VS06 Benchmarking Pyroclastic Density Current Models: Code Inter-Comparison and Field Validation

Geological data and petrography indicate that the Armenian ignimbrites can be subdivided into three main groups: the welded ashy-tuffs of Yerevan-Leninakan type, the "flame" tuffs of Shamiram-Byurakan type, and the welded ignimbrites of Artik type. The first two types have an ash matrix and are distinguished from each other by the degree of welding and fiamme content, as well as the relative abundances of vitro- and crystal-clasts. The Yerevan-Leninakan type and Shamiram-Byurakan type ignimbrites are characterized by distinct features, including ash matrix composition and fiamme content. In contrast, the Artik tuffs are characterized by eutaxitic textures and low litic clasts content. Bulk rock major element compositions of Middle Pleistocene ignimbrites correspond to high-K trachydacites and trachyandesites, while fiamme and glass separates from the matrix are silica-rich and correspond to rhyolite and high silica trachydacite magma source. Recent 40Ar/39Ar dating of some Aragats ignimbrites by AIST, Japan, yielded ages of 0.65±0.038 Ma for Shamiram-Byurakan type and 0.66±0.040 Ma for Yerevan-Leninakan ignimbrites. These ages are consistent with earlier K-Ar age determinations of associated lava flows and paleontological data on rodents. The new ignimbrite ages provide valuable information on the timing of volcanic activity in the region. The study of Quaternary ignimbrites in Armenia is significant for understanding the geological history of the region. The subdivision of ignimbrites into three main groups provides valuable insights into the petrology and stratigraphy of the area. The results of this study have implications for the understanding of volcanic activity in the Eurasia-Arabia collision zone and the formation of ignimbrites in this region.