Relative sea level changes during the Holocene in the Sisimiut area,south‐western Greenland

Holocene relative sea level (RSL) changes have been investigated by analysing and dating isolation sequences from five lakes near Sisimiut in south‐western Greenland. The transitions between marine and lacustrine sediments were determined from elemental analyses and analyses of macroscopic plant and animal remains. Radiocarbon dating was used to provide minimum ages for the transitions and to construct a RSL curve. Dating of a shell of the marine bivalve Macoma balthica indicates that deglaciation of the lowlands occurred in the early Holocene, at around 10 900 cal a BP. The RSL curve shows initial rapid regression from the marine limit at around 140 m, implying strong glacio‐isostatic rebound. We suggest that the margin of the Greenland Ice Sheet was located at the shelf break during the Last Glacial Maximum. Frequent remains of the ostracode Sarcypridopsis aculeata, which is a thermophilous brackish water species that is unknown from the extant fauna of Greenland, in one of the basins around 8500 cal a BP may mark the beginning of the Holocene thermal maximum in the region. Copyright © 2011 John Wiley & Sons, Ltd.     

A simultaneous X-ray and optical study of TT Arietis

Prelimary results of an extended program of coordinated X-ray and optical observations of TT Ari are presented. The object was observed on August 21/22 1985 both in X-rays (EXOSAT) and optical range, about 100 days after the return to the active state. The first detailed simultaneous study of TT Ari in active state indicates the presence of strongly absorbing structure in the system.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

Administrative-territorial division of Croatia

A new administrative-territorial system was introduced in Croatia in late 1992, after the country has passed through a tumultuous period and reached independence. The new internal territorial organization is a compromise between several different criterias. It reflects Croatia's position and geographic characteristics as well as the country's history and variety of traditional regions existing on those bases, but the most decisive was the functional principle. Counties, the first order units of the new division, are primarily functional regions of main centres. Beside counties, there is also a lower level of the division, namely municipalities created in predominantly rural areas and towns in more urbanized parts. The new civil division also provided a model of territorial autonomy for areas inhabited mostly by the Serbs, the second largest ethnic group in Croatia. For that purpose two districts with special status were proposed.     

Constraints on the origin and the genesis of graphite-bearing rocks from the variegated sequence of the Bohemian Massif (Austria)

Summary Transitions between graphitic gneisses, graphite-bearing calcsilicate rocks and marbles of the Variegated Sequence (Bunte Serie) in the Moldanubian zone of the Bohemian massif were examined for their primary sedimentary signatures. The bulk chemistry of the graphitic gneisses is similar to those of common black shales. Chondrite-normalized rare earth element (REE) distribution patterns of graphite-bearing rocks resemble those of average pelitic sediments. Graphite ¹³C-values around –22%o (PDB) show primary organic isotopic characteristics in the silicate rocks and confirm their organogenic origin. Traces of metasomatic mobilizations were found for a number of elements such as Ba, Rb, Cs, the REEs and Mn.Carbon isotope thermometry using the calibration ofScheele andHoefs (1992) suggests a peak-temperature of 640–780°C for the graphite-bearing calcsilicates and marbles. Small scale isotopic studies at the interface between gneisses and marbles argue against a pervasive streaming CO₂-rich fluid derived from an external source and imply that the fluid was controlled more locally by lithology. Ore petrographic investigations showed iron-rich alabandite as an abundant phase within the calcsilicate rocks and marbles. The occurrence and metamorphic origin of alabandite within these rocks indicates high S- and low CO₂-, O₂-fugacities in local layers of the Variegated Sequence.

