Diatremes of the Vedi Rift with a Rb-Sr age of 173–102 Ma are mainly made up of holohyaline (vitroclastic) tuffs, a variety atypical of alkaline lamprophyres. In terms of morphology and mineral-geochemical features, they are subdivided into small pipes (< 90×30 m) of near-axial relatively deep-seated part of the rift basin and large (450×280m) pipe of shoal zone. The tuffs contain intratelluric minerals cognate to the alkaline lamprophyres, as well as high-pressure xenocrysts and crustal and mantle xenoliths. The diatremes were formed during post-Permian rifting of the continental crust of the southern Transcaucasian geotraverse complicated by short-term pulses of compression that triggered the explosive activity of diatremes. The explosive activity was promoted by weakening of the crustal permeability, accumulation of fluids in the primary basanite magma, and its unmixing.