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

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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Results of a 36-hour storm surge prediction of the North Sea for 3 January 1976 on the basis of numerical models

Summary To explore the feasibility of forescasting North Sea storm surges by integrating numerically a combined atmospheric-oceanographic physical model, the severe storm and the resulting water levels occurring on 3 January 1976 were simulated as a first step into this direction. For this purpose, the atmospheric model was run with a resolution of 8 levels in the vertical and a horizontal grid spacing of 1.4° in latitude and 2.8° in longitude on the hemisphere. The initial conditions are based upon observations of 2 January 1976, 12 GMT, i.e. about 24 hours before the storm reached its greatest intensity in the southern parts of the North Sea.The surface wind predicted by the atmospheric model was converted into stress values through a bulk formula which then entered the vertically integrated North Sea model, to yield the desired water elevations in a 22 km-grid. Moreover, also the observed wind, stemming from a careful re-analysis of the storm situation, was handled in the same way. The numerically obtained results were compared with gauge measurements at a number of coastal stations.

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Ergebnisse einer 36stündigen Vorhersage der Nordsee-Sturmflut am 3. Januar 1976 aufgrund von numerischen Modellen

Zusammenfassung Zur Untersuchung der Möglichkeiten, Sturmfluten mit physikalischen Modellen der Atmosphäre und der Nordsee vorherzusagen, wurde als erster Schritt in dieser Richtung die schwere Sturmflut an der deutschen Nordseeküste vom 3. Januar 1976 nachgerechnet. Hierzu wurde das im Sonderforschungsbereich 94 entwickelte Atmosphärenmodell auf der Grundlage der hydro- und thermodynamischen Gleichungen mit einer Auflösung von 8 Flächen in der Vertikalen sowie 1,4° in der geographischen Breite und 2,8° in der geographischen Länge auf der gesamten Nordhalbkugel über 36 Stunden numerisch integriert. Als Eingangsdaten dienten die Beobachtungen vom 2. Januar 1976, 12 Uhr. dieser Termin liegt ca. 24 Stunden vor Eintritt des stärksten Sturmes im Bereich der Deutschen Bucht.Die auf diese Weise prognostizierte Windverteilung wurde über der Nordsee in Schubspannungswerte überführt, woraus das Nordseemodell mit den hydrodynamischen Gleichungen die Wasserstandswerte in einem 22-km-Netz berechnete. In entsprechender Weise wurde mit einem aus Beobachtungen während dieses Zeitraums gewonnenen Windfeld verfahren; diesem lag eine besonders sorgfältige, nachträglich angefertigte Analyse des Seewetteramts Hamburg zugrunde. Die so errechneten Wasserstände sind dann mit Pegelmessungen verglichen worden.

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Résultats d'une prédiction d'onde de tempête de 36 heures de la mer du Nord pour le 3 janvier 1976 sur la base de modèles numériques

Résumé Afin d'étudier la possibilité de prévior les ondes de tempête en mer du Nord en intégrant numériquement un modèle physique combiné atmosphère-océan, la forte tempête du 3 janvier 1976 et des niveaux d'eau qui en ont résulté ont été simulés comme premier pas dans cette voie. Dans ce but, on a fait fonctionner le modèle atmosphérique avec une résolution de 8 niveaux dans le plan vertical et un réseau horizontal aux pas de 1,4° en latitude et de 2,8° en longitude sur l'hémisphère. Les conditions initiales sont basées sur les observations du 2 janvier 1976 à 12h GMT, c'est-à-dire environ 24 heures avant que la tempête n'atteignît sa plus forte intensité dans les parties méridionales de la mer du Nord.Le vent en surface prédit par le modèle atmosphérique était converti par l'intermédiaire d'une formule globale en valeurs de tensions qui étaient alors introduites dans le modèle de la mer du Nord intégré verticalement, pour obtenir les hauteurs d'eau désirées, dans un réseau de 22 km de côté. En outre, le vent observé, issu d'une nouvelle analyse soignée de la situation de tempête, était aussi traité de la même manière. Les résultats obtenus numériquement furent comparés aux mesures fournies par les marégraphes en un certain nombre de stations côtières.

