2.8-Ma ash-flow caldera at Chegem River in the northern Caucasus Mountains (Russia), contemporaneous granites, and associated ore deposits - Lipman, P.; Bogatikov, O.A.; Tsvetkov, A.A.; Gazis, C.; Gurbanov, A.G.; Hon, K.; Koronovsky, N.V.; Kovalenko, V.I.; Marchev, P. (Journal of Volcanology and Geothermal Research, 1993)