ALBERT

Description: The global sediment mass-age distribution indicates large variations in the rates of carbonate sedimentation through time. The largest mass of carbonate deposited during the entire history of the earth was produced during the Cambrian, possibly following on an episode of phosphogenesis in the Late Precambrian. A second major episode occurred during the Late Devonian, probably reflecting the invasion of land by plants that altered the rock-weathering and soil-forming regimes. Other lesser pulses of carbonate deposition occurred in the Late Permian, Triassic, and Cretaceous. A shift in the locus of carbonate deposition from shallow waters to the deep sea occurred during the Cretaceous.

Description: At Aqaba in the Northern Gulf of Aqaba, Red Sea, the stable oxygen isotope record of a Por#es lutea coral colony was studied. From a vertical and a horizontal core two parts from the base of the colony (10 years of coral growth), and two parts from the living surface (12 years of coral growth) were analysed with a monthly sampling resolution. The results show that seasonality of sea surface temperatures (SST) in the northem GulfofAqaba has increased since the early 19th century, mainly due to higher summer temper- atures. 8~80-ratios indicate that SST increased by at least 1.3~ Horizontal and vertical cores display dif- ferent variations in the modern parts, probably caused by the very shallow water depth of the youngest part of the vertical core.

Description: Repeatable species dominance patterns across nutrient ratio gradients are found both in culture competition experiments and in natural waters. However, the mechanisms behind these similar patterns need not to be identical. In chemostat experiments, such patterns are caused by the two-way competitive interactions between contemporaneously occurring organisms. Nutrient competition may be important in situ too, but there is an additional effect of early successional species influencing the nutrient environment for later successional species, without being influenced themselves by their successors.

Description: Cyanobacteria are important constituents of most aquatic ecosystems on earth, and planktonic forms frequently show mass development in lakes and estuaries. Despite extensive scientific efforts directed towards research on cyanobacteria, a comprehensive theory explaining their success is lacking. Because cyanobacteria comprise a diverse group of organisms, it is concluded that any analysis of the conditions leading to cyanobacterial dominance in pelagic ecosystems should consider at least three different subgroups, classified based on presence or absence of (i) buoyancy regulation and (ii) the ability to fix molecular nitrogen. In this review, nine single-factor hypotheses regarding regulation of cyanobacterial development are examined against the background of physiological and ecological characteristics of these organisms. Special emphasis has been put on understanding differences in nitrogen metabolism between cyanobacteria and algae which directly relate to a hypothesis conceming inorganic nitrogen forms and cyanobacterial success previously presented by our research group. The review lends support to the theory that cyanobacteria have a low competitive ability for nitrate compared with algae and a high ability to compete for ammonium, particularly under nitrogen-limiting conditions. Finally it is concluded that to understand cyanobacterial devlopment and how high Standing Stocks in pelagic ecosystems are maintained requires parts o f all the single-factor hypotheses initially presented.

Description: The density of seawater is a complex function of temperature, salinity, and pressure. Because of the non-linearity of the equation of state of seawater, the densities of sea waters having the same temperature and the same salinity differences (with respect to the mean salinity of the ocean) will vary with the mean salinity of the ocean. Although this strange property of seawater is evident in a plot of the equation of state, it has never been considered in trying to reconstruct ancient ocean circulation. These differences in the density field may have caused the ocean to respond differently to atmospheric forcing in the past. The different response may hold the key to understanding "ocean anoxic events" and episodes of large-scale burial of organic carbon and production of petroleum source rocks.

Description: The Late Cretaceous was much warmer than today. There was no significant ice at high latitudes, meridional thermal gradients were low, and continental interiors remained warm during winter. Late Cretaceous atmospheric C02 concentrations were about four times greater than today and an enhanced "greenhouse" effect contributed to the overall warmth of the Late Cretaceous. However , increases in atmospheric C02 tend to increase temperatures at all latitudes and do not explain the very low thermal gradients recognized in the geologic record. Increased poleward ocean heat transport has been cited as a mechanism for maintaining low meridional thermal gradients during the Cretaceous. However , ocean heat transport values larger than the present day are difficult to reconcile. In addition, low meridional thermal gradients suggest sluggish atmospheric circulation, implying that the advection of heat from the warm oceans into the continental interiors was limited. In general, paleoclimate simulations using Atmospheric General Circulations Models (AGCMs) have not been successful in simulating the low meridional thermal gradients and warm winter continental interiors of the Cretaceous, forcing the concept of "equability" to be questioned. Until recently, the physical effects of vegetation on pre-Quaternary climates have largely been ignored. Terrestrial ecosystems influence global climate by affecting the exchange of energy, water, and momentum between the land surface and the atmosphere. In a new approach to pre-Quaternary paleoclimate modeling, Campanian (80 Ma) climate and vegetation have been simulated using a global climate model (GENESIS Version 2.0), coupled to a predictive vegetation model (EVE), resulting in a realistic simulation of Late Cretaceous climate. The predicted distribution of Late Cretaceous vegetation played an important role in the maintenance of low meridional thermal gradients, polar warmth, and equable continental interiors. High latitude forests reduced albedo, especially during snowcovered months, and increased net surface radiation and latent heat flux.

