Richtlinien zur stratigraphischen Nomenklatur     

Jürgen Remane&#;  Thierry Adatte  Jean-Pierre Berger  Reto Burkhalter  Stephan Dall&#;Agnolo  Danielle Decrouez  Hermann Fischer  Hanspeter Funk  Heinz Furrer  Hans-Rudolf Graf  Yves Gouffon  Werner Heckendorn  Wilfried Winkler 《Eclogae Geologicae Helvetiae》2005,98(3):385-405

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GPS monitoring of vertical ground motion in northern Ardenne–Eifel: five campaigns (1999–2003) of the HARD project     

A. Demoulin  J. Campbell  A. De. Wulf  A. Muls  R. Arnould  B. Görres  D. Fischer  T. Kötter  M. Brondeel  D. Van. Damme  J. M. Jacqmotte 《International Journal of Earth Sciences》2005,94(4):515-524

We present the HARD project of GPS monitoring of vertical ground motion in NE Ardenne and Eifel (western Europe). Its main purposes are to get a better insight into the present-day rates of vertical ground motion in intraplate settings and to identify the various causes of these motions. Since 1999, we have carried out yearly campaigns of simultaneous GPS measurements at 12 sites situated so as to sample the different tectonic subunits of the study area and especially to record potential displacements across the seismogenic Hockai fault zone. Five campaigns (1999–2003) have been processed currently. Key issues of the data processing with the Gamit software are discussed and first results are presented. Though temporally consistent in many cases, the obtained vertical motion rates are spatially highly variable. They are also much too high (several mm/year) to support a tectonic interpretation, and a long-term influence of groundwater level variations is proposed to account for the observed motions. This influence should be distinguished from seasonal variations and from inter-survey variations linked to the varying degree of soil and subsoil drying off during the successive spring surveys.  相似文献   

Blind Source Separation for Compositional Time Series     

Nordhausen  Klaus  Fischer  Gregor  Filzmoser  Peter 《Mathematical Geosciences》2021,53(5):905-924

Many geological phenomena are regularly measured over time to follow developments and changes. For many of these phenomena, the absolute values are not of interest, but rather the relative information, which means that the data are compositional time series. Thus, the serial nature and the compositional geometry should be considered when analyzing the data. Multivariate time series are already challenging, especially if they are higher dimensional, and latent variable models are a popular way to deal with this kind of data. Blind source separation techniques are well-established latent factor models for time series, with many variants covering quite different time series models. Here, several such methods and their assumptions are reviewed, and it is shown how they can be applied to high-dimensional compositional time series. Also, a novel blind source separation method is suggested which is quite flexible regarding the assumptions of the latent time series. The methodology is illustrated using simulations and in an application to light absorbance data from water samples taken from a small stream in Lower Austria.

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The magnetotelluric dispersion relations over 2-D structures     

Gaston Fischer  P.-A. Schnegg 《Geophysical Journal International》1993,115(3):1119-1123

The causal properties of the magnetotelluric response, first derived by Weidelt, and Fischer & Schnegg in the 1-D limit, are confirmed numerically in the 2-D limit for the particular structure consisting of two uniform quarter spaces. This finding is of interest from several points of view: (1) the dispersion relations in their 1-D form seem to retain their validity for all 2-D tensor elements, irrespective of any rotation of the coordinate system chosen at the surface; in particular, (2) they appear equally valid for the E- and B-polarization configurations. (3) Whereas the question recently debated in the literature (whether the Earth can always be considered as a linear, passive and causal system) is perhaps not yet entirely resolved, the present empirical demonstration suggests that it may in general be safe to apply the 1-D dispersion relations to structures with 2-D character.  相似文献   