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Herkunft und Genese von graphitführenden Gesteinen der Bunten Serie aus der Böhmischen Masse (Österreich)

Zusammenfassung Übergänge zwischen Graphitgneisen, Kalksilikatgesteinen und Marmoren der Bunten Serie im Moldanubikum der Böhmischen Masse wurden auf primäre sedimentäre Merkmale hin untersucht. Die Gesamtzusammensetzung der Graphitgneise gleicht der von durchschnittlichen Schwarzschiefern. Chondrit-normierte Verteilungsmuster der Seltenen Erdelemente (SEE) der graphitführenden Gesteine spiegeln pelitische Sedimente wider. Kohlenstoffisotopenzusammensetzungen der Graphite mit ¹³C-Werten um –22 (PDB) aus den Graphitgneisen lassen eindeutig auf einen organogenen Ursprung der Graphite schließen. Hinweise auf metasomatische Mobilisierungen finden sich bei den Elementen Ba, Rb, Cs, den SEE und Mn.Graphit-Kalzit Isotopenthermometrie nachScheele undHoefs (1992) ergibt eine Peak-Temperatur zwischen 640–780°C für das prägende Metamorphoseereignis. Isotopengeochelnische Kleinbereichsuntersuchungen erlauben es, ein während der prägenden Metamorphose lithologische Grenzen pervasiv durchströmendes CO₂-reiches Fluid, das von einer externen Quelle abgeleitet wird, auszuschließen und weisen auf eine eher lokale, von der Lithologie abhängige, Prägung des Fluids hin. Im Zuge der erzpetrographischen Untersuchung wurde Alabandin in den Kalksilikatgesteinen und Marmoren gefunden. Die Gegenwart von Alabandin, der in diesen Gesteinen als metamorphe Bildung angesehen wird, kann als Anzeiger für bereichsweise höhere S- und niedere CO₂- bzw. O₂-Fugazitäten in lokalen Bereichen der Bunten Serie gewertet werden.

     

Abrupt light changes and multiperiodicity in Be stars: EW Lacertae revisited

The combined 1983 campaign and Seoul data on the variable Be star EW Lac is reanalyzed. CLEANing of the Fourier transform of the present time series clearly shows more than a single period. A multiperiodic fit can account also for a sudden brightness change through frequency beating. Comparison with previous multiperiodic solutions based on data obtained in different seasons shows highly variable amplitudes of the pulsational frequencies. The consequence of this finding to variable shell activity of EW Lac is briefly pointed out.Yonsei University Observatory Contribution No. 98.     

ON THE POSSIBLE CHANGES OF THE SOLAR DIFFERENTIAL ROTATION DURING THE ACTIVITY CYCLE DETERMINED USING MICROWAVE LOW-BRIGHTNESS-TEMPERATURE REGIONS AND Hα FILAMENTS AS TRACERS

The solar rotation rate obtained using the microwave Low-brightness-Temperature Regions (LTRs) as tracers in the heliographic range ± 55° from the years 1979–1980, 1981–1982, 1987–1988, and 1989–1991 varied from 3% to 4% in medium latitudes, and below 1% at the equator. Using H filaments as tracers at higher latitudes from the years 1979, 1980, 1982, 1984, and 1987, the solar rotation rate variation was between 2% and 8%. This represents an upper limit on the rotation rate variation during the solar activity cycle. Such changes could be caused by short-lived, large-scale velocity patterns on the solar surface. The Sun revealed a higher rotation rate on the average during the maxima of the solar activity cycles 21 and 22, i.e., in the periods 1979–1980 and 1989–1991, respectively, which differs from the rotation rates (lower on the average) in some years, 1981–1982 and 1987–1988, between the activity maximum and minimum (LTR data). Simultaneous comparison of rotation rates from LTRs and H filament tracings was possible in very limited time intervals and latitude bands only, and no systematic relationship was found, although the rotation rates determined by LTRs were mostly smaller than the rotation rates determined by H filaments. The errors obtained by applying different fitting procedures of the LTR data were analyzed, as well as the influence of the height correction. Finally, the north–south asymmetry in the rotation rate investigated by LTRs indicates that the southern solar hemisphere rotated slower in the periods under consideration, the difference being about 1%. The reliability of all obtained results is discussed and a comparison with other related studies was performed.     

