Fakultät für Geowissenschaften - Digitale Hochschulschriften der LMU Archiv

-Resumen extendido- Investigaciones realizadas en conjunto con la Universidad de Chile, en las áreas geotermales activas entre Lago Ranco y Lago Rupanco en el Sur de Chile (40.5ºS) han sido enfocadas a establecer balances hídricos e hidroquímicos. Esta tesis muestra los resultados de dos estudios de terreno realizados en las temporadas enero-marzo 2001 y enero-febrero 2002, y una investigación bibliográfica y recopilación de datos llevada a cabo en Chile. Los cálculos del caudal total se basan en un cálculo diferencial superficial entre el promedio de la precipitación y la evapotranspiración potencial media anual. Con la aplicación de un paquete geoinformático (GIS-Geographic Information System) y con el uso de una base de datos disponibles, se ha podido establecer un balance hídrico general de varias zonas dentro del área de investigación. La cantidad de precipitación media anual es bastante alta y alcanza desde un valor de 2000 mm/a en los valles hasta más de 7000 mm/a en las cumbres. Sin embargo, la base de datos es bastante pobre y las suposiciones sobre valores de precipitación en altura están basados en una recopilación realizada durante cinco años por la estación climática "Antillanca" perteneciente a la CONAF a una altura de aproximadamente 1000 m.s.n.m. Como consecuencia de fluctuaciones climáticas como ENSO por ejemplo, los valores de precipitación pueden llegar a variar en rangos de miles de milímetros por año. Un reporte climático de larga duración y especialmente datos más precisos de las zonas elevadas son esenciales para un balance hídrico detallado. La precipitación media anual calculada, para toda la zona investigada es del orden de 4300 mm/a mientras que la evapotranspiración potencial promedia de 540 mm/a es sólo 1/8 de los valores de precipitación. Esto significa, que la mayor parte de la precipitación está disponible para el caudal. Los valores medios de caudal medidos en el área de captación del Río Puleufú en la orilla noreste del Lago Rupanco posibilitan una evaluación e interpretación de líneas de caudal superficial llamadas hidrógrafos. Esto muestra que la posibilidad de infiltración y la permeabilidad hidráulica parecen ser bastante alta en las rocas volcánicas, geológicamente muy heterogéneas. La precipitación media calculada en el área de captación es de aproximadamente 5500 mm/a y la evapotranspiración potencial es de 480 mm/a. El caudal medio anual es aproximadamente 2800 mm/a quedando asi, más de 2000 mm/a para la infiltración en las partes profundas de las secuencias volcánicas y en el basamento intrusivo. En este contexto, los grandes lagos Ranco, Puyehue y Rupanco situados junto a los macizos volcánicos ejercen una importante función como cauces principales de aguas subterráneas en esta zona. Las cantidades de recargas de agua subterránea se han calculado para diferentes áreas de captación. Especialmente las áreas de gran altitud con escasa vegetación, grandes cantidades de precipitación y capas muy permeables de lava en bloque, pómez y lapilli en la superficie son probablemente las áreas de recarga mas importantes. En el altiplano de Cordón Caulle (1300-1500 m s.n.m.) por ejemplo casi toda la precipitación es infiltrada inicialmente. Eso significa un valor extremadamente alto de recarga de aguas subterráneas de mas de 200 l/(s·km²). Incluso parte de esta recarga alcanza la superficie muy pronto en las vecindades del altiplano de Cordón Caulle por medio de pequeñas fuentes y, en ocasiones, hacia la parte terminal de coladas de lava con estructuras de túneles una cierta cantidad queda disponible para la infiltración en niveles más profundos. Localidads importantes para la recarga de sistemas acuíferos profundos son, en este contexto, especialmente zonas tectónicas compuestas por rocas intensamente fracturadas como ocurre en la zona de Falla Liquiñe-Ofqui, complejos volcánicos y fisuras así como en los alrededores de fisuras volcánicas. Aparte del descenso del agua, estos localidads son también importantes para la circulación de aguas termales. Los manantiales calientes alrededor del macizo Antillanca están localizados cerca de los valles y están relacionados con estructuras tectónicas. Las fracturas y fallas parecen estar relacionadas a la zona de Falla Liquiñe-Ofqui. Las características hidroquímicas de las aguas superficiales y cercanas a la superficie, aguas subterráneas frías, están por una parte compuestas por grandes cantidades de precipitación con baja salinidad (conductividad eléctrica (eC) < 80 µS/cm) como resultado. Por otra parte, debido a la lixiviación de cenizas volcánicas recientes y lapilli así como pómez con una gran superficie de reacción y el desgaste intensivo de estos depósitos por agentes atmosféricos, la cantidad de ácido silícico disuelto en esta agua es moderadamente alta con valores de 15-40 mg/L. El principal tipo de agua sódica-bicarbonatada tiene un pH entre neutro a ligeramente básico. En contraste, las precipitaciones y el agua de deshielo muestran valores de salinidad muy bajos con eC < 5µS/cm, un pH ligeramente ácido y excepto en temporadas con entradas atmosféricas