The nature, distribution and origin of a sapropelic layer in sediments of the Silicia Basin, northeastern Mediterranean

Abstract

A sapropelic layer with organic carbon contents of 1.0–1.5%, in contrast to the usual 0.2–0.5% of adjacent normal basin sediments, is found to be widespread in sediment cores collected from the Cilicia Basin, northeastern Mediterranean. The horizon is thought to be equivalent to the S 1 sapropel of other workers. It is finely laminated with no evidence of bioturbation, has a very markedly low magnetic susceptibility, and contains a significantly higher content of pollen and plant debris than is found in the normal basin sediment. The stable oxygen and carbon isotope values suggest that the layer formed during post-glacial climatic warming when fresh nutrient-rich surface water flowed into the Cilicia Basin from the surrounding land to produce a stratified water mass which allowed the development of anoxic bottom waters. The distribution of the sapropelic layer indicates that anoxic conditions extended to within approximately 350 m of sea level during deposition, a depth shallower than previously recorded in the Eastern Mediterranean.