Thrust tectonics in the North Pyrenees     

M.W. Fischer 《Journal of Structural Geology》1984,6(6):721-726

Balanced and restored cross-sections through the central and eastern Pyrenees, constructed using both surface and borehole data, demonstrate the presence of c.18km of shortening above a flat lying N-directed Alpine décollement surface. Hangingwall diagrams show how the North Pyrenean satellite massifs are culminations within this thrust system. Pre-thrusting structures such as subhorizontal stretching lineations in the North Pyrenean Fault zone became rotated above these culminations as the North Pyrenean Fault was cut by Alpine thrusts. Stratigraphic evidence demonstrates that N-directed thrust movements occurred between mid Eocene and Oligocene time, and this is similar to the age of major S-directed thrust movements on the south side of the Axial Zone. The N-directed thrust system probably originated as a series of backthrusts to the dominant S-directed structures.  相似文献   

Preface     

B. A. Hobbs  G. Fischer 《Surveys in Geophysics》1987,9(3-4):233-234

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Excess K-Ar ages of glauconite from the Upper Marine Molasse and evidence for glauconitization of mica     

Hans Fischer 《International Journal of Earth Sciences》1987,76(3):885-902

K-Ar age determinations along with optical investigations were used to examine whether glauconite from the Upper Marine Molasse (OMM) is of authigenic, allogenic or transformed origin. For this purpose 16 glauconite samples from 14 different localities were investigated from the Burdigalian Muschelsandstein collected along a traverse from Lake Constance to west of Geneva.Optical observations on washed grain concentrates reveal the presence of different alteration products of biotite, confirming earlier studies. Moreover, thin-section preparations of sample aliquots showed that the glauconite grains contain biotite-relics, which might account for the elevated absolute ages.The optical evidence is confirmed by individual mineral fractions, which show chlorite with biotite-»nucleii«, chlorite-lamellae, and »layered«-glauconites. All these observations point to glauconite genesis by transformation of biotite. The complete transformation from biotite via chlorite to glauconite apparently results in a chemically more stable state.The K-content of the samples varies from 5.6 to 7.0% K₂O, indicating mature but not highly evolved glauconite. 19 apparent K-Ar dates range from 17.7 to 34.9 Ma. In comparison with the biostratigraphy and the estimated Burdigalian age of about 18 Ma nearly all dates are too high. These strongly scattered dates are thus stratigraphically meaningless and seem to exclude an authigenic formation of these glauconites from faecal pellets. Furthermore, geologic arguments exclude an allogenic (= detrital) origin.Glauconite genesis in the Upper Marine Molasse must therefore be distinguished from both authigenic and allogenic formation mechanisms. A new term »meta-allogenic« is therefore used to describe glauconite growth by transformation of allogenic mica.

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Zusammenfassung Um zu prüfen, ob Glaukonite aus der Oberen Meeresmolasse (OMM) authigen, allothigen oder durch Umwandlung aus anderen Mineralien entstanden sind, wurden sie — nebst mineraloptischen und röntgenographischen Untersuchungen — mit der K-Ar-Methode datiert. Aus 14 verschiedenen Lokalitäten zwischen Bodensee und einigen Kilometern westlich von Genf wurden 16 Glaukonit-Proben aus dem burdigalen Muschelsandstein entnommen.Sedimentpetrologische Studien an Körner-Konzentraten offenbarten verschiedene Umwandlungsprodukte von Biotit. Zudem zeigten Aliquots von Dünnschliff-Präparaten, daß einzelne Körner unterschiedlich große Relikte von Biotit enthalten, die die zu hohen Alterswerte verursachen können.Die verschiedenen Mineralfraktionen bestätigen den Charakter von Übergangsstadien: Chlorit mit Biotit-Kernen, Chloritlamellen und »Schicht«-Glaukonit. Alle diese Beobachtungen deuten auf eine Glaukonitgenese aus der Umwandlung von Biotit. Die vollständige Umwandlung von Biotit über Chlorit zu Glaukonit scheint mit dem End-produkt einen chemisch stabileren Zustand anzustreben.Der K₂O-Gehalt aller Proben variert von 5.6 bis 7.0%. Dies weist auf »reifen«, aber nicht hochentwickelten Glaukonit hin. Die 19 K-Ar-»Alter« liegen zwischen 17.7 und 34.9 Ma. Im Vergleich mit der Biostratigraphie und dem geschätzten burdigalen Alter von ca. 18 Ma, sind diese Daten zu hoch und daher stratigraphisch bedeutungslos. Eine authigene Bildung von Glaukonit aus Kotpillen (faecal pellets) muß somit ausgeschlossen werden. Außerdem kommt aus geologischen Gründen eine detritische (allothigene) Herkunft ebenfalls nicht in Betracht.Für die Glaukonit-Genese in der Oberen Meeresmolasse muß daher ein anderer Bildungsprozess verantwortlich sein. Um die Umwandlung von eingeschwemmtem (= allothigenem) Biotit zu Glaukonit zu beschreiben, wurde der neue Term »meta-allothigen« eingeführt.

