Geochronology of an archaean tonalitic gneiss dome in Northern Finland and its relation with an unusual overlying volcanic conglomerate and komatiitic greenstone     

A. Kröner  K. Puustinen  M. Hickman 《Contributions to Mineralogy and Petrology》1981,76(1):33-41

Archaean gneiss-greenstone relationships are still unresolved in many ancient cratonic terrains although there is growing evidence that most of the late Archaean greenstone assemblages were deposited on older tonalitic crust.We report here well defined basement-cover relationships from a late Archaean greenstone belt in Lapland, north of the Polar Circle. The basal greenstone sequence contains quartzite, schist, komatiitic volcanics and an unusual volcanic conglomerate with well preserved granite pebbles of an older basement. These rocks surround a gneiss dome composed of foliated tonalite which shows a polyphase deformation pattern not seen in the neighbouring greenstones.Zircon fractions of the gneisses plot on two discordia lines and give upper intercept ages with concordia at 3,069±16 Ma and 3,110±17 Ma respectively. One fraction contains metamict zircons with components at least 3,135 Ma old. These are the oldest reliable ages yet reported from the Archaean of the Baltic Shield. Rb-Sr whole-rock dating of the tonalitic gneiss yielded an isochron age of 2,729±122 Ma and an I_Sr of 0.703±0.001. This is interpreted to reflect a resetting event during which the gneisses may have acquired their present tectonic fabric.Rb-Sr model age calculations yield mantle values for I_Sr at about 2,950±115 Ma and suggest that the tonalite was intruded into the crust as juvenile material at about 3.1 Ga ago as reflected by the zircon ages. It was subsequently deformed and isotopically reset at about 2.7 Ga ago, prior to greenstone deposition.Comparison with tonalitic gneisses of eastern Karelia displays significant differences and suggests that the Archaean of Finland may contain several generations of pre-greenstone granitoid rocks.  相似文献   

Dispersion of uranium in accessory apatite in crystalline rocks and its possible petrogenetic meaning     

Ján Kráĺ  Jan Burchart 《Earth and Planetary Science Letters》1983,63(1):34-40

The coefficient of variation for grain-by-grain fission track uranium analysis of apatites from igneous rocks seems to reflect the temperature of crystallization and the cooling rate. For metamorphic rocks the coefficient represents a complex record of the homogeneity of the source and of metamorphic neocrystallization. As a test case 41 West Carpathian rocks have been examined and the coefficients of variation for U in apatites found to be: granitic rocks 0.30–0.79, paragneisses 0.35–0.95, migmatites 0.55–0.87, and volcanic rocks 0.30–0.40. Most of the frequency distributions are lognormal, though for some cases a normal distribution gives a better fit, and some are incompatible with either of the two distributions.  相似文献   

Turbulent fluxes of momentum,heat and water vapor in the atmospheric surface layer at sea during ATEX     

M. Dunckel  L. Hasse  L. Krügermeyer  D. Schriever  J. Wucknitz 《Boundary-Layer Meteorology》1974,6(1-2):81-106

The vertical turbulent fluxes have been determined during the Atlantic Trade Wind Experiment (ATEX) both by direct and profile methods. The drag coefficient obtained from direct measurements was c _D = 1.39 × 10^–3. A distortion of the wind profile due to wave action could be demonstrated, this produced an increased drag coefficient estimated by the profile method. The dissipation technique using the downwind spectrum gave a lower drag coefficient of 1.26 × 10^–3, probably due to non-isotropic conditions (the ratio of vertical to downwind spectrum at high frequencies scattered considerably with an average of 1 instead of 4/3).From direct measurements, the sensible heat flux showed a poor correlation with the bulk parameter product U, contrary to the heat flux obtained from profiles. It is shown that this is due to the higher frequency part of the cospectrum, say above 0.25 Hz, which contributes more than 50 % of the total flux. Determination of the heat flux from temperature fluctuations by the dissipation method would be in agreement with the direct determination only if the corresponding Kolmogoroff constant were 2.1 instead of 0.8.For the vertical flux of water vapor obtained from profiles, the bulk transfer coefficient was 1.28 × 10^–3.This work was supported by the Deutsche Forschungsgemeinschaft, Schwerpunktprogramm Meeresforschung and later the Sonderforschungsbereich Meeresforschung Hamburg.  相似文献   

Über eine optisch markante Stromgrenze an der Polarfront in der Dänemark Straße     

Friedrich Krügler 《Ocean Dynamics》1966,19(4):159-170

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A review and assessment of tributyltin contamination in the North Sea,based on surveys of butyltin tissue burdens and imposex/intersex in four species of neogastropods   总被引：4，自引：0，他引：4  

Birchenough AC  Barnes N  Evans SM  Hinz H  Krönke I  Moss C 《Marine pollution bulletin》2002,44(6):534-543

It is evident from measures of butyltin tissue burdens and imposex or intersex in neogastropods that tributyltin (TBT) contamination of coastal waters and open parts of the North Sea is now low. It has been declining for at least the past decade. This is probably due to two measures. First, regulations prohibiting the use of TBT-based paints on small boats and fish farms have reduced inputs of TBT from these sources so that they are now negligible (except possibly where the regulations are flaunted). Second, there is evidence from sites, where commercial vessels are the sole source of TBT, that the adoption of TBT SPC paints has been effective in reducing environmental levels of these contaminants. However, poor dockyard practices, allowing TBT-contaminated wastes, including paint flakes, to accumulate in sediments have left a legacy of hot-spots of contamination in some ports. The impact is localised so that TBT contamination is low in coastal areas immediately adjacent to ports.  相似文献   