Deformationsverhalten tektonisch unterschiedlich beanspruchter Carnallitite

Four different stressed carnallite-rocks were microscopically investigated by U-stage and the indicatrix orientation pattern was treated in topotropic analysis (AVA). The investigation involved a young, post-tectonic carnallitite, a layered carnallite-rock and a weakly cataclastic carnallitite, as well as so-called Trümmercarnallitite, and had as its objective observation of changes in fabric orientation.The youngest, uninfluenced carnallitite is a megagrained (handspecimen 3 grains), the other varieties are heterogenous, and respectively middleto finegrained carnallitite.With increasing tectonically strain, the number of grains with similar indicatrix orientation diminishs from that of the wholegrain. Neighbouring grains are shifted more and more and respectively show varying degrees of recristallisation from layered carnallitite up to the cataclastic Trümmercarnallitite.In addition for interpretation the mechanics undulations, kinkbands and rotationcristallisation by twinning were investigated.An attempt is made to explain the mechanism of the deformation.

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Zusammenfassung Vier unterschiedlich beanspruchte Carnallitite wurden mikroskopisch mit dem U-Tisch gemessen und Achsenverteilungsanalysen angefertigt. Ausgehend von einem posttektonisch entstandenen, jüngeren Carnallitit wurden ein gut geschichteter, ein schwach kataklastischer und sog. Trümmercarnallitit auf die Änderung ihrer Gefüge hin untersucht. Der jüngere unbeeinflußte Carnallitit ist riesenkörnig (Handstück 3 Körner), die anderen Varietäten sind heterogen- und mittel- bis kleinkörnig.Mit zunehmender tektonischer Beanspruchung wird die Zahl der Körner kleiner, die ursprünglich ein Großkorn gebildet haben, d. h. die Lage der Indikatrix benachbarter Körner ist stärker verstellt.Zur Feststellung der Mechanismen werden Messungen an Verbiegungen (undulöse Auslöschungen), Knickbändern und die Rotationskristallisation durch Zwillingsbildung untersucht. Es wird der Versuch unternommen, den mechanischen Ablauf der Deformation zu erklären.

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Résumé Quatre roches à carnallite, ayant subi des sollicitations différentes, ont fait l'objet d'une analyse topotropique («Achsenverteilungsanalyse») au moyen de la platine universelle. Ces quatre roches sont des carnallitites respectivement: (1) grenue posttectonique, (2) à rubanement bien exprimé, (3) légèrement cataclastique, (4) dite «Trümmercarnallitite». La roche jeune non affectée (1) est une Carnallitite à grains géants (3 grains pour l'échantillon); les autres sont des roches à granularité hétérogène moyenne à fine.Lorsque la sollicitation tectonique augmente, on voit diminuer le nombre de grains issus d'un même grain originel; en d'autres termes on voit se modifier de plus en plus la position des indicatrices de grains voisins.En outre, il a été procédé à une investigation des extinctions onduleuses, des kink-bands et des macles de déformation. La note présente finalement un essai d'interprétation du mécanisme de la déformation.

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An ozone depletion event in the sub-arctic surface layer over Hudson Bay,Canada

During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) program, aircraft flights during April 7–11, 2000 revealed a large area air mass capped below ∼500 m altitude over Hudson Bay, Canada in which ozone was reduced from normal levels of 30–40 ppbv to as low as 0.5 ppbv. From some of the in-situ aircraft measurements, back-trajectory calculations, the tropospheric column of BrO derived from GOME satellite measurements, and results from a regional model, we conclude that the event did not originate from triggering of reactive halogen release in the sub-Arctic region of Hudson Bay but resulted from such an event occurring at higher latitudes over the islands of the northern Canada Archipelago and nearby Arctic Ocean with subsequent transport over a distance of 1,000–1,500 km to Hudson Bay. BrO _x remained active during this transport despite considerable changes in the conditions of the underlying surface suggesting that chemical recycling during transport dominated any local halogen input from the surface. If all of the tropospheric column density of BrO is distributed uniformly within the surface layer, then the mixing ratio of BrO derived from the satellite measurements is at least a factor of 2–3 larger than derived indirectly from in situ aircraft measurements of the NO/NO₂ ratio.