Optical Absorption Spectra of (Mg,Fe)SiO3 Silicate Perovskites

Electronic absorption spectra have been measured at room temperature and pressure for polycrystalline samples of (Mg, Fe)SiO₃ silicate perovskites synthesized by multi-anvil device. One strong near-infrared band at about 7000 cm^-1 and several weak bands in the visible region were found. The near-infrared band at 7000 cm^-1 is assigned to a spin-allowed transition of Fe²⁺ at the 8–12 coordinated site in perovskite. However, definite assignments of the weak bands in the visible region are difficult because of their low intensities and the scattering effect at the gain boundaries. Crystal field calculations for Fe²⁺ at different sites in perovskite have been carried out based on the crystal structure data. The results agree with the assignment of Fe²⁺ to the 8–12 coordinated site in perovskite. Crystal field stabilization energy of Fe²⁺ with coordination number of 8 in perovskite is 3332 cm^-1 which is small compared to the octahedral site of magnesiowüstite (4320 cm^-1), another important lower-mantle mineral.     

Zur Anwendung der Kathodolumineszenz in der Karbonatpetrographie

Mn-activated cathodoluminescence can be used in several fields of carbonate petrography. It may, for instance, be possible to recognize

1. cement sequences and their correlation (Tab. 1, Figs. 1, 2, 4; Tab. 2, Fig. 1)
2. growth fabrics of skeletons (Tab. 2, Figs. 2, 3, 4; Tab. 3, Figs. 1, 2)
3. dolomitisation processes and problems (Tab. 1, Figs. 1, 2; Tab. 4, Fig. 2)
4. transformation paths from Mg-calcite to calcite and from aragonite to calcite (Tab. 2, Fig. 1; Tab. 3, Figs. 3, 4; Tab. 4, Fig. 1)
5. growth structures in certain types of ooids (Tab. 1, Fig. 4; Tab. 3, Fig. 3; Tab. 4, Fig. 1)
6. reworked skeletal particles (Tab. 3, Fig. 4)
7. phantom grains and fossil-outlines in a micro- or macrocrystalline groundmass (Tab. 4, Figs. 2, 3)
8. healed fissures crossing micro- or macrocrystalline carbonate rocks (Tab. 4, Fig. 4).

These are, however, no general luminescence criteria indicating the depositional environment. Luminescence of calcite and dolomite requires 20–40 ppm Mn, with the equipments used in this study. Aragonite is not yet investigated systematically. Zonal luminescence in carbonate cements may indicate changes of the chemical composition of the aquifer and may be used for “cement stratigraphy”. In skeletons it rather indicates physiological changes. While aragonitic skeletons lose their luminescence Zonation during replacement by calcite, Mg-calcite skeletons may keep parts of it, because their replacement preserves the original crystal fabric. Blotchy luminescence developes in Mg-calcitic particles during their adjustment to lower Mg-calcites by dissolution-precipitation processes in solutions with changing Mn/Fe-ratios.     

The Uppsala urban meteorology project

An extensive urban meteorology project in Uppsala, Sweden, is described. The city itself is considered suitable as a kind of model city, being almost circular, having sharp urban/rural boundaries and being situated in a relatively flat area. The project incorporates numerous measurements. A main station with a 100-m mast is situated at the NE urban/rural border. Its instrumentation consists of a slow-response (profile) system and a turbulence system. The profile instrumentation is described in detail. In addition to the main station, the project comprises: measurements from two 14-m masts, one on the top of a centrally located building, the other mobile; pilot balloon ascents; tethered balloon soundings, car-borne temperature traverses etc. Some preliminary results are presented: analyses of wind profiles from the mast and three-dimensional heat island studies.     

The Lyngen Gabbro: the lower crust of an Ordovician Incipient Arc

We present evidence for the origin of the Lyngen Gabbro of the Ordovician Lyngen Magmatic Complex in Troms, Northern Norway. The two magmatic suites of the Lyngen Gabbro strike parallel NNE-SSW, and have distinct magmatic signatures. We define these signatures by using major and trace-element analyses together with selected major- and trace-element mineral analyses and ¹⁴³Nd/¹⁴⁴Nd-isotope whole-rock analyses of gabbroic to tonalitic plutonic rocks from seven detailed cross-sections from this large gabbro-complex. The Western suite of the Lyngen Gabbro precipitated from magma that may have been derived from the same system as the associated volcanic rocks. The gabbros have high An-content (An_>90) of their plagioclases relative to co-existing mafic minerals. Together with somewhat high _Nd(t) values (+6), this implies that the parental magmas were hydrous tholeiites similar to those found in back arc basins today. The Eastern suite, on the other hand, consist of cumulates that were precipitated from melts resembling those of ultra-depleted high-Ca boninitic magmas found in fore-arcs. Extremely high-An plagioclases (An_>95) co-exist with evolved mafic minerals and oxides, and the _Nd(t) values are lower (+4) than in the Western suite. The Eastern suite has no volcanic counterpart, but dikes intersecting the suites have compositions that possibly represent its parental magma. The oceanic Rypdalen Shear Zone generally separates the two suites in the north, but several non-tectonic transitions from boninitic to tholeiitic signatures southwards advocate that the magmatism happened concurrently. The magmatic proximity between the suites, the hydrous magmatism and the absence of a silicic or calc-alkaline mature arc section, suggests that the Lyngen Gabbro formed in the Iapetus Ocean under conditions presently found in incipient arcs later emplaced as outer arc highs.     