     

Die Entgiftung von zyanidhaltigen Abwässern durch Oxydation mit Hypochlorit

Ohne Zusammenfassung Mitteilung Nr. 84     

Automatic Location of Swarm Earthquakes from Local Network Data

An advanced method of automated seismic phase picking and exact location and magnitude determination of swarm micro-earthquakes from local network data is presented. The phase picker is applied in two steps: first, S-wave groups are identified using a polarisation detector, and then corresponding P-wave groups are searched for. The times of maximum P- and S-amplitudes are then used as starting points for the determination of accurate P- and S-arrival times. The maximum S-wave amplitudes are utilised for determining local magnitudes. The whole procedure is checked by simultaneous preliminary hypocentre location providing estimates of local magnitudes and a compatibility check of the candidate P- and S-phases. The closest station to the earthquake cluster is used as a master, and the phase search at the remaining stations is governed by the P- and S-phases identified at the master station. Thanks to the use of apriori information on the approximate position of hypocentres, the procedure is also capable of picking the individual P- and S-phases of sequences of overlapping swarm events. The performance of the procedure was tested by comparison of the automatically and interactively created catalogues of the January 1997 NW-Bohemia micro-earthquake swarm. With stations located at epicentral distances between 0 and 20 km, the difference between hypocentre coordinates obtained by automatic and interactive processing did not exceed 80 m for 86% events. All events above magnitude 0.5 were identified, and the automatically determined polarity of first P-wave motion proved to be correct in 89% of them.     

Monitoring of atmospheric deposition in European forests and an overview on its implication on forest condition

Forest conditions in Europe have been monitored over 20 years jointly by the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and the European Union (EU). Maps for mean bulk SO₄, NO₃ and NH₄ deposition at around 400 intensive monitoring plots in the years 1999–2001, as well as time trends for the period 1996–2001, are presented. Mean bulk SO₄ deposition at 169 plots mostly located in central Europe decreased from 7.4 to 5.8 kgS ha⁻¹ a⁻¹. Mean NH₄ bulk deposition decreased from 6.2 to 5.3 kgN ha⁻¹ a⁻¹. Nitrate bulk deposition fluctuated around 5 kgN ha⁻¹ a⁻¹. On average, throughfall deposition was considerably higher than bulk deposition. Time trends for mean tree crown defoliation as an overall indicator for forest condition show a peak in the mid 1990s for most of the monitored main tree species and a recent increase for the years 2003 and 2004. Multivariate linear regression analyses show some significant relations between deposition and defoliation. These relations depend on the tree species and site characteristics. Effects of deposition are moderated by the influence of biotic stress factors such as insects and fungi and by abiotic stress factors, such as weather.     

Environmental control of the oxygen isotope composition of Porites coral microatolls

