Composition and properties of glacigenic sediments in the southwestern Barents Sea

Abstract

The composition and properties of glacigenic sediments in the southwestern Barents Sea are described based on data from 33 shallow boreholes (< 143 m below seabed) and 11 seabed cores (<4.2m below seabed). The cores are tied into a regional seismostratigraphic framework, illustrating the relationships between different boreholes.

A massive, muddy diamicton (silty, sandy clay with scattered gravel) is found in nearly all cores. Average clay content (<2 pm) of this lithology is about 38%, but varies between about 25% and 50%. Short intervals of finely laminated, waterlain sediments or gravelly sand are cored in a few occasions. A high content of sand and gravel in the cores from near the Norwegian coast shows an influence of sediment input from the mainland, while material eroded from sedimentary rocks dominates farther offshore.

The data presented on physical properties include undisturbed and remolded undrained shear strength, natural water content, bulk density, compressional sound velocity (P waves), Atterberg consistency limits, effective preconsolidation pressure, and consolidation coefficient.

Prediction of overconsolidation from seismic mapping of erosional surfaces is confirmed by the borehole cores. High compaction is found both in Weichselian and older deposits, with a general increase in compaction toward the east as well as toward shallower water. Cores that are “underconsolidated” at their present burial depth are also reported.

The average compressional sound velocity is about 1780 m/s for the borehole cores, 1550 m/s for the seabed cores, and increases with increasing shear strength and consolidation. Both horizontal and vertical sound velocities are measured in several cores, and although the data have a considerable scatter, a slightly aniso‐tropic sound velocity is indicated.     

A Lightweight Approach for the Sensor Observation Service to Share Environmental Data across Europe

The importance of near real‐time access to environmental data has increased steadily over the last few years. In this article, the focus is on the European Environment Agency (EEA), which receives environmental data from a large number of providers. The heterogeneous data formats and data transfer mechanisms make the data collection and integration a difficult task for the EEA. An approach is needed for facilitating the interoperable exchange of environmental data on a large scale. A core element of this approach is the Sensor WebEnablement (SWE) technology of the Open Geospatial Consortium (OGC) which allows the standardized, interoperable, vendor and domain independent exchange of sensor data. The main contribution of this article is a lightweight profile for the OGC Sensor Observation Service that ensures the necessary interoperability for seamlessly integrating the environmental data provided by the EEA's member states and thus forms the foundation for the developed data exchange mechanisms. This is complemented by information about the resulting Sensor Web architecture and the integration into the EEA's existing IT infrastructure. In summary, this article describes a practical scenario in which SWE technology enables the exchange of near real‐time environmental data on a large scale.     

Autumn atmospheric response to the 2007 low Arctic sea ice extent in coupled ocean–atmosphere hindcasts

The autumn and early winter atmospheric response to the record-low Arctic sea ice extent at the end of summer 2007 is examined in ensemble hindcasts with prescribed sea ice extent, made with the European Centre for Medium-Range Weather Forecasts state-of-the-art coupled ocean–atmosphere seasonal forecast model. Robust, warm anomalies over the Pacific and Siberian sectors of the Arctic, as high as 10°C at the surface, are found in October and November. A regime change occurs by December, characterized by weaker temperatures anomalies extending through the troposphere. Geopotential anomalies extend from the surface up to the stratosphere, associated to deeper Aleutian and Icelandic Lows. While the upper-level jet is weakened and shifted southward over the continents, it is intensified over both oceanic sectors, especially over the Pacific Ocean. On the American and Eurasian continents, intensified surface Highs are associated with anomalous advection of cold (warm) polar air on their eastern (western) sides, bringing cooler temperatures along the Pacific coast of Asia and Northeastern North America. Transient eddy activity is reduced over Eurasia, intensified over the entrance and exit regions of the Pacific and Atlantic storm tracks, in broad qualitative agreement with the upper-level wind anomalies. Potential predictability calculations indicate a strong influence of sea ice upon surface temperatures over the Arctic in autumn, but also along the Pacific coast of Asia in December. When the observed sea ice extent from 2007 is prescribed throughout the autumn, a higher correlation of surface temperatures with meteorological re-analyses is found at high latitudes from October until mid-November. This further emphasises the relevance of sea ice for seasonal forecasting in the Arctic region, in the autumn.     

Wave-trains in the solar wind

The equations of motion of all relevant parameters of Alfvén waves propagating from the sun outwardly into the expanding interplanetary medium are discussed for the case of a quiet, ideal, isotropic, one-fluid solar wind plasma. It is found that the frequency of the wave reamains constant, while the wave vector and the amplitudes depend, in general, on the evolution of the background medium and on the angle between the wave vector and the interplanetary magnetic field. This latter dependence cancels approximately for the evolution of the amplitudes in the case of a pure, overall spiral magnetic field. It is shown that in this case the results of earlier discussions can be derived by less decisive restrictions.     

Untersuchungen über die Fruchtbarkeit des Blaufelchens (Coregonus wartmanni Bloch) im Bodensee

Ohne Zusammenfassung Herrn Prof. Dr. P. Meyer-Waarden zum 60. Geburtstag gewidmet Mit Unterstützung des Ministeriums für Ern?hrung, Landwirtschaft und Forsten, Baden-Württemberg, und des Bayerischen Staatsministeriums für Ern?hrung, Landwirtschaft und Forsten.     

A general method for an explicit determination of the shape of the earth from gravimetric data

Summary The principal formulae of the geophysical geodesy are based on the famous explicit expression of Stokes (1849). Up to now, there has been no method for a computation of the corresponding explicit expression of a (non-spherical) surface with masses outside the geoid. In this paper there is a solution of this problem. Another paper on this subject was presented to “Nordiska geodetm?tet” in Copenhagen May 1959 (in Swedish).     