Description: In this study, the impact of oceanic data assimilation on ENSO simulations and predictions is investigated. The authors’ main objective is to compare the impact of the assimilation of sea level observations and three-dimensional temperature measurements relative to each other. Three experiments were performed. In a control run the ocean model was forced with observed winds only, and in two assimilation runs three-dimensional temperatures and sea levels were assimilated one by one. The root-mean-square differences between the model solution and observations were computed and heat content anomalies of the upper 275 m compared to each other. Three ensembles of ENSO forecasts were performed additionally to investigate the impact of data assimilation on ENSO predictions. In a control ensemble a hybrid coupled ocean–atmosphere model was initialized with observed winds only, while either three-dimensional temperatures or sea level data were assimilated during the initialization phase in two additional forecast ensembles. The predicted sea surface temperature anomalies were averaged over the eastern equatorial Pacific and compared to observations. Two different objective skill measures were computed to evaluate the impact of data assimilation on ENSO forecasts. The authors’ experiments indicate that sea level observations contain useful information and that this information can be inserted successfully into an oceanic general circulation model. It is inferred from the forecast ensembles that the benefit of sea level and temperature assimilation is comparable. However, the positive impact of sea level assimilation could be shown more clearly when the forecasted temperature differences rather than the temperature anomalies themselves were compared with observations.

Description: This paper presents trace element and Sm-Nd isotope data on the Mönchalpgneiss in order to compare the geochemistry of the two polymetamorphic igneous suites that comprise over 30% of the Austroalpine Silvretta nappe. The first are the so-called "Younger Orthogneisses" of the "Fliielagranitic Association" and the second are the "Older Orthogneisses" including the Mönchalpgneisswhich are associated with metagabbros, metadiorites, metatonalites and metagranitoids. U-Pb zircon results from the Mönchalpgneiss are indicative of anatectic processes in late Cambrian to Ordovician times. A volcanic-arc (VA) tectonic environment during intrusion explains the direct association of gabbroic and metagranitoid rocks in the Engadine area. This model is in line with the distribution of major, trace and rare earth elements in these anatectic rocks. However, the significance of the geochemical results remains ambiguous, since the average continental crust and paragneisses of the Silvretta also show VA-type signatures in the respective diagrams. Nd model ages on four Mönchalpgneiss whole-rock samples from the type locality are closely grouped around 1.70 Ga, which is a commonly obtained value for European continental crust. This age is interpreted to be the result of a homogeneous mixture of different crustal components

Description: In this paper the performance of the global coupled general circulation model (CGCM) ECHO-2, which was integrated for 10 years without the application of flux correction, is described. Although the integration is rather short, strong and weak points of this CGCM can be clearly identified, especially in view of the model's performance of the annual cycle in the tropical Pacific. The latter is simulated with more success relative to the earlier version, ECHO-I. A better representation of the low-level stratus clouds in the atmosphere model associated with a reduction in the shortwave radiative flux at the air-sea interface improved the coupled model's performance in the southeastern tropical oceans, with a strongly reduced warm bias in these regions. Modifications in the atmospheric convection scheme also eliminated the AGCM's tendency to simulate a double ITCZ, and this behavior is maintained in the CGCM simulation. Finally, a new numerical scheme for active tracer advection in the ocean model strongly reduced the numerical mixing, which seems to enhance considerably the level of interannual variability in the equatorial Pacific. One weak point is an overall cold bias in the Tropics and midlatitudes, which typically amounts to 1°C in open ocean regions. Another weak point is the still too strong equatorial cold tongue, which penetrates too far into the western equatorial Pacific. Although this model deficiency is not as pronounced as in ECHO-1, the too strong cold tongue reduces the level of interannual rainfall variability in the western and central equatorial Pacific. Finally, the interannual fluctuations in equatorial Pacific sea surface temperatures (SSTs) are too equatorially trapped, a problem that is also found in ocean-only simulations. Overall, however, the authors believe that the ECHO-2 CGCM has been considerably improved relative to ECHO-1.

