Time-dependent surface impedance from sferics

Attempts to use discrete sferics for low-frequency impedance mapping have relied on Fourier analysis to derive time-independent frequency profiles of the earth. A one-dimensional transmission line model of the earth above a perfectly conducting layer is used to demonstrate that the impedance is time dependent. Assuming a sferic-type transient for the applied magnetic field, the electric field is changed significantly corresponding to the time of flight of the radiation in the lossy earth. In an attempt to maintain this timing information and its link with the frequency components, the wavelet transform was implemented to analyze the data. The associated surface impedance may be approximated as the input impedance of the earth during excitation but reverts to the impedance of free space once the source field returns to zero.     

Zircon geochronology and compositional record of late- to post-kinematic granitoids associated with the Bavarian Pfahl zone (Bavarian Forest)

Summary The northwest-striking Pfahl zone, Bavarian Forest, is a mylonitic shear zone that is associated with brittle-ductile deformation fabrics and a conspicuous hydrothermal quartz mineralization. Two granites from this shear zone yield U–Pb and Pb–Pb evaporation ages between 321–329 Ma and two granodiorites give concordant ²³⁸U–²⁰⁶Pb and ²³⁵U–²⁰⁷Pb ages of 325±3 Ma and 326±3 Ma, respectively. Zircon populations of the granitoids show sub-types clustering around S₂₀, S₁₀ (granite) and S₂₂ to S₂₄ (granodiorite) testifying different magma affinity. Compositional and isotopic characteristics indicate that the granites and granodiorites were coeval melts, but not differentiates of a single parent magma. The granodiorites were derived from a source with higher time-integrated ⁸⁷Rb/⁸⁶Sr and lower ¹⁴⁷Sm/¹⁴⁴Nd ratios than the granites. One granite body is transected by the shear zone but the main mass of the granite is largely undeformed. This finding suggests that granite intrusion predates the final stage of ductile deformation along the Pfahl shear zone.     

Spatial cointegration and heteroscedasticity

A two-step Lagrange Multiplier test strategy has recently been suggested as a tool to reveal spatial cointegration. The present paper generalises the test procedure by incorporating control for unobserved heteroscedasticity. Using Monte Carlo simulation, the behaviour of several relevant tests for spatial cointegration and/or heteroscedasticity is investigated. The two-step test for spatial cointegration appears to be robust towards heteroscedasticity. While several tests for heteroscedasticity prove to be inconclusive under certain circumstances, a Lagrange Multiplier test for heteroscedasticity based on spatially differenced variables is shown to serve well as an indication of heteroscedasticity irrespective of cointegration status.      

Organic Geochemical Microanalysis by Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS)

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) is a powerful method for the chemical analysis of solid surfaces. In this paper, the capabilities and limitations of this technique and the potential for its use in geochemical research are outlined. Using ToF‐SIMS, the chemical composition of sample structures down to 10–100 μm can be determined, without the need for pre‐selection or labelling of the analysed substances. In addition, the lateral distribution of organic and inorganic compounds can be mapped in geochemical samples at a resolution in the micrometre range. The capabilities of the technique in geochemistry are illustrated by two examples. In the first example, it is shown that ToF‐SIMS can be used to detect biomarkers in oil samples, making it a promising method for the analysis of biomarkers in fluid inclusions. In the second example, a number of specific lipid biomarkers were identified and mapped on the surface of a microbial mat cryosection surface. Post‐measurement optical microscopy correlated the localisation of the lipids with the presence of methanotrophic archaea in the microbial mat.     

Abhängigkeit des Dispersionsgrades der mit RaB bzw. fallout beladenen Aerosolpartikel in der unteren Troposphäre zwischen 700 und 3000 m NN von Luftkörpertyp und Austauschintensität

Zusammenfassung Bei den fortlaufenden Messungen der natürlichen und künstlichen Radioaktivität des Aerosols, welche seit Dezember 1963 gleichzeitig in 0.7, 1.8 und 3 km Höhe ausgeführt worden sind, wurde eine Doppelfiltermethode angew andt. Sie diente dazu, einen Relativwert für den Dispersionsgrad (Feinheitsgrad) der die natürliche bzw. künstliche Radioaktivität tragenden Partikel zu gewinnen. Den höchsten Dispersionsgrad fanden wir im Falle der natürlichen (RaB-)Radioaktivität in tropisch-maritimen, den geringsten in polar-maritimen und polaren Luftkörpern. Im Falle der fallout-Radioaktivität ergab sich der höchste Dispersionsgrad in tropischen, der geringste in kontinentalen Luftkörpern und ausserdem eine stark ausgeprägte Abnahme des Dispersionsgrades mit der Höhe. Der Dispersionsgrad der die RaB-Aktivität tragenden Partikel zeigt ausserdem eine charakteristische Abhängigkeit von der Intensität des vertikalen Austausches; es ergeben sich für die 3 verschiedenen Meereshöhen unterschiedlichen Type der Abhängigkeit.

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Summary A double aerosol filter method was used in order to gain relative values which characterize the existing type of size distribution of the atmospheric aerosol particles; labelled by natural or fallout radioactivity. Continuous measurements were carried out simultaneously at 0.7, 1.8 and 3 km altitude since December 1963. Concerning natural (RaB) radioactivity we found the minimum of aerosolparticle size in tropical maritime air, its maximum in polar maritime and polar air masses. In the case of fallout radioactivity the minimum of particle size is found in tropical, the maximum in continental air. With increasing altitude, the mean size of the fallout particles decreases obviously. The size distribution of the aerosol particles, labelled by RaB radioactivity, is a function of vertical mass exchange intensity. The pattern of this function depends strongly on altitude.

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Physikalisch-Bioklimatische Forschungsstelle Garmisch-Partenkirchen der Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung.     

Observations of the Green Flash and slant range ‘seeing’

The phenomenon of the Green Flash and its temporal and spatial undulations were visually observed with a Questar telescope at sun elevations between 10° and-5°. The undulations in the green cover a typical frequency range between 0.5 and 10 Hz, respectively 5 to 30 arc seconds. Both depend strongly on the local site characteristics. Control observations at 1000 m range with red He-Ne laser light near the same line of sight confirm the temporal frequencies but did not agree with the spatial of behavior. The asymmetry of the target point of the laser light approximates zero, while the asymmetry of the green flashes around the line of sight resembles a horizontally deformed ellipse with an axis ratio around 1/3 to 1/6.     

Uranium redistribution in weathered conglomerates of the early precambrian pongola supergroup, South Africa - inferences from a study by alpha spectrometry and fission track micromapping

Samples of potentially uranium-bearing conglomerates from deeply weathered outcrops of the 2900 to 3200 m.y. old Pongola Supergroup were investigated from three different localities in the southeastern Transvaal and northern Zululand. Uranium isotope and uranium fission track analyses were carried out to study and to unravel the complex uranium redistribution processes which took place and which are still in progress in the weathering zone of the conglomerates. It is proposed that the combination of the two radiochemical methods can provide valuable information assisting the exploration of uranium mineralization in early Precambrian quartz-pebble conglomerates.