Last Interglacial (Eemian) hydrographic conditions in the southwestern Baltic Sea based on dinoflagellate cysts from Ristinge Klint, Denmark

Abstract

A dinoflagellate cyst record with strong Mediterranean/Lusitanian affinities is described from marine deposits of Eemian age (Last Interglacial; Late Pleistocene) at Ristinge Klint, Denmark, revealing new information about the hydrographic evolution of the southwestern Baltic Sea. A revised correlation of the pollen record at Ristinge Klint with that of the annually laminated site at Bispingen in northern Germany provides temporal control. Approximately the first quarter of Eemian time is represented. A marine ingression into a lake took place during the Quercus rise, about 300 years into the interglacial, and is marked by low (< c. 3 psu) salinities at the base of the Cyprina Clay that increased progressively. An abrupt and significant rise in the inflow of warm, saline waters from the North Sea occurred at about 750 years into the interglacial (the Corylus rise), and at about 1900 years into the interglacial, strongly stratified waters developed. Higher in the Cyprina Clay and continuing to its top, at nearly 3000 years into the interglacial, more open-marine waters are indicated, although fully marine conditions were not reached. The dinoflagellate record throughout the Cyprina Clay at Ristinge Klint is therefore one of increasing marine influence. Summer sea-surface temperatures approached, and may have exceeded, 26-28 • C during early Eemian time, indicating temperatures at least 5 • C warmer than at present. These warm conditions persisted to the top of the record at Ristinge Klint. No evidence exists at Ristinge Klint for the influence of Arctic watermasses, and the paucity of cold-water species throughout the section reflects mild winter temperatures in the southwestern Baltic Sea. The new species Spiniferites ristingensis is formally described, and the name Operculodinium centrocarpum var. cezare de Vernal, Goyette & Rodrigues, 1989 is validated.

Early Last Interglacial palaeoenvironments in the western Baltic Sea: benthic foraminiferal stable isotopes and diatom-based sea-surface salinity

“…The environmental development is, furthermore, discussed in relation to previously published results from the western Baltic, including studies of foraminifera and ostracods (Kristensen et al 2000), dinoflagellate cyst assemblages (Head 2007) and molluscs (Nielsen et al 2007) from the Ristinge Klint section, as well as environmental proxies for the almost complete Eemian marine sequence at Mommark (Eirı´ksson et al 2006;Funder & Balic-Zunic 2006;Gibbard & Glaister 2006;Haila et al 2006;). Because of their location close to the Danish Belts ( Fig.…”

“…1) in the western Baltic Sea area show the presence of a continuous early Eemian sediment succession, gradually changing from a freshwater environment in the basal shell-free Shiny Clay and the overlying thin layer of Freshwater Sand to a marine interglacial greenish-grey clay, the Cyprina Clay with a sparse mollusc fauna (e.g. Madsen et al 1908;Sjørring et al 1982;Kristensen et al 2000;Head 2007;Nielsen et al 2007). The Cyprina Clay is about 300 cm in thickness and is, in turn, overlain by Weichselian glaciofluvial deposits and tills (Figs 2, 3; for further details, see references above).…”

“…Pollen chronology, combined with the study of foraminifera and ostracods from Ristinge Klint (Kristensen et al 2000), as well as of dinoflagellate cysts (Head 2007), reveals a transition from freshwater lacustrine environments to marine conditions about 300 years after the beginning of the interglacial, and marine conditions persisted until about 3400 years into the interglacial (cf. Kristensen et al 2000).…”

Operational taxonomy and (paleo-)autecology of round, brown, spiny dinoflagellate cysts from the Quaternary of high northern latitudes

“…However, little is known about the ecological affinity of these two species. "E. transparatum" was initially described from sediment traps from the Arabian Sea (Zonneveld, 1997), whereas Head (2003) described E. zonneveldiae from last interglacial (Late Pleistocene) deposits of the Baltic Sea where it occurs in association with the thermophilic species Tuberculodinium vancampoae and Tectatodinium pellitum Head, 2007). The occurrence of "E. transparantum"/ zonneveldiae in subpolar regions with percentages up to 3% suggests a distribution not restricted to warm environments.…”

Upwelling conditions in the Early Miocene Central Paratethys Sea

“…6.2-3) have been revealed from the lower part of the Limberg section. The occurrence of such morphotypes has often been linked to reduced salinity (Head et al 2005;Head 2007). However, a major change in salinity seems unlikely for the studied sections as the stable isotope data clearly contradict this idea by showing no distinct trend.…”