Deciphering the magma storage conditions and preeruptive processes at Cumaçay: a Plio-Quaternary volcanic eruption center in Eastern Anatolia, Turkey

Abstract

: We investigate the geology and petrology of Cumaçay, one of the Plio-Quaternary eruption centers of postcollisional volcanism in Eastern Turkey, using a combination of geochronology, bulk-rock geochemistry, thermobarometry, and thermodynamic simulations. Our new K-Ar ages reveal an age of 3.5–0.97 Ma for the eruptive products, which spread around an area of approximately 1000 km 2 . Mineral-melt equilibria for olivine, orthopyroxene, clinopyroxene, and plagioclase allow estimation of crystallization pressures, and temperatures indicate two separate crustal storage of crystallization at 14–28 km and 5–15 km. The temperature estimation from diverse methods ranges from 954 °C to 1224 °C. Thermodynamic modelings using Magma Chamber Simulator (MCS) at a representative pressure (5 kbar) imply that the assimilation and crustal contamination (AFC) resulted in evolved melts with various SiO 2 contents at mid to lower crustal depths. Calculated wide range of temperatures, compositional variety from evolved members, and MCS recharge simulation at a representative pressure (2.5 kbar) reveal that the magma mixing between contrasted melts characterizes the final chemical dispersal of the erupted lavas.