ALBERT

Description: research

Description: research

Description: thesis

Description: research

Description: The cruise took place from 14.8.2005 (Akureyri) – 22.8.2005 (Akureyri) Research subject: ROV studies, mapping and sampling of the Tjörnes Offset (Storagrunn, Hollinn, Nafir) Chief Scientist: Prof. Dr. Colin W. Devey, IFM-GEOMAR, Kiel Number of Scientists: 10 Project: DFG De572/13-1 Fracture Zone

Description: Zur Unterstützung einer lithostratigraphischen Neugliederung der Rotliegend- Sedimente der Saar-Nahe-Senke wurden im Donnersberg-Raum zwei Bohrungen niedergebracht. Durch diese konnten Aufbau und Mächtigkeiten mehrerer lithostratigraphisch wichtiger Einheiten aus dem mittleren Teil der Nahe-Gruppe erfaßt werden.

Description: Abstract: Two 300 and 392 m deep holes where drilled to gain detailed Information on the Rotliegend-stratigraphy in the Donnersberg-area, which is part of the Permocarboniferous Saar-Nahe-Basin (SW-Germany). The results lead to a better knowledge of lithostratigraphic important units from the upper part of the Rotliegend (the Nahe-Group).

Description: research

Description: research

Description: Eine erste taxonomische Übersicht der bisher unbeschriebenen Taphoflora aus dem Unterrotliegend (Oberkarbon – Unterperm) von Niedermoschel bei Alsenz (Saar-Becken-Becken, SW-Deutschland) wird vorgestellt. Die Flora umfasst nach aktuellem Kenntnisstand folgende Taxa: Lepidostrobophyllum sp., Sphenophyllum thoniiMAHR, Sphenophyllum cf. oblongifolium (GERMAR & KAULFUSS) UNGER, Sphenophyllum spp. (unbest. Achsen), Annularia spinulosa STERNBERG, Annularia spicata (GUTBIER) SCHIMPER, Asterophyllites equisetiformis (SCHLOTHEIM ex STERNBERG) BRONGNIART, Asterophyllites longifolius (STERNBERG) BRONGNIART, cf. Palaeostachya sp., Calamites spp., Scolecopteris cf. arborescens (SCHLOTHEIM ex BRONGNIART) STUR, Pecopteris (Scolecopteris) cf. oreopteridia (SCHLOTHEIM) BRONGNIART, Pecopteris (Scolecopteris) candolleana BRONGNIART, Pecopteris (Scolecopteris) cf. densifolia GÖPPERT, Pecopteris monyi ZEILLER, Pecopteris spp. indet, Remia pinnatifida (GUTBIER) KNIGHT, Asterotheca sternbergii (GÖPPERT) STUR, Crossotheca sp., Autunia conferta (STERNBERG) KERP, Rhachiphyllum schenkii (HEYER) KERP, Dicksonites pluckenetii (SCHLOTHEIM ex STERNBERG) STERZEL, cf. Neurodontopteris auriculata (BRONGNIART) POTONIÉ, Cordaites sp., Coniferae indet., Gomphostrobus bifidus (GEINITZ) POTONIÉ, cf. Dicranophyllum gallicum GRAND´EURY sowie verschiedene, nicht näher bestimmbare karpologische Reste, Wurzeln und Problematika. Die Flora repräsentiert damit eine der diversesten, bisher bekannt gewordenen Floren aus dem Unteren Rotliegend des Saar-Nahe-Beckens. Basierend auf der taxonomischen Zusammensetzung und der autökologischen Interpretation der nachgewiesenen Taxa wird die Taphoflora als eine allochthone Vermischung mindestens zweier Vegetationseinheiten gedeutet: der ufernahen, feuchtigkeitsliebenden Vegetation (deren Reste die Taphoflora dominieren) und der Vegetation des eher trockeneren Hinterlandes.