por erupciones volcánicas, no hay una contaminación significativa debido a la polución del aire. El análisis de muestras de suelo y sedimento con respecto a la lixiviación, muestra gran capacidad potencial de intercambio catiónico así como experimentos de lixiviación con agua destilada (24h-batch) muestran una resolución de ácido silícico en valores de hasta 12 mg/L. Sólo los ríos Nilahue y Contrafuerte al Norte del volcán Puyehue con descargas de alrededor de 9.4 m³/s y 4 m3/s respectivamente medidos en temporada de sequía tienen significantemente alta salinidad (< 200µS/cm), debido a la incorporación de aguas termales desde la parte SE del Cordón Caulle. Incluso aun con la descarga de las aguas termales desde Trahuilco que fluye directamente al Río Riñinahue, no se pudo observar en el agua del río ningún aumento significativo de salinidad debido a la extremadamente alta disolución con agua de precipitación. Manifestaciones termales superficiales como manantiales calientes, géiseres y fumarolas se concentran en el Cordón Caulle al NE del volcán Puyehue, así como varios otros manantiales calientes en los alrededores del macizo Antillanca como las famosas Termas de Puyehue. El grupo volcánico activo Carán-Los Venados, al NE del Cordón Caulle no muestra actividad geotermal superficial alguna. La mayoría de las manifestaciones geotermales en el Cordón Caulle están localizadas a lo largo de las fallas y fisuras orientadas NO-SE, que representan los bordes de un graben de 15 x 5 km en area. Actividad fumarólica relacionada con rocas intensamente alteradas y la aparición de aguas de tipo sulfato-ácidas están concentradas en la parte alta del altiplano (1500 s.n.m.) en Las Sopas y Los Venados. La principal zona de descarga de fluidos desde el Cordón Caulle está localizada en Trauhilco (1000 s.n.m.) en el centro de la caldera Cordillera Nevada y descarga varias decenas de litros por segundo a una temperatura mayor de 90°C. Las aguas son del tipo alcalinas bicarbonatadas y se observan depósitos silíceos alrededor de la fuentes. Debido a la ausencia de aguas cloruradas en superficie la aplicación de geotermómetros de sílice y catiónicos tiene que ser tratada con cuidado porque el equilibrio agua-roca parece estar ausente en los sistemas o al menos cuando las fuentes termales tienen su origen en un reservorio en profundidad. Aplicando el geotermómetro de cuarzo se calculan temperaturas de al menos 200°C en el reservorio. Geotermómetros de gas parecen proporcionar una información más fiable. Investigaciones isotópicas (18O, ²H) indican que el agua es de origen meteórico local. Procesos de evaporación ocurren en las fuentes termales del Cordón Caulle. Sólo existe poco evidencia isotópica de procesos de interacción agua-roca intensivos, y el desplazamiento de 18O de las muestras de aguas termales es bajo. Concentraciones de tritio de 0.4-1.8 TU no dan resultados inequívocos. Con la información existente el sistema geotermal del Cordón Caulle representa un sistema dominado por vapor donde el agua subterránea local es calentada a través de vapor en ascenso. La condensación y oxidación del vapor así como procesos de mezcla en el acuífero superior tienden a resultar en una composición de las aguas termales de tipo bicarbonatadas y sulfatada, explicando la ausencia de aguas cloruradas. En este contexto, el afloramiento de aguas de tipo bicarbonatada con una temperatura máxima de 70°C en la cima del Cordón Caulle cerca de la pendiente noroeste del volcán Puyehue, tiene su origen en pequeños niveles 'colgados' de agua subterránea calentada por vapor. La química de las fuentes termales Termas de Puyehue-Antillanca es diferente de aquellas del Cordón Caulle con respecto a pequeños incrementos en el contenido de cloro, pequeñas variaciones en la razón B/Cl y altas concentraciones de arsénico (varios cientos de µg/L). Incluso muestras de agua potable "Agua Mineral Puyehue" presentan concentraciones de arsénico de alrededor de 100 µg/L. Además de estas diferencias geoquímicas, existe una larga distancia geográfica y una diferencia de altura en la localización de fuentes termales. Además la separación hidráulica de los acuíferos locales y probablemente también de las zonas de descarga en las cercanías del Río Gol Gol y del Lago Puyehue deben ser mencionadas. Esto probablemente caracteriza dos flujos ascendentes y dos sistemas separados. 1) El primero está situado debajo del rango del Cordón Caulle con su principal descarga en el borde de un graben. 2) El segundo, bajo el macizo Antillanca donde la descarga de fluidos esta asociada a rasgos tectónicos en el basamento intrusivo. Clasificaciones hidroquímicas muestran que todas las aguas termales investigadas son inmaduras con respecto a su afinidad geotermal. Incrementos en las concentraciones de boro y arsénico muestran influencia de fluidos volcánicos y el joven desarrollo de los sistemas geotermales. La presencia de sistemas dominados por vapor en el Sur de Chile es diferente a la del Norte, donde predominan los sistemas líquidos de alta entalpía en terrenos volcánicos abruptos. En todo caso, la energía potencial de estos sistemas dominados por vapor en el Sur promete ser muy alta.

