LATE QUATERNARY EVOLUTION OF THE LOWER REACHES OF ZILIANA STREAM IN SOUTH MT. OLYMPUS, GREECE

It is well accepted that active tectonics directly influences the evolution of hydrographic networks. This is the case of Mount Olympus where uplift and fault tectonism control the development of its major drainage networks. This work examines the paleogeographic evolution of the lower reaches of Lazi Griva, Ziliana and Vathyrema streams flowing at the southwestern edge of the eastern piedmont of mountain Olympus in east Central Greece. For this purpose, detailed field work and large scale geomorphological analysis and mapping, were performed. A spatial database was created, and ArcGIS 10 software was used to process the collected data. The Late Pleistocene - Holocene uplift of Mount Olympus has led to downcutting in the upper reaches of the three streams. The Lazi Griva stream formed the southern alluvial fan of the Olympus piedmont. The reactivation of a major normal fault zone running roughly N-S along the eastern front of Mount Olympus affected the flow direction of Lazi Griva stream at its exit from the mountain mass. The three streams join immediately after the fault zone and reach the sea as a single main channel of Ziliana. Six fluvial terraces were recognized, the oldest one at 224 to 260 m, followed by the others at 124-236 m, 104-134 m, 74-104 m, 16-104 m, and the youngest at 12-100 m. Near the apex of the inactive alluvial fan a displacement of about 11 m was observed which indicates that the most recent reactivation of the eastern major fault of Mt. Olympus occurred in Holocene.