will include field work for tephra and sediments sampling, characterization of paleogeographic and paleoenviromental conditions of tephra deposition, and subsequent geochemical analysis (EMPA, LA-ICP-MS, TIMS) and dating (Ar-Ar, U/Pb, (U-Th)/He) of the tephras. The project team includes volcanologists and geochemists from Germany and Russia who have extensive experience in cooperative tephra studies, as well as young Russian paleogeographers and geomorphologists with an expertise in paleoenvironmental research in south Russia. We believe that joint efforts will permit us to (i) decipher a long-anticipated tephra record from southern Russia, (ii) delineate distribution of tephras from different sources, and (iii) estimate the ages and magnitudes of parent eruptions. The identified tephra layers will be integrated into the European tephra framework and contribute to the integration of the Russian paleoenvironmental data into the all-European context.