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: Evolution of the Caribbean Plate can be modeled by motions about six successive rotation poles. Opening of Cayman Trough has occurred since 49.5 Ma through westward motion of the Caribbean Plate, eastern Greater Antilles and Chortis Block. Before 49.5 Ma, the eastern Greater-Antilles were west of Cuba, and the southeastern margins of Yucatan and the Nicaragua Rise (Chortis) were aligned. From 67.5 to 49.5 Ma the Caribbean Plate rotated clockwise, opening the Yucatan Basin. From 100 Ma to 67.5 Ma, the Caribbean Plate, with Cuba attached, moved along the southeastern margin of Yucatan-Chortis. At 130 Ma it was attached to northwestern South America.

Description: Microspectralphotometric examinations of various recent pollen point to a different sporopollenin chemistry of the different taxa which is distinguishable by the UV-VIS absorptionspectra. The measurement areas have a diameter of 6 micron, by which several measurements for the spectra control in one pollen grain are possible. Labaratory experiments with chemical treatments as used by palynological preparation, show a clear change in the sporopollenin chemistry whichcould be identified by the absorption spectra. Therefore a new preparation technique for fossil and recent palynomorphs has to be developed to avoid chemical changes. First investigations of recent and fossil Pinus pollen have been clone on material from various facies types and a sediment core. The variations in the absorption spectra of the pollen indicate the different chemical influence of different facies types which could be used for facies analyses. Furthermore, significant changes in the absorption spectra are useful to identify reworked pollen or pollen with a different burial history. Zusammenfassung: Vergleichende mikrospektralphotometrische Untersuchungen der UV-VIS Absorptionsspektren verschiedener rezenter Pollen-Taxa zeigen, daß die Zusammensetzung bzw. Struktur des Sporopollenins bei verschiedenen Taxa variiert und daß diese anhand der Absorptionsspektren klar unterschieden werden kann. Die gemessene Fläche auf den jeweiligen Pollen hat einen Durchmesser von 6 j.lm, so daß mehrere Kontrollmessungen an einem Pollen möglich sind. Laborversuche an rezenten Pollen zeigen, daß chemische Einflüsse (z. B. HN03, Acetolyse) deutlich meßbare Veränderungen in der Struktur des Sporopollenins verursachen. Um Veränderungen des Sporepollenins durch die chemische Probenaufbereitung auszuschließen, wurde eine neue Präparationsmethode für fossile und rezente Palynomorphen entwickelt.

Description: ana marit., 27 (3/6): 145-150, 2 figs.; Frankfurt a. M.] According to the (neo-)Darwinian theory of evolution the appearance of "design" and optimization of biological properties are the results of natural selection and not of teleology. An opti· mization by selection is only possible for entities which are able to reproduce ("units of selection"). The "unit-of-selection"-problem will be discussed in relation to the atomism-holism-continuum of ecological and evolutionary concepts which range from Dawkins' "selfish gene" to LoveJock's "Gaia". Special emphasis will be given to the discussion of the group-selection problem which seems to be the critical breakpoint along this continuum. It will be shown that optimization through natural selection is only possible for units which can multiply and preserve their identity to a sufficient degree through multiplications. Such units are called replicators. Associations, communities, ecosystems and the biosphere do not qualify as replicators.

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: The chemical composition of sediments from the Reykjanes Ridge is controlled by allochthonous and autochthonous processes. The surface sediments are characterized by relatively high contents of calciumoxide and strontium. Calcium and strontium dominate in the carbonate phase due to the high content of biogenic carbonate. A high percentage of iron and manganese are bound to oxides and hydroxides. An indication of hydrothermal activity was not observed. A considerable portion of adsorbed barium is transported in clay minerals. The higher amounts of aluminium in glacial sequences indicate an enhanced input of terrigenous material; the increase of stable bonding elemen~s points toward the large influence of detrital minerals. The distinct differences in the bonding characteristics of elements in these marine sediments in comparison to fluvial and coastal - deposits could be due to the different environmental conditions.

