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Progradational and backstepping shoreface deposits in the Ladinian to Early Norian Snadd Formation of the Barents Sea 
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下载免费PDF全文 Tore G. Klausen Alf Ryseth William Helland‐Hansen Helge K. Gjelberg 《Sedimentology》2016,63(4):893-916
Shoreface sandstone deposits within the Early Carnian part of the Snadd Formation of the Norwegian Barents Sea can be traced for hundreds of kilometres in the depositional strike direction and for tens of kilometres in the depositional‐dip direction. This study uses three‐dimensional seismic attribute mapping and two‐dimensional regional seismic profiles to visualize the seismic facies of these shoreface deposits and to map their internal stratigraphic architecture at a regional scale. The shoreface deposits are generally elongate but show variable width from north‐east to south‐west, which corresponds to a sediment source in the northern part of the basin and a southward decrease in longshore sediment transport. The Snadd Formation presents an example of how large‐scale progradational shoreface deposits develop. The linear nature of its shoreface deposits contrasts with more irregular, cuspate wave‐dominated deltaic shorelines that contain river outlets, and instead implies longshore drift as the main sediment source. In map view, discrete sets of linear features bounded by truncation surfaces scale directly to beach ridge sets in modern counterparts. The shoreface deposits studied here are characteristic in terms of scale and basin‐wide continuity, and offer insight into the contrast between shallow marine deposition under stable Triassic Greenhouse and fluctuating Holocene Icehouse climates. Findings presented herein are also important for hydrocarbon exploration in the Barents Sea, because they describe a hitherto poorly understood reservoir play in the Triassic interval, wherein the most prominent reservoir plays have so far been considered to be found in channelized deposits in net‐progradational delta‐plain strata that form the topsets to shelf‐edge clinoforms. The documented presence of widespread wave‐dominated shoreface deposits also has implications for how the relative importance of different sedimentary processes is considered within the basin during this period. 相似文献
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Alf Amsler 《International Journal of Earth Sciences》1929,20(4-5):342-342
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Jingran Zhang Sumiko Tsukamoto Alf Grube Manfred Frechen 《Boreas: An International Journal of Quaternary Research》2014,43(4):856-868
The history of sea‐level change and sediment accumulation since the last deglaciation along the German North Sea coast is still controversial because of a limitation in the quantity and quality of chronological data. In the current study, the chronology of a 16‐ka coastal sedimentary record from the Garding‐2 core, retrieved from the Eiderstedt Peninsula in Schleswig‐Holstein, northern Germany, was established using OSL and AMS 14C dating techniques. The robust chronology using 14 radiocarbon and 25 OSL dates from the Garding‐2 core is the first long‐term record that covers the Holocene as well as the last deglaciation period in one succession in the German North Sea area. It provides a new insight into understanding the Holocene transgression and coastal accumulation histories. The combined evidence from the sedimentology and chronology investigations indicates that an estuarine environment dominated in Eiderstedt Peninsula from 16 to 13 ka, followed by a depositional hiatus between 13 and 8.3 ka, attributed to erosion caused by the Holocene transgression; the onset of the Holocene transgression at the core site occurred at around 8.3 ka. The sea level continued to rise with a decelerated rate until around 3 ka. Since 3 ka, the shoreline has begun to prograde. Foreshore (tidal flat) sediments have been deposited at the drilling site with a very high sedimentation rate of about 10 m ka?1. At around 2 ka, a sandy beach deposit accumulated in the sedimentary succession, indicating that the coastline shifted landward, which may represent a small‐scale transgression in the late Holocene. At around 1.5 ka, terrestrial clastic sediment started to accumulate, indicating a retreat of the relative sea level in this area, which may be related to local diking activities undertaken since the 11th century. 相似文献
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Alf Nyberg 《Meteorology and Atmospheric Physics》1954,7(1):99-113
Summary Horizontal flux of enthalpy and latent heat has been computed from synoptic maps over a large part of the northern hemisphere for several isobaric levels during 3 months. The flux of enthalpy and also the flux of latent heat is lowest in July and 3 to 4 times larger in winter. The flux is largest at 850 mb. The large scale eddy conductivity for the enthalpy increases with the horizontal meridional temperature gradient showing that the atmospheric energy exchange processes become more effective when the gradients are strong. From the convergence of the flux values the mean heating of an air column has been computed. This heating has a winter maximum of about 1° C/24 hrs at latitude 60°–70° N. The values for the polar region are considerably lower, indicating a considerable mean descending motion in the region. The correlation between flux or convergence of flux and circulation indices is found to be rather small. There is even a negative correlation between convergence of enthalpy and the zonal index.
