GEOLOGY OF GEORGIA – EASTERN BLACK SEA: A REVIEW

The tectonics and geological evolution of the Black Sea-Caspian Sea region, on the whole, are largely determined by its position between the still-converging Eurasian and Africa-Arabian plates, within the zone of a continent-continent collision and deformations. The region during the Late Proterozoic-Early Cenozoic belonged to the now-vanished Tethys Ocean and its northern and southern margins. Within this convergence zone, there existed a system of island arcs, back-arc basins characteristic of the pre-collisional stage of the region.

In the Mesozoic – Early Cenozoic the region was a part of the arc–back-arc system of the Tethys. Under conditions of shrinking oceanic space, the Tethys was reduced to a chain of intercontinental basins of the Mediterranean type. The collision between the Africa–Arabian and Eurasian plates caused inversion of the relief and at the place of intra-arc and back-arc basins were formed mountain fold–and-thrust belts of the Great- and Lesser Caucasus with the Transcaucasian intermountain depression in between. The marine basins of the Tethys were replaced by basins of euxinic type (Paratethys) and later on – by continental basins with shallow marine and subaerial conditions of sedimentation and postcollisional volcanic activity. The Black Sea overlies different structures of the region. Submarine prolongation of the Great Caucasus occurs along pre-Caucasian strip of the sea; the eastern Black Sea high is submarine prolongation of the Georgian block; the Atchara-Trialeti is traced in the central part of the basin, while the submarine prolongation of the Artvin –Bolnisi block occurs along the southern off-shore zone.

The Region is an earthquake prone, where devastating earthquakes have repeatedly caused significant loss of lives, infrastructure and buildings. High geodynamic activity of the region expressed in both seismic and aseismic deformations, is conditioned by northward propagation of the Africa-Arabian continent at a rate of several cm/year. Considerable shortening of the Earth’s crust has been realized in the region through: crustal deformation with development of compressional structures; warping and displacement of crustal blocks with their uplifting, subsidence, underthrusting and lateral escaping.