Provenance of Cretaceous clastics in the Subhercynian Basin: constraints to exhumation of the Harz Mountains and timing of inversion tectonics in Central Europe

The Harz Mountains and the adjacent Subhercynian Cretaceous Basin figure as the most prominent surface representative for Late Cretaceous inversion structures in Central Europe. Facies, depositional architecture and provenance of the basin fill reflect mechanisms and timing of the exhumation of the Harz. From Hauterivian to Early Santonian there is no evidence for detrital input from the nearby Harz area. Sediments are mature quartzarenites derived from Paleozoic basement rocks and/or recycled Permian to Mesozoic sedimentary rocks. This situation changed drastically in Middle to Late Santonian when freshly exhumed and eroded Mesozoic sedimentary cover rocks of the Harz were delivered into the basin. Feldspar and lithoclasts reflect erosion of Triassic and, in places, Jurassic to Turonian strata. Apatite and garnet in heavy mineral spectra are derived from largely unweathered Lower Triassic Buntsandstein as indicated by apatite and garnet chemistry. In Early Campanian, Paleozoic lithoclasts indicate erosion cutting down into the basement of the Harz. Simultaneous strong decrease of feldspar, garnet and apatite suggest an almost complete removal of the 2–3 km thick Mesozoic cover of the Harz within only 2–4 Myr. This translates into an exhumation rate of approximately 1 mm/a consistent with apatite fission track data from granitoid rocks of the Harz Mountains.     

Numerical investigation of undrained cavity expansion in fine-grained soils

Based on the spherical cavity expansion (SCE) problem, Cudmani and Osinov (Can Geotech J 38:622–638, 2001), Osinov and Cudmani (Int J Numer Anal Method Geomech 25:473–495, 2001) developed a semi-empirical method of interpretation of CPT for coarse-grained soils (sand, gravel) using a hypoplastic constitutive model. Using a material-independent shape factor, the cone penetration resistance was related to the limit pressure required to expand a spherical cavity. The shape factor was observed to be a function of the soil state only, in particular the pressure-dependent relative density. This paper presents an analogous interpretation technique for CPT in fine-grained soils using the shape factor concept, Cavity Expansion approach, and a hypoplastic constitutive model. Relations for the shape factor and the limit pressure have been proposed based on the parameters affecting these quantities. A validation of the proposed interpretation technique with experimental results has also been performed.     

Magnetically Dominated Accretion Flows (MDAFS) and Jet Production in the Lowhard State

In this paper I propose that the inner part of a black hole accretion inflow (< 100 r_g) may enter a magnetically dominated, magnetosphere-like phase in which the strong, well-ordered fields play a more important role than weak, turbulent fields. In the low/hard state this flow is interior to the standard ADAF usually invoked to explain the observed hot, optically thin emission. Preliminary solutions for these new MDAFs are presented. Time-dependent X-ray and radio observations give considerable insight into these processes, and a new interpretation of the X-ray power spectrum (as arising from many disk radii) may be in order. While an evaporative ADAF model explains the noise power above 0.01 Hz, an inner MDAF is needed to explain the high-frequency cutoff near 1 Hz, the presence of a QPO, and the production of a jet. The MDAF scenario also is consistent with the phenomonological models presented at this meeting by several authors.     

Field comparison of passive sampling and biological approaches for measuring exposure to PAH and alkylphenols from offshore produced water discharges

Polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP) that are present in routine discharges of produced water (PW) from the offshore industry continue to cause concern. The suitability of biological methods and chemical based passive samplers to determine exposure to these compounds was tested by deploying them around an oil installation and at reference locations in the North Sea. PAH and AP were analysed either as parent compounds in passive samplers and mussel tissue or as metabolites in fish bile. Generally the pattern of exposure relative to proximity to the discharge was represented by mussels, SPMDs and fish for PAH. Fish and SPMDs showed good correlation for PAH accumulations, whereas some differences were apparent between mussels and SPMDs. POCIS was the only technique tested that could accurately measure the most abundant AP in PW. The advantages of biologically independent measures of exposure for inclusion in discharge monitoring studies are outlined.     

Noble gases in 18 Martian meteorites and angrite Northwest Africa 7812—Exposure ages,trapped gases,and a re‐evaluation of the evidence for solar cosmic ray‐produced neon in shergottites and other achondrites

We present noble gas data for 16 shergottites, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the shergottites fall in the 1–6 Ma range found in previous studies. Three depleted olivine‐phyric shergottites (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9–13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event. A Tissint glass sample contains Xe from the Martian atmosphere. Several samples show a remarkably low (²¹Ne/²²Ne)_cos ratio < 0.80, as previously observed in a many shergottites and in various other rare achondrites. This was explained by solar cosmic ray‐produced Ne (SCR Ne) in addition to the commonly found galactic cosmic ray‐produced Ne, implying very low preatmospheric shielding and ablation loss. We revisit this by comparing measured (²¹Ne/²²Ne)_cos ratios with predictions by cosmogenic nuclide production models. Indeed, several shergottites, acalpulcoites/lodranites, angrites (including NWA 7812), and the Brachina‐like meteorite LEW 88763 likely contain SCR Ne, as previously postulated for many of them. The SCR contribution may influence the calculation of exposure ages. One likely reason that SCR nuclides are predominantly detected in meteorites from rare classes is because they usually are analyzed for cosmogenic nuclides even if they had a very small (preatmospheric) mass and hence low ablation loss.     