Description: Abstract: A first taxonomic survey of the so far undescribed taphoflora from the Lower Rotliegend (Upper Carboniferous – Lower Permian) of Niedermoschel near Alsenz (Saar-Nahe basin, Southwest Germany) is presented. The following taxa have been identified so far: Lepidostrobophyllum sp., Sphenophyllum thoniiMAHR, Sphenophyllum cf. oblongifolium (GERMAR & KAULFUSS) UNGER, Sphenophyllum spp., Annularia spinulosa STERNBERG, Annularia spicata (GUTBIER) SCHIMPER, Asterophyllites equisetiformis (SCHLOTHEIM ex STERNBERG) BRONGNIART, Asterophyllites longifolius (STERNBERG) BRONGNIART , cf. Palaeostachya sp., Calamites spp., Scolecopteris cf. arborescens (SCHLOTHEIM ex BRONGNIART) STUR, Pecopteris (Scolecopteris) cf. oreopteridia (SCHLOTHEIM) BRONGNIART, Pecopteris (Scolecopteris) candolleana BRONGNIART, Pecopteris (Scolecopteris) cf. densifolia GÖPPERT, Pecopteris monyi ZEILLER, Pecopteris spp. indet, Remia pinnatifida (GUTBIER) KNIGHT, Asterotheca sternbergii (GÖPPERT) STUR, Crossotheca sp., Autunia conferta (STERNBERG) KERP, Rhachiphyllum schenkii (HEYER) KERP, Dicksonites pluckenetii (SCHLOTHEIM ex STERNBERG) STERZEL, cf. Neurodontopteris auriculata (BRONGNIART) POTONIÉ, Cordaites sp., Coniferae indet., Gomphostrobus bifidus (GEINITZ) POTONIÉ, cf. Dicranophyllum gallicum GRAND´EURY, as well as several unidentified carpological remains, roots and problematics. Thus this flora represents one of the most diverse (in terms of species richness) floras from the Lower Rotliegend of the Saar-Nahe basin. Based on the taxonomic composition and autecological interpretations of the taxa this flora is interpretated to represent an allochthonous mix of at least two different source vegetation types: i.e. from the vegetation of wet environments (dominating the assemblage) and the vegetation of the more dry Hinterland.

Description: 1. Einleitung 2. Geologie und Material 3. Die Flora 3.1. Lycopsiden 3.2. Sphenopsiden 3.2.1. Calamiten 3.2.2. Sphenophyllen 3.3. Farne 3.4. Pteridospermen 3.4.1. Peltaspermaceen 3.4.2. Callistophytaceen 3.4.3. Medullosaceen 3.5. Cordaiten 3.6. Koniferen 3.7. „Koniferophyten“ 3.8. Incertae sedis und Problematika 4. Taphonomie und Ökologie Schriften

