The palaeoenvironment associated with a partial Iguanodon skeleton from the Upper Weald Clay (Barremian, Early Cretaceous) at Smokejacks Brickworks (Ockley, Surrey, UK), based on palynomorphs and ostracods     

Eleanor Nye  Susanne Feist-Burkhardt  David J. Horne  Andrew J. Ross  John E. Whittaker 《Cretaceous Research》2008,29(3):417-444

In 2001 a partial skeleton of an Iguanodon was discovered in the Upper Weald Clay (Barremian, Early Cretaceous) at Smokejacks Brickworks near Ockley, Surrey, UK. When the dinosaur was excavated, a detailed stratigraphic section was logged and 25 samples taken for palynological and micropalaeontological (ostracod and megaspore) analysis, including a detailed sample set of the dinosaur bed itself. Qualitative and quantitative analysis of the palynoflora revealed rich and well-preserved non-marine assemblages of pollen and spores, including early angiosperms, and freshwater green algae. Four types of angiosperm pollen are described and assigned to the genus Retimonocolpites Pierce, 1961, but left in open nomenclature. Some marine elements such as dinoflagellate cysts are identified as the result of reworking of Middle and Upper Jurassic sediments. The pollen/spore assemblages depict a vegetational change from principally gymnosperm-dominated assemblages at the base to principally pteridophyte-dominated assemblages at the top of the section. The dinosaur bed shows a pteridophyte-dominated assemblage, with a significantly high amount of the freshwater green alga Scenedesmus novilunaris He Cheng-quan et al., 1992. Samples close to the dinosaur bed yielded the first useful ostracod finds from Smokejacks Brickworks: well-preserved assemblages containing Cypridea clavata (Anderson, 1939), Damonella cf. pygmaea (Anderson, 1941), Stenestroemia cf. cressida Anderson, 1971 and Stenestroemia sp. A, and fragments and damaged valves of a thin-shelled ostracod, possibly belonging to Mantelliana Anderson, 1966. Those identified as Cypridea clavata show a wide range of morphological variety and in opposition to Anderson's (1967, 1985) taxonomic scheme, which would assign them to up to five different taxa, they are considered to be intraspecific variants of a single species. The possibilities and limitations of age determination of the Wealden sediments using palynomorphs and ostracods are discussed; distinct forms of early angiosperm pollen, together with the ostracod fauna, are consistent with an early Barremian age. Pollen and spores are discussed in terms of their parent plants and the reconstruction of vegetation and palaeoclimate. Palynology and ostracods give evidence for temporary freshwater conditions at the time when the Iguanodon died and the carcase was buried.  相似文献   

Palynofacies and sea-level changes in the Upper Cretaceous of the Vocontian Basin, southeast France     

Annette E. Gtz  Susanne Feist-Burkhardt  Katrin Ruckwied 《Cretaceous Research》2008,29(5-6):1047

Upper Cretaceous platform carbonates of the Vocontian Basin (southeastern France) have been investigated in a cross-section from the proximal deposits exposed in the lower Rhône Valley to the distal part of the basin in the Southern Subalpine Ranges north of Nice. The stratigraphic interval studied in detail spans the uppermost Turonian and Coniacian.Palynofacies patterns were used to detect eustatic signals at a third-order scale and are the tool for correlation of proximal and distal platform deposits. The organic constituents observed in the studied samples have been grouped into a continental fraction, including higher plant debris (phytoclasts) and sporomorphs, and a marine fraction with dinoflagellate cysts, acritarchs, prasinophytes, and foraminiferal test linings. The main factors influencing the stratigraphic and spatial distribution of land-derived, allochthonous, and marine, relatively autochthonous, organic particles are the proximity of land, the organic productivity, the degree of biodegradation and the hydrodynamic conditions of the depositional system. Palynofacies parameters used for the sequence stratigraphic interpretation are: (1) the ratio of continental to marine constituents (CONT/MAR ratio); (2) the ratio of opaque to translucent phytoclasts (OP/TR ratio); (3) the phytoclast particle size and shape; and (4) the relative proportion and species diversity of marine plankton. Ternary diagrams illustrating significant proximality changes were used to decipher transgressive-regressive trends within the succession.High amounts of translucent phytoclasts and decreasing values of the CONT/MAR ratio occur during the phase of relative sea-level rise in the upper Turonian. The stratigraphic interval of maximum flooding around the Turonian/Coniacian boundary is marked by the highest abundance and species diversity of dinoflagellate cysts, and by high percentages of opaque, equidimensional particles within the phytoclast group. The OP/TR ratio is still high within the lower Coniacian representing the early highstand deposits, whereas the relative abundance of marine constituents is again decreasing. Sedimentary organic matter of the upper Coniacian is dominated by large, blade-shaped, mainly opaque phytoclasts, which are a characteristic palynofacies signature of late highstand deposits.The present study demonstrates the high potential of palynofacies analysis in high-resolution stratigraphy and correlation of sedimentary series of shallow epeiric seas.  相似文献   