Numerous applications of hydrologic models have shown their capability to simulate hydrologic processes up to a reasonable degree of certainty. In terms of flood modeling, the hereby required quality of the key input parameter precipitation is of vast importance but often remains questionable. This Ph.D. thesis presents a critical review of experiences made in the EU-funded RAPHAEL project. Different meteorological data sources are evaluated to assess their applicability for flood modeling and forecasting in the Bavarian pre-alpine watershed of the Ammer river (709 km²), for which the manifold hydrologic aspects of runoff production as well as the complex nature of floods are described. Apart from conventional rain gauge data, forecasts of several Numerical Weather Prediction Models (NWP) as well as rain radar data and precipitation derived from METEOSAT are examined, scaled and applied within the framework of a GIS-structured and physically based hydrologic model. Multi-scenario results are quantitatively compared and analysed. The synergetic approach leads to promising results under certain meteorological conditions, but also emphasizes a variety of drawbacks. At present, NWPs are the only data source to provide placed rainfall forecasts (up to 96 hours) with large spatial coverage and high temporal resolution. On the other hand, the coarse spatial resolution of NWP grids cannot as yet image the heterogeneous structures of orographic rainfields in complex convective situations and hence introduces a major downscaling problem for mountain catchment applications. As shown for two selected Ammer flood events, a high variability in prediction accuracy still has to be accepted at present. Sensitivity analysis of both meteo-data input and hydrological model performance in terms of process description are discussed, drawing positive conclusions for future applications of an advanced meteo-hydro model synergy.

Unter der Annahme, dass Anzeichen von Umweltveränderungen durch den Klimawandel besonders in sensiblen, wenig genutzten Hochgebirgsökosystemen gut erkennbar sind, ist im Einzugsgebiet des Königssees im Nationalpark Berchtesgaden ein landschaftsökologisches Projekt unter dem Titel „Landschaftsökologische Analysen im Königsseeeinzugsgebiet“ (LAKE) durchgeführt worden. Hauptziel war die Erfassung, Darstellung und das Ergründen von Ursachen dieser Umweltveränderungen im Energie- und Stoffhaushalt an Hand ausgewählter Parameter. Ebenso galt es, den Naturschutzaspekt zu beleuchten, der sich aus dem Anspruch von Nationalparks ergibt. Die Fragestellung in diesem Zusammenhang war, ob sich Nutzungs- und Naturschutzinteressen vereinbaren lassen. Als Untersuchungsgebiet wurde der Nationalpark Berchtesgaden ausgewählt, der für diese Fragestellung ideale Vorraussetzungen bietet. Es handelt sich um ein Gebiet welches unter gegenwärtigen Bedingungen eine geringe anthropogene Beeinflussung erfährt. Das Reaktionsverhalten der Landschaft bleibt erklärbar, da es durch wenige Faktoren bestimmt wird. Zur Realisierung dieses Anliegens wurde ein landschaftsökologischer Methodikansatz verwendet. Hauptaugenmerk der Untersuchungen war das Einzugsgebiet des als oligothroph eingestuften Referenzsees Königssee. Vor allem die Untersuchung und der Vergleich der abiotischen Parameter zu einer Studie aus den Jahren 1978-1980 war Teil der Zielstellung. Deshalb wurden im wesentlichen in einem wöchentlichen (im Winter 14-tägigen) Rhythmus Tiefenprofile zu Temperatur bzw. Sauerstoff an zwei verschiedenen Messstellen im Königssee ermittelt und darüber hinaus Wasserproben von den Zuflüssen und vom See selbst genommen. Die Wasserproben wurden dann ionenchromatographisch auf Nitrat, Phosphat, Sulfat und Chlorid untersucht. Festgestellte Umweltveränderungen wurden mit Nutzungserscheinungen in Beziehung gesetzt. Letztere konnten an Hand der Auswertung von vorhandenen Quellen und Befragungen der lokalen Interessenvertreter für Tourismus und Almwirtschaft dargestellt werden. Im Ergebnisteil sind die Zusammenhänge der Reaktion des limnischen Systems Königssee bezüglich seiner abiotischen Faktoren in Zusammenhang mit physischgeographischen Parametern und anthropogenen Einflüssen dargestellt und erläutert. Insbesondere Gründe für die Temperatur- und Sauerstoffverteilung im Seekörper in Zusammenhang mit Windeinwirkung, Strahlung bzw. Lufttemperatur werden aufgezeigt. In Kap. 5.1 erfolgte eine Analyse der Veränderung klimatischer Randparameter. Die Station Bad Reichenhall zeigt in den Tendenzen des Monatsmittelwertes der Lufttemperatur gute Übereinstimmung mit der Region Berchtesgaden. Für Bad Reichenhall konnte eine Erhöhung der Lufttemperatur in den letzten 28 Jahren um ca. 2K festgestellt werden. Die jährliche Gesamtsonnenscheindauer ist im Mittel um 100 Stunden gestiegen. Bezüglich der Veränderungen des Systems durch eine mögliche Klimaveränderung lässt sich zusammenfassend sagen, dass die theoretisch zu erwartenden Veränderungen und Beobachtungen von anderen Autoren in anderen Regionen in limnischen Systemen in Bezug auf die abiotische Komponente durchaus in ähnlicher Form am Königssee zu bestätigen sind, wenn man die Zeiträume von 1978 bis 1980 und 1999 bis Juni 2003 miteinander vergleicht. Der jährliche Wärmeinhalt des Königssees ist durchschnittlich um 10% gestiegen, und dies obgleich die extrem warmen Verhältnisse aus dem Hochsommer 2003 nicht mehr in allen Statistiken berücksichtigt werden konnten. Auch bei den Hypolimniontemperaturen sind zum gegenwärtigen Zeitpunkt durchschnittlich 0,2 bis 0,3K höhere Messwerte festzustellen. Vor allem die im Rahmen der Klimaveränderung zu erwartenden Verhältnisse zu Stabilität und Schichtung lassen sich am Königssee beobachten: Die Stagnationsphasen haben sich verlängert, und die Zirkulationsphasen sind kürzer geworden. Gleichermaßen ist der Beginn der Stagnation um ca. 11-12 Tage früher im Jahr zu erwarten, und die Auflösung der Schichtung tritt im Durchschnitt ca. 20 Tage später im Jahr ein. Auch eine Verlagerung der Thermokline um ca. 1m in die Tiefe ist erkennbar. Der