Evidence for a mid‐Pleistocene shift of ice‐drift pattern in the Nordic seas

Sediment proxy records from a continuous, 1.5 million year long deep‐sea sediment core from a site in the western Norwegian Sea were used to obtain new insights into the nature of palaeoceanographic change in the northern North Atlantic (Nordic seas) during the climatic shift of the Mid‐Pleistocene Revolution (MPR). Red‐green sediment colour and magnetic susceptibility records both reveal significant differences in their mean values when comparing the intervals older than 700 000 yr (700 ka) with those from the past 500 kyr. The timing and duration of these changes indicates that the MPR in the Nordic seas is characterised by a gradual transition lasting about 200 kyr. Together with further sedimentological evidence this suggests that the mid‐Pleistocene climate shift was accompanied by a general change in ice‐drift pattern. It is further proposed that prior to the onset of the major late Pleistocene glaciations in the Northern Hemisphere a significant proportion of the ice in the eastern Nordic seas originated from a southern provenance, whereas later it dominantly came from the surrounding landmasses. Copyright © 2003 John Wiley & Sons, Ltd.     

Dust metamorphosis in the galaxy

Summary Cosmic dust grains play an important role for the thermal, dynamical, and chemical structure of the interstellar medium. This is especially true for the star formation process and the late stages of stellar evolution. Dust grains determine the spectral appearance of protostars, very young stellar objects with disk-like structures as well as of evolved stars with circumstellar envelopes.In this review, we will demonstrate that solid particles in interstellar space are both agent and subject of galactic evolution. We will especially discuss the different dust populations in circumstellar envelopes, the diffuse interstellar medium, and the molecular clouds with strong emphasis on the evolutionary aspects and the metamorphosis of these populations.     

The influence of synoptic airflow on UK daily precipitation extremes. Part II: regional climate model and E-OBS data validation

We investigate how well the variability of extreme daily precipitation events across the United Kingdom is represented in a set of regional climate models and the E-OBS gridded data set. Instead of simply evaluating the climatologies of extreme precipitation measures, we develop an approach to validate the representation of physical mechanisms controlling extreme precipitation variability. In part I of this study we applied a statistical model to investigate the influence of the synoptic scale atmospheric circulation on extreme precipitation using observational rain gauge data. More specifically, airflow strength, direction and vorticity are used as predictors for the parameters of the generalised extreme value (GEV) distribution of local precipitation extremes. Here we employ this statistical model for our validation study. In a first step, the statistical model is calibrated against a gridded precipitation data set provided by the UK Met Office. In a second step, the same statistical model is calibrated against 14 ERA40 driven 25?km resolution RCMs from the ENSEMBLES project and the E-OBS gridded data set. Validation indices describing relevant physical mechanisms are derived from the statistical models for observations and RCMs and are compared using pattern standard deviation, pattern correlation and centered pattern root mean squared error as validation measures. The results for the different RCMs and E-OBS are visualised using Taylor diagrams. We show that the RCMs adequately simulate moderately extreme precipitation and the influence of airflow strength and vorticity on precipitation extremes, but show deficits in representing the influence of airflow direction. Also very rare extremes are misrepresented, but this result is afflicted with a high uncertainty. E-OBS shows considerable biases, in particular in regions of sparse data. The proposed approach might be used to validate other physical relationships in regional as well as global climate models.     

Zur Ostracoden-Fauna eines marinen Schlammbodens an der istrischen Küste (Limski kanal,NW-Jugoslawien)

Zusammenfassung Die Ostracoden mariner Schlammböden an der istrischen Küste werden am Beispiel des Limski kanal nördlich Rovinj untersucht und erste ökologische Ergebnisse anhand von 74 Proben mitgeteilt.Die Lebendfärbung mit Bengalspiritus nachLutze (1964) hat sich auch für ökologische Untersuchungen an Ostracoden bewährt.Einxe kurze Charakteristik der morphologischen, hydrologischen und sedimentologischen Verhältnisse im Limski kanal umreißt den Rahmen für eine mit etwa 25 Arten relativ artenarme Fauna. Die hydrographischen Bedingungen entsprechen weitgehend denen der offenen Adria. Die Ostracoden-Fauna zeigt jedoch einen selbständigen Charakter, was vor allem auf Art und Gefüge des Sediments zurückzuführen ist. Es werden 2 Assoziationen unterschieden und den Thanatozönosen gegenübergestellt. Dabei zeigt sich, daß im westlichen, von der Adria stärker beeinflußten Teil des Kanals etwa ein Drittel der Ostracoden-Schalen aus dem engeren Litoral-Bereich eingeschwemmt ist.