Long-wavelength heterogeneities in the upper mantle as seen by satellites

Modern satellite methods have made it possible to study the gravity field of the earth with methods that primarily give increased information of the lower harmonics in a spherical harmonic expansion. For areas covered with water we have recently obtained very interesting results from the SEASAT-satellite. Earlier studies of the gravity field have mainly resulted in geophysical evaluations for the very low degrees, which mostly reflect information from the core and the lower mantle. Now available studies seem to give evidence for geophysical activities which originate from convection currents as well as glacio-isostatic uplifts. Most of this information is probably generated in the upper mantle. Methods for mapping of the terrestrial gravity field with satellite technique are presented and some of the problems with the geophysical evaluation are further discussed.     

RbSr total rock isotope studies on Precambrian charnockitic gneisses from South Norway: evidence for isochron resetting during a low-grade metamorphic-deformational event

The quartzo-feldspathic charnockitic orthogneisses within the Bamble sector of the so-called Sveconorwegian (1.2–0.9 b.y.) zone are highly fractionated in K and Rb such that they comprise two chemically contrasting zones — one highly K, Rb-deficient and the other with values of the same order as upper crustal lithologies.Eight series of samples, each collected from single outcrops, have yielded Rb-Sr total rock apparent ages in two distinct groups, at ～1540 and ～1060 m.y. Outcrops in both the K-deficient and normal-K suites have produced examples of each age. The older age relates to the high-grade charnockite event, and the younger to a superimposed low-grade event which occurred at the same time as the intrusion of undeformed granite sheets and pegmatite dikes; one of the granites has yielded an isochron age of 1063 ± 20 m.y. The low-grade event involved only the partial alteration of orthopyroxenes to chlorite and/or serpentine, coupled with some corrosion of biotite; the alterations were initiated along narrow, irregularly spaced, cracks and it was their development which facilitated open system behaviour of the total rock isotopic systems at some localities. The degree of rehomogenisation is a function of the intensity of the secondary alterations.Confirmation of resetting at ～1060 m.y. is given by four mineral + host rock isochrons all yielding ages within error of the age for the intrusive granite; two of these are from outcrops where the rocks retain the older ～1540-m.y. age.The secondary total rock isotopic homogenisation cannot be explained adequately by Rb mobility or by simple mixing with a fluid having its own initial⁸⁷Sr/⁸⁶Sr composition. The primary mineralogy may have determined whether individual localities and/or samples suffered net increases or net decreases in⁸⁷Sr/⁸⁶Sr.An important implication of the results is that in this, or any similar geological situation, there would be a very real possibility of drawing erroneous conclusions from regionally-collected samples, particularly if the full significance of the later, relatively minor P-T event remained undetected and/or the scale of isotopic (re-)homogenisation, were unknown. It is only because of the methods adopted that it can be stated that there is no isotopic evidence for a high grade Sveconorwegian (Grenvillian) event in this part of southern Norway.     

The age of the sub Mid-Jurassic tropical weathering profile of andoya,northern Norway,and the implications for the late palaeozoic palaeography in the North Atlantic region

Results are given of a programme of K-Ar age determinations from an equatorial weathering profile beneath the Mid-Jurassic unconformitiy of Anøya, northern Norway. A model is presented where the original age of weathering is considered as Lower Carboniferous with partial resetting of ages during subsequent diagenesis. It is concluded that the Kaolinite of the weathering profile became a closed system of⁴⁰Ar diffusion in late Triassic times, and that a sufficient thickness of Mesozoic-Tertiary strata was never developed to occasion the resetting of the ages. The implication of the results is that a former thick cover of Upper Palaezoic age formerly existed in the region which was effectively removed by erosion in late Triassic — early Jurassic times. The results of the study are reviewed in a context of North Atlantic palaeogeographical evolution.

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Zusammenfassung Aus einem fossilen Bodenprofil unterhalb der mitteljurassischen Diskordanz in Nordnorwegen wurden K-Ar-Alter bestimmt, die auf eine Verwitterung während des Unterkarbons hinweisen. Während der folgenden Diagenese sind die Alter teilweise neu eingestellt worden. Dabei zeigt sich, daß der Kaolinite des ursprünglichen Bodenprofils erst ab Obertrias einem für Ar⁴⁰-Diffusion geschlossenen System angehört. Es folgt weiter, daß während des Mesozoikums und Tertiärs keine größere Sedimentbedeckung mehr über diesen Profilen möglich war, wohingegen eine erhebliche Mächtigkeit von jungpaläozoischen Sedimenten ehedem vorlag, die während der Obertrias abgetragen wurde. Diese Beobachtungen können mit der paläogeographischen Entwicklung des Nord-Atlantik in Zusammenhang gebracht werden.

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Résumé On a déterminé les âges K-Ar, donnés par un sol d'alteration formé pendant le Carbonifère inférieur et sous-jacent à la discordance du jurassique moyen, au nord de la Norvège. Les âges ont été en partie de nouveau déterminés, lors des diagénèses suivantes. Il en ressort que la Kaolinite du profil du sol originel n'appartient à un système fermé de diffusion Ar⁴⁰ qu'à partir du Trias supérieur. Il s'ensuit qu'un recouvrement sédimentaire épais n'a pu se déposer sur ce profil au cours du Secondaire et du Tertiaire, tandis qu'une épaisseur considérable de sédiments du Paléozoique supérieur existait, enlevès ensuite par érosion au Trias supérieur. Ces observations peuvent être mises en rapport avec le développement paléogéographique de l'Atlantique-Nord.

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