Schichtungsindex nach SCHMIDT ist bei den monatlichen Werten (April-Dezember) im Durchschnitt um ca. 40% gestiegen. Bislang scheinen die Reaktionen des Umweltsystems durch die festgestellten Umweltveränderungen im Energie- und Stoffhaushalt im Einzugsgebiet weniger auf direkte, im Untersuchungsgebiet zu suchende Einflussfaktoren zurückführen zu sein, als auf überregionale oder gar globale Ursachen. So ist – zumindest unter Betrachtung der ausgewählten Parameter und über den untersuchten, relativ kurzen Zeitraum festzustellen, dass das Umweltsystem in sich trotz des anthropogenen Einflusses tragfähig erscheint. Es lässt sich somit die erfreuliche Aussage treffen, dass es sich bei dem Nationalpark Berchtesgaden um ein Schutzgebiet handelt, welches den an sich selbst gerichteten harten Kriterien seiner Bezeichnung derzeit zwar nicht im vollen Umfang gerecht wird, dennoch zum gegenwärtigen Zeitpunkt keine negative Beeinflussung durch regionale anthropogene Ursachen zu befürchten hat. Da in Zukunft möglicherweise die regionalen Auswirkungen von Global Change noch drastischer ablaufen können, muss diese Bewertung unablässig erneuert werden und beispielsweise u. a. an Hand der in dieser Studie ausgewiesenen Parameter beharrlich kontrolliert werden.

One of the main goals of current palaeomagnetic research is the attempt to acquire high-resolution data on palaeodirections and -intensities in order to obtain detailed information about the Earth's magnetic field in the geological past. The material best suited for such studies are basaltic rocks. For these high-quality directional investigations and especially for palaeointensity determinations, a profound knowledge about the stability, magnetomineralogical character and the domain state of the carriers of remanence is imperative. The emphasis of the present work was placed on the investigation of basalts exhibiting partial or complete self-reversal of natural remanent magnetisation (NRM). This phenomenon is not an exotic rarity but a widespread characteristic of many basaltic rocks. However it remains usually unnoticed by routine palaeomagnetic measurements as it requires special techniques for its detection. In this work samples from Olby and Laschamp (France) and Vogelsberg (Germany) showing the phenomenon were studied with rock magnetic, microscopic and microanalytical techniques in order to identify the carriers of self-reversed remanent magnetisation. Further aims were to determine the exact mechanism of self-reversal acting in basalts and to evaluate the consequences for the reliability of palaeomagnetic data. On the basis of the experimental work a numerical model was developed which shows that, from the physical point of view, the observed magnetomineralogy is capable of causing self-reversal. The present work provides the following new insights: The phenomenon is caused by two magnetic phases with different blocking temperatures which are magnetically coupled. The lower blocking temperature corresponds to the primary titanomagnetite (mother phase) crystallising from the basaltic magma. The remanence with higher blocking temperature is carried by titanomaghemite (daughter phase) evolving from the primary titanomagnetite by partial low-temperature oxidation. The daughter phase forms narrow bands along cracks in the otherwise unaffected mother phase particles. This yields a close side-by-side assemblage of titanomagnetite and titanomaghemite with markedly different magnetic properties in one and the same grain. By applying the various microscopic techniques on identical grains, it was possible to directly correlate magnetomineralogy with magnetic domain structure. Numerical calculations of remanence acquisition demonstrate that two-phase particles with the experimentally observed geometry and magnetic properties are able to acquire a partially or completely self-reversed remanent magnetisation. The calculations also prove that the two magnetic phases present in the studied samples are coupled by magnetostatic interaction. The experimental results indicate that the low-temperature oxidation process responsible for the formation of the second magnetic phase takes place at temperatures at or above the blocking temperature of this daughter phase during primary cooling. This titanomaghemite phase is thus carrying a stable remanence in direction of the ambient magnetic field. Although the original titanomagnetite as the mother phase is in a strict sense the primary magnetic mineral, it does not carry the primary magnetic remanence but is at least in part magnetostatically coupled to the titanomaghemite. Therefore, its remanence is - at least in part - antiparallel to the external field. MFM domain observations present evidence that the mother phase is in the magnetic multidomain range. Hence, its magnetic remanence is not stable and is replaced by a viscous overprint acquired at ambient temperatures. In contrast, the daughter phase has a higher coercivity due to oxidation induced stresses and an increased domain width. Regarding the samples from Olby, these magnetomineralogical investigations directly lead to new arguments in favour of the existence of the Laschamp geomagnetic event: As the high blocking temperature daughter phase carries a stable remanence in direction of the external magnetic field, the local geomagnetic field direction was indeed reversed at the time of emplacement. Due to their complex magnetomineralogy and remanence acquisition, samples exhibiting partial or complete self-reversal are not suitable for palaeointensity determinations. In order to identify and exclude such samples in the course of such experiments, a modification of the existing Thellier-Thellier method is proposed. Additionally, this new procedure is also able to detect remanence carried by multidomain (MD) particles. The method substantially improves the reliability and quality of palaeointensity estimates as multidomain behaviour is among the most common reasons for erroneous results in Thellier-type palaeointensity determinations.