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Ostracods were studied from Recent marine clayey and silty sediments of the Limski Channel north of Rovinj, Istrian peninsula. On the basis of 74 samples from bottom cores, first ecological results are given.Staining with rose bengal according toLutze (1964) turned out to be a practicable method for ecological studies of living ostracods, as well.The morphological, hydrological, and sedimentological conditions of the Limski Channel are outlined which affected the environmental position of a relatively poor fauna of about 25 species. The hydrographical conditions correspond with those of the open Adriatic. The ostracod fauna, however, reveals an individual character which is attributed, above all, to the kind and structure of the sediment. Two assemblages may be distinguished. They are compared with the dead populations. There is evidence that in the western part of the channel, which is more strongly influenced by the sea, one third of the ostracod shell material has been transported from the littoral and the uppermost part of the sublittoral to deeper parts of the channel.

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Résumé Des recherches sur les Ostracodes marins, originaires des fonds vaseux de la côte d'Istrie, ont été fait dans le Canal Limski au nord de Rovinj. Les premiers résultats écologiques ont été publiés avec 74 échantillons à l'appui.Nous avons acquis de bons résultats pour des études écologiques d'Ostracodes vivants en nous servant du «Bengalspiritus» suivant la méthode deLutze (1964).Les caractéristiques des conditions morphologiques, hydrologiques et sédimentologiques du Canal Limski, qui constituent le cadre de la faune relativement pauvre en Ostracodes (25 espèces), sont esquissées. Les conditions hydrographiques correspondent dans une large mesure à celles de la Mer Adriatique. Cependant la faune d'Ostracodes présente un caractère particulier attribué avant tout à la nature sédimentologique et à la structure du substratum. Deux associations sont à différencier et sont comparées avec les thanatocénoses. Il en résulte que dans la partie ouest du canal, qui est ouverte à l'influence de la mer, environ un tiers des valves d'Ostracodes provient du voisinage immédiat du littoral.

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74 Limski Rovinj. . — Lutze (1964). — , , Limski, . — , . , . , , , 1/3 .

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Erweiterte Fassung eines am 27. Februar 1970 auf der 60. Jahrestagung der Geologischen Vereinigung in Kiel unter dem Titel: Zur Ökologie der Ostracoden des Limski kanal bei Rovinj (nördliche Adria) gehaltenen Vortrages.     

Die großen Gräben: Harmonische Strukturen in einer disharmonisch struierten Erdkruste

A system of intracontinental grabens extends over Western Europe, the Levant and East Africa. Small crustal segments framed by elevated shoulders are sunken along parallel escarpments and disintegrated by antithetic normal faults. The shoulders are risen up as outward tilted blocks and thought to form a closed vault at the base of the crust, corresponding to the wedge block of the graben. Underneath the Rhinegraben exists, as detected by seismic refraction measurements, a pillow-shaped body of material with P-wave velocities of 7.4 to 7.9 km/sec, intercalated between crust and mantle. The taphrogenesis of all larger grabens is assumed to be induced by the formation and growth of subcrustal swells of this type. Also the specific graben volcanism is thought to be connected with the intruded laccolithic body of mantle-derived material. The tensional breakup and the faulting of the warped crustal masses was favoured by the gravity slide of the crust which was uncoupled from the substratum by the intercalated magmatic layer. Along the Red Sea Rift the crust tore completely releasing the basaltic substratum in the inner graben. The pattern of its magnetic anomalies leads to the assumption that the pillow body is recruited by simatic dike injections according to the principle of sea-floor spreading. Therefore, there is a great conformity between the intercontinental and the mid-oceanic rift systems. The supplies of mantle material along the Mid-Atlantic and the Carlsberg Rift are related to the drift of the continental frames. The mid-oceanic rift systems in their medial position to the framing continental margins correspond to the intracontinental graben swarm, equidistant from both fronts of circum-Pacific tectonics. A reciprocating action is presumed between the ascending masses along the rift zones and the suction of masses along the deep-sea trenches and geosynclines. The observed crustal movements imply an equilibrant plastic flow within the upper mantle, probably impelled by mechanical convection currents. The continental unbalance between the Pacific and the anti-Pacific hemisphere is discussed as causing mantle currents. Within this interplay between crust and mantle and between continents and ocean floors, the oceanic crust had obtained harmonical features moulded directly by the deduced mobility. The continental crust, however, is passively stressed, its rocks are affected by heterogeneous deformations from which the continents got its polygenetic multiform fabric.     

Three varieties of alpine-type ultramafic rocks in the Norwegian Caledonides and basal gnesis complex

Three varieties of alpine-type ultramafic rocks are distinguish in the Norwegian Caledonides associated Basal Gneiss Complex. Type one rocks have primary (magmatic) olivine, clinopyroxene, orthopyroxene and chromite, and are partly or completely serpentinised. They are found exclusively in rocks of Cambro-Silurian age. Type two are polymetamorphic metaperidotites or sagvandites consisting of olivine, enstatite and carbonate minerals, with talc and amphibole commonly being present. They are found in medium- to high-grade metamorphic rocks. Type three also show a metamorphic mineral association of olivine, orthopyroxene and minor chromite, while clinopyroxene, amphibole and chrome-bearing chlorite may also be present in some samples. Garnet may or may not occur and, where present, is often surrounded by reaction rims of spinel and amphibole. The type three ultramafic bodies are serpentinised to varying degrees and occur in high-grade metamorphic gneisses which may also contain eclogites and anorthosites. Distinction of these three varieties of ultramafic body may be useful for correlation purposes and for more detailed studies on the nature of their metamorphism.     

