Time constraints on the Variscan magmatism along Iskar River Gorge and Botevgrad basin, Bulgaria

The Variscan basement outcropping along the Iskar River Gorge and in the Botevgrad basin gives a perfect opportunity to study the entire late Carboniferous to early Permian magmatic episode including several stages. The initial stage of a K-alkaline magmatism at 330 to 310 Ma, which points to a melting of enriched mantle source, was followed by a voluminous calk-alkaline to K calk-alkaline magmatism and emplacement of several plutons in the interval between 309 and 306 Ma as well as volcanics (307.4±2.2 Ma). Coeval sporadic K-alkaline events are constrained as well. During the third stage, in the interval 288–286 Ma, an intrusion of predominantly acid subvolcanic bodies and dikes took place. After ca. 35 Ma long period of magmatic quiescence, a new episode of magmatic activity started at late Permian–Early Triassic when “A-type” magmatism specific to rifting setting was initiated. The same event is geochronologically proved further east in the Central Balkan and Sliven region (Sinite kamani).