A contribution to the migration of gold in the biosphere of the humid mild zone

The content of gold in plants has been used as an indicator in the prospecting for gold. For this purpose non-destructive analytical methods have been developed. In the humid mild zone — where the process of weathering is of a kaolinitic character — there is practically no migration of gold, and consequently its increased content indicates the presence of a gold deposit.     

The impact of discharge change on physical instream habitats and its response to river morphology

The impact of climate-induced discharge change on fish habitats, based on 1951–2008 time series, was investigated within the crystalline catchment of the Grosse Mühl River in Northern Austria. A significant trend change of air temperature, based on Mann–Whitney statistical testing, was recorded for spring 1989 (P?=?98.9 %) and summer 1990 (P?=?99.9 %). This led to a pronounced increase in summer low flow periods. Hydrodynamic-numerical (one-dimensional/two-dimensional) modelling was applied to simulate the changing habitat characteristics due to decreasing discharge in relation to various morphological patterns (riffle-pool/plane-bed reaches). Using bathymetric data, which were sampled on cross sectional measurements, we clearly determined that plane-bed reaches (featureless bed forms) are sensitive to climate-related, reduced discharge, whereas riffle-pool reaches continued to exhibit suitable physical fish habitats even under extreme low-flow conditions. The impact of the decreased summer discharge on instream habitats was strong for subadult and adult grayling which have been used as target fish species. In situ measurements in microhabitats (velocity/depth) revealed habitat suitabilities. These values were taken as biotic input for habitat evaluation on the micro scale. The findings clearly show that river morphology is a decisive parameter in terms of habitat preservation and restoration in the context of the future impacts of climate change (decreased discharge).     

Heterotype Mischbarkeit zwischen Wolframit- und Rutilgruppe

Zusammenfassung Untersucht wurden die heterotypen Mischsysteme zwischen Wolframit- und Rutilgruppe FeNbO₄-TiO₂, FeNbO₄-FeTaO₄, FeWO₄- FeTaO₄ und FeWO₄-TiO₂. Aus der Stereometrie der Gitter läßt sich abschätzen, daß ein statistischer Übergang beider Gittertypen nicht wahrscheinlich ist.Im System FeWO₄-FeTaO₄ verkleinert sich die Mischungslücke mit sinkender Temperatur und verschwindet nach unten am FeTaO₄-Rand. Infolge des gleichsinnig geneigten Verlaufes beider Phasengrenzen ist die Temperatur der Umwandlung Rutil-Wolframitgitter für FeTaO₄ nicht extrapolierbar, die wahrscheinlich noch unter 570° C liegt.In den Systemen FeNbO₄- TiO₂ und FeNbO₄-FeTaO₄ hat die Mischungslücke ebenfalls gleichsinnig geneigte Begrenzungen. Die Mischungslücke verschwindet in diesen Systemen mit steigender Temperatur schon vor dem Systemrand. Es koexistieren dann in 1. Ordnung zwei heterotype Mischkristalle gleicher Zusammensetzung, aber verschiedenen Molvolumens. Der experimentell gefundene Diagrammtyp wird diskutiert.Aus Extrapolationen von Gitterkonstanten und Volumen von Mischkristallreihen gegen die Systemränder lassen sich diese Daten für die Rutilmodifikation von FeNbO₄ und die Wolframitmodifikation von FeTaO₄ finden, die beide in den experimentell untersuchten Zustandsbereichen instabil gegen die Wolframitmodifikation von FeNbO₄ bzw. die Rutilmodifikation von FeTaO₄ sind.Die Gehalte von Fe₂O₃ + Nb₂O₅ in Rutil (Ilmenorutil) sind Rutil-FeNbO₄-Mischkristalle.     

Geochemical study on a well in the Western Canada Basin: relation of the aromatic distribution pattern to maturity of organic matter

Thirty-one rock samples from a Western Canada Basin well have been analysed for aromatics, using glass capillary gas chromatography with simultaneous flame ionization and sulfur-selective flame photometric detection. A uniform aromatic distribution pattern with a marked predominance of di- and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising Cretaceous and Jurassic sediments. The very high relative abundance of sulfur aromatics at two narrow intervals in the Triassic and Mississippian is attributed to a major change in facies. Gradual changes with increasing depth have been observed for a series of compound ratios, which had been calculated from the isomers of methyl- and dimethylphenanthrene, and their parent compounds. These changes reflect the increasing thermal maturation of the sedimentary organic matter. A Methylphenanthrene Index (MPI) has been introduced, which exhibited a very good correlation with vitrinite reflectance data. The MPI is the first maturity parameter which is based on a series of aromatic hydrocarbons. This hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity (e.g. vitrinite reflectance) of source rocks.     