Die Porositäten toniger Keuper- und Jura-Sedimente Südwestdeutschlands     

Dr. Dietrich Heling 《Contributions to Mineralogy and Petrology》1967,15(3):224-232

After a short review of the basic principles governing compaction of clayey sediments, investigations of the porosities of Mesozoic shales from southwestern Germany are reported. The results reveal the influence of grain size, mineral content, temperature, and organic matter on the porosity of shales. All these and other factors have to be considered when evaluating primary porosities of shales at the time of deposition.  相似文献   

Sedimentologische Untersuchungen an Grimmelfinger Graupensanden     

Dr. Dietrich Heling 《Contributions to Mineralogy and Petrology》1966,12(2):192-201

Zusammenfassung Die Untersuchung von Korngrößenverteilung und Rundungsgrad der Grimmelfinger Graupensande an zwei durch 150 km Transportweg unterschiedenen Aufschlüssen gibt Hinweise auf die Einwirkungen auf das verfrachtete Sedimentmaterial unter gleichförmigen, fluviatilen Bedingungen.Am Anfang des untersuchten Rinnenabschnittes besteht das Sediment überwiegend aus je einer Modalfraktion im Mittelsandbereich, Grobsandbereich und Feinkiesbereich¹.Auf dem Transport wird die Mittelsandfraktion — vermutlich infolge der Schlagwirkung des Feinkieses — aufgerieben und fortgeführt. In den beiden gröberen Fraktionen wird am Ende des untersuchten Abschnittes keine Korngrößenabnahme und damit verbunden auch keine Rundungsgraderhöhung beobachtet. Dieses Ergebnis wird verglichen mit den in der Literatur mitgeteilten Untersuchungen in Abriebmühlen und Feldbeobachtungen. Danach dürfte der Rundungsgrad in der Feinkiesfraktion seinem unter den gegebenen Umständen erreichbaren Grenzwert sehr nahe sein und sich auch bei weiter fortgesetztem Transport kaum noch ändern. In der Grobsandfraktion wird der Anteil, dessen Rundung verbessert wird, infolge der damit verbundenen höheren Kugeligkeit bevorzugt fortgeführt.Die Untersuchungen bestätigen, daß die Abrundungseffekte an Sedimentmaterial in strömendem Wasser in Abhängigkeit von der Korngröße betrachtet werden müssen.

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The mechanical effects of fluvial transport over a distance of 150 km were studied by means of size frequency distributions and analysis of roundness in a Tertiary flow channel in Southern Germany filled by sand mixed with fine gravel.When entering the-channel the deposited material shows characteristic trimodal size frequency distributions. During transport the finer modal fraction (0.2...0.63 mm) is destroyed — probably through breakage by the gravel — and removed, while the sizes of the two coarser fractions remain unaffected. The roundness of the coarser fractions also remains unchanged by transport. This suggests that the roundness of the gravel material has approached its limiting roundness which is the optimum that can be achieved under the prevailing conditions. That part of the coarse sand fraction which becomes better rounded by transport may be removed preferably, because the grains getting higher sphericity by being rounded are transported more easily.Grain sizes have to be considered when abrasion effects are studied.

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Herrn Professor Dr. H. Aldinger danke ich für die Möglichkeit, die vorliegende Arbeit im Geologisch-Paläontologischen Institut der Technischen Hochschule Stuttgart anzufertigen, Herrn Dr. D. Elwert, Kiel, für die Überlassung von Probenmaterial.  相似文献   

Development of fouling communities on vertical structures in the Baltic Sea   总被引：6，自引：2，他引：6  

Susanne Qvarfordt  Hans Kautsky  Torleif Malm 《Estuarine, Coastal and Shelf Science》2006,67(4):618-628

The pillars of the bridge connecting the Island of Öland with the Swedish mainland were rebuilt between 1990 and 2000. The renovation produced pristine vertical concrete substrates, which became submerged in known years and seasons. The fouling communities on the pillars were examined in 2001 to determine whether the community structure could be explained in terms of either orderly successional development or of seasonal variation in the settlement of benthic organisms. As well, the communities on the pillars were compared to communities on the vertical surfaces of boulders in the area. The results indicated that an annual species composition is the final stage in the succession on the observed, vertical constructions. The few perennial species add to the variation between pillars as they increase in biomass (Polysiphonia fucoides) or become out-competed (Balanus improvisus). Also, observed seasonal differences in the biomass of these perennial species indicated that the time of year free space becomes available might be an important determinant of the future structure of the community. Comparison between the pillar and boulder communities showed that the artificial structures were not surrogates for the natural hard substrate: pillar communities differed in that they lacked most perennial algal species and had a high biomass of B. improvisus.  相似文献   