The use of bisnorhopane as a stratigraphic marker in the Oseberg Back Basin, North Viking Graben, Norwegian North Sea

This paper discusses the occurrence of 28,30-dinor-17α,18α,21β-hopane (bisnorhopane) in stratigraphically, fairly well preserved Viking Group sections from wells in local depressions in the North Viking Graben Area. The results show the presence of high relative amounts of bisnorhopane in the “Syn-rift sections”, whilst the “Post-rift sections” contain little or no bisnorhopane. Since most exploration wells are drilled on structural highs, primarily penetrating the “Post-rift Draupne”, this may explain why many analyzed source rock sections in this area contain little bisnorhopane.As a correlation of Draupne sections using the vertical, relative bisnorhopane distributions, it is suggested to be a potential stratigraphic marker for the area, indicating the presence of “Syn-rift Draupne” sediments.The relative bisnorhopane amounts follow a logarithmic reduction with depth and thermal maturity. The bisnorhopane signal is nearly extinguished at 3700 m depth at a maturity of R_o = 0.9–1.0%.     

Gene Expression Analysis for Exposure to Estrogenic Substances

Zebrafish (Danio rerio) were exposed with 17β‐estradiol (E2) and nonylphenol (NP) in different concentrations. Gene expression analysis was carried out by two different approaches. First, RT‐PCR experiments were performed for the examination of expression levels of the two marker genes vitellogenin and aromatase. This approach showed a significant increase in the expression of the vitellogenin gene in exposed male fish (500 ng/L 17β‐estradiol and 250 μg/L nonylphenol). This egg yolk protein is usually not synthesized in male vertebrates. A slight decrease of expression of the aromatase gene was observed in exposed female zebrafish. Aromatase is known to catalyze the conversion of androgens to estrogens. Second, DNA microarray experiments were carried out, which allow the simultaneous examination of the expression levels of a great number of marker genes. The microarray experiments resulted in an up‐regulation of vitellogenin up to 850‐fold. In addition, several other genes were identified to be up‐regulated by estrogens, for example the high mobility group box protein ssrp1 (78‐fold) or the chaperonin containing t‐complex polypeptide 1, beta subunit cctb (22‐fold).     

The Glueckstadt Graben, a sedimentary record between the North and Baltic Sea in north Central Europe

The Glueckstadt Graben is one of the deepest post-Permian structures within the Central European Basin system and is located right at its “heart” at the transition from the North Sea to the Baltic Sea and from the Lower Saxony Basin to the Rynkoebing–Fyn High.The Mesozoic to recent evolution is investigated by use of selected seismic lines, seismic flattening and a 3D structural model. A major tectonic event in the latest Middle–Late Triassic (Keuper) was accompanied by strong salt tectonics within the Glueckstadt Graben. At that time, a rapid subsidence took place within the central part, which provides the “core” of the Glueckstadt Graben. The post-Triassic tectonic evolution of the area does not follow the typical scheme of thermal subsidence. In contrast, it seems that there is a slow progressive activation of salt movements triggered by the initial Triassic event. Starting with the Jurassic, the subsidence centre partitioned into two parts located adjacent to the Triassic “core.” In comparison with other areas of the Central European Basin system, the Glueckstadt Graben was not strongly affected by additional Jurassic and Cretaceous events. During the late Jurassic to Early Cretaceous, the area around the Glueckstadt Graben was affected by relative uplift with regional erosion of the elevated relief. However, subsidence was reactivated and accelerated during the Cenozoic when a strong subsidence centre developed in the North Sea. During Paleogene and Quaternary–Neogene, the two centres of sedimentation moved gradually towards the flanks of the basin.The data indeed point toward a control of post-Permian evolution by gradual withdrawal of salt triggered by the initial exhaustion along the Triassic subsidence centre. In this sense, the Glueckstadt Graben was formed at least partially as “basin scale rim syncline” during post-Permian times. The present day Hamburger, East and Westholstein Troughs are the actual final state of this long-term process which still may continue and may play a role in terms of young processes and, e.g., for coastal protection.     

