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The Arabia‐Eurasia continental collision created the Caucasus Mountains and the Anatolian and Iranian plateaus. Between the two plateaus, the Armenian Highland features young Holocene‐aged volcanoes. In this study, the P‐wave receiver functions from a new seismic array reveal a thick crust (up to ~52 km thick) beneath the Central Greater Caucasus and an unusually thin crust (32–35 km thick) beneath the northwestern part of Armenia near the Aragats stratovolcano and Gegham volcanic ridge formed by Pleistocene to Holocene monogenetic cinder cones. The average crustal VP/VS ratio in the Armenian Highland is anomalously high (≥1.9), with the highest value approaching 2.1 under the Gegham Ridge. Such high VP/VS ratios cannot be explained by an overall mafic crustal composition. Instead, the presence of partial melts is inferred in the lower crust based on the depth of the low‐velocity structure obtained by inversion of receiver function waveforms. Our study suggests that the postcollisional volcanism was potentially facilitated by the small‐scale removal of lithospheric mantle, resulting in a localized thinner crust balanced by thermal buoyancy and dynamic flow in the uppermost mantle beneath the Armenian Highland. Key Points: Thin crust with unusually high VP/VS ratios is found beneath the volcanoes Aragats and Gegham in the Armenian Highland based on a new arrayPartial melts probably exist near the base of the crust, where high heat flow is supplied from the uppermost mantleLithospheric mantle beneath northwestern Armenia may have been thinned or even completely removed during previous eruptions [ABSTRACT FROM AUTHOR]

Located in the heart of the Lesser Caucasus mountains, where the Arabian and Eurasian tectonic plates collide, Armenia occupies an exceptional geological position shaped through millions of years of subduction and collision. It is a unique place on the Earth recording extensive intrusive and volcanic activity related to the long‐standing continental convergence. The volcanoes of Armenia provide a rare opportunity to study the sources and processes involved in this unusual type of magmatism. More than 500 Quaternary volcanoes have been mapped in Armenia, most of them formed from single eruptive episodes. Among several large composite volcanoes, the mighty Aragats stands out as the largest volcano in Armenia and the region altogether. Volcanic deposits testify to the range of eruptive styles—from the ignimbrites formed in eruptions as explosive and voluminous as any seen globally in the modern era to the enormous fissure‐fed lava flows that form the Southern Caucasus flood basalt province, the smallest and youngest Large Igneous Province in the world. Several pre‐historical and historical eruptions have been documented, highlighting the potential for future volcanic activity in the region. In recent years, research has focused on the volcanic hazards associated with the Armenian Nuclear Power Plant, located in the foothills of Aragats volcano. This article highlights some of the extraordinary volcanic and intrusive features observed in Armenia and summarizes aspects of recent volcanological and petrological research. [ABSTRACT FROM AUTHOR]