ENGINEERING-GEOLOGICAL FEATURES OF THE TERRRITORY ALONG THE TURKISH-GEORGIAN BORDER Emil Tsereteli*, N. Gogua*, D. Kalandadze*, T. Lazarashvili*, E. Megrelishvili*, Ali Yılmaz**, Erdal Herece** and Ergun Karacan*** * - Georgian State Department of Geology, 380062, Tbilisi, Georgia. ** - General Directorate of Mineral Research and Exploration, 06520, Ankara, Turkey. *** - C.U. Faculty of Engineering Department of Geological Engineering ABSTRACT This part of the study deals with the engineering-geological features of the Turkish- Georgian border area. According to engineering, lithological and genetical characteristics, 6 continental-cover rock formations with 14 geological-genetical complexes and 6 basement rock units with 11 geological-genetical complexes are wholly distinguished. The general characteristics of the formations and geological-genetical complexes, their lithological and petrographical properties and varieties have been presented. There are characteristic wide spectrum of recent geodynamic processes such as landslides, rock- avalanches, erosion and abrasion. In addition, Quaternary glaciation and its fluvio-glacial sediments within the Eastern Pontides and Adjara-Trialeti mountain systems occurred extensively and in the hyposmetricaly lower levels than the setting which was known before. As a result, the schematic engineering-geological map of the region at 1/200 000 scale has been compiled and also the main directions of further engineering-geological investigations are presented. INTRODUCTION By the united efforts of the General Directorate of Mineral Research and Exploration (MTA)-Turkey and the Georgian State Department of Geology (SDG), between 1994-1996, the first international project was executed foreseening and conducting joint geological investigations and exchanging existing data, on the example of two adjacent territories. There was foreseen, in this project, compiling of engineering-geological map at 1/200 000 scale (Appendix,6), which should represent the coordinated methods, as a model basis of investigations on the territory of the two countries and possible beyond their borders. Georgian side gave information to their Turkish colleagues about the investigations of engineering geology and dangerous geological processes, forecasting and managing 402 problems, carried out in their country, submitted engineering-geological and geodynamic maps at various scales, compiled in Georgia and in the frame of the program in the joint investigations, for the Black Sea Countries. For preparing of mentioned maps, which were used special engineering-geological investigations at 1/200 000, 1/50 000, 1/25 000 and 1/10 000 scale maps used in Georgia for the investigation of special geological studies along the border have been taken as a base for the study in this project. Because of the absence of regional engineering-geological investigations in Turkey, an initial study was carried out between 1995-1996 along the Çoruh River basin and the upper part of the Kura River trough 35 days. The generalization of the engineering- geological map was based on the regional geological map at 1/100 000 scale, jointly prepared by the Turkish and Georgian geologists, and field materials mainly connected to geodynamic and Quaternary sediments. For the engineering-geological characteristics of the rocks were used their physical-mechanical characteristics, presented in Georgia, which give us possibility, by the analogue method, spreading of stratigraphical-lithological properties of complexes with same stratigraphical-lithological properties along the territory of Turkey. So, the analysis, generalization of the existed materials and conducted field works provided a possibility to compile a generalized engineering-geological map of the Turkish-Georgian border-line. Shortage of field materials in the territory of Turkey and absence of geotectonic data from rocks units made the map to be more like a schematic map. GENERAL ENGINEERING - GEOLOGICAL PROPERTIES OF THE ROCKS The study of qualitative nature and engineering-geological peculiarities of building rocks, the establishment of regularity of its physical-mechanical properties spatial changes, are the main fundamental estimations of the territories, used in engineering-economic purposes. Stability of the slopes and nature of the development of the dangerous geological process development, scale, reliability of the location of engineering buildings and totally, organize management of the territory, depend on their properties. Here with, the study on of properties and peculiarities of rocks need long time. The properties change from diagenesis to hypergenesis, in continual interaction with natural and tectogenic environment, estimation of their main characteristics. The limits of the geological environment zones, which built the extreme upper part of the geological section of the lithosphere are given and determined as a multicomponent dynamic system of the human's activity. Spatial characteristics of the engineering-geological properties of rock units, are given according to engineering-geological formations, in conditions of special geotectonical and paleogeographical regime from their properties and peculiarities. 