Untersuchungen über die Bildung von Analcim aus natürlichen Silikaten

Zusammenfassung Im Temperaturbereich zwischen 100–180° C wurde experimentell die Umwandlung einiger natürlicher Silikate und silikatischer Gesteine in Analcim untersucht. Der Analcim bildete sich im alkalischen Milieu nach Abbau der einzelnen Ausgangssubstanzen direkt und ohne das Auftreten irgendeiner Zwischenphase. Die Entstehung des Analcims zeigte sich dabei abhängig von der Art und der Konzentration der einwirkenden Lösungen, von der Temperatur und von den Ausgangssubstanzen. Bei geringeren Konzentrationen der Lösungen war die Reaktion bedeutend langsamer als bei größeren. Der Analcim bildete sich nur in einem bestimmten Konzentrationsbereich der alkalischen Lösungen, wobei dieser für die einzelnen Substanzen unterschiedlich war. In Abhängigkeit von der Ausgangssubstanz entstanden bei geringeren Alkalikonzentrationen an Stelle des Analcims Zeolithe und bei größeren Alkallkonzentrationen SiO₂-Mineralien.

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Investigations on the formation of analcite from natural silicates

The transformation of some natural silicates and silicatic rocks into analcite was experimentally investigated over a temperature range of 100° C to 180° C. Analcite was directly formed in alkaline surroundings after reduction of the various starting substances without any intermediate phases. The formation of analcite depended on the kind and concentration of the reacting solutions, on the temperature and on the starting substance. At lower concentrations of the solutions the reaction was considerably slower than at higher ones. Analcite was formed only within a certain concentration range of the alkaline solutions, this range being different for the different substances. Depending on the starting substance, zeolites were formed at lower alkali concentrations. At higher alkali concentrations SiO₂ minerals were formed.

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Herrn Prof. Dr. H. Heritsch danke ich für sein dauerndes Interesse an dieser Arbeit, für Ratschläge und kritische Bemerkungen sowie für die Zurverfügungstellung der Mittel des Institutes für Mineralogie und Petrographie der Universität Graz.

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Herrn Prof. Dr. C. W. Correns möchte ich auch an dieser Stelle für die Möglichkeit, die experimentelle Technik in Göttingen kennenzulernen, meinen Dank sagen.     

Bedload transport measurements with impact plate geophones: comparison of sensor calibration in different gravel‐bed streams

Indirect bedload transport measurements have been made with the Swiss plate geophone system in five gravel‐bed mountain streams. These geophone sensors record the motion of bedload particles transported over a steel plate mounted flush with the channel bed. To calibrate the geophone system, direct bedload transport measurements were undertaken simultaneously. At the Erlenbach in Switzerland, a moving‐basket sampler was used. At the Fischbach and Ruetz streams in Austria, a Helley–Smith type bedload sampler provided the calibration measurements. A Bunte‐type bedload trap was used at the Rofenache stream in Austria. At the Nahal Eshtemoa in Israel, Reid‐type slot bedload samplers were used. To characterize the response of the geophone signal to bedload particles impacting on the plate, geophone summary values were calculated from the raw signal and stored at one second intervals. The number of impulses, i.e. the number of peaks above a pre‐defined threshold value of the geophone output signal, correlated well with field measured gravel transport loads and was found to be a robust parameter. The relations of impulses to gravel transport loads were generally near‐linear, but the steepness of the calibration relations differed from site to site. By comparing the calibration measurements from the different field sites and utilizing insights gained during preliminary flume experiments, it has been possible to identify the main factors that are responsible for site specific differences in the calibration coefficient. The analysis of these calibration measurements indicates that the geophone signal also contains some information about the grain size distribution of bedload. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparison of Mathematical Methods of Potential Modeling

Various attempts are known to turn the “catalogue” of mineral deposit models compiled by Cox and Singer (1986) operational, and have initiated activities called “potential mapping”, “potential modeling”, or “targeting”. The common ultimate objective is to estimate the probability for a given location that a mineralization of a given type occurred. The mathematics range from “weights of evidence” and others featuring a Bayesian approach to logistic regression by maximum likelihood, and include other realizations by means of fuzzy methods, genetic programming, and artificial neural nets. Once developed and coded, applications are not restricted to mineral prospection and exploration but include any kind of occurrences and their estimated probabilities, e.g., risk assessment of land slides and many others.     

Frontal substructures within the planetary boundary layer

A two-dimensional mesoscale model, extended by a TKE closure for the subgrid-scale terms and coupled with a soil model, is used to investigate the role of the Planetary Boundary Layer (PBL) for the development and the substructures of two different types of cold fronts. The effects of turbulent friction, large-scale (geostrophic) forcing and the diurnal variation of the terms of the surface energy balance (SEB) equation on the frontal development are studied by 10 different model runs. The ageostrophic cross-frontal circulation in the lowest two kilometres of a cold front results from friction as well as from large-scale forcing. The first one dominates the PBL processes and causes a special boundary-layer structure, which becomes apparent through the existence of seven characteristic zones defined for the x-z cross sections of potential temperature. The arrangement of these characteristic zones depends on the sense of rotation of the frictionally induced part of the ageostrophic circulation and hence on the direction of the along-front jet within the boundary layer. The daytime increase of the terms of the SEB equation for a midlatitude midsummer case leads to a strong enhancement of the frictionally induced cross-frontal circulation. The arrangement of the seven characteristic zones, however, is approximately conserved.