Understanding the influence of climatic and non-climatic factors on geochemical signals in corals is critical for assessing coral-derived records of tropical climate variability. Porites microatolls form large, disk-shaped colonies constrained in their upward growth by exposure at or close to mean spring low water level, and occur on Indo-Pacific reefs. Microatolls appear suitable for paleoclimate reconstruction, however the systematics of the microatoll chemistry-climate relationship are yet to be characterized. In this study, the δ¹⁸O signal in Porites microatolls from well-flushed reef flats on Kiritimati (Christmas) Island, central Pacific was investigated for intra-coral (growth aspect and extension rate effects) and between-coral effects, and to explore the climate signal contained within their skeletons. Samples for δ¹⁸O analysis were taken from six individual transects from different positions within Porites microatoll XM22. The results show that: (1) the average standard deviation for the mean δ¹⁸O values of transects that represent the same time periods is 0.03‰, and is within measurement error for a single analysis (0.04‰); (2) the average standard deviation for time-equivalent, near-monthly samples along the transects within the same microatoll is 0.07‰ and; (3) comparison of the average δ¹⁸O values of records for different microatolls from across Kiritimati Island show only a small between-coral differences of 0.04‰ and 0.11‰ for different time periods. These differences in mean δ¹⁸O are within the range for intra- and inter-colony differences in seasonal and interannual δ¹⁸O reported for dome-shaped Porites. Based on these results, a stacked microatoll δ¹⁸O record was constructed for the period 1978-2007 for comparison with published coral δ¹⁸O records for nearby dome-shaped Porites. There is a systematic offset between the two types of records, which is probably due to variations in δ¹⁸O seawater across Kiritimati Island. Despite the offset, all records show similar amplitudes for the seasonal-cycle of δ¹⁸O, and there is a strong correlation (r = −0.71) between microatoll δ¹⁸O and local sea surface temperature (SST). The δ¹⁸O-SST slope relationship for microatolls is −0.15‰/°C, very similar to that reported for fast-growing domed corals (−0.18‰ to −0.22‰/°C). Statistical analysis of the stacked microatoll δ¹⁸O record shows that it is correlated with both local and large-scale climate variables (primarily SST) at semiannual, annual and interannual timescales. Our results show that the signal reproducibility and fidelity of skeletal δ¹⁸O in coral microatolls is comparable to that observed for more conventional coral growth forms. Longer-lived, and fossil, Porites microatolls, where they have grown in suitably flushed environments, are likely to contain δ¹⁸O signals that can significantly extend instrumental records of tropical climate variability.     

In vitro screening for endocrine disruptive activity in selected South African harbours and river mouths

Various waterborne anthropogenic contaminants disrupt the endocrine systems of wildlife and humans, targeting reproductive pathways, among others. Very little is known, however, regarding the occurrence of endocrine disruptive activity in South African freshwater ecosystems, and coastal ecosystems have not been studied in this regard. In a first attempt to investigate endocrine disruptive activity in South African coastal waters, surface water samples collected from harbours, river mouths and estuaries in three metropolitan municipalities, eThekwini (which includes Durban), Nelson Mandela (specifically Port Elizabeth Harbour) and City of Cape Town, were screened for (anti) oestrogenicity and (anti)androgenicity using recombinant yeast bioassays. Moreover, levels of the female hormone 17β-(o)estradiol (E2) were determined in all samples, as well as a selection of hydrocarbons in the eThekwini samples. A high proportion of samples collected from eThekwini were oestrogenic, whereas none from Port Elizabeth Harbour and only a single river mouth sampled in the City of Cape Town were oestrogenic. E2 was detected in all the samples tested, but at higher concentrations at the eThekwini and City of Cape Town localities than Port Elizabeth Harbour. In addition, the recombinant yeast assays revealed that anti-androgenicity was widespread, being detected in the majority of samples screened apart from those representing Port Elizabeth Harbour. Conversely, no anti-oestrogenic or androgenic activity was detected. Anti-androgenicity did not associate with hydrocarbon loads, providing evidence that other anti-androgens were responsible for the observed activity. The present data suggest potential reproductive disruption in marine and estuarine fauna inhabiting the eThekwini and City of Cape Town regions.     

Optical closure of parameterized bio-optical relationships

An optical closure study on bio-optical relationships was carried out using radiative transfer model matrix operator method developed by Freie Universitt Berlin.As a case study,the optical closure of bio-optical relationships empirically parameterized with in situ data for the East China Sea was examined.Remote-sensing refl ectance(R rs)was computed from the inherent optical properties predicted by these biooptical relationships and compared with published in situ data.It was found that the simulated R rs was overestimated for turbid water.To achieve optical closure,bio-optical relationships for absorption and scattering coeffi cients for suspended particulate matter were adjusted.Furthermore,the results show that the Fournier and Forand phase functions obtained from the adjusted relationships perform better than the Petzold phase function.Therefore,before bio-optical relationships are used for a local sea area,the optical closure should be examined.