Development History of the Migaria Massif Karst Terrain

Abstract

On the basis of many years of field, experimental and laboratory (dye tracing, laboratory study of bedrocks, data analysis of geological sections, etc.) studies and analysis of available literary sources, the history of karst terrain development was restored on the Migaria limestone massif. Based on the mentioned materials, it can be said that the karstification on the Migaria limestone massif took place throughout the Pliocene and partially in the Upper Miocene, and therefore, the beginning of the formation of the karst terrain can be considered the entire Pliocene and possibly the Upper Miocene as well. The Rhodanian orogeny phase (after the Middle Pliocene, during the Cuialnic era), which was continued into the Wallachian orophase, led to a new uplift of the Caucasus, followed by the activation of karst processes on the surface and underground. New orogenic movements of the Early Pleistocene enhanced the splitting of limestone suites and the activity of karst formation processes. The same period should be related to the formation of caves (Shurubumu, Koko, Khuru, etc.) developed in the gorges of the rivers of Khobistskali, Ochkhomuri and their tributaries, namely, the transition from the phreatic to the vadose period and their further development. Thus, it can be said that the formation of the karst cavities of the Migaria massif occurred mainly before the Pleistocene or in the Lower Pleistocene. In the post-glacial period, along with karst processes, rockfalls, landslides, and mudflows played an important role in the change of the terrain of the study area, as indicated by the displaced boulders of volcanic origin of the Bajocian age (tuff sandstone) distributed in the gorges of the Khobistskali River and its tributaries, as well as on the terrace steps and verified by our laboratory tests. The bedrocks are found in the upper reaches of the Khobistskali River and thay are brought as a result of powerful landslide-mudflow processes. In the last stage of the modern geomorphological cycle, surface and underground karst forms are actively modified by the flows of melted snow and rain water.