The present work combines palaeomagnetic and rock magnetic methods with clay mineralogy, isotope geochemistry of clay minerals and trace element geochemistry of Fe-oxide leachates to study remagnetised sedimentary rocks from Palaeozoic outcrops in Middle and Eastern Europe. Three areas were selected (NE Rhenish Massif, Barrandian and Holy Cross Mountains), where the causes of Late Palaeozoic remagnetisations are yet unclear. The results yield important implications for the processes and mechanisms responsible for the remagnetisations in the areas studied. NE Rhenish Massif: A Late Carboniferous remagnetisation (component B) is identified in Late Palaeozoic carbonate and clastic rocks from the NE Rhenish Massif. Three individual incremental regional fold tests across the area show a unique and distinctive variation in timing of remagnetisation relative to the age of folding. The remagnetisation is postfolding in the South and of synfolding origin in the North of the area. Consequently, the timing and the duration of the remagnetisation event is constrained by the age of folding, which varies throughout the area and reflects a northward migration of the deformation front during 325 Ma to 300 Ma. Comparison of the resulting palaeolatitude of the NE Rhenish Massif with the palaeolatitudinal drift history for the region yields an estimate for the age of remagnetisation of ca. 315 - 300 Ma, which is in good agreement with the age of deformation. The concordance of the magnetic palaeoinclinations obtained from the entire area indicates that the rocks were remagnetised during a relatively short period of only a few My. The thermal stability of the remanence up to 550°C the comparably low palaeotemperatures in the studied region and the short duration of the remagnetisation event favour a chemical remagnetisation process. Rock magnetic experiments reveal a complex magnetomineralogy of the remagnetised Palaeozoic sediments from the NE Rhenish Massif. The dominant carrier of the Carboniferous magnetisation component is magnetite, but pyrrhotite and hematite accompany magnetite as carrier of the NRM in some grey carbonates and red sandstones or red nodular limestones, respectively. The hysteresis ratios, magnetic viscosity and low temperature behaviour of the carbonate rocks give strong evidence for the presence of very fine grained (superparamagnetic) magnetic minerals. This material is also thought to be responsible for similar rock magnetic properties of siliciclastic rocks. This interpretation, however, is not unique for the siliciclastic rocks, due to the predominance of detrital MD magnetite and the high amount of paramagnetic material. The hysteresis ratios from medium to coarse grained rocks and reef carbonates fall in or close to the fields of MD magnetite and remagnetised carbonates, respectively. The fine grained clastic rocks (siltstones) and limestone turbidites have intermediate hysteresis properties. This implies the presence of very fine grained magnetic material in all lithologies of the NE Rhenish Massif, which is indicative for authigenic growth of magnetic minerals and formation of a CRM. However, the magnetic fingerprint of SP grains gets increasingly disguised with increasing amount of detrital MD magnetite in clastic rocks. K-Ar dating of

The Earth's magnetic field is generated by the motion of liquid iron-rich material in the outer core. One of the most drastic manifestations of the dynamics in the outer core are polarity reversals of the magnetic field. The processes controlling geomagnetic reversals, however, are still poorly understood. The mathematical formulation of the dynamics of the liquid outer core show such a degree of complexity that a universal numerical model still remains elusive. Given that the last reversal occurred about 780,000 years ago, direct observations of a reversal have never been possible. Thus we are left with records of ancient reversals recorded in sequences of sedimentary and igneous rocks. Documenting any systematics in reversal processes will provide substantial information about the outer core and core mantle boundary conditions. However, despite the advances in deciphering the behaviour of the field during polarity transitions, reversal records yield controversial results and thus answers to several key questions are still enigmatic. Detailed studies of palaeodirectional and absolute palaeointensity patterns of geomagnetic reversals are scarce and are restricted to the Cenozoic so far. In order to verify or reject concepts developed on the basis of this dataset, reversal records which occurred in the more distant geological past of the Earth are needed. This work presents the results obtained from the Siberian Trap Basalts (Russia) which are coeval with the Permo-Triassic boundary (250 Ma). The sequence yields the by far oldest hitherto studied detailed record of a geomagnetic transition from reversed to normal polarity and provides new insights in transitional field behaviour. Three sections (Talnakh, Listvjanka and Abagalakh) comprising a total of 86 lava flows have been sampled in the Noril'sk region, located at the northwestern rim of the Siberian Trap Basalt province. They provide a complete coverage of the lava pile outcropping in the area. The samples have been subjected to palaeomagnetic direction analysis and to Thellier-type palaeointensity experiments. Extensive rockmagnetic investigations and microscopical studies have been carried out to asses the reliability of the palaeomagnetic information recorded by the lava flows. Magnetite and Ti-poor titanomagnetites were identified to be the carriers of the characteristic remanent magnetisation. The reversibility of the thermomagnetic curves and the observation of exsolution lamellae by ore microscopy give clear evidence for a primary high-temperature oxidation of the titanomagnetite. It can thus be inferred that the measured palaeodirectional and intensity information obtained from these flows was acquired shortly after extrusion of each flow. The demagnetisation of the natural remanence reveals only one direction of magnetisation for most samples. Thermal and alternating field demagnetisation methods are equally effective in isolating the characteristic remanent magnetisation. Occasional overprints have maximum unblocking temperatures of 350°C or remanence coercivities less than 20 mT. Reliable palaeointensity estimates were obtained for approx. 