Holocene Raised shorelines along Athos Peninsula, Northern Aegean Sea, Greece – First data

Athos or Agion Oros peninsula is the eastern of the three smaller peninsulas of Khalkidhiki in northern Aegean Sea. It is an elongated highly mountainous peninsula exceeding up to 2,030 m asl at Mt. Athos, surrounded by steep and high rocky coasts eroded by the sea. The peninsula consists of granite and metamorphic rocks mainly schist and gneiss in northern and central part, while the south part is dominated by marble. In this paper are presented the first data concerning the discovery of fossil raised shorelines that were located along the west and south coast of the peninsula. Due to steep coastal morphology that restricts any access from the land, geological reconnaissance was completed with a boat that shipped along the coastline from Ouranoupolis (at NW) up to Scala Kafsokalyvion pier (at SE). More than 40km of coastline were visually inspected and photographed in detail with a digital camera. Detail observations and the photographic record were used to document the fossil shorelines and to estimate their rising. On land reconnaissance of the coast line was realized at the Monastery of Agiou Dionysiou and along the footpath from Agiou Dionysiou towards Agiou Pavlou monasteries.
   Results: The raised shorelines comprise marine notches, benches and micro-platforms that were cut on the hard rocks along the coast. Marble preserves the best traces especially the solution notches. On the contrary granite, schist and gneiss did not favour notches formation but in some places some relics of fossil raised wave-cut abrasion platforms were located, still surviving the coastal erosion. Very well preserved raised notches on the marble exceeding up to ~2m height from present sea-level were traced along a distance of ~4 km from Cape Diaporti to Cape Fonias and Skala Kafsokalyvion. They reveal at least 3 raised notches along the vertical marble coast from Cape Diaporti & “Simonos rock” up to Karoulia and Katounakia pier. While eastwards to Kafsokalyvia pier, where the coast reveals less inclination, one to two raised benches and micro-platforms were observed accompanied also with one or two notches. At Agiou Dionysiou monastery, where green-schist exposes, relics of a fossil wave-cut abrasion platform were found along the coast. At the top surface of this platform, raised at ~1m asl, some remnants of hard cemented coarse sands with gravel, pebbles and cobbles were found. These sediments, suffering present wave erosion, correspond to older coastal clastic sediments; they also contain many shell fragments of marine molluscs. Dating of a shell sample with the C14 AMS technique gave an age 3263 ± 45 BP.
   Conclusions: It is the first time that raised coastlines are located in Northern Aegean Sea. The south part of Athos Peninsula reveals characteristic visible marks of neotectonic uplift; raised notches. Height of raised shorelines above present sea level indicates that rate of neotectonic movements overpasses the rate of Holocene sea level rise. Although one C14 AMS age is not enough to monitor the neotectonic uplift, it allows a first time estimation of the neotectonic event. If this age is representative for the neotectonic movement then a mean rate of neotectonic uplift (estimated at 0.9mm/year) can be calculated, in comparison with the mean rate (estimated at 0.6 mm/year) of Holocene sea level rise based on isostatic model for Aegean. Research is still in progress, in order to investigate the coastline along south and east side of the peninsula, especially in the area that marble expose along the coast, including more visits for sampling and topographic measurements. Geological Reconnaissance was realized on November 2009, along the route followed by the small ferry-boat “Agia Anna”, the only boat that is allowed to ship the visitors to the few small piers of the monasteries along Athos coast.