Late Holocene terrestrial tephra record at western Anatolia, Turkey: Possible evidence of an explosive eruption outside Santorini in the eastern Mediterranean

A 27 cm thick, loose tephra deposits has been observed within coarse-grained colluvium at Çardak area of Denizli on the northern apron of the Acıgöl graben in western Anatolia, Turkey. It is a biotite-rich tephra with mean grain-size of coarse silt. Chemically it is dacite and rhyolite with average of 66.35% SiO2 and 4.70% alcalia (Na2O + K2O) in bulk analyses. It was deposited a time between 5380 ± 90 and 2395 ± 65 yrs cal. BP, possibly between 4750 and 3385 yrs cal. BP according to 14C dating of two palaeosol layers within the colluvium. This is only and the thickest Holocene air-fall tuff layer found in terrestrial sediments in this region so far, and according to present knowledge there is no young volcanic source for such a formation in western Turkey. Analyses and comparisons of the analytic results with those of various young volcanic rocks suggest that the Çardak tephra originated from a volcanic source in the Aegean Sea. Besides, its geochemical composition, formation time and significant thickness represent probably a separate late Holocene explosive eruption in the eastern Mediterranean, apart from the Santorini event.