Biosensors for marine pollution research,monitoring and control     

Kröger S  Piletsky S  Turner AP 《Marine pollution bulletin》2002,45(1-12):24-34

Measurement of ecological, climatic and anthropogenic changes underpins the formulation of effective management strategies for sustainable use and protection of the marine environment. Sensors are traditionally used in marine studies to determine physical parameters, but there is increasing demand for real-time information about chemical and biological parameters. These parameters are currently measured in samples collected at sea and subsequently analysed in the laboratory. Biosensors fuse the exquisite sensitivity and specificity of living systems with the processing power of microelectronics to deliver simple, inexpensive measurement systems for use in the field or deployment in situ. While their potential for use in the marine environment is enormous, much published work to date has focussed on applications in freshwater and wastewater. Marine applications pose a substantial challenge in the robustness required for remote application, but recent developments in portable medical devices and receptor design suggest that these demands can now be realistically tackled.  相似文献   

Backazimuthal Variations of Splitting Parameters of Teleseismic SKS Phases Observed at the Broadband Stations in Germany     

S. Brechner  K. Klinge  F. Krüger  T. Plenefisch 《Pure and Applied Geophysics》1998,151(2-4):305-331

—SKS phases observed at broadband stations in Germany show significant shear-wave splitting. We have analyzed SKS and SKKS phases for shear-wave splitting from 13 stations of the German Regional Seismic Network (GRSN), from 3 three-component stations of the Gräfenberg array (GRF) and from one Austrian station (SQTA). The data reveal strong differences in the splitting parameters (fast direction φ and delay time δt from a single event at various stations as well as variations at the individual stations for events with different backazimuths. The backazimuthal variations of the splitting parameters at some stations can be explained by two-layer anisotropy models with horizontal symmetry axes. The best resolved two-layer model is the GRA1 model (upper layer φ = 40°, δt = 1.15s; lower layer φ = 115°, δt = 1.95s). The upper layer can be attributed to the lithosphere. Because of the magnitude of the delay time of the upper layer, the lower layer must lie within the asthenosphere. At other stations splitting parameters are consistent with an anisotropic one-layer model for the upper mantle. Stations near the Bohemian Massif show fast directions near EW. Throughout NE Germany the directions are oriented NW/SE. The reason for this direction is probably the nearby Tornquist-Teisseyre line. The observed fast axes are subparallel to this prominent Transeuropean suture zone. At stations in southern Germany near the Alps we observed ENE/WSW directions. Below some stations we also found indications of inclined anisotropic layers.  相似文献   

A Fully Depleted pn-Junction CCD for Infrared-, UV- and X- ray detection     

C. von Zanthier  H. Bräuninger  K. Dennerl  R. Hartmann  G. Hartner  H. Hippmann  A. Kaltenberger  E. Kastelic  W. Kink  N. Krause  N. Meidinger  G. Metzner  E. Pfeffermann  M. Popp  C. Reppin  J. Riedl  D. Stötter  L. Strüder  J. Trümper  W. Weber  D. Carathanassis  S. Engelhard  Th. Gebhart  D. Hauff  G. Lutz  R. H. Richter  H. Seitz  P. Solc  E. Biehler  H. Böttcher  E. Kendziorra  J. Krämer  B. Pflüger  R. Staubert  P. Holl  J. Kemmer  P. Lechner  B. Maier  H. Soltau  R. Stötter  E. Bihler 《Experimental Astronomy》1998,8(1):89-96

This paper describes the performance of the Fully Depleted pn-junction CCD (pn-CCD) system, developed for ESA's XMM-satellite mission for soft x-ray imaging and spectroscopy in the single photon counting mode in the 100 eV to 10 keV photon range. The 58 mm x 60 mm large pn-CCD array, designed and fabricated at the Semiconductor Lab (Halbleiterlabor) of the Max-Planck-Institut, uses pn-junctions for registers and as backside structure. This concept naturally enables full depletion of the detector volume independent of the silicon wafer's resistivity and thickness, and as such make it an efficient detector for the x-ray region and the infrared. For high detection efficiency in the soft x-ray region and UV, an ultrathin pn-CCD backside deadlayer has been realized. Each pn-CCD-channel is equipped with its own on-chip JFET amplifier which, in combination with the CAMEX-amplifier and multiplexing chip, facilitates parallel readout and fast data rate: the cooled pn-CCD system can be read out at a data rate up to 3 MHz with an electronic noise floor of ENC < 5 e-.  相似文献   

Professor Dr. Albert W. Bally     

A. Kröner 《International Journal of Earth Sciences》1988,77(3):I-II

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Remote sensing in landscape diagnosis     

H. Barsch Dr.  R. Krönet Dr. 《GeoJournal》1984,8(1):81-89

In landscape diagnosis landscapes are evaluated on the basis of their natural and technological characteristics with regard to the possibilities and risks of intensive utilization. Land use is an essential criterion for the evaluation of the condition of landscapes. Remote sensing will allow for an analysis of large areas with regard to land use. Landscape diagnosis through satellite photographs will be illustrated in two examples. In the first one multitemporal evaluation of satellite photographs is discussed with particular reference to attempts made to characterize the utilization of landscape potentials. In the second example attempts have been made to classify medium-sized landscape units by satellite photographs, with additional characterization through thematic maps based on the Atlas GDR.  相似文献