Aufruf

Kolonialkriegerdank e.V. Herzog Johann Albrecht zu Mecklenburg ; [Georg] Freiherr von Gayl

Clay mineral assemblages in the western Baltic Sea

Surface samples and nine cores from the western Baltic Sea and marginal water bodies were investigated for clay mineral composition. The clay mineral assemblages of recent sediments are rather homogeneous. Variations result mainly from the erosion of different glacial source deposits. High percentages of illite and low kaolinite/chlorite and quartz/feldspar ratios are characteristic for this glacial source. Advection of kaolinite-rich suspensions from the North Sea is believed to account for higher kaolinite/chlorite ratios in the Mecklenburg Bight. A contribution of the rivers Trave and Oder to the western Baltic Sea is indicated by increased smectite values in marginal water bodies. They correspond to increased kaolinite/chlorite and quartz/feldspar ratios. In the main basins the river signal is diluted beyond recognition. Cores from the Arkona, Bornholm and Gotland Basins penetrate through post-Littorina muds and sediments of the Ancylus Lake/Yoldia Sea into Late Glacial sediments of the Baltic Ice Lake. Clay mineral assemblages are characterized by an increase in kaolinite/chlorite ratios from Late Glacial to Holocene sediments, with a distinct shift at each facies change. This allows the distinction and core to core correlation of main lithological units with kaolinite/chlorite ratios. Kaolinite enrichment of Holocene muds corresponds to a brackish-marine facies and may reflect influx of kaolinite-rich suspensions from the North Sea. Cores from the lagoon of the Oderhaff show fluctuations in the contributions of the two main sediment sources: river suspension and glacial deposits during the Late Glacial and Postglacial sequence. Lacustrine sediments, which were deposited prior to 5500 years B.P. are characterized by smectite, kaolinite and quartz from the drainage area of the Oder river. Erosion of coastal and offshore glacial boulder clays with the Littorina transgression supplied a marine component rich in illite, chlorite and feldspars to the brackish muds of the Oderhaff.

Abundance of plant macrofossils, mollusca and ostracoda in sediments obtained near Tessin, north Germany

A depression filled with Late Glacial and Holocene sediments was excavated during the geological exploration and recovery of a dump area near Tessin close to Rostock, and initiated the studies of the present paper. Pebble analysis of three exposed or respectively drilled till horizons as well as pollenanalytical, carpological and faunistical studies carried out allow the stratigraphical subdivision of the Quaternary sequence of the dump area. The basal till was probably the result of dead ice decay, and was lithostratigraphically assigned to the Pomerian Stage (qw2). The palynological results of boreholes RKS 19/93 and A/92 reveal pre-Allerod and other sediments instead of the expected interweichselian deposits. Based on the palynological and carpological findings, we correlated the beginning of the late glacial development in the locality with the end of the Meiendorf-lnterstadial sensu Menke in Bock et al. (1985, doi:10.3285/eg.35.1.18). The limnic-telmatic sedimentation could be observed pollen floristically probably starting with the Meiendorf-lnterstadial (Hippophae-Betula nana-phase) followed by the Bolling-(Betula nana-B. alba s.l.-Artemisia-Helianthemum-Poaceae-phase) and the Allerad-lnterstadial [Betula alba s.l.-(Pinus)-Cyperaceae-phase] lasting up to the Younger Dryas (Juniperus-Artemisia-Poaceae-phase). Sedimentation closed during the Younger Dryas with the accumulation of fine sands. It was reactivated later during the Holocene due to the anthropogene influence (Older and Younger Subatlantic, dampness of the depression by clearing).

Pollen record from Blankensee, Germany

Lake Blankensee is filled with 14 m of late- and postglacial deposits, Lake Siethener See with 22,5 m. The lacustrine sedimentation begins in Lake Siethener See in the middle of the Alleröd with annual lamination which partly continues in the Younger Dryas. A 2 cm thick layer of the Laacher See tephra was found in both lakes, the Saksunarvatn tephra only in Lake Siethener See where the cool Rammelbeek-phase (Preboreal) could be shown. The youngest part of the sediment profiles is suspended drifting mud. Masses of Pediastrum (algae) indicate an increasing shoaling of Lake Blankensee after the Subboreal.