Description: The seasonal cycle over the tropical Pacific simulated by 11 coupled ocean–atmosphere general circulation models (GCMs) is examined. Each model consists of a high-resolution ocean GCM of either the tropical Pacific or near-global means coupled to a moderate- or high-resolution atmospheric GCM, without the use of flux correction. The seasonal behavior of sea surface temperature (SST) and eastern Pacific rainfall is presented for each model. The results show that current state-of-the-art coupled GCMs share important successes and troublesome systematic errors. All 11 models are able to simulate the mean zonal gradient in SST at the equator over the central Pacific. The simulated equatorial cold tongue generally tends to be too strong, too narrow, and extend too far west. SSTs are generally too warm in a broad region west of Peru and in a band near 10°S. This is accompanied in some models by a double intertropical convergence zone (ITCZ) straddling the equator over the eastern Pacific, and in others by an ITCZ that migrates across the equator with the seasons; neither behavior is realistic. There is considerable spread in the simulated seasonal cycles of equatorial SST in the eastern Pacific. Some simulations do capture the annual harmonic quite realistically, although the seasonal cold tongue tends to appear prematurely. Others overestimate the amplitude of the semiannual harmonic. Nonetheless, the results constitute a marked improvement over the simulations of only a few years ago when serious climate drift was still widespread and simulated zonal gradients of SST along the equator were often very weak.

Description: We have used a new General Circulation Model, GENESIS Version 1.02, derived from the U. S. National Center for Atmospheric Research Community Climate Model I (NCAR-CCM I) to simulate the climate of an Earth with realistic Pangaean geography. The climate model was run assuming that the ocean heat flux was similar to that of today, atmospheric C02 content was four times that of today, the solar constant was 2 % less than today, and the Earth's orbit was circular, with mean obliquity 23.4°. Models were run for paleogeographies at 245 Ma (Scythian) and 225 Ma (Carnian). The results indicate that no ice cap would develop over the land, and there is no permanent sea ice. The seasonal temperature Variation in the interior of the continent is in the order of 50 °C. The Continental areas are very dry except for a few Coastal areas and along uplifts. The models both suggest an extreme seasonal monsoonal circulation, with strong westerly winds parallel to the entire coast of Gondwana and the east coast of Laurasia during the northern hemisphere summet. In both hemispheres, the effect is to cause coastal upwelling. The model also predicts permafrost in the deeper soil layers poleward of 50° N and S. The effects of topographic uplifts on the atmospheric circulation are pervasive. Topography strongly affects the monsoonal circulation causing major deviations of the wind Systems suggested in model runs with idealized geographies. Topography also plays a crucial role in concentrating rainfall in a few small areas. It is evident that in order to have a realistic Simulation of paleoclimate, an accurate representation of the paleotopography is essential. It is also evident that the paleoclimate models may be useful in suggesting geological criteria that can confirm or reject the predicted paleoclimatic conditions.

Description: Digitised outlines of a serially sectioned K-feldspar grain from a Cordilleran granitoid have been analysed for their fractal dimension. Although the grain boundary outlines are not truly fractal in the sense of Mandlebrot (1982), they do show a self-similarity over a statistically definable range, and can thus be assigned a dimensional value between 1 and 2. Each grain section has fractal dimension (D) 〉 1, ranging from 1.21-1.30. Scatter within the data sets have been used to define separate (pseudo)fractal elements that further characterise each grain outline. The development of fractal geometries within a particular granitoid can be broadly related to crystallisation within Ab-An-Or-Qz space. For example, Cordilleran T-type granitoids that crystallise from An-rich liquids may be expected to show both Euclidean and fractal geometries, while minimum melts and 'S'-type granites that crystallise in broadly eutectic proportions will have textures dominated by (pseudo)fractal grain outlines. The non-integer values that describe grain shape may also be useful in estimating the total grain (porosity) volume within the rock.

Description: Late Pleistocene climatic and paleoceanographic changes in the Norwegian-Greenland Sea are reflected in eleven long sediment cores by variations in calcium carbonate content and calcareous biogenic components versus coarse terrigenous ice-rafted detritus (IRD). High contents of IRD in glacial sequences are evidence for an enhanced melting of sea ice and icebergs. In contrast, high calcium carbonate contents indicate the inflow of warm Atlantic surface waters. The petrographic IRD composition in cores from the eastern and central Norwegian-Greenland Sea shows that the terrigenous material was predominantly derived from Scandinavia. Thus, it can be concluded that changes in the terrigenous input were caused by oscillations of the Late Pleistocene Scandinavian ice sheet. Changes in the extension of this ice sheet during the last 130 ky correlate well with our IRD data.

