Geomorphic Evolution of the Lilas River Fan Delta (Central Evia Island, Greece)

摘要

This paper presents the results of geomorphological investigations carried out on the Lilas River fan delta in central Evia Isl., Greece. A geomorphological map has been prepared using Digital Elevation Model analysis, aerial photos and Google Earth image interpretation, a reliable map of 1846, and extensive fieldwork. The Holocene sequence stratigraphy of the fan delta has been studied based on profiles of seven deep cores drilled by the municipal authorities. Two additional shallow boreholes were drilled with a portable drilling set and collected samples were analyzed using micropaleontological and grain size analysis methods while four sediment samples were dated using optically stimulated luminescence (OSL) techniques. During the early Holocene, most of the fan delta plain was a shallow marine environment. Between 4530 ± 220 and 3600 ± 240 years BP the depositional environment at the area of Nea Lampsakos changed from shallow marine to a lower energy lagoonal one. The main distributary changed its course several times leading to the building and subsequent abandonment of five fan delta lobes, through which the fan delta advanced during the late Holocene. The eastern part of the Kampos abandoned lobe is retreating with a maximum mean rate of ?0.94 m/year for the period 1945–2009, whereas the presently active mouth of the river and its immediate surrounds are prograding with a mean rate of about +3.2 m/year.