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重复时间。然而，已知的爆炸性喷发的规模往往受到很大的限制，因为大多数估计都是完全基于近端沉积物，而不考虑远端火山灰的大量面纱。许多火山灰羽流被盛行的西风吹向东欧平原，在那里火山灰随处可见，通常与考古层有关。尽管这些火山灰的发现对于古火山学、古气候和考古学研究具有重要意义，但这些发现从未用现代分析工具进行过研究。火山灰只有一个地方，一个集群的旧石器时代遗址的Kostenki-Borschevo（中顿河，俄罗斯），地球化学特征和连接到著名的~40 ka坎帕尼亚火山灰岩喷发（意大利）。大约有100个火山灰遗址分布在俄罗斯南部的大草原上，从北部的彭扎和坦波夫城市到南部的高加索山脉，这些遗址仍然没有得到确认，也没有注明日期。大多数火山岩产于数十米厚的黄土序列中，而少数火山岩也在考古发掘过程中的洞穴中发现。这些火山岩可能来自地中海，喀尔巴阡山脉，土耳其，伊朗北部和高加索地区的火山爆发，一旦进行地球化学分析，就可以了解早期未知的火山事件，其规模和母岩浆的成分。此外，地球化学指纹和定年火山灰层提供了一个很好的工具，精确的相关性和不同的古环境和考古档案定年。我们提出了一个合作的区域研究，在俄罗斯南部，这将包括火山灰和沉积物取样，火山灰沉积的古地理和古环境条件的表征，和随后的地球化学分析（EMPA，LA-ICP-MS，TIMS）和定年（Ar-Ar，U/Pb，（U-Th）/He）的火山灰的现场工作。该项目小组包括来自德国和俄罗斯的火山学家和地球化学家，他们在火山灰合作研究方面具有丰富的经验，以及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（一）破译一个长期期待的火山喷发记录从俄罗斯南部，（二）描绘分布火山喷发从不同的来源，（三）估计年龄和规模的母火山喷发。已确定的火山灰层将被纳入欧洲火山灰框架，并有助于将俄罗斯古环境数据纳入全欧洲范围。

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.