Browsing by Author "Lezhava, Zaza"
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Item Karst Caves Origination Conditions in the Zemo Imereti (Chiatura) Structural Plateau, Georgia.(2019-11-05) Lezhava, Zaza; Asanidze, Lasha; Tsikarishvili, Kukuri; Chikhradze, Nino; Sherozia, Ani; Chartolani, GiorgiZemo 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.Item ON THE EVOLUTION OF KARST CAVES IN THE CONDITIONS OF PLATFORM KARST (ZEMO IMERETI PLATEAU CASE STUDY; GEORGIA)(Ivane Javakhishvili Tbilisi State University, 2019-09-13) Lezhava, Zaza; Asanidze, Lasha; Tsikarishvili, Kukuri; Chikhradze, Nino; Chartolani, Giorgi; Sherozia, AniThe actual materials obtained as a result of our studies carried out during years in the ZemoImereti Plateau, namely, the morphological analysis of karst caves, hydrological-hydrogeological studies, results of tracing (indicator tests) of underground waters, borehole data and others, allow us to prove that the influence of phreatic, vadose and dry epochs has been reflected in the evolution of caves. An important part of karst caves has undergone the phreatic stage of development, though nowadays the traces of pressured flows in most cases have been erased by impact of vadose waters and other processes (corrosion, destruction, formation of speleothems, etc.). It is being also identified that the process of evolution of caves is not similar within the same karst massif that is related to the violation of the normal course of cave development by the influence of tectonic movements or other conditions.In the modern stage of development, the phreatic regime is well expressed in the Ghrudo underground basin, and the traces of both the vadose and dry epochs are well preserved in the higher located caves that went through the cycle of development. The periodic streams play an active role in the next stage of cave development, which, in turn, has been reflected in cyclical nature of sedimentation.