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

Description: The dependency of metabolic rates on cell size and the effect of temperature are demonstrated on a hypothetical size spectrum for a phytoplankton population in an oligotrophic open ocean region under steady-state conditions. The model spectrum illustrates the preponderance of small cells over large ones, especially their much higher weight-specific growth rates. It also shows that the allometric advantage of small cells, for instance in competing for limiting nutrients, is further enhanced by temperature increase. These basic facts are used to characterize the microbial and classical food web in relation to cold- and warm-water ecosystems and to new and regenerated production. It appears that the microbial food web is controlled by grazing and the classical food chain by nutrients. The former is present in all environments but is best adapted to oligotrophic warmwater ecosystems where regenerated production predominates. The microbial food web may be regarded as the original and normal form of life in the pelagic zone and the classical food web more as an exceptional feature depending on new production, which in turn is governed by the changing wind and temperature regime over the world ocean.

Description: A variety of survey instruments and systems designed for measuring the behavior of individual zooplankton have been built around video technology. Systems designed for studying behavior are already producing remarkable observations of biological interactions in situ. If the survey tools under development achieve their potential, they will surpass the spatial and temporal resolution of conventional sampling methods, reduce the amount of human effort required for data processing, and also collect taxonomic information that is not available from acoustic devices or the Optical Plankton Counter. This paper (i) describes a variety of video systems for studying zoo plankton in situ; (ii) discusses common design considerations and technical challenges; and (iii) compares the present and future capabilities of video devices with other methods of studying zooplankton in situ.

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: Während des Spätpleistozäns und Holozäns werden auf der langgestreckten Sulu-See Tiefsee-Ebene Turbidite mit einer Häufigkeit von 3 bis 94 Ereignissen pro 1000 Jahre im Wechsel mit hemipelagischem Sediment abgelagert. Eine Tephralage und isotopenstratigraphische Untersuchungen ermöglichten es, 10 untersuchte Kolbenlotkerne zu korrelieren und in fünf bis ins letzte Hochglazial reichende Zeitscheiben zu gliedern. Entsprechend dem Gefüge der Basislagen der terrigenen Turbidite können im nördlichen Teil der Tiefsee-Ebene proximale und im Süden distale Ablagerungsbereiche unterschieden weren. Die Turbidithäufigkeiten bleiben bis ins Spätpleistozän konstant, nehmen jedoch regional von 94 Turbiditen/1000 Jahre im Norden auf 11 Turbidite/1000 Jahre im Südteil der Tiefsee-Ebene ab. Dieser Gradient und die Gefügemerkmale zeigen, daß die meisten Turbiditströme die Tiefsee-Ebene durch den sich nördlich anschließenden Panay-Canyon erreichen. Von allen berücksichtigten Faktoren ist der taifuninduzierte Einstrom dichterer Wassermassen aus dem Südchinesischen Meer durch die Mindoro-Straße und den Panay-Canyon der wahrscheinlichste Auslöser für hochfrequente terrigene Turbiditströme. A narrow deep-sea abyssal plain is situated in the deepest part of the south-eastern Sulu Sea subbasin. The trench sediments which were recovered with piston cores during RV Sonne cruises SO 49 and SO 58 comprise numerous Late Pleistocene to Holocene turbidites with intercalated hemipelagic mud layers. While a proximal turbidite facies is recognized only in the northern trench, distal terrigenous turbidites are frequent in the whole basin. The occurrence of calcareous turbidites is restricted, however, to the southern trench. Although terrigenous turbidite frequencies remain rather constant over the past 22,000 years, they show a decrease from 94 in the northern trench to 11 turbidites/ka in the southern part of the basin. This gradient points to the Panay Canyon north of the trench as the main source for terrigenous turbidites. Features of erosion and gravity-driven downslope-transport are observed on the Panay Canyon floor. From all factors considered, typhoon-induced water inflow from the South China Sea through the Mindoro Strait seems to be the most important trigger mechanism for the frequent release of terrigenous turbiditic flows passing through the Panay Canyon to the Sulu Sea abyssal plain.

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.