403 The 12 engineering-geological formations are distinguished in the corresponding complexes, according to lithological and genetical signs, in the studied territory. These formations are; (1) basement rocks: terrigenous, flysch, volcanogenic sediments, carbonates, contact-metamorphic and magmatic rocks; (2) continental cover: coastal-delta, river ravines, slopes, close depressions, and mountain glaciation. At first, the engineering-geological characteristics of the basement rocks, were determined in high mountains. Characteristics of all continental cover depend on petrological composition, stability of the basement rocks and the intensity of exodynamic processes. Formations involded by the basement rocks Terrigenous formation Terrigenous formation is represented by geological-genetical complex of the Upper Eocene-Oligocene clayey-sandstone suite. It has wide spread cover on the Eastern part of Akhaltsikhe depression, in Aspindza region, Şavşat and heads of the Potskhovi River. In Şavşat, these sediments have extensive coverage around the Tepeköy, Usluca, Sarıca, Atalar, Çoraklı, Kutlugün, Pınarlı, Meydan, Kocabey and Kirazlı Villages. Hypsometrically these sediments are developed on 700-800 m height, at the bottom of the Şartuldere River ravine and at 2600 m height, in pre-ridge part of Arsiani range. At the heads of the Potskhovi (Posof) river, rocks of this complex crop out in small areas in erosional windows of Goderdzi formations, around the Beykent, Kolköy, Kaleönü and Aşıkzülali Villages. The rocks of the complex, are represented clays, marls, argillites, clays with gypsum, sandstones and conglomerates. Clays and marly clays are the major units. Their thickness ranges from 5 - 10 cm to 0.5 -1 m as a separate layer, and create 80 - 100 m. thick benches. Clays are light blue-grey and dark grey, mainly pelitic, rarely sandy and carbonaceous. They are characterized by bedding and containing of fish scales. The main characteristics of the clays are: natural water content 7.2 – 34.8 %, dry unit weight 1.27 – 1.7 g/cm3, wet unit weight 1.67 – 2.0 g /cm3, specific weight 2.67 – 2.77 and porosity 29.4 – 50.5 %. Quantity of clay grains is 52 – 74 %, within colloidic part (< 0.001 mm) 40 – 45 %. Angle of internal friction 12 - 250, cohesion 0.043 – 0.14 MPa. After saturation (last natural water content 40–50 %), the angle of internal friction decreases from 80 to 120 and cohesion from 0.045 MPa to 0.015 MPa. Modulus of elastisity is 5.0 kg/cm2 in case of loading between 38 - 62, coefficient of porosity 0.7-1.38, after loading 0.62 - 0.82. The some index and mechanical properties of the terrigenous formation are given Table, 1 according to Tsagurishvili (1979). Clays turn into argilite-like rocks in some places according to degree of lithification. Also they include rarelly gypsum minerals. 404 On the surface, clays are fractured and weathered. Fractures are different in size and direction. Usualy, they are directed along or across the bedding, because of this, clays disintegrate into thin sheets and plates, which are dusted by the yellow Iarosite and there are well noticed spots of iron oxide. In zone of weathering clays become brown-yellowish colour and keep habitus of Maicopian clays. Thickness of the crust of weathering reaches 10-20 m, rarely 20-25 m. Marls are developed rarely than clays. In normal conditions marls are light blue-grey and bedded. Thickness of the beds is 0,05-0,4 m, in some places, it formes 10-15 m thick benches. Marls often contain sand, fish scales and planty fragments. Marls weather very fast and change from yellowish-grey to yellow color on the surfaces. Characterized by shily sheeting or disintegration into thin plates, they create medium and fine detrital road material. Sandstones are mostly coarse and medium grained, in places, contain medium inter-layers of fine conglomerates, and represented by the quartzic and quartz-feldsparic composition. They are dark grey, characterized by medium and thick bedding. Thickness of separate layers is 0,1-1,0 m, benches - 20-25 m. Sandstones are weathered and fractured on the surface, separated into 0,25-1 cubic meters volume boulders. Fractures often are open or rarely filled by the alluvial clay. In weathering zone, coarse grained varieties are almost in loose condition (sand, road material). Sharp