Zur Sedimentologie der oberoligozänen Seesedimente von Enspel/Westerwald: On the sedimentology of Late Oligocene lake sediments from Enspel/Westerwald

Vulkanoklastisch geprägte lakustrine Ablagerungen des oberoligozänen Enspel-Sees wurden anhand von Bohrkernen aus drei Kurzbohrungen sowie an Oberflächenproben sedimentologisch und petrographisch untersucht. In dem bearbeiteten ca. 24 m mächtigen Abschnitt der Seesedimente sind Ablagerungsbedingungen eines tiefen, mesotrophen bis eutrophen Sees dokumentiert. Unter meromiktischen Stillwasser-Verhältnissen mit geringer allochthoner Sedimentzufuhr kam es zur  Hintergrund-Sedimentation von Schwarzpeliten, die volumenmäßig stark zurücktreten gegenüber den gröberklastischen Ereignissedimenten. Die Anlieferung klastischen Materials erfolgte vorrangig punktuell durch Kleindeltas. Eine eindeutige Richtung ist nicht rekonstruierbar. Außerdem trugen pyroklastische Ereignisse zur Unterbrechung der tieflakustrinen meromiktischen Stillwasser-Sedimentation bei. Instabile Zwischenlagerung auf steileren(?) Reliefgradienten am Beckenhang führte zu episodischer Resedimentation, die zusammen mit fluviatil-deltaischen Schüttungsereignissen für kurzzeitige und zumindest teilweise Durchmischungen des Wasserkörpers sorgten. Saisonale Laminite (Warven) und faziell eigenständige Sedimente flacher Litoralzonen konnten bislang nicht belegt werden.Lacustrine, partly volcanoclastic deposits of Late Oligocene Lake Enspel (Rhenish Massif, Westerwald, Germany) were investigated with sedimentologic and petrographic techniques, us ing cores and surface samples. The stratigraphic section of 24 m length indicates sediments of a small, deep, mesotrophic to eutrophic lake. Background still-water sedimentation under meromiktic conditions with low rates of sediment supply resulted in minor amounts of black shale, which are subordinate to coarse clastic event deposits. Supply of coarse clastic material mainly occurred through small deltaic entry points. Preferred directions of sediment supply can not be detected yet. Both pyroclastic deposition and gravitational redeposition from steep marginal slopes of the lake basin, episodically interrupted deep water lacustrine background sedimentation. Collapse of oversteepened slopes and fluvial -deltaic runoff events lead to at least partial and short term mixis of the lacustrine water body. Saisonal laminites (varves) and littoral shallow water deposits have not yet been observed

X-ray CT analyses, models and numerical simulations : a comparison with petrophysical analyses in an experimental CO2 study

An essential part of the collaborative research project H2STORE (hydrogen to store), which is funded by the German government, was a comparison of various analytical methods for characterizing reservoir sandstones from different stratigraphic units. In this context, Permian, Triassic, and Tertiary reservoir sandstones were analysed. Rock core materials, provided by RWE Gasspeicher GmbH (Dortmund, Germany), GDF Suez E&P Deutschland GmbH (Lingen,Germany), E.ON Gas Storage GmbH (Essen,Germany) and RAG Rohöl-Aufsuchungs Aktiengesellschaft (Vienna, Austria), were processed by different laboratory techniques; thin sections were prepared, rock fragments were crushed and cubes of 1 cm edge length and plugs 3 to 5 cm in length with a Diameter of about 2.5 cm were sawn from macroscopic homogeneous cores. With this prepared sample material, polarized light microscopy and scanning electron microscopy coupled with image analyses, specific surface area measurements (after Brunauer, Emmet and Teller, 1938; BET), He-porosity and N2-permeability measurements and high resolution microcomputer tomography (µ-CT), which were used for numerical simulations, were applied. All These methods were practised on most of the same sample material, before and on selected Permian sandstones also after static CO2 experiments under reservoir conditions. A major concern in comparing the results of these methods is an appraisal of the reliability of the given porosity, permeability and mineral-specific reactive (inner) surface area data. The CO2 experiments modified the petrophysical as well as the mineralogical/geochemical rock properties. These changes are detectable by all applied analytical methods. Nevertheless, a major outcome of the high-resolution µ-CT analyses and following numerical data simulations was that quite similar data sets and data interpretations were maintained by the different petrophysical standard methods. Moreover, the µ-CT analyses are not only time saving, but also nondestructive. This is an important point if only minor sample material is available and a detailed comparison before and after the experimental tests on micrometre pore scale of specific rock features is envisaged

Examining Flow Paths In Bunter Sediments In Thuringian Basin

We would like to present a study on the Thuringian Basin, a large area in central Germany. Within this basin exist areas with very different interesting geo- and hydrological properties. We set up models and simulations for four subdomains within the basin, which describe different depositional environments - Eolian, Fluvial, Sandflat and Lacustrine. Researchers would like to investigate which paths is the water taking in the subsurface and how fast it is moving. The aim of this study is to gain knowledge about flow paths within these four model areas with regard to their architectural design. First simulation results suggest dependencies of flow paths and flow velocities due to different architectural elements (from the sequence of the subsurface layers) and characteristics such as the varying permeabilities

Die pal\ue4ogeographische Bedeutung der Konglomerate in den Losensteiner Schichten (Alb, N\uf6rdliche Kalkalpen)

Volume: 10Start Page: 155End Page: 17

Sedimentationsgeschichte und Pal\ue4otektonik der kalkalpinen Mittelkreide (Allg\ue4u, Tirol, Vorarlberg)

Volume: 8Start Page: 33End Page: 7

Latest Carboniferous to early Permian volcano-stratigraphic evolution in Central Europe: U–Pb CA–ID–TIMS ages of volcanic rocks in the Thuringian Forest Basin (Germany)

Mainly acidic Stephanian to early Permian volcanic rocks and intercalated sediments accumulated in the Thuringian Forest Basin (TFB) in central Germany to a total thickness of ca. 2000 m. This basin offers a wide range of biostratigraphic information. New high-precision U–Pb CA–ID–TIMS (chemical abrasion–isotope dilution–thermal ionization mass spectrometry) zircon data are obtained from volcanic rocks for the first time in the TFB. Pre-treatment of the zircons by chemical abrasion was important to get rid of severe Pb loss. The zircon ages of the investigated formations indicate that the total duration of the volcanic activity in the TFB was considerably shorter [ca. 4 Myr: from 300 Ma for the oldest formation (Möhrenbach) until ca. 296 Ma for the youngest volcanic-rock-bearing formation (Rotterode)] than suggested in previous studies (ca. 20 Myr; 295 Ma to 275 Ma). Consequently, the well-documented gap of the sedimentary record from the early Permian volcanic rocks up to the Illawarra geomagnetic reversal has to be extended to ca. 25 Myr from the previously proposed 5 Myr. The zircon ages of the investigated volcanic rocks allow the constraining of some intercalated fossiliferous horizons crucial for biostratigraphic correlation of latest Carboniferous–early Permian (Rotliegend) sections. The high-precision age data require a new interpretation of the evolution of the TFB but also offer the chance to obtain a more reliable comparison of the timing of the main magmatic activity across intramontane basins as well as to obtain links to the Standard Global Stratigraphic Scale.Technische Universität Bergakademie Freiberg (3135