Les coraux (Scléractiniaires et Hydro-coralliaires) de 'atoll de Takapoto, îles Tuamotu: Aspects écologiques     

Dietrich H.H.  Kühlmann  Jean-Pierre  Chevalier 《Marine Ecology》1986,7(1):75-104

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Baltic cod recruitment - the impact of climate variability on key processes   总被引：3，自引：0，他引：3  

Koster  Friedrich W.; Mollmann  Christian; Hinrichsen  Hans-Harald; Wieland  Kai; Tomkiewicz  Jonna; Kraus  Gerd; Voss  Rudiger; Makarchouk  Andrei; MacKenzie  Brian R.; St. John  Michael A.; Schnack  Dietrich; Rohlf  Norbert; Linkowski  Tomasz; Beyer  Jan E. 《ICES Journal of Marine Science》2005,62(7):1408-1425

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Coupling an ocean wave model to an atmospheric general circulation model     

Susanne L Weber  Hans von Storch  Pedro Viterbo  Liana Zambresky 《Climate Dynamics》1993,9(2):63-69

A coupled model, consisting of an ocean wave model and an atmospheric general circulation model (AGCM), is integrated under permanent July conditions. The wave model is forced by the AGCM wind stress, whereas the wind waves modify the AGCM surface fluxes of momentum, sensible and latent heat. We investigate the following aspects of the coupled model: how realistic are the wave fields, how strong is the coupling, and how sensitive is the atmospheric circulation to the spatially and temporally varying wave field. The wave climatology of the coupled model compares favorably with observational data. The interaction between the two models is largest (although weak) in the storm track in the Southern Hemisphere. Young windsea, which is associated with enhanced surface fluxes is generated mostly in the equatorward frontal area of an individual cyclone. However, the enhancement of the surface fluxes is too small to significantly modify the climatological mean atmospheric circulation.This paper was presented at the Second International Conference on Modelling of Global Climate Variability, held in Hamburg 7–11 September 1992 under the auspices of the Max Planck Institute for Meteorology. Guest Editor for these papers is L. Dümenil  相似文献   

Efficient generation of conditional simulations by chebyshev matrix polynomial approximations to the symmetric square root of the covariance matrix     

C. R. Dietrich  G. N. Newsam 《Mathematical Geology》1995,27(2):207-228

Consider the problem of generating a realization y₁ of a Gaussian random field on a dense grid of points ₁ conditioned on field observations y₂ collected on a sparse grid of points ₂. An approach to this is to generate first an unconditional realization y over the grid =_{1 2}, and then to produce y₁ by conditioning y on the data y₂. As standard methods for generating y, such as the turning bands, spectral or Cholesky approaches can have various limitations, it has been proposed by M. W. Davis to generate realizations from a matrix polynomial approximations to the square root of the covariance matrix. In this paper we describe how to generate a direct approximation to the conditional realization y₁, on ₁ using a variant of Davis' approach based on approximation by Chebyshev polynomials. The resulting algorithm is simple to implement, numerically stable, and bounds on the approximation error are readily available. Furthermore we show that the conditional realization y₁ can be generated directly with a lower order polynomial than the unconditional realization y, and that further reductions can be achieved by exploiting a nugget effect if one is present. A pseudocode version of the algorithm is provided that can be implemented using the fast Fourier transform if the field is stationary and the grid ₁ is rectangular. Finally, numerical illustrations are given of the algorithm's performance in generating various 2-D realizations of conditional processes on large sampling grids.  相似文献   

Diffusion-limited REE uptake by eclogite garnets and its consequences for Lu–Hf and Sm–Nd geochronology     

Susanne Skora  Lukas P. Baumgartner  Nancy J. Mahlen  Clark M. Johnson  Sébastien Pilet  Eric Hellebrand 《Contributions to Mineralogy and Petrology》2006,152(6):703-720

Garnets from the Zermatt-Saas Fee eclogites contain narrow central peaks for Lu + Yb + Tm ± Er and at least one additional small peak towards the rim. The REE Sm + Eu + Gd + Tb ± Dy are depleted in the cores but show one prominent peak close to the rim. These patterns cannot be modeled using Rayleigh fractionation accompanied by mineral breakdown reactions. Instead, the patterns are well explained using a transient matrix diffusion model where REE uptake is limited by diffusion in the matrix surrounding the porphyroblast. Observed profiles are well matched if a roughly linear radius growth rate is used. The secondary peaks in the garnet profiles are interpreted to reflect thermally activated diffusion due to temperature increase during prograde metamorphism. The model predicts anomalously low ¹⁷⁶Lu/¹⁷⁷Hf and ¹⁴⁷Sm/¹⁴⁴Nd ratios in garnets where growth rates are fast compared to diffusion of the REE, and these results have important implications for Lu–Hf and Sm–Nd geochronology using garnet.  相似文献