ALBERT

Description: The histopathology of larval Aniskis simplex B in naturally infected squids off south-eastern North Atlantic is described. Host tissue response to invading nematode larvae and their eventual encapsulation in the stomach of the squid hosts suggests a cell-mediated immune response in defence against parasitic invasions.

Description: Abstract The famous association of metagabbros, eclogites, glaucophanites, jadeite rocks and ultramafics from the island of Syros forms a distinct lithostratigraphic or tectonic unit. It is interpreted as a high-pressure metamorphic ophiolite suite. This paper provides geochemical and Sr-isotope constraints on the geotectonic setting in which the magmatic protoliths of the Syros metabasites were formed. A compositional gap exists between the metagabbros with Mg-numbers [Mg# = Mg/(0.85Fetot + Mg) atomic ratio] of 0.75-0.88 on the one hand and eclogites and garnet-glaucophanites on the other hand with Mg# of 0.35-0.62, and maximum total iron contents of up to 18 wt.% FeOtot. Metagabbros from various localities and glaucophanites collected around Manna form geochemically coherent groups with smooth correlations between compatible as well as immobile incompatible elements and Mg#. By contrast, the behaviour of immobile incompatible elements, and to some extent also of compatible elements, is highly unsystematic in the eclogites and garnet-glaucophanites. Also, the more mobile elements display a wide scatter in all rocks. This, in conjunction with the unsystematic variation of Sr-isotopes, is thought to be due to secondary alteration. From the strong correlation of Ni and Cr with Mg# and the flat REE patterns lacking Eu-anomalies, a cumulus nature is inferred for olivine, clinopyroxene, and spinel, associated with intercumulus formation of plagioclase in the magmatic protoliths of the metagabbros. There is no direct genetic link between these rocks and the precursors of the Manna-type glaucophanites with REE characteristics typical of N- to T-type MORB. The extremely high geochemical diversity of the eclogites and garnet-glaucophanites from Syros favours individual evolution of their protoliths in small magma bodies as suggested for superferric eclogites from the Western and Ligurian Alps, as well as the ferrogabbros from the ophiolites of the Northern Apennines. From the geochemistry of the Syros metabasites along with the initial 87Sr/86Sr ratios of the metagabbros between 0.7031 and 0.7033, as well as an eNd value of 7.7 from a garnet glaucophanite, the magmatic protoliths are inferred to have formed in a back-arc setting. By analogy to the association of gabbros and ferrogabbros adjacent to the Atlantis II fracture zone of the SW Indian Ridge, we further suggest an origin at a spreading ridge in proximity to a transform fault.

Description: In der Schreibkreide von Helgoland (NW-Deutschland) wurden leitende Foraminiferenarten an einer Profiltraverse im Seegebiet südwestlich der Insel (Görtel) untersucht. Die Kenntnis der Lagerungsverhältnisse der Kreideschichten und der genauen Probenpositionen erlaubte unter Berücksichtigung der Bathymetrie die Konstruktion eines synthetischen Prof1les für die höhere Oberkreide (Unter-Coniac bis Ober-Santon) und die Festlegung der stratigraphischen Lage für die einzelnen Proben. Eine Aufstellung der Vertikalreichweiten leitender Arten führte zur Untergliederung in sechs Foraminiferen-Zonen, die bereits im Schreibkreide-Richtprofil von Lägerdarf/Holstein an der Makroinvertebraten-Gliederung geeicht wurden. Stark reduzierte Mächtigkeiten im Unter-Santon und aufgearbeitete Gehäuse von Stensioeina granulata polonica WITWICKA im Ober-Santonweisen in Verbindung mit Grobkreidelagen im Coniac und Ober-Santon auf wiederholte Erosionsphasen hin.

Description: In Sedimenten aus flachen Bohrungen in der Nordsee wurden gasförmige Kohlenwasserstoffe gefunden. Kohlenstoff- (Methan bis Propan) und Wasserstoff-Isotopanwerte lassen auf eine Mischung von Gasen bakterieller und thermischer Entstehung schließen. Die thermischen Gase sind in größerer Tiefe aus überwiegend mariner organischer Substanz entstanden und in die oberflächennahen Sedimente migriert. [Methane through pentane have been found in sediments from shallow North Sea boreholes. Carbon (methane through propane) and hydrogen (methane) isotope ratlos indicate both bacterial and thermal origins. The gases of thermal origin are interpreted as having been generated at considerable depth from predominantly marine source rocks and then to have migrated into the overlying sediments.]

Description: In situ irradiance measurements were performed during 1986 and 1987, to obtain information on the nature of the light climate and on factors governing the absorption (a), scattering (b) and beam attenuation coefficient (c) in the water column of a shallow eutrophic lake (Lake Veluwe). Phytoplankton chlorophyll-a concentration ranged from 2 to 85 mg cntdot m-3, the seston concentration from 8 to 148 mg dry weight cntdot l-1 and gilvin concentration from 0.79 to 1.11 m-1 (g-440). The vertical attenuation coefficient (K-d) varied between 1.56 and 6.76 m-1. The relative effects of water itself, gilvin, phytoplankton, and tripton on a, b and c showed relatively small seasonal variation. The relative effects of water and gilvin on c were of minor importance (less than 10%). Phytoplankton contributed 6 to 20% to a, 3 to 33% (with a peak value of 55%) to b and less than 30% to c. Tripton was the dominant factor determining the diminution of irradiance penetrating the water column in Lake Veluwe. Irradiance was strongly scattered which was mainly due to tripton. The spectral distribution of the photosynthetically active radiation was progressively compressed with depth into a region between 550 and 700 nm. Water absorbed strongly in the red regions of the spectrum, and gilvin and seston in the blue regions. The seston concentration was positively correlated with wind-induced resuspension of bottom material. It was concluded that an improvement of the underwater light climate requires a reduction of resuspension of bottom particles.

Description: Überreicht zum Kolloquium anläßlich des 75. Geburtstages von Prof. Dr. Dr. h.c. Eugen Seibold "Geosciences as a basis for Understanding the Modern World", Freitag, den 21. Mai 1993 im Auditorium Maximum der Christian-Albrechts-Universität