Description: research

Description: Vertical phytoplankton distribution, temperol fluctuations and sedimentation rates were studied in the central Baltic Sea during the "Baltic Sea Patchiness Experiment 1986" (PEX'86). Vertical particle flux was measured with free sediment traps deployed at 30 and 60m depth for ten April/May 1986 within the PEX grid (20 x 40 nautical drifting days in miles). In the vicinity of one drifting trap water samples were collected in 10-12 depths down to 70m and vertical profiles of temperature, salinity, beam attenuation and light intensity were measured at three hour intervals. Water samples were analyzed for Chl.a, POC and PON content, dry weight and nutrients. Particulate parameters including the activity of 137 Cs were measured in trap samples. Suspended and sedimented particulates were counted under an inverted microscope. Precision and accuracy of the microscopical counts are discussed and confidence limits are calculated for different spec1es and applied counting schemes. Errors in all cases were smaller than the observed in situ variability. A general description of spring blooms in the central Baltic is given and the particular situation of spring 1986 is summarized. Within the station grid of PEX'86 an anticyclonic eddy was observed in which this study was conducted. Here the phytoplankton had reached peak concentrations and mass sedimentation of diatoms was about to start. The bloom was dominated by Thalassiosira levanderi and Chaetoceros spp. (lOµm size). Achnantes taeniata, Mesodinium rubrum, Gonyaulax catenata and an autotrophic Gymnodinium species (26-30µm) were also abundant. Horizontal patchiness and advection caused greater variability in the distribution of phytoplankton biomass blooms as well as temperature and attenuation during the first days than during the latter half of the investigation period. In four different areas within the PEX grid different developed independently. On still smaller time and space scales, the phytoplankton species composition also changed. The degree of patchiness was different for different species. General concepts explaining vertical distribution patterns of phytoplankton by physical and biological mechanisms are discussed. The species-specific distribution of selected diatoms, dinoflagellates and of the funktionally autotrophic ciliate M.rubrum are described. None of the species were homogeneously distributed although no vertical density stratification was observed. Whereas the diatoms and M.rubrum were present within the whole trophogenic layer, the dinoflagellates were only found in the upper 30m. The vertical distribution was different for concentrations were encountered each at species and different maximum depths respectively. Mechanisms affecting species-specific distribution of mobile and non-mobile phytoplankters in isopycnal layers are discussed in light of the particular situation of this study. Diurnal vertical migration is shown for two dinoflagellates and the phytociliate and triggering factors are discussed. All three species migrated upwards during the day and downwards at night. In its detail, however, the migratory behaviour differed between species and also within single populations. Different strategies of adaptation of phytoplankton to changing environmental conditions are suggested: Wheras diatoms adapt to fluctuations of the light climate by physiological adaptations, mobile organisms have the possibility to stay in an isolume layer. The significance of turbulence, of chainformation and of resting stages in the life cycles of phytoplankton is also evaluated. Trap deployments reveiled that only T.levanderi and Chaetoceros spp. sedimented. Their daily relative sedimentation rates (losses as % of standing stocks) increased over time and were species-specific (for T.levanderi max. 50%). Since part of the T.levanderi population was actively dividing (20% of the standing stock was found as paired cells) their suspended concentration decreased slower than that of Chaetoceros spp., although the daily sedimentation of the latter species was only about 30% of the standing stock. T.levanderi occured in chains in the water column but only single cells were found in sedimented material and paired cells were never found in the trap samples. Chaetoceros spores were rare in the water column and only sporadically collected by the sediment traps. The relative sedimentation rate of all other species was less than 5% per day. The settling velocity of the cells was estimated in different independent ways to be about 40-60m/d. This high sinking speed was attributed to aggregate formation. The results indicate that aggregate formation is not only species-specific but also differs between life-stages within one species. Variability of sedimentation rates on a timescale of hours was high, suggesting a diurnal pattern. Sedimentation did not change the vertical distribution patterns, indicating that cells were sinking with similar rates from all depths. The advantages of a Lagrangian sampling strategy (time series measurements 1n the vicinity of a free drifting buoy) for investigating phytoplankton development in time are evaluated and compared to a sampling at a moored station (Eulerian approach). In an environment that exhibits an intense patchiness even at spatial scales of lOOm, as encountered in this study, the influence of advection and patchiness on a time-series with a resolution of hours to days can not be neglected even if the Lagrangian approach is followed. Furthermore, in this study the variability of var1ous parameters measured in an Eulerian mode was not generally higher than that following the Lagrangian one, as one would have expected.

