Sediments from a boxcore in the previously anoxic brine-filled Poseidon Basin, eastern Mediterranean, have been studied and compared to sediments deposited in a `normal' eastern Mediterranean environment. The boxcore can be divided into three main sedimentary intervals based on AMS-radiocarbon ages, foraminiferal and geochemical zonations. From the base of the core upwards these are: (1) 12.3–31.2 cm, organic-rich sediments redeposited from within the brine; (2) 6.6–12.3 cm, sediment containing a `cold' foraminifera fauna redeposited from above the brine into the basin while the brine was still present; (3) 0–6.6 cm, oxic pelagic sediment accumulated since the reoxygenation of Poseidon Basin which occurred ∼1800 yrs BP. Near the base of the latter unit, a Mn-oxide peak has formed and it marks the present boundary between oxic and suboxic environments. A progressive downward oxidation front, which is usually found in `normal' sapropel S1 sediments, has never formed in Poseidon Basin sediments. This has resulted in the preservation of the relationship between organic carbon and organic-related trace elements, e.g. Se, in the organic-rich sediments of Poseidon Basin, whereas such a relationship has been obliterated in `normal' sapropel S1 sediments. On the basis of the carbonate content as well as the Sr/Ca ratio, preservation of carbonates appears to be better in the brine sapropel sediments of BC15 than it is in `normal' sapropel S1 sediments. The high opal content of BC15 shows that biogenic opal is also much better preserved. The overall lower Corg/Ba ratio in BC15 suggests a better preservation of barite relative to that of organic carbon in shallow brine sediments, but is as yet inconclusive for the organic carbon preservation potential of brine relative to `normal' unoxidised sediments.