NEW INSIGHTS IN THE POST GLACIAL FLOODPLAIN EVOLUTION OF SOMESU MIC RIVER, TRANSYLVANIAN DEPRESSION, ROMANIA

In this paper we present the evolution of the Somesu Mic River’s floodplain over the past 22 kyrs, based on morphologic and sedimentary evidences. The chronologic framework is based on seven OSL and radiocarbon ages. The inorganic (OSL dating) and organic (conventional ¹⁴C) materials were collected from bank exposures or artificial openings disposed along the river. The results give us the possibility to outline a set of moments of the floodplain’s and river’s history: deposition of coarse gravel sediments from LGM through Lateglacial (22 – 11 ka), meandering behaviour at 9.2 ka, strong incision in alluvial sediments at ca. 5.5 ka, and an important vertical aggradation phase during the Little Ice Age (1300 – 1850 AD). Correlation of these moments with the main paleoclimatic features of the area show that the climate acted as the main factor in the development of the floodplain and the behaviour of the river, while local, small scale tectonics, modulates its influence.