Tethyan evolution and continental collision in Georgia

Authors: Sh. Adamia, A. Chabukiani, T. Chkhotua, O. Enukidze N. Sadradze, G. Zakariadze

Georgia, the westernmost part of the southern Caucasus, is located at the junc- tion of the European and Asiatic branches of the Alpine-Himalayan orogenic belt and represents a unique area where the Tethys Ocean was completely closed only in the late Cenozoic as a result of prolonged convergence between the Eurasian and Africa-Arabian plates.

During the Neoproterozoic–early Cenozoic, the territory of Georgia and the adjacent area of the Caucasus were parts of the Tethys Ocean and its northern margin. The Tethys was not a single continuous oceanic plate, but rather developed in branches separating continental terrains of different sizes, which rifted and drifted away from the Gondwana margin and eventually collided with Laurasia. Prior to the final collision in the late Cenozoic, the region hosted systems of island arc, intra-arc, and back-arc basins located between the East European continent and the oceanic basins of the Tethys.

Integrative geological and paleogeographical studies show a collage of several tectonic units (terranes) in Georgia and adjoin- ing areas that have distinctive geological histories with marine Tethyan, Eurasian, or Gondwanan affinities. These include the Scythian platform, the Great Caucasus, the Transcaucasus-Pontides, and the Lesser Caucasus–Alborz–West Iran regions. Their position between the Africa-Arabian and Eurasiatic continents provides a rea- son for grouping them into the Northern Tethyan (Eurasian) and Southern Tethyan (Gondwanan) domains. The Scythian platform, Great Caucasus, and Transcaucasus- Pontian belts are of North Tethyan origin, while Anatolia, Taurus, Iran, and the southern Lesser Caucasus belong to the South Tethys. The Arabia-Nubian Shield, at the end of the Proterozoic, experienced basement consolidation related to the final stages of the Pan-African cycle of tectogenesis.

In contrast to the southern Lesser Caucasus (Daralagöz), the Transcaucasus did not undergo this process because it broke away from the Arabia-Nubia Shield and, during Cambrian–Devonian times