Petrogeochemical Model of Neogene-Quaternary Collision Volcanism of Lesser Caucasus

Neogene volcanism in the Lesser Caucasus is mainly manifested itself, starting from the upper Sarmatian, Meotis-Ponte to the Upper Pliocene. Volcanites composition meets mainly andesites and trachyandesites, dacites and trachydacites and also rhyolites (SiO2-60-78%). The volcanism was very powerful in relation to the attic tectonic activity of Late Miocene-Early Pliocene. During this period there occurs Pre-Mesozoic base uplift and volcanism is mainly manifested in the central parts of the anticlinal zones of the Lesser Caucasus. The andesites and andesidacites with acid pyroclasts dominate in the products’ composition at the beginning of the volcanic phase and at its end - andesite lavas. Magmatism of the main composition of high alkalinity has locally been manifested in the extreme parts of the anticlinal zones. Subvolcanic appearings of formation invaded after volcanogenic strata (Basarkechar suite) formation and have more acid composition. After active effusive-explosive activity of Meotian-Pontian-Early Pliocene volcanoes, more acid and viscous magma, cooling at a depth, rising along fractures at shallow depths hardened in the form of dikes and other subvolcanic bodies (Imamverdiyev, 2000).