50% of the samples. The relatively high success rate can be attributed to the enhanced magnetic and thermal stability of high-temperature oxidised titanomagnetites. In the lower part of the sequence reversed polarity of the Earth's magnetic field is identified. The associated palaeointensities yield values around 10 µT. The subsequent flows recorded transitional configurations. A tight cluster of virtual geomagnetic poles (VGPs) in mid northerly latitudes, comprising the results of 15 flows, is observed during the transition. Within the cluster the record shows a pronounced and well defined increase in intensity from around 6 to 13 µT. A doubling of local field intensity infers that large scale dynamic processes in the outer core are responsible for this feature, making a strong case for a reasonable temporal stability (several hundreds to a few thousand years) of the VGP cluster. Moreover, the VGP clustering is identified in two parallel sections (Talnakh and Listvjanka). This observation makes it unlikely that this feature is an artifact of a localised burst in volcanic activity and supports the concept of stabilised phases of the geomagnetic field during reversals. The VGPs of the overlying flows move towards the position expected for normal polarity. After rotating of the VGPs into the Late Permian/Early Triassic geographic reference system it is evident that most of the transitional VGPs are strongly confined to a narrow longitudinal band which is perpendicular to near- or far-sided VGP paths. Such near- or far-sided paths would be indicative for the dominance of zonal, and thus axis-symmetric, non-dipole fields. The VGP path of this transition suggests the contribution of strong sectorial components of the Earth's magnetic field. Following the transition itself, normal polarity is reached for a brief time interval. Subsequently, the VGPs depart from this position to form another well defined directional cluster recorded by 14 successive flows. During this clustering, which is interpreted as an excursion of the Earth's magnetic field, no characteristic variation in palaeointensity is identified (mean value 14 µT). Such post-transitional excursions are frequently observed in younger reversal records and are explained by instabilities of the geodynamo after the reversal. However, VGPs associated with post-transitional excursions usually reach positions similar to those occupied by VGPs during the transition. In contrast to such "rebound" effects, the excursion-related VGPs of this record are still confined to the latitudinal band defined by the transition, but "overshoot" normal polarity. This geometrical constraint suggests that non-dipole components similar to those dominating the transitional VGP path are responsible for this observation. Remarkably, the geomagnetic polarity transition described here shares many similarities - such as directional clustering, longitudinal confinement of the VGP path, the existence of a post-transitional excursion and generally low palaeointensities - with previously published reversal records of mainly Tertiary age. It may, therefore, be inferred that the underlying reversal processes are similar to those observed for the Cenozoic. The results obtained of the superjacent 41 flows, which were extruded immediately after the reversal-related excursion, indicate that only at this stage of the record stable normal polarity is reached allowing to determine several characteristic parameters of the Early Triassic Earth's magnetic field. The mean palaeointensity for this part of the sequence is 19 µT, which corresponds to a virtual geomagnetic dipole moment (VDM) of 2.3 * 10^22 Am^2. These findings confirm that the Mesozoic dipole low extends at least down to the Permo-Triassic boundary. Calculation of the recorded secular variation yields values similar to those averaged over the last 5 Ma, a period with distinctly higher mean VDM (5.5 * 10^22 Am^2) compared to the data presented here. The hypothesis of enhanced secular variation during phases of a low mean VDM can, therefore, not be substantiated by this study. Secular variation and the strength of the dipole moment seem to be - at least in the Early Mesozoic - more complexly coupled than previously assumed. Magnetostratigraphic results of borehole samples obtained from basalts related to the Siberian Trap volcanism including the West Siberian basin yield in total 6 polarity intervals. Comparison to the global magnetostratigraphic scale indicates that the volcanic activity lasted no more than 3.2 Ma. However, the lava sequence in the Noril'sk area (more than 1700 m thick), representing the bulk of the erupted material, recorded only one polarity transition. This finding has been supported by data derived from boreholes in close vicinity to the surface sections which makes the presence of further undetected polarity transitions highly unlikely. It can be thus inferred that the emplacement of the sequence occurred much faster than the aforementioned 3.2 Ma. Radiometric ages suggest an upper limit for the duration of the emplacement of approximately 1 Ma. Based on the assumptions of similar rates of angular secular variation in the Early Triassic and in the Holocene and an average duration of the transition itself the time interval covered is estimated to be in the order of 15000 years. This value has to be regarded as a lowermost limit for the duration of the emplacement. Such a rapid development of the volcanic province in the Noril'sk area would imply an enormous eruption rate making a strong case for the Siberian Trap basalts as cause for the Permo-Triassic crisis.

