NEW DATA ON THE LOCATION AND AGES OF THE LATE HOLOCENE SEA-SHORELINES IN THE KUBAN RIVER DELTA

In 1989, the authors published a paper on reconstruction and dating of the Holocene sea shorelines in the Kuban River delta (Izmailov, et al., 1989). A further geological, geomorphological and geochronological investigations were mostly concentrated in the southern part of the delta in Temruk Bay. Along the sea shoreline, a complicated landform exists, represented by as high as 1.2 m. Late Holocene sandy beach-ridges, from 100-150 m to 300-400 m wide, separated by swampy depressions of about the same width. The total width occupied by such landforms is up to 1.7 km. The belt is divided in 3 sectors: the western one is known as Golubitskaya ridge system, the central is Chaikinskaya system and the eastern (to the east from the Kuban River mouth) is Verbjanaya spit. Mollusk shells (Cerastoderma glaucum (L.), Mytilus galloprovincialis (Lam.)) for radiocarbon dating were sampled over the late Holocene ridges from several, most representative holes as deep as 2.5 m. The oldest ages are obtained in two sites of the Golubitskaya ridge system, at the farthest distance from the sea: 3,050±70 BP and 2,910±80 BP (Ridge 1) and 2,700±80 BP (Ridge 2). The dates obtained seem to correspond to the end of Jemete stage of the basin evolution. The date 2,880±70 BP for an embayment ridge in the north from Temruk town may be referred to the same stage. Other measured dates correspond to Nimphey stage occurring after the antic Phanagorian regression. The oldest ridge from this stage is dated as 2,330±120 BP (Nimphey-1 phase), whereas 5 dates (from 1,840±60 BP to 1,450±50 BP) within Golubitskaya and Chaikinskaya ridge systems appear to be a rather strongly expressed Nimphei-2 phase. Radiocarbon ages of ridges (from 1,330±80 BP to 900±60 BP) are supposedly Nimphey-3 phase in the Verbjanaya spit and nearby. Nimphey-4 formations have received two identical dates - 510±80 BP and 510±70 BP. In the modern coastal waters and formations Nimphey-3 and Nimphey-4 fauna complex, Cerastoderma glaucum dominates, and in addition 10-11 euryhaline are present here. Sediments of older ridges (formations Nimphey-1 and Nimphey-2) and especially of Jemete ridges have more diversified mollusk fauna shifted to higher salinities. Here are frequent Ostrea edulis, Solen vagina and larger Mytilus sp. Nearly all the systems of the Nimphean and Jemetian beach-ridges that are expressed in the modern delta topography have now been referenced to C-14 chronology.