The age of young intrusions of Tsana Complex (Greater Caucasus) and isotope-geochemical evidence for their origin from hybrid magmas

A study of the Tsana Complex in Upper Svaneti, Georgia, reveals that its granitoids formed from hybrid magmas through the mixing of mantle-derived and crustal melts. Using K-Ar and Rb-Sr isotope dating, researchers identified two distinct pulses of Pliocene magmatism: one at 4.80 ± 0.15 Ma and another at 4.15 ± 0.10 Ma. The Tsurungal Group, characterized by its diverse rock types (diorite to granite), shows evidence of both crystallization differentiation and crustal contamination, while the Karobi Group, consisting of rhyodacite bodies and trachyandesite dikes, formed during the earlier pulse. Isotope-geochemical analysis further supports the hybrid origin, with notable differences in Sr isotope composition between the two phases (0.7053 vs. 0.7071). This research sheds light on the complex petrogenesis of post-collisional granites and the spatiotemporal evolution of magmatic activity in the Greater Caucasus.

Lebedev, V. A., Dudauri, O. Z., Togonidze, M. G., & Gol’tsman, Yu. V. (2016). The age of young intrusions of Tsana Complex (Greater Caucasus) and isotope-geochemical evidence for their origin from hybrid magmas. Petrology, 24(4), 315–335. https://doi.org/10.1134/s0869591116040032