Age and compositional evolution of Sahand volcano in the context of post-collisional magmatism in northwestern Iran: Evidence for time-transgressive magmatism away from the collisional suture

摘要: Abstract Sahand volcano along with the two neighbouring volcanic systems of Saray and Sabalan are three Late Miocene-Quaternary volcanoes that formed in wake collision between Arabian Eurasian continental plates Neo-Tethyan suture zone northwestern Iran. is an isolated, extensive (3707 m elevation; >3000 km2 area) stratovolcanic complex, which located ~165 km north was constructed over ~45 km thick crust. Andesitic to dacitic pyroclastic deposits, ignimbrites, lava flows form now strongly eroded Paleo- Meso-Sahand edifice. Paleo-Sahand rocks mostly restricted central part edifice, where they underlie deposits. By contrast, Neo-Sahand intruded older successions within outside a largely caldera margin, likely during stage. units comprise several basaltic andesitic rhyolitic domes center complex as well small parasitic cones subvolcanic dikes. High spatial resolution sensitivity U-Pb geochronology using secondary ionization mass spectrometry (SIMS) define formation Paleo-, Meso-, ca. 8 3 Ma, 1 Ma, 600