Structure and evolution of the Glueckstadt Graben due to salt movements

The salt tectonics of the Glueckstadt Graben has been investigated in relation to major tectonic events within the basin. The lithologic features of salt sections from Rotliegend, Zechstein and Keuper show that almost pure salt is prominent in the Zechstein, dominating diapiric movements that have influenced the regional evolution of the Glueckstadt Graben. Three main phases of growth of the salt structures have been identified from the analysis of the seismic pattern. The strongest salt movements occurred at the beginning of the Keuper when the area was affected by extension. This activation of salt tectonics was followed by a Jurassic extensional event in the Pompeckj Block and Lower Saxony Basin and possibly in the Glueckstadt Graben. The Paleogene–Neogene tectonic event caused significant growth and amplification of the salt structures mainly at the margins of the basin. This event was extensional with a possible horizontal component of the tectonic movements. 3D modelling shows that the distribution of the initial thickness of the Permian salt controls the structural style of the basin, regionally. Where salt was thick, salt diapirs and walls formed and where salt was relatively thin, simple salt pillows and shallow anticlines developed.     

Chronometric calibration of a comparative time scale for the mesozoic and paleozoic

The relationship between radiometric and biostratigraphic ages is analyzed by local empirical methods and illustrated in chronograms for the mesozoic and paleozoic stages. The chronograms allow estimates for stage boundaries and their errors. Consequently, the ages for epoch boundaries and their errors are discussed which, for several reasons, may not be identical with the age and error of the oldest stage of an epoch.The analysis results in a comparative time scale which could be a compromise between the time scales currently under discussion. A specific feature of the derived time scale is its rather strong cyclicity with periods around 74 (73±1) ma.

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Zusammenfassung Alter und Fehlergrenzen für mesozoische und paläozoische Stufengrenzen werden mittels einer lokalen empirischen Schätzmethode neu berechnet. Daraus ergeben sich Schätzungen für die Alter und Fehler der Epochengrenzen, die aus verschiedenen Gründen nicht mit denen derältesten Stufe einer Epoche zusammenfallen.Die Auswertung der Chronogramme führt zu einer vergleichenden Zeitskala, die im wesentlichen einen Kompromi\ zwischen den gegenwärtig gängigen Zeitskalen darstellt. Bemerkenswert ist, da\ die Zeitskala ein hohes Ma\ an Zyklizität aufweist, wobei sich Perioden von 74 (73±1) ma ergeben.

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Résumé Les relations entre les âges radiométriques et les âges biostratigraphiques sont analysées par des méthodes locales et empiriques. Elles sont présentées dans des chronogrammes se référant aux étages du MésozoÏque et du PaléozoÏque. Ces chronogrammes permettent d'estimer les limites d'étages et les erreurs de cette estimation. Les âges des limites de systèmes et leurs erreurs sont discutés en conséquence. Pour diverses raisons ils ne sont pas identiques à ceux de l'étage le plus ancien d'un système.L'analyse des chronogrammes aboutit à une échelle de temps comparative qui représente un compromis entre les échelles de temps couramment discutées. Une propriété remarquable de cette échelle est de faire apparaÎtre une cyclicité dont la période est de 74 (73±1) Ma.

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Sediment compaction in large scale systems

The classical partial differential equation for compaction proves to provide a rather singular model, if the deformations caused by overload become reasonably large. An alternative model for compaction is derived by adapting an Eulerian view and by deriving the model equations from integral equations rather than from a priori differentiability assumptions. The result is not — as usual — a single partial differential equation, but an infinite set of differential equations, interesting in both mathematical and geological terms.Although there are still several simplifications and linearizations in the derived model, the model illustrates at least that the classical Terzaghi equation and mathematical models in its vicinity are highly idealized and probably instable, if applied to large scale systems.

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Zusammenfassung Die klassische partielle Differentialgleichung für die Kompaktion stellt ein sehr vereinfachtes Modell dar, zumindest für den Fall, daß die Deformationen infolge Auflast sehr groß werden. Hier wird ein alternatives Modell entwickelt, das nicht von der Voraussetzung der Differenzierbarkeit ausgeht, sondern über Integralgleichungen entwickelt wird, wobei die Eulersche Sicht des Raum-Zeitbezuges zur Anwendung kommt. Das Resultat ist dann nicht mehr eine einfache partielle Differentialgleichung, sondern ein unendliches System solcher Gleichungen.Obwohl auch das entwickelte Modell vereinfachte Annahmen erfordert und stark linearisiert, so verdeutlicht es doch zumindest, daß die klassische Therzaghi Gleichung und modifizierte Modelle, die auf diese Gleichung aufbauen, sehr wahrscheinlich instabil sind, wenn sie auf Systeme mit großen Deformationen angewandt werden.

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Résumé L'équation classique aux dérivées partielles de la compaction fournit un modèle très simplifié, particulièrement dans le cas où les déformations dues à la surcharge deviennent considérables. L'auteur propose en alternative un modèle, adapté des conceptions eulériennes, qui repose sur les équations intégrales plutót que sur la présomption de différenciabilité. Le résultat n'est plus une simple équation aux dérivées partielles, mais un système infini de telles équations.Bien que le modèle présenté implique des hypothèses simplificatrices et des linéarisations, on peut néanmoins en déduire que l'équation classique de Terzaghi, ainsi que les modèles modifiés qui en découlent, sont très probablement instables s'ils sont appliqués à des systèmes à forte déformation.

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