A 3D refraction and reflection seismic travel time tomography was developed on the basis of the widespread Local Earthquake Tomography (LET) method SIMULPS. To include crustal scale refraction seismic observations in the inversion the accuracy of this method was adjusted for long ray paths and high resolution. Floating or discontinuous reflectors are modelled on separate grids by bi-cubic splines, and an appropriate reflection ray tracer was developed using the Approximate Ray Tracing/Pseudo Bending (ART/PB) method. Accuracy was adjusted by several means: arcuate ART trajectories are roughly adjusted to the velocity field before bending, multiple ART travel time minima are perturbed and step length along the ray path for distant observations is reduced by iterative resegmentation. The resulting ray tracer also finds head waves as long as interface geometry is not too complex. The extensions have been tested with some simple synthetic models focusing on problems connected with discontinuities and low velocity zones. The inversion algorithm was then applied to a wide-angle data set from the Eastern Alps recorded by seismological three-component stations during the TRANSALP campaign. From Vibroseis records a high resolved model for the upper crust was derived, which was extended to depth with low resolution using distant observations from dynamite shots. The resulting model correlates well with known geologic structures in the upper crust. The middle and lower crust shows distinct velocity functions for the European and the Adriatic part of the profile. The European Moho is resolved from the Northern Calcareous Alps in 40 km depth to the Alpine root in ca. 55 km depth, where it seems to lose its reflective character. Only few reflections from the Adriatic Moho were recorded yielding a depth of ca. 40 km. Lower crustal structure is interpreted as a result of southward subduction of Penninic oceanic crust before collision.

Long-term threats to groundwater quality arising at regional scale from the exploitation of deep groundwaters, and some ways to tackle with them have been revealed by Seiler (1983, 1987, 2001), Seiler & Lindner (1995). They have shown that, once the passive recharge zone of a groundwater system is penetrated by pumping wells and the duration and/or rate at which these are operated exceeds a certain threshold, the natural hydrogeologic barrier between the passive and the active recharge zone gets disrupted, and deep water turnover rates get visibly accelerated; alongside with them, the migration of near-subsurface pollutants towards greater aquifer depths is enhanced in such a way that (a) it remains unnoticeable to standard water quality monitoring for a good number of years, and (b) by the time it is perceived by standard monitoring instruments, it has already affected depths and areas so large that it has turned into a major, irreversible degradation of water quality at regional scale. The deep water abstraction rate beyond which such negative effects occur lies far below the bulk recharge rate estimation; moreover, the actual 'feeding streamlines' of a deep pumping well stretch laterally far upstream the well, so that the usual protection zones concentric around the well itself will not really protect it (Seiler 1987, 2001). Here, the possibility of an early-warning system regarding deep aquifer contamination, and of a process-oriented control of deep groundwater abstractions is examined anew: first explained in terms of a time scale contrast between the transport of 'polluting' and of 'monitoring' species, it is then investigated numerically for two hydrogeologic situations, one with a mild and one with a marked permeability change over depth. The progressive contamination of the deep aquifer is simulated assuming a simplified, yet realistic scenario of shallow aquifer pollution; and the environmental radioisotope response to deep water abstractions is predicted as a function of pumping rate, duration and depth, and of aquifer heterogeneity. The readjustment time of environmental radioisotope repartitions under given hydraulic stress lies somewhere between the (relatively short) pressure adjustment time (determined by hydraulic diffusivities, or T/S) and the (depth-dependent) groundwater age value. The time scope of radioisotope response to hydraulic stress will thus increase with depth, however in competition with radioactive decay which makes isotope concentrations decrease with depth and become irrelevant below a so-called 'nil-line' defined by the detection limit of the respective isotope (the latter may advance toward greater depths, as detection techniques improve). The possibility of an EARLY-WARNING system resides in the time-scale contrast between the ('slow') migration of polluting species and the ('rapid') spatial readjustment of monitoring species. The time scope of a PROCESS-ORIENTED control is confined to the interval in which the response of monitoring species correlates monotonously with the magnitude of the applied stress (pumping rate). For deep porous aquifers of the (Bavarian) Upper Freshwater Molasse with an average porosity over 10%, the time scope of a process-oriented control, before the environmental radioisotope responses under different pumping regimes approach a common plateau, comprises at least 4-5 decades. Besides hydraulics and solute transport, an interest arose for dealing with transient groundwater ages, during or following hydraulic stress. Groundwater age, or 'flow-time', or residence time repartitions are often invoked as a 'microscopic' foundation of lumped-parameter models for (conservative) solute transport in groundwater. How stable are these repartitions against hydraulic perturbations? can their hydraulically-induced shift with time be related consistently and unequivocally to variations in the lumped-parameter values used by black-box models to assess system change? Part of the answer is provided by groundwater age - hydraulic head phase portraits, which are marked by hysterese. The direct, unsteady age modeling furthermore reveals the possibility of a 'groundwater age mining' to occur even without having a 'groundwater mining'.

Ziel der Arbeit ist die Untersuchung der geometrischen und zeitlichen Abfolge der Bewegungen an der Salzachstörung und der Achentaler Schubmasse. Die Untersuchungen stützen sich vorwiegend auf Paäostressuntersuchungen, Untersuchungen von fluiden Einschlüssen und seismischen Daten.

