Decoding a post-collisional multistage magma system: The Quaternary ignimbrites of Aragats stratovolcano, western Armenia

Locally Thin Crust and High Crustal VP/VS Ratio Beneath the Armenian Volcanic Highland of the Lesser Caucasus: A Case for Recent Delamination

“…Activity in the Early-Mid Pleistocene mainly produced layers of trachybasalts, trachybasaltic andesites, dacites, and pyroclastic flows (Gevorgyan et al, 2018;Karakhanian et al, 2003;Meliksetian et al, 2014). The latest major ignimbrite units (0.72-0.65 Ma) are approximately 30-40 m thick and cover an area of more than 5,000 km 2 (Gevorgyan et al, 2018). The youngest lavas overlying the top ignimbrite layers are dated to~0.5 Ma (Chernyshev et al, 2002;IAEA, 2016).…”

“…The youngest lavas overlying the top ignimbrite layers are dated to~0.5 Ma (Chernyshev et al, 2002;IAEA, 2016). Based on the geochemical signatures and mineral chemistry, Gevorgyan et al (2018) proposed multistage eruptions; furthermore, the magmatic chamber of Aragats' mid-Quaternary ignimbrite eruption is estimated to be at a depth of~25 km, and the main magma is inferred to have been derived from the shallow upper mantle (depth <75 km). These depths are comparable with the low-velocity structures under the stations ZARN, SHEN, BYUR, and ARZA in our study (Figures 4 and S2).…”

“…Although the overall crustal structure beneath the CIA has been constrained using large-scale seismic arrays (e.g., Gök et al, 2011), features in the Armenian Highland and the Lesser Caucasus remain uncertain due to sparse sampling. With a new local array in Armenia (Figure 2), this study provides a unique chance to compare structures under two distinct types of volcano clusters, the Early-Middle Pleistocene stratovolcano Aragats (Gevorgyan et al, 2018;IAEA, 2016;Meliksetian et al, 2014) and the Gegham volcanic ridge, which was active during the Networks IU (Global Seismograph Network), KO (Kandilli Observatory of Turkey), and GO (Georgian National Seismic Network) consist of permanent stations with data available to the public. Holocene and Pleistocene volcanoes are obtained from the Global Volcanism Program (2013).…”

“…Although the overall crustal structure beneath the CIA has been constrained using large‐scale seismic arrays (e.g., Gök et al, 2011), features in the Armenian Highland and the Lesser Caucasus remain uncertain due to sparse sampling. With a new local array in Armenia (Figure 2), this study provides a unique chance to compare structures under two distinct types of volcano clusters, the Early‐Middle Pleistocene stratovolcano Aragats (Gevorgyan et al, 2018; IAEA, 2016; Meliksetian et al, 2014) and the Gegham volcanic ridge, which was active during the Pleistocene‐Holocene in Armenia (Karakhanian et al, 2003; Sherriff et al, 2019). We present detailed variations in the crustal structure constrained by receiver functions (RFs) in the Armenian Highland for the first time and discuss the possible control of delamination styles during continental collision.…”

Pleistocene volcanism and the geomorphological record of the Hrazdan valley, central Armenia: linking landscape dynamics and the Palaeolithic record

“…Other PDC deposits generated by explosive eruptions of the Aragats volcano are found throughout the Aragats volcanic massif and beyond (e.g. outcropping below mafic lavas at Aramus on the E side of the Hrazdan valley) and comprise at least six stratigraphically distinct ignimbrites (Gevorgyan et al, 2018). K-Ar age estimates on ignimbrite units to the W and S of Arailer span the period 0.9-0.6 ma (Mitchell and Westaway, 1999;IAEA-TECDOC-1795.…”