Description: Highlights • Combined U-Pb and (U-Th)/He dating provides accurate eruption ages for the Gorelka tephra. • The largest marine transgression of the Eastern Paratethys in the Miocene was at ∼11.5 Ma. • VEI ∼7.4 eruption from a volcanic source in the Carpathians produced the Gorelka tephra. • Westerly winds transported the Gorelka tephra ∼1500 km ENE from the volcanic source. Volcanic ash layers (tephras) dispersed over large areas may offer important time markers in the geological record provided their age and geochemical fingerprint can be established. Accurately dated and geochemically characterized tephras are essential in correlation of temporally and spatially discontinuous geological records, which is key for paleoenvironmental, paleoclimatic, and paleogeographic reconstructions. Here we report geochronological and geochemical data for the Gorelka tephra (southwestern Russia) – a prominent tephra of uncertain age and origin that provides a key time marker for the largest marine transgression of the Eastern Paratethys Sea in the Miocene. Coupled U-Pb and (U-Th)/He dating of zircon crystals constrains the eruption age of the Gorelka tephra, and hence the age of the highest stand of Eastern Paratethys in the Miocene, to 11.5±0.5 Ma. Geochemical characteristics in combination with the new eruption age and tephra volume estimates suggest a magnitude ∼7.4 eruption from a volcanic source in the Transcarpathian region. The Gorelka tephra was transported ∼1,500 km ENE from its source by westerly winds, which were typical for the atmospheric circulation regime within the Ferrel cell in Central Europe during Sarmatian times. Based on the results presented here, the Gorelka tephra provides a reliable tie-point for paleoenvironmental and stratigraphic correlations across southeastern Europe.