Türkiye Jeoloji Bülteni

Beachrock Formations on the Mediterranean Coast of Turkey: Implications for Holocene Sea Level Changes and Tectonics

Abstract: Beachrocks, which rapidly form along intertidal zones by early carbonate cementation, can be used inHolocene sea level change and neotectonic studies, as their formation requires vertical stabilization ofthe shoreline. In this paper, three generations of beachrocks at different depths between Finike and theSyrian border are 14C dated and a mid-Holocene to recent sea level change history is tentativelyproposed.The beachrocks and raised shorelines in the study area are geographically subdivided in fiveareas: I) The westernmost beachrock in Finike Bay and Roman ruins of Andriake and Batıkşehir whichare found submerged -1.5 m to - 4 m below after post-Roman earthquakes. II) Three beachrocks levelsobserved between Finike-Antalya and Çimtur, the uppermost beachrock indicating sea levelstabilization at c. AD 400-700. III) Between İncekum and Karataş-Osmaniye Fault Zone wherebeachrocks above sea level are also observed. In İncekum surf benches between 0.5 m and 1.2 m werepreviously dated as 1815 BP to 1545 BP. IV) The southern and northern part of İskenderun Bay limitsthis area. Two generations of beachrocks, corresponding to two fossil intertidal zones are distinguishedhere: the first between 0.3 m and -0.8 m (c. AD 400-700) and the second between -0.7 m and -1.7 m. V)No beachrocks are present along the Levant coast of Turkey. However two erosional notches were previously dated as 2500 ± 100 BP (2.9 m) and c. AD 500-600 (0.8 m). A possible third notch at 1.4 m isundated.Four relative sea level stands are recognized in the study area: 1) The earliest sea level (?midHolocene) is represented by beachrocks at -3 m (±0.5 m). 2) The second stabilization of the sea leveloccurred c. AD 500-700 and is represented by beachrocks at -2 m (±0.5 m). The raised shorelinerepresented by an erosional notch at 2 m and 3 m near Samandağ (Area V) also belongs to this period.3) The third stabilization of sea level and the formation of beachrocks at -0.4 m (±0.5 m) as in Kemer(Area II) and Gözcüler (Area IV) date back to c. AD 400-600. Several Roman ruins (Area I) and a notchat 0.8 m (Area V) are known to have been raised to their present positions between c. AD 400-600. Thebench at 0.5 m (Area III) is known to have developed around AD 200-600. 4) The sea level reached itspresent position at the latest after the Selchukid era (c. AD 1200) and most probably after the EarlyByzantine period (c. AD 400-700). Our data indicate that the major causes of sea level changesobserved along the Turkish Mediterranean coast during the last 5000 years can be attributed to localtectonics rather than to climate and/or glacio-eustacy.