Description: In der vorliegenden Arbeit werden Untersuchungen zur Verteilung des elektrischen Widerstandes in den südlichen zentralen Anden vorgestellt. Gestützt auf eine breite Datenbasis konnten mit Hilfe von ein- und überwiegend zweidimensionalen Modellierungen für Daten der Magnetotellurik und der Erdmagnetischen Tiefensondierung Modelle zur Verteilung des elektrischen Widerstandes in der andinen Kruste erstellt werden. Sie erlauben qualitative und quantitative Aussagen zur elektrischen Struktur in der Kruste. Im Andensegment von 21° bis 25° S wurden für einzelne Meßpunkte und für fünf mehrere 100 km lange Profile aus Nord-Chile, Süd-Bolivien und Nordwest-Argentinien Leitfähigkeitsmodelle erarbeitet. Elektromagnetische Untersuchnungen werden an einem aktiven Kontinentalrand durch den ’Küsteneffekt’ stark erschwert. Um den Küsteneffekt zu berücksichtigen, wurde der Pazifische Ozean bei einem zweidimensionalen Modell für ein Profil von der Küste bis in die Hochkordillere als ’Randbedingung’ mitmodelliert. Aus drei zweidimensional modellierten W-E-Profilen konnte ein alle morphostrukturellen Einheiten der Anden querendes Gesamtmodell auf der Breite von ca. 21°30’ S abgeleitet werden. Folgende Hauptmerkmale werden im Modell von W nach E beobachtet: • Unterhalb der Küstenkordillere ist der Widerstand mit größer als 3000 ihn relativ hoch. In diesem Bereich wird aber parallel zur Streichrichtung ein guter Leiter in der oberen Kruste gefunden, der lamelliert vorliegen muß. • Der Widerstand der ’normalen’ andinen Kruste ist bis in große Tiefen mit Werten von 50 bis 200 Ωm relativ gering. • Eine große Leitfähigkeitsanomalie liegt unterhalb der Westkordillere in geringer Tiefe. Sie erreicht eine integrierte Leitfähigkeit von ca. 25000 S. • Eine weitere Leitfähigkeitsanomalie mit einer integrierten Leitfähigkeit von ca. 14000 S wird unterhalb des Altiplano in der unteren Kruste beobachtet. Sie steigt von W nach E in die obere Kruste auf, und die integrierte Leitfähigkeit nimmt im westlichen Teil der Ostkordillere deutlich zu. Die Anomalie endet abrupt östlich von La Quiaca (ca. 65°30’ W). Im Ostteil der Ostkordillere wird ein relativ hoher Widerstand (ca. 500 Ωm) von der Oberfläche bis in große Tiefen beobachtet. • Das Vorland der Anden ist durch eine gut leitende Bedeckung charakterisiert. Der Widerstand der Lithosphäre nimmt von W nach E auf mehr als 3000 Ωm zu. Als Ursache der erhöhten elektrischen Leitfähigkeit werden für den guten Leiter unter der Küstenkordillere Kluftsysteme angesehen, in denen das in der subduzierten Platte vorhandene freie Wasser aufsteigt. Der extrem gute Leiter unter der Westkordillere kann im Einklang mit seismischen und gravimetrischen Untersuchungen als partiell geschmolzene Kruste interpretiert werden. Die Leitfähigkeitsanomalie unterhalb des Altiplano und der westlichen Ostkordillere könnte hingegen teilweise durch massive Vererzungen aber auch durch tektonische Ursachen begründet sein, wie z.B. tiefreichende Auf- und Abschiebungshorizonte, in denen Fluide vorhanden sind.

Description: The purpose of the present work is the research regarding the distribution of the electrical resistivity in the southern part of Central Andes. Supported by a considerable database and with the aid of one- and two-dimensional modelling tools developed for magnetotelurics and deep geomagnetical sounding, several models of the distribution of the electrical resistivity in the Andean crust were developed. They allow qualitative and quantitative insights related to the electrical structure within it. In the Andean segment between 21° and 25° S, several isolated measure stations and five regional profiles each of several 100 km length were processed to establish conductivity models for northern Chile, southern Bolivia and northwestern Argentina. Within this research work the ’coast effect’ at an active plate margin has to be taken into account and for this purpose, the Pacific Ocean was included as a boundary condition in a 2D model extending from the Pacific up to the High Andes. Based on three 2D modelled E-W oriented profiles, a greater model could be derived that involves all the present morphostructural units at a latitude of 21° 30’ S. These models showed mainly that: • below the Coastal Cordillera, the resistivity ranging within 3000 Ωm is comparatively high. Nevertheless, in this region a strike-parallel oriented conductor in the upper crust could be identified, which has to be lamellated. • down to great depths the resistivity of the ’normal’ Andean crust is relatively small, having values of 50 to 200 Ωm. • beneath the Western Cordillera, a shallow conductivity anomaly reaches total conductance of about 25000 S. • another conductivity anomaly with a total conductance of ca. 14000 S has been identified in the lower crust below the Altiplano. This anomaly reaches shallower levels to the east, and in the western part of the Eastern Cordillera, the total conductance increases. Eastwards of La Quiaca (ca. 65° 30’ W) the anomaly terminates abruptly. In the eastern part of the Eastern Cordillera a relatively high resistivity from the surface down to great depths was observed. • the Andean foreland shows a cover with good conductivity values. Beneath, the resistivity increases downward up to more than 3000 ßm from W to E. As a cause of the increased conductivity beneath the Coastal Cordillera, joint systems could account for the uprise of free water generated during the subduction of the Nazca plate. The extremely good conductor below the Western Cordillera can be interpreted together with gravity and seismic evidences as a partial melted crust. Besides, the conductivity anomaly beneath the Altiplano and the western Eastern Cordillera can be explained partly through the existence of ore deposits but also in terms of thrust tectonics, where the detachment zones are characterized by the presence of fluids.

Description: thesis

Description: DFG, SUB Göttingen