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Résumé Afin de rechercher si les glauconites de la OMM (= molasse marine supérieure) sont authigènes, allothigènes ou proviennent de la transformation d'autres minéraux, on les a datées par la méthode K-Ar, conjointement à une étude optique et röntgenographique. 14 localités, situées depuis de lac de Constance jusqu'à quelques kilomètres à l'ouest de Genève, ont fourni 16 échantillons de glauconite du Muschelsandstein burdigalien.L'étude optique des grains, effectuée sur des concentrés, a révélé divers produits de transformation de la biotite. En outre, les examens en coupes minces ont montré, dans les grains de glauconite, des restes de biotite d'importance variable. Ces restes de biotite peuvent être responsables de valeurs trop élevées obtenues dans les mesures d'âge.L'examen des diverses fractions minérales permet de préciser les stades de transformation: chlorite avec noyaux de biotite, lamelles de chlorite et glauconite »stratifiées«. Toutes ces observations indiquent une genèse de la glauconite par transformation de la biotite. La transformation complète de la biotite en chlorite puis en glauconite semble ainsi correspondre à un état chimique plus stable.La teneur en K₂O de tous les échantillons varie entre 5,6 et 7,0%, indiquant une glauconite »mature«, mais pas très évoluée. Les 19 »âges« K-Ar sont compris entre 17,7 et 34,9 Ma. Comparés à la biostratigraphie et à l'âge burdigalien, estimé à environ 18 Ma, ces résultats sont nettement trop élevés et ne présentent donc aucune valeur stratigraphique. Il faut ainsi exclure une formation authigène de la glauconite à partir de pelotes fécales. De plus, une origine détritique (= allothigène) ne peut être envisagée pour des raisons géologiques.En conséquence, c'est bien un processus différent qui est responsable de la genése de la glauconite dans la OMM. Le terme nouveau »méta-allogénique« est proposé pour indiquer la transformation de la biotite détritique en glauconite.

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Latitude variation of the LHR frequency in the outer ionosphere as an indicator of the degree of magnetospheric perturbance     

Jaroslava Bošková  František Jiřiček  Pavel Tříska  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1983,27(3):298-304

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Whistler-mode propagation of omega VLF navigation signals as observed on board of satellites     

František Jiříček  Pavel Tříska  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1983,27(4):393-407

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A 1,000-year ice core record of interannual to multidecadal variations in atmospheric circulation over the North Atlantic     

Hubertus Fischer  Birgit Mieding 《Climate Dynamics》2005,25(1):65-74

Interannual to multidecadal modes in ocean/atmosphere dynamics in the North Atlantic region have been identified using sea salt aerosol proxy records from northern Greenland ice cores over the last 1,000 years. Sea salt concentrations show a consistent relationship with anomalies in the meridional pressure gradient over the North Atlantic region over all considered time scales. These pressure anomalies are connected to shifts in storm tracks, leading to lower pressure and higher storm activity, hence, higher sea salt export over the Greenland ice sheet. Two modes of long-term variability with a period of 10.4 years and 62 years could be identified. The latter is connected to long-term changes in sea surface temperature (SST) as documented by a high correlation of North Atlantic SST with our sea salt record over the last 150 years. Long-term reconstruction of these modes shows that the 10.4-year cycle has been a phenomenon persistent over the last millennium while the 62-year cycle has been mainly active after 1700. Accordingly, the longer-term persistence of this multidecadal variability in sea salt points also to significant variations in SST over the last 300 years.  相似文献