Wilmsen M.,Senckenberg Naturhistorische Sammlungen Dresden |
Niebuhr B.,Senckenberg Naturhistorische Sammlungen Dresden |
Chellouche P.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Purner T.,Bayerisches Landesamt fur Umwelt
Facies | Year: 2010
The facies development and onlap pattern of the lower Danubian Cretaceous Group (Bavaria, southern Germany) have been evaluated based on detailed logging, subdivision, and correlation of four key sections using an integrated stratigraphic approach as well as litho-, bio-, and microfacies analyses. Contrary to statements in the literature, the transgressive onlap of the Regensburg Formation started in the Regensburg-Kelheim area already in the early Early Cenomanian Mantelliceras mantelli ammonite Zone and not in the Late Cenomanian. In the Early Cenomanian, nearshore glauconitic-bioclastic sandstones prevailed (Saal Member), followed by Middle to lower Upper Cenomanian mid-shelf siliceous carbonates intercalated with fine-sandy to silty marls (Bad Abbach Member). Starting in the mid-Late Cenomanian (Metoicoceras geslinianum ammonite Zone), a considerable deepening pulse during the Cenomanian-Turonian Boundary Event (CTBE) initiated the deposition of the deeper shelf silty marls of the Eibrunn Formation, which range into the early Early Turonian. During the CTBE transgression, also the proximal Bodenwöhrer Senke (ca. 40 km NE of Regensburg) was flooded, indicated by the onlap of the Regensburg Formation onto Variscan granites of the Bohemian Massif, overlain by a thin tongue of lowermost Turonian Eibrunn Formation. A detailed record of the positive δ13C excursion of the global Oceanic Anoxic Event (OAE) 2 has been retrieved from this shallow-water setting. An integrated approach of bio-, event-, carbon stable isotope and sequence stratigraphy was applied to correlate the sections and to decipher the dynamics of this overall transgressive depositional system. The Cenomanian successions show five prominent unconformities, which correlate with those being known from basins in Europe and elsewhere, indicating their eustatic origin. The rate of sea-level rise during the CTBE suggests glacio-eustasy as a driving mechanism for Late Cenomanian sea-level changes. The Regensburg and Eibrunn formations of the lower Danubian Cretaceous Group are highly diachronous lithostratigraphic units. Their regional distribution and northeast-directed onlap pattern onto the southwestern margin of the Bohemian Massif can readily be explained by the lateral movements of roughly coast-parallel (i.e., NW/SE-trending) facies belts of a graded shelf system transgressing on a northeastwardrising substrate. It took the Cenomanian coastline ca. 6 Ma to transgress from southwest of Regensburg to the topographically elevated granite cliffs southeast of Roding in the Bodenwöhrer Senke (=60 km distance). © 2010 Springer-Verlag.
Richardt N.,Senckenberg Naturhistorische Sammlungen Dresden |
Wilmsen M.,Senckenberg Naturhistorische Sammlungen Dresden |
Niebuhr B.,Bayerisches Landesamt fur Umwelt
Facies | Year: 2013
The Upper Cenomanian-Lower Turonian litho-stratigraphic units of the Danubian Cretaceous Group of the proximal Bodenwöhrer Senke (Regensburg, Eibrunn and Winzerberg formations, the latter consisting of a lower Reinhausen Member and an upper Knollensand Member), have been investigated with a focus on facies analysis and sequence stratigraphy. Analyses of litho-, bio-, and microfacies resulted in the recognition of 12 predominantly marine facies types for the Eibrunn and Winzerberg formations. Petrographic and paleontological properties as well as gradual transitions in the sections suggest that their depositional environment was a texturally graded, predominantly siliciclastic, storm-dominated shelf. The muddy-siliceous facies types FT 1-3 have been deposited below the storm wave-base in an outer shelf setting. Mid-shelf deposits are represented by fine- to medium-grained, bioturbated, partly glauconitic sandstones (FT 4-6). Coarse-grained, gravelly and/or shell-bearing sandstones (FT 7-10) developed in the inner shelf zone. Highly immature, arkosic coarse-grained sandstones and conglomerates (FT 11 and 12) characterize an incised, high-gradient braided river system. The Winzerberg Formation with its general coarsening- and thickening-upward trend reflects a regressive cycle culminating in a subaerial unconformity associated with a coarse-grained, gravelly unit of marine to fluvial origin known as the "Hornsand" which is demonstrably diachronous. The overlying Altenkreith Member of the Roding Formation signifies the onset of a new transgressive cycle in the early Middle Turonian. The sequence stratigraphic analysis suggests that the deposition of the Upper Cenomanian and Lower Turonian strata of the Bodenwöhrer Senke took place in a single cycle of third-order eustatic sea-level change between the major sequence boundaries SB Ce 5 (mid-Late Cenomanian) and SB Tu 1 (Early-Middle Turonian boundary interval). The southeastern part of the Bodenwöhrer Senke was flooded in the mid-Late Cenomanian (Praeactinocamax plenus transgression) and a second transgressive event occurred in the earliest Turonian. In the central and northwestern parts of the Bodenwöhrer Senke, however, the initial transgression occurred during the earliest Turonian, related to pre-transgression topography. Thus, the Regensburg and Eibrunn formations are increasingly condensed here and cannot be separated anymore. Following an earliest Turonian maximum flooding, the Lower Turonian Winzerberg Formation filled the available accommodation space, explaining its constant thickness of 35-40 m across the Bodenwöhrer Senke and excluding tectonic activity during this interval. Rapid sea-level fall at SB Tu 1 terminated this depositional sequence. This study shows that Late Cenomanian-Early Turonian deposition in the Bodenwöhrer Senke was governed by eustatic sea-level changes. © 2012 Springer-Verlag Berlin Heidelberg.
