Karst Caves Origination Conditions in the Zemo Imereti (Chiatura) Structural Plateau, Georgia.

Abstract

Zemo Imereti structural karst region comprises the easternmost part of the limestone strip of Georgia and it is the only platform karst region in Georgia. The peculiarity of the relief of the mentioned plateau, namely, dense and deep (100-250 m) fragmentation, sharp distinction of plateaus, their altitudinal (400-800 m above sea level) distribution, plain surfaces (6-12° sloping), as well as the climatic conditions, positive annual balance of runoff and hydrological regime along with the structural-tectonical conditions of substrate constructed karstified rocks creates favourable conditions for karst development. Unlike the geosynclinal karst zone of Georgia, formation of the mentioned region proceeded under the platform conditions. Existence of this solid platform stipulated the relatively simple tectonic structure of Zemo Imereti Plateau; namely, smooth subhorizontal layout of Cretaceous and Tertiary suites over the Hercynian platform and dominated distribution of stratification fissures, which stipulated formation of hydrodynamic zones and wider development of subhorizontal caves (80% of caves are subhorizontal). Karst caves in the Zemo Imereti Plateau are the product of the evolution of hydrodynamic zones significantly. The evolution starts from Pliocene and is still underway. During this long process the hydrodynamic zones are under the permanent changes: dying-drying of upper zones and conceiving-watering of lower zones. Post-Sarmatian intensive ascending tectonic movements and short-term delay epochs mainly stipulated the storey distribution of represented caves and wide distribution of tunnel type caves. Correlation of relative heights of caves levels and terrace stairs, as well as the absolute heights of caves entrances and karst sources outlets lets us assume that there should be at least 4-5 slow down epochs of ascending tectonic movements.