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1.
Kaare L. Rasmussen Hans J. F. Olsen Raymond Gwozdz Evgeniy M. Kolesnikov 《Meteoritics & planetary science》2001,36(7):1001-1006
Abstract— Jull et al. propose an alternative interpretation of our depth vs. 14C data measured on a peat core from the central Tunguska impact site (Rasmussen et al., 1999). We find that the proposed alternative is untenable. 相似文献
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In the Bavarian Alps (Germany), west of the Isar River, the abyssal deposits of the Lower Barremian to Upper Campanian Rhenodanubian Group consist of siliciclastic and calcareous turbidites alternating with hemipelagic non-calcareous mudstones. The up to 1500-m-thick succession, deposited in the Penninic Basin to the south of the European Plate, is characterized by a low mean sedimentation rate (c. 25 mm kyr−1) over 60 million years. Palaeocurrents and turbidite facies distribution patterns suggest that sedimentation occurred on a weakly inclined abyssal plain. The highest sedimentation rates (up to 240 mm kyr−1) were associated with the calcareous mud turbidites of the newly defined Röthenbach Subgroup, which includes the Piesenkopf, Kalkgraben and Hällritz formations (Middle Coniacian to Middle Campanian). These calcareous turbidites prograded from the west, and interfinger towards the east with red hemipelagic claystone. A high sea level presumably favoured pelagic carbonate production and accumulation on the shelves and on internal platforms in the western part of the basin, whereas siliciclastic shelves with steep slope angles have bordered the eastern part of the basin, where a dearth of turbidite sedimentation and increased Cretaceous oceanic red beds deposition occurred. In contrast to the eustatically-induced Middle Coniacian to Lower Campanian Cretaceous oceanic red beds (calcareous nannoplankton zones CC14 to CC18), red hemipelagites of Early Cenomanian age (upper part of calcareous nannoplankton zone CC9) and early Late Campanian age (upper part of zone CC21 and zone CC22) are interpreted as the result of regional tectonic activity. 相似文献
3.
Barite has been found for the first time in the Swiss Jura (Hirni, Passwang). Small, white crystals of barite with yellow ankerite grow on calcite in different chambers of a Bajocian ammonite. Chemical data (by microprobe analysis) and lattice parameters (refined by leastsquares from powder patterns) are given for the two minerals. There is a distinct correlation between the cell dimensions and the chemical composition for both of them. The genesis is discussed. 相似文献
4.
Prof. Dr. Hans Ertel 《Pure and Applied Geophysics》1962,53(1):77-80
Resumen Presentamos una solución numérica del problema del efecto de embalse con ayuda de una ecuación lineal inhomogénea en diferencias finitas de primer orden, suponiendo una ley lineal del desagüe. Este método numérico es de maneje cómodo para un cálculo aproximado.
Zusammenfassung Es wird die numerische Bestimmung der Seeretention mittels der Lösung einer linearen inhomogenen Differenzengleichung 1. Ordnung dargelegt. Dieses numerische Verfahren ist für eine Näherungsrechnung besonders geeignet.相似文献
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Bishwajit Chakraborty Hans Werner Schenke Vijay Kodagali Rick Hagen 《Marine Geodesy》2002,25(1):19-26
Utilizing a hull-mounted, multinarrow beam echosounder onboard RV Polarstern, we measured variation of acoustic backscatter with incidence angles at two different sites in the Southern Oceans (Agulhas Plateau and the Riiser Larsen Sea). We modeled the data, using a composite roughness model, including water-sediment interface roughness and sediment volume roughness parameters. The model effectively uses the near normal incidence angle backscatter to determine the seafloor interface roughness parameters employing Helmholtz-Kirchhoff theory. Beyond 20° incidence angles, an application of Rayleigh-Rice theory is made by using a necessary splicing technique (combining both of the theories at 20° incidence angle). The estimated interface and volume roughness parameters are found to be in accordance with the known area geology. 相似文献
8.
Flounder (Platichthys flesus L.), 18–48 cm total length were sampled in the mouth of the Elbe River during a 3-year interdisciplinary project ‘Fish Diseases in the Wadden Sea’. Lysosomal changes (lysosomal membrane stability) and the activity of biotransforming enzymes (MFOs/EROD) were measured parallel to investigations of ultrastructural changes in liver cells, tissue pathologies and macroscopically visible changes. The aim of the study was to investigate if these cyto- and biochemical parameters were able to reflect contaminant induced biological effects. Interlinking of the results of the MFO activity to the pathological alterations observed at the electron- and light-microscopic levels as well as during macroscopic inspection of identical individuals evidenced that the activity of the biotransformation enzymes (EROD) was not induced in healthy livers, increased considerably with the onset of liver changes and dropped again in those livers with degenerative, preneoplastic and neoplastic lesions. In contrast, concurrent studies of lysosomal membrane stability measured in parallel showed a decrease with the onset and progression of liver lesions from reversible to irreversible, neoplastic change. 相似文献
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Benthic photosynthesis in submerged Wadden Sea intertidal flats 总被引:3,自引:1,他引:3
Markus Billerbeck Hans Ry Katja Bosselmann Markus Huettel 《Estuarine, Coastal and Shelf Science》2007,71(3-4):704-716
In this study we compare benthic photosynthesis during inundation in coarse sand, fine sand, and mixed sediment (sand/mud) intertidal flats in the German Wadden Sea. In situ determinations of oxygen-, DIC- and nutrient fluxes in stirred benthic chamber incubations were combined with measurements of sedimentary chlorophyll, incident light intensity at the sediment surface and scalar irradiance within the sediment. During submergence, microphytobenthos was light limited at all study sites as indicated by rapid response of gross photosynthesis to increasing incident light at the sea floor. However, depth integrated scalar irradiance was 2 to 3 times higher in the sands than in the mud. Consequently, gross photosynthesis in the net autotrophic fine sand and coarse sand flats during inundation was on average 4 and 11 times higher than in the net heterotrophic mud flat, despite higher total chlorophyll concentration in mud. Benthic photosynthesis may be enhanced in intertidal sands during inundation due to: (1) higher light availability to the microphytobenthos in the sands compared to muds, (2) more efficient transport of photosynthesis-limiting solutes to the microalgae with pore water flows in the permeable sands, and (3) more active metabolic state and different life strategies of microphytobenthos inhabiting sands. 相似文献