With 6 Figures. 相似文献
Zusammenfassung Der horizontale Transport von Enthalpie und latenter Wärme wurde auf Grund von Wetterkarten für verschiedene Druckniveaus über einem großen Teil der nördlichen Hemisphäre für drei verschiedene Monate berechnet. Sowohl der Enthalpie- wie der latente Wärmestrom ist am geringsten im Juli und drei- bis viermal größer im Winter; am größten ist er bei 850 mb. Der Großaustauschkoeffizient der Enthalpie nimmt mit dem horizontalen meridionalen Temperaturgradienten zu, was sich durch die Steigerung der atmosphärischen Energieaustauschprozesse bei Verstärkung des Gradienten erklärt. Aus der Strömungskonvergenz wurde die durchschnittliche Erwärmung einer Luftsäule berechnet. Diese Erwärmung zeigt ein Maximum von zirka 1° C/24 Studen im Winter in einer Breite von 60 bis 70° N. Die Werte für das Polargebiet sind beträchtlich niedriger und lassen eine merkliche absinkende Strömung erkennen. Die Korrelation zwischen Strömung oder Strömungskonvergenz und Zirkulationsgrößen hat sich als eher niedrig erwiesen. Die Korrelation zwischen der Konvergenz der Enthalpie und dem Zonalindex ist sogar negativ.
Résumé Le flux horizontal d'enthalpie et de chaleur latente a été calculé à partir de cartes synoptiques couvrant une grande partie de l'hémisphère nord et cela pendant 3 mois pour plusieurs niveaux isobariques. Le flux d'enthalpie ainsi que celui de chaleur latente est à son minimum en juillet et est 3 à 4 fois plus grand en hiver. Le flux le plus important se trouve au niveau de 850 mb. Le coefficient de la conductivité turbulente de l'enthalpie à grande échelle croît avec le gradient horizontal méridional de température, et montre ainsi que les processus de l'échange d'énergie atmosphérique augmentent avec la force du gradient. L'auteur a calculé le réchauffement moyen d'une colonne d'air en partant de la convergence des valeurs du flux. Ce réchauffement atteint un maximum hivernal d'environ 1° C/24 h à 60°–70° de latitude N. Les valeurs des régions polaires sont notablement plus petites et laissent reconnaître un mouvement descendant considérable dans cette région. La corrélation entre le courant ou la convergence de flux et les valeurs de la circulation s'est avérée plutôt petite. Il y a même une corrélation négative entre la convergence de l'enthalpie et l'index zonal.
With 6 Figures. 相似文献
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Alf Nyberg 《Pure and Applied Geophysics》1980,119(3):510-514
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J?rg E. Aarnes Vegard Kippe Knut-Andreas Lie Alf Birger Rustad 《Computational Geosciences》2002,6(1):1-4
Introduction
Upscaling of Geological Models for Reservoir Simulation: Issues and Approaches 相似文献8.
In support of IGCP Project 259 (International Geochemical Mapping), a pilot survey designed to test the effectiveness of analysing dried humus collected at an extremely low sampling density (one composite sample per 23 000 km2) for geochemical mapping was carried out in 49 large catchment basins in Fennoscandia. The samples were analysed for their aqua-regia leachable contents of 30 elements by ICP-ES. The results were compared with those of till sampled at the same sites and with moss from previous surveys. The correlation with underlying bedrock was also studied.Geological features exert only a weak influence on the regional distribution of elements in humus. Exceptions are high levels of Ca and Sr in areas of carbonate bedrock and low contents of K in areas of Archean rocks. The distribution patterns of Co, Cr, Cu, Mg, Ni and Zn in humus coincide partly, and the levels correlate positively with those in till. The contents of Ni, Cr and Cu are lower in humus overlying acid magmatic rocks and arkose than other rock types.Pollution is the obvious source of high concentrations of Pb, Cd and Zn in southern Sweden and southern Norway. Acid fallout seems to cause leaching of Al, P and La from the humus horizon. The contents of these elements are low in the south where deposition of S and N is high and pH of rainwater is below 4.5. Deposition of sea salts gives high levels of Na, Mg, K and B along the coast of Norway and southern Sweden.The contents of several elements in humus correlate positively with the amount of organic matter (LOI). Comparison between four types of forest shows that the contents of Ca, Mg and Na in birch forest and of Cd, Mn, Pb and Zn in spruce forest are significantly higher than in other forest types. These features, however, are considered false and are due to sources such as atmospheric deposition of anthropogenic metals and sea salt.The results of the relatively strong chemical attack used for analyses of humus samples are less informative than those from till and overbank sediments. A weaker attack may have given more useful information. The humus horizon could be suited for environmental monitoring if used in global geochemical mapping. 相似文献
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Statistics and the precautionary principle 总被引：2，自引：0，他引：2
Alf B. Josefson 《Marine pollution bulletin》1990,21(12):598
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We have tested the use of a supercontinuum laser source in laser-based spectral backscatter measurement. The calibration and first results with the prototype instrument are presented with a discussion of improvements and applications in laser-based hyperspectral remote sensing and laboratory measurements. This technique enables the spectral study of the backscatter effects and the calibration and test measurements for the purpose of airborne laser measurement. We also explore the prospect of using a supercontinuum laser source in a broadband (hyperspectral) lidar 相似文献