Numerical modeling and inverse parameter estimation of the large-scale mass movement Gradenbach in Carinthia (Austria)

This paper deals with the inverse problem of using time-displacement monitoring data to determine the material parameters of a numerical model of a large-scale mass movement. A finite element model for simulating the mechanical behavior is presented for the Gradenbach landslide in Carinthia, Austria. Particular attention is paid to the calibration of the constitutive relationships, which represent a prerequisite for a realistic quantitative analysis. After a short introduction to the concept of model-parameter identification, this paper demonstrates how to apply the proposed model identification strategy to determine model parameters for the Gradenbach example. The impact of the amount of reference data available for the inverse model-parameter analysis is evaluated by means of artificial reference data. Subsequently, the numerical model is calibrated using field measurement data. The results obtained are presented, and the benefits and drawbacks of the proposed concept are evaluated.     

Fall,classification, and exposure history of the Mifflin L5 chondrite

The Mifflin meteorite fell on the night of April 14, 2010, in southwestern Wisconsin. A bright fireball was observed throughout a wide area of the midwestern United States. The petrography, mineral compositions, and oxygen isotope ratios indicate that the meteorite is a L5 chondrite fragmental breccia with light/dark structure. The meteorite shows a low shock stage of S2, although some shock‐melted veins are present. The U,Th‐He age is 0.7 Ga, and the K‐Ar age is 1.8 Ga, indicating that Mifflin might have been heated at the time of the 470 Ma L‐chondrite parent body breakup and that U, Th‐He, and K‐Ar ages were partially reset. The cosmogenic radionuclide data indicate that Mifflin was exposed to cosmic rays while its radius was 30–65 cm. Assuming this exposure geometry, a cosmic‐ray exposure age of 25 ± 3 Ma is calculated from cosmogenic noble gas concentrations. The low ²²Ne/²¹Ne ratio may, however, indicate a two‐stage exposure with a longer first‐stage exposure at high shielding. Mifflin is unusual in having a low radiogenic gas content combined with a low shock stage and no evidence of late stage annealing; this inconsistency remains unexplained.     

Effects of the invasive plant Lupinus polyphyllus on vertical accretion of fine sediment and nutrient availability in bars of the gravel-bed Paloma river

Floodplain vegetation is fundamental in fluvial systems, controlling river corridor geomorphology and ecology through a series of hydraulic, sedimentological, and biological processes. Changes caused by introduced plant species can thus result in shifts in river regime, succession trajectories and nutrient availability, affecting native biodiversity. The exotic bigleaf or marsh lupine Lupinus polyphyllus, introduced in Patagonia in the last decades, is aggressively invading fluvial corridors. It fills unoccupied ecological niches in southern Chilean rivers, due to its capacity for nitrogen fixation, its perennial habit, and high shoot density and leaf surface area.We investigated the effects of L. polyphyllus on vertical accretion of fine sediment, and soil carbon and nitrogen content, on gravel bars of the Paloma river, Chilean Patagonia, where lupine is believed to have been introduced in 1994. We sampled plot pairs with and without lupine, with each pair located at the same elevation above river stage, and plots distributed over the reach scale. We measured the thickness of the fine soil horizon, grain size distribution, and soil carbon and nitrogen content. We also compared aerial photographs to evaluate changes in spatial coverage of lupine along the study reach.Presence of lupine was strongly correlated with a thicker layer of finer sediment, in turn characterized by higher organic carbon, carbon to nitrogen ratio, and inorganic carbon content. Contrary to our expectations, we did not find any significant differences in total nitrogen. Aerial photographs did not reveal important differences in coverage between 2007 and 2010, but plant density appears to have increased between the two dates, and invaded gravel bars also appear to be more stable. Lupine dominance of otherwise sparsely vegetated gravel bars in Patagonian rivers appears to have greatest consequences on bar physical structure (increased rates of accretion of fines) and secondary repercussions on soil quality (increase in recalcitrant organic matter), with potential transient effects on nutrient availability (possible increased soil metabolism, followed by carbon mineralization and loss of lupine nitrogen subsidy).     

Biomarker responses in Atlantic cod (Gadus morhua) exposed to produced water from a North Sea oil field: laboratory and field assessments

Biological markers of produced water (PW) exposure were studied in Atlantic cod (Gadus morhua) in both laboratory and field experiments, using authentic PW from a North Sea oil field. In the laboratory study, the PW exposure yielded significantly elevated levels of metabolites of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs) in bile even at the lowest exposure dose (0.125% PW). Other biomarkers (hepatic CYP1A induction and DNA adduct formation) responded at 0.25% and 0.5% PW concentrations. In the field study, bile metabolite markers and hepatic CYP1A were clearly increased in fish caged close to the PW outfall. Induction of plasma vitellogenin was not found in laboratory or field exposures, suggesting that the levels of oestrogen agonists (such as APs) might not have been sufficient to elicit induction, under the present conditions. The applicability of the biomarkers for use in water column biomonitoring programs is discussed.