Vamvaka A.,Aristotle University of Thessaloniki |
Siebel W.,University of Tubingen |
Chen F.,Hefei University of Technology |
Rohrmuller J.,Bayerisches Landesamt fur Umwelt
International Journal of Earth Sciences | Year: 2014
Apatite fission-track (AFT) dating applied to uplifted Variscan basement blocks of the Bavarian Forest is employed to unravel the low-temperature history of this segment of the Bohemian Massif. Twenty samples were dated and confined track lengths of four samples were measured. Most samples define Cretaceous APT ages between 110 and 82 Ma (Albian to Campanian) and three samples give older ~148-140 Ma (Jurassic-Cretaceous boundary) ages. No discernible regional age variations exist between the areas north-east and south-west of the Pfahl shear zone, but >500 m post-Jurassic and post-Cretaceous vertical offsets along this and other faults can be inferred from elevation profile analyses. The AFT ages clearly postdate the Variscan exhumation history of the Bavarian Forest. Thermal modeling reveals that the ages are best explained by a slight reheating of the basement rocks to temperatures within the apatite partial annealing zone during the middle and late Jurassic and/or by late Cretaceous marine transgression causing burial heating, which affected marginal low-lying areas of the Bohemian Massif and the Bavarian Forest. Late Jurassic period was followed by enhanced cooling through the 120-60 °C temperature interval during the subsequent exhumation phase for which denudation rates of ~100 m myr-1 were calculated. On a regional scale, Jurassic-Cretaceous AFT ages are ubiquitous in marginal structural blocks of the Bohemian Massif and seem to reflect the exhumation of these zones more distinctly compared to central parts. © 2013 Springer-Verlag Berlin Heidelberg.
Auerswald K.,TU Munich |
Fiener P.,University of Augsburg |
Martin W.,Bayerisches Landesamt fur Umwelt |
Elhaus D.,Geologischer Dienst Nordrhein Westfalen
Catena | Year: 2014
The K factor of the Universal Soil Loss Equation is the most important measure of soil erodibility that was adopted in many erosion models. The K factor can be estimated from simple soil properties by a nomograph. Later, the classical K factor equation was published to assist the calculation of K. This equation, however, does not fully agree with the nomograph, which still has to be used in these deviating cases. Here we show for a large soil data set from Central Europe (approximately 20,000 soil analyses) that the equation fails in considerably more than 50% of all cases. The failure can be large and may amount to half of the K factor. To facilitate the K factor calculation, we developed a set of equations that fully emulates the nomograph and supersedes the cumbersome reading of the nomograph. © 2014 Elsevier B.V.
Korner W.,Bayerisches Landesamt fur Umwelt |
Walker G.,Emden Leer University of Applied Sciences
Gefahrstoffe Reinhaltung der Luft | Year: 2013
The various methods for sampling and sample processing of house dust for analysis of semi volatile organic compounds (SVOC) were summarized in the German guideline VDI 4300-8 "Measurement of indoor air pollution - sampling of house dust" in 2001. However, this guideline was withdrawn in 2012 because of an increasing number of cases in which analyses of house dust were performed inadequately and results misinterpretated although referring to this guideline. Some cases even ended up in wrong recommendations for rehabilitation of buildings. This paper summarizes the different applications of house dust analyses. Frequently occurring errors of sampling and interpretation of results are described.