Die Entstehungsgeschichte eines Maares in Süd-Chile

Zusammenfassung Die südchilenische, aktive Vulkanprovinz begleitet den Anden-Westrand gegen das Längstal. Die 1300 km lange Vulkanzone sitzt auf einer tektonischen Naht zwischen dem alten Sockel der Küstenkordillere im W und dem andinen Orogen im E. Der Vulkanismus begann mit andesitischen Ergüssen an der Tertiär/Quartär-Wende im Gefolge germanotyper Zerrbewegungen. Im letzten Interglazial und in der Nacheiszeit bildeten sich infolge starker Aschenförderung zahlreiche Stratovulkane. In der Gegenwart überwiegen explosive Aschenausbrüche mit Förderung gasreicher Blocklava. Teilweise hat Maarbildung und postvulkanische Tätigkeit eingesetzt. Als jüngstes Ereignis enstand in der Provinz Valdivia am 27. Juli 1955 durch einen Initialdurchbruch ein neuer Ausbläser, dessen Sprengtrichter sich nach Art eines Maares bald mit Grundwasser füllte. Die Beobachtungen während dieses Ausbruches werden aktuo-geologisch zur Deutung von Erscheinungen an den Eifel-Maaren verwertet.     

The Swedish Deep Drilling Program: the quest for the Earth's inner secrets

The Swedish Deep Drilling Program (SDDP) has been initiated to study fundamental problems of the dynamic Earth system, its natural history and evolution. Many key scientific questions can be addressed through in situ investigations only, requiring deep continental drilling. Some are unique to Scandinavia, most are of international interest and significance. At present, five core projects ( Fig. 1 ) with international teams are integrating scientific problems with societal and industrial applications. If SDDP succeeds to attract the funding required, Sweden will have a number of world‐class boreholes at key locations by 2020.

Figure 1 Open in figure viewer PowerPoint Locations of SDDP drilling project proposals. PFDP—Postglacial Fault Drilling Project; PaMVAS—Palaeoproterozoic mineralized volcanic arc systems: the Skellefte District; COSC—Collisional Orogeny in the Scandinavian Caledonides; DRL—The Dellen Impact Crater, a geoscientific deep rock laboratory; SELHO—Svecofennian accretion, an example of the early structural evolution in a large hot orogen; CISP—Concentric Impact Structures in the Palaeozoic: the Lockne and Siljan craters. Background and inset image from Blue Marble Next Generation data set (NASA Earth Observatory, http://earthobservatory.nasa.gov/Features/BlueMarble/ ).     

Late Pliocene sand ridges at the western margin of the Barents Sea—do they monitor Late Pliocene glaciations?

Seismic data combined with core analysis of the northwesternmost exploration well on the Norwegian continental margin, well 7316/5-1, has been used to map and discuss the genesis of three well-defined sand ridges. The sand ridges have a NE-SW to N-S orientation and are of Late Pliocene age. The dimensions of the ridges are: height 40 m, length 2–4 km and width 0.5–1 km.In relation to the glaciation models of the Barents Sea, the position of well 7316/5-1, and especially information from a core that penetrated one of the sand ridges, provide important information. The ridges are not, in themselves, diagnostic for grounded glaciers at the margin of the Barents Sea shelf during the Late Pliocene, although the presence of pebbles in a cored section of the ridges may represent ice-dropped material. Whether the possible influx of glaciogenic material is related to local or regional glaciations on the Barents Shelf remains to be evaluated.     

On the properties of very young massive infrared sources (Mitteilungen der Universitäts-Sternwarte zu Jena Nr. 169)

The data compiled for 34 very young massive compact infrared source (Becklin-Neugebauer objects) in a separately published catalogue serve as the basis for an investigation of their general properties. First, the correlations of the strength of the ice and silicate bands at 3.1 μm and 10 μm, resp., with each other and with other parameters of the sources are investigated. In accordance with theoretical expectations the strengths of both bands are not well correlated with each other. The ratio τ₁₀/τ₃ of their optical depths veries from 0.85 to 8 (and possibly up to 22). That implies for the number densities of the grains that (naked) silicate grains always are considerably more abundant than ice grains (grains with ice mantles). It follows from the discussion of the relationships between τ₁₀, the temperature parameter of the sources, and their luminosity that relations between τ₁₀ and temperature and possibly between τ₁₀ and the luminosity exist. Stellar wind models for the ionized region around the embedded star are favoured after the analysis of the intensities of the hydrogen infrred emission lines and the radio continuum. The limited observational data do not yet allow a decision on a correlation between the silicate band depth and energy content and/or the velocity of the bipolar outflow detected in a number of sources. The BN objects are clearly more frequently associated with H₂O masers than OH masers. The linear separations of the infrared peaks from the masers are compatible with models where the H₂O masers are situated near the edges the gas-dust shells of the BN objects.