U-Pb-SHRIMP dating of zircons, zircon morphology, geochemistry and isotopic data of metamagmatites from the Bayerischer Wald (Germany) reveal a complex evolution of this section of the Moldanubian Zone exposed in the western Bohemian Massif of the central European Variscan belt. In the south-western part of the Bayerischer Wald Upper Vendian magmatism is constrained by SHRIMP ages of 555 ± 12, 549 ± 7 and 549 ± 6 Ma from metarhyolites and a metabasite. Inherited zircon cores were not observed. Zircon overgrowths yielding pooled ages of 316 ± 10 and 319 ± 5 Ma provide evidence for Variscan metamorphic zircon growth; cathodoluminescence imaging reveals a two-stage metamorphic overprint. In contrast, Lower Ordovician magmatism and anatexis are documented in the north-eastern parts of the Bayerischer Wald by metagranitoids (480 ± 6, 486 ± 7 Ma) and a leucosome (491 to 457 Ma). Inherited zircon cores are found in Lower Ordovician metamagmatites indicating a Palaeoproterozoic-Archaean (2.70, 2.02 Ga) source region, presumably of Gondwana affinity (West African craton), and documenting Cadomian magmatism (>615 to 560 Ma). Upper Vendian magmatism is assumed at an active continental margin with ensialic back-arc development (εNd(t) –4.58 to +1.22). An active continental margin setting, possibly with some lateral variation (accretion/collision) is envisaged for the Lower Ordovician producing granitoids, rhyolites, leucosomes (εNd(t) -0.5 to -6.27) and andesites. A tentative palaeogeographic reconstruction puts the "Bayerischer Wald" in a close relationship with the Habach terrane (proto-Alps), as the "eastern" extension of terranes of the northern Gondwana margin.

The aim of this study is to obtain a better understanding of the hydrological and geochemical contexts of the heavy metal transport in watersaturated porous aquifer sediments, where both copper (Cu) and antimony (Sb) are the main focus. The background of investigation is based on questions within the scope of the redevelopement of past industrial waste deposits areas and groundwater protection. The functional and experimental part of this study was initially comprised of planning, conception and set-up of a column arrangement which served as a model of the sediment-/groundwater system as well as the development of appropriate preparation and sampling techniques. The experimental set-up run was suitable for simulation of groundwater flow with velocities between centimetre and metre per day. In order to differentiate results concerning the migration behaviour of the heavy metals copper and antimony, laboratory experiments were conduced in three water aquifer systems Quaternary Gravel, Tertiary Sand and Dogger-Sand of southern Germany. Between the systems carbonate, clay, or iron contents vary. Quartz-Sand was served as the reference material. Copper was injected as the cationic form of copper nitrate (Cu(NO3)2) and antimony as anionic potassium antimonat (K[Sb(OH)6]). The investigations included short-term (Dirac-impulse) and long-term (Pulse-injection) experiments. A calcareous water served as an eluent for sediments with high buffer capacity and a rainwater-mimic modelwater as an eluent for the sediment with lower buffer capacity. Determination of distribution coefficients (batch-experiments) and thermodynamic modelling of solubility in different experimental waters led to maximum values in the calcareous water for copper as well as antimony, where the solubility of copper was 30 % lower than for antimony. Due to the additional complexes found in the DOC-water of the Dachauer Moos copper has a significantly higher mobility. The effect is even more significant by applying EDTA-water. Mass balance of the column experiments show that copper is fundamentally less mobile (recovery 0-18 %) in contrast to antimony (recovery 85-99 %). Differences in the sorption behaviour were reflected in the retardation values, which subsequently distinguished almost three orders for both elements. Cumulatively, these results show that the sorption capacities for copper can not be achieved even after a total input of 201 mg Cu (Quaternary Gravel) by injection pulses over two years. However, sorption capacities can be attained with antimony after only 10.4 days (Tertiary Sand), after 11.4 days (Dogger-Sand) and after 1.5 years (Quaternary Gravel), respectively. Qualitatively, the results of copper can be described with a fast irreversible sorption kinetic, and antimony with a slow reversible one. Three mathematical models were applied to simulate the experimental data set. The observed Sb-breakthrough curves modelled quite well with the one-dimensional linear reaction model of CAMERON & KLUTE (1977) and the determination of corresponding dynamic reaction parameters. However, a satisfying fit could not be found for copper with this model in a buffered system for the two following reasons: 1.) The precipitation processes and 2.) the complex surface-active processes which were assumed next to the predominant sorption reactions. Therefore non-linear model approaches were employed for the fit. Initially, the observed Sb-curves were fitted using two-site Langmuir-isotherm first order kinetics, allowing for quantification of sorption capacities, -affinities and –rates. Applying three-site Langmuir-isotherm first order kinetics also includes precipitation processes. With all models, a satisfying fit of the desorption processes in the declining curve part emerged. However the sorption processes could still not be satisfactorily described. Experiments investigating the influence of both complexing agents, DOC and EDTA, on the migration behaviour of copper showed more or less a stoichiometric complexation of the heavy metal copper. With the stronger complexing agent EDTA at least twice as high remobilisation as with DOC could be achieved. The strongest EDTA-mediated remobilisation could be observed in the unbuffered sediments (49-50%), significantly lower values were attained in the buffered sediments with 17-26 %. Of the injected copper mass in unbuffered sediment 82 % could be recovered from Dogger-Sand, and 83 % from Quartz-Sand. A maximum of 55 % could be recovered from the buffered sediments. In order to support mobility data of copper and antimony sequential extractions of column beds were performed after the column experiments. As an essential result, it emerged that copper is accumulated increasingly in areas near the surface, while antimony is distributed in the whole profile. Therefore, copper in contrast to antimony is stable bound at neutral pH and is not transferred. As a consequence, a different behaviour of availability of both elements can be observed. The results of the column experiments indicate that copper is preferentially occluded at organic matter binding fractions as well as in the immobile aqua regia fraction. Antimony is mainly bound in the mobile and easy exchangeable fraction and in both the iron and manganese fraction. As this result allows immediate conclusions on the availability and transfer potential of heavy metals, it also permits estimations of the ecotoxicological efficacy of copper and antimony and the assessment of the endangering risk potential of the contaminated sediments.