GEOMORPHOLOGICAL CHARACTERISTICS OF THE KRATOVO ZLETOVO PALAEOVOLCANIC AREA Ivica Milevski ! " # Introduction Morphological characteristics of larger palaeovolcanic centers in the Kratovo Zletovo area Kratovo Zletovo area is one of the most remarkable palaeovolcanic areas in the F.Y.R. of Macedonia and one of the most charac teristic on the Balkan Peninsula. It is located in the north east part of the country (Fig. 1) extended in NW SE direction with length of 55 km and width of 15 20 km, covering a total area of 970.1 km2. The position and direction of this palaeovolcanic area matches up the deep dislocation line which separates the Serbo Macedonian tectonic unit on east from the Vardar unit to the west. The main volcanic centers are located around Kratovo, Probištip and Zletovo, while several centers are located to the north (Dudarova Korija, Kaludjerica), and south of these (Preslap, Rajčani). Apart from large structures (cones and calderas), there are also many smaller landforms, directly or indirectly related to previous similar volcanic rocks shaped by weathering, earth pyramids, characte ristic valleys, gullies and even badlands in tuffs. In Kratovo Zletovo palaeovolcanic area, there are several larger palaeovolcanic centers, marked on the map in fig. 5. The basic characteristics of these centers (from north to south direction) are: Vidim Kaludjerica is a volcanic center formed by the volcanic activity of nearby hot spots Vidim (825 m), Kaludjerica (791 m) and Ramni Rid (757 m). According to the arch shaped remnants around, Kriva River was probably deeply incised and has destroyed the large volcanic cone and its crater in the middle. There are also several parasitic cones, such as Ostrovica (641 m), Pobien Čovek, etc. Dudarova Korija (768 m) is the volcanic center with several semicircular caldera like remnants on its west side, and several parasitic cones in vicinity. This structure, which is significantly eroded by Petrošnica River, is considered to belong to the Miocene Pliocene phases of volcanism (Serafimovski, 1993). Similar characteristics and dimensions also has the palaeovolcanic center Kujbul, 5 km west of Dudarova Korija, identified by Marković (1971). Plavica (1297 m) is large palaeovolcanic center among Kratovo and Probištip with diameter of 3 4 km and 7 smaller parasitic cones in vicinity up to 50 to 150 m high. The slopes of Plavica have noticeable traces of the flowing lava, especially in the south and southeast direction. The higher part of Plavica (above 1000 m) has a semi circular shape and looks like a quite destroyed caldera. Uvo Bukovec is volcanic center with two remarkable cones: Bukovec (1423 m) to the west and Uvo (1472 m) to the east, 1 km apart and separated by a fault in the direction NNE SSW. Cones have a very symmetrical appearance, and their relative height is about 250 m. Lesnovo is one of the best preserved palaeovolcanic structures which takes up an area of 12 km2 and resembles a volcanic cone with a diameter of 4 km. The cone has steep sides and rises up to 400 m over the surrounding landscape. On top of the cone is an impressive, well preserved caldera (Fig. 3) with a diameter of 1.5 km and 150 to 200 m deep. Preconditions for the volcanic landscape in the Kratovo Zletovo area The volcanism in the Kratovo Zletovo area is in close connection with the development of Cenozoic extension tectonics in the southern Balkan Peninsula with two phases: the first at the end of Paleogene and the second from the middle Miocene until today. During the first east west extension phase (Eocene Oligocene), dislocations in northwest southeast direction were activated and volcanic centers are created on the intersection of these dislocation lines with local fault lines. Younger, north south extension started in the middle Miocene and lasts until today, expressed by the formation of young (neotecto nic) fault structures with opposite (longitudinal) direction (Kjustendil Debar fault; Kočani fault). At their intersection with the old fault lines, were reactivated old or new volcanic centers was formed. Stratigraphy and K Ar dating of volcanic rocks, indicate that in the Kratovo Zletovo area, volcanic activity began in the Oligocene, 32 29 million years ago and with some interruptions, lasted almost 25 million years, ending in the early Pliocene. Taken as a whole, volcanic activity was of mixed type; calm eruptions with lava flows, occasionally changed with violent explosions and disposal of pyroclastic material. Volcanic phenomena were mainly of continen tal type, with the middle Miocene to Pliocene have emerged phases of accumulation and consolidation of material from eruptions in the surrounding Neogene lakes. !" # $ ! Rajčani is among the youngest palaeovolcanic centers in the area with remnants of two calderas: external and internal, both better preserved from the northern side. Pyroclastic material is presented with breccias and to a lesser extent with andesitic tuffs, mostly deposed in water environment. Their status and composition suggest lower Pliocene volcanic activity. Mangovica (741 m) is volcanic center which resembles highly destroyed caldera, about 2 km wide, heavily eroded by the Mavrovica River. Here, large amounts of the pyroclastic material are expelled on about 50 km2, showing explosive volcanic activity. After an intensive volcanism during the Pliocene, these structures are being gradually destructed by many occurren ces of denudation landforms today (earth pyramids, columnar and mushroom rocks, balls etc.). Conclusion Volcanic activity in the Kratovo Zletovo volcanic area started at the end of Eocene or lower Oligocene, and, with some pauses, lasted until the lower Pliocene. During that period, the volcanic activity successively moved from the north east to the south west (Boev and Yanev, 2001), with changes in volcanic intensity (violent eruption followed by expel of pyroclastic material; with silent phases followed by lava flows). The volcanism in this region was generally caused by deep sub meridian dislocations, activated by the Paleogene east west extension. At the end of Miocene, volcanic activity is reestablished by longitudinal neotectonic dislocations, starting with an earlier north south extension. Geomorphologically, in the Kratovo Zletovo area there are about 20 volcanic cones and calderas, highly eroded by post volcanic fluvial denudation processes. Bibliography: Boev B., Yanev Y., 2001. Tertiary magmatism within the Republic of Macedonia: A review. Acta Volcanologica Vol. 13 (1 2), 57 71 % & ' ( ) ' Marković M., 1971. Contribution to the knowledge of volcanic morphology of the Kratovo Zletovo area. Geological annals of Balkan Peninsula. Book 36, Belgrade, 39 44 Serafimovski T., 1993. Structural Metallogenic Features of the Lece Chalkidiki Zone: Types of Mineral Deposits and Distribution, Faculty of Mining and Geology, Spec.issue No2, 328p.