ALBERT

Description: Cretaceous deposits, covered by Quaternary sediments in the Osterzgebirge (Saxony) between Bad Gottleuba and Börnersdorf have been investigated. Beside the interpretation of existing drill logs, 15 new short wells were drilled as well as three seismic profiles were shot. Samples were taken for micropaleontologic analysis. The existence of Upper Cretaceous marls with a lateral extent of about 500 by 600 metres was proven. Due to the results of the seismic and stratigraphic interpretation, a thickness of 250 to 300 m of sediments can be assumed. The Cretaceous deposits are bounded by NW-SE and NE-SW striking faults. The foraminifera assemblage indicates early to middle Coniacian age of the marls. From the occurrence of Cenomanian and lower Turonian sandstones nearby a fairly complete upper Cretaceous succession can be concluded. The origin of such a narrow delimited basin, with such a huge depth is not yet fully understood. At present we suggest that a pull-apart-basin is responsible for the preservation of the sediments.

Description: Pleistocene and late Pliocene benthic foraminifera from the Manihiki Plateau (southwestern tropical Pacific) were studied at piston-core 34KL. A new benthic foraminiferal biozonation is proposed. It comprises the Nodogenerina sagriensis Partial Range Zone from core base to 566.5 cm and the Fissurina seminiformis Partial Range Zone from this level to core top. The boundary is defined by the last occurence of Nodogenerina sagriensis which is time equivalent to the ‘Stilostomella extinction’ in the Eastern Atlantic. High abundances of Cibicidoides wuellerstorfi indicate a strong influence of near-bottom currents. The absence of high-productivity sensitive species reveals a low flux of organic matter to the sea floor from which a considerable amount is adduced by lateral advection.

Description: The Schrammstein Formation of the Upper Cretaceous Elbtal Group comprises 30–60 m thick medium- to coarse-grained sandstone units (named d and e) divided by thin marker beds of finer sands. The cyclic pattern of the re-occurring marker beds, named boundary horizons, and their widespread distribution suggested they were formed by sea-level fluctuations. Basinwards, they correlate to argillaceous marly units of several metres thickness. The geometry of sedimentary bodies, inventory of sedimentary structures, and grain size distribution of sandstones d and e, and boundary horizons γ3 and δ2 were investigated at the Schrammstein and Affensteine rock massifs close to Schmilka. The sedimentary facies indicated a shoaling from lower to upper shoreface and beach environments, from the massive sandstones to the basal boundary horizons and back. The influence of along shore currents and wave action was additionally inferred from grain size distributions and sedimentary structures. The geometry of the sandstones revealed that they were composed of stacked fan lobes with a diameter of a few hundred metres and a sediment source to the north. The geometry also reveals that synsedimentary tectonics along the Lausitz Thrust had only a minor influence on the sediment accumulation but southeastward currents along the ancient coast mainly effected the sediment redistribution. Sedimentary structures and large-scale geometry indicate that sea-level fluctuations shaped the sedimentary bodies. They reflect fast sediment accumulation during transgression and following rapid progradation during highstands. As the accommodation potential was rapidly exhausted, slow aggradation with low sedimentation rates and frequent reworking led to the almost massive appearance of sandstones. Kurzfassung Die Schrammstein-Formation der kreidezeitlichen Elbtal-Gruppe besteht aus 30 bis 60 m mächtigen, mittel- bis grobsandigen Quadersandsteinen (d und e), die durch dünne, feinsandige Schichten begrenzt werden. Das zyklische Wiederauftreten dieser Grenzhorizonte und ihre weite Verbreitung weisen darauf hin, dass sie durch Meeresspiegelschwankungen gebildet wurden. Die Grenzhorizonte gehen beckenwärts in mehrere Meter mächtige, tonig-mergelige Zwischenmittel über. Die Geometrie des proximalen Sandsteins d und der Grenzhorizonte γ3 und δ2, sowie ihre sedimentären Gefüge und Korngrößenverteilungen wurden an den Felsmassiven Schrammstein und Affensteine bei Schmilka in der Sächsischen Schweiz untersucht. Die Sedimentfazies weist auf eine zunehmende Verflachung hin, vom küstennahen, inneren Schelf, in dem die Quadersandsteine abgelagert wurden, zum Vorstrandbereich, wo die basalen Grenzhorizonte gebildet wurden. Der darüber folgende Sandstein zeigt wieder eine zunehmende Wassertiefe an. Die Sedimentstrukturen und Korngrößenkurven weisen auch auf überlagernde Einflüsse von küstenparallelen Strömungen und Welleneinwirkung hin. Die Lagerungsverhältnisse im Sandstein d zeigen, dass der Quadersandstein aus gestapelten, linsenförmigen Sedimentkörpern aufgebaut ist, die einen Durchmesser von mehreren hundert Metern haben und von einer Sedimentquelle im Norden gespeist wurden. Synsedimentäre Tektonik entlang der Lausitzer Überschiebung hatte nur einen untergeordneten Einfluss auf die Sedimentakkumulation, wobei persistente Strömungen entlang der ehemaligen Küste entscheidend zur Sedimentverteilung beigetragen haben. Sedimentstrukturen und Lagerungsverhältnisse belegen, dass die Geometrie der sedimentären Körper durch Meeresspiegelschwankungen geprägt wurde. Die Sedimentfazies spiegelt eine schnelle Akkumulation während der Transgressionen und nachfolgende Progradation während der Meeresspiegel-Hochstände wieder. Der zur Verfügung stehende Akkomodationsraum war schnell ausgefüllt, langsame Aggradation mit niedrigen Sedimentationsraten und häufigen Umlagerungsphänomenen generierte das homogene Erscheinungsbild der Quadersandsteine.

Description: Supratidal sands are vitally important for coastal defence in the German Wadden Sea. They are less affected by human activities than other areas as they are located far off the mainland shore, touristical and commercial activities are generally prohibited. Therefore, supratidal sands are of high ecological interest. Nevertheless, the faunal inventory and distribution pattern of microorganisms on these sands were studied very little. The composition of living and dead foraminiferal assemblages was therefore investigated along a transect from the supratidal sand Japsand up to Hallig Hooge. Both assemblages were dominated by calcareous foraminifera of which Ammonia batava was the most abundant species. Elphidium selseyense and Elphidium williamsoni were also common in the living assemblage, but Elphidium williamsoni was comparably rare in the dead assemblage. The high proportions of Ammonia batava and Elphidium selseyense in the living assemblage arose from the reproduction season that differed between species. While Ammonia batava and Elphidium selseyense just finished their reproductive cycles, Elphidium williamsoni was just about to start. This was also confirmed by the size distribution patterns of the different species. The dead assemblage revealed 20 species that were not found in the living assemblage of which some were reworked from older sediments (e.g., Bucella frigida) and some were transported via tidal currents from other areas in the North Sea (e.g., Jadammina macrescens). The living foraminiferal faunas depicted close linkages between the open North Sea and the mainland. Key species revealing exchange between distant populations were Haynesina germanica, Ammonia batava and different Elphidium species. All these species share an opportunistic behaviour and are able to inhabit a variety of different environments; hence, they well may cope with changing environmental conditions. The benthic foraminiferal association from Japsand revealed that transport mechanisms via tides and currents play a major ecological role and strongly influence the faunal composition at this site.