IV. Stratigraphie Die fazielle Einstufung fossilführender Sedimente     

Hermann Schmidt  Karl Hoffmann  Erich Brand  Wolfgang Schott  Otto Seitz  Johannes Wolburg  Franz Bettenstaedt  F. E. Hecht  Hilmar Schumann  F. Heidorn 《International Journal of Earth Sciences》1948,35(2):175-178

Ohne Zusammenfassung  相似文献   

Atmospheric deposition of cadmium in the northeastern USA     

Stephen A. Norton  Tiffany Wilson  Michael Handley  Erich C. Osterberg 《Applied Geochemistry》2007

Lake sediment cores, dated by ²¹⁰Pb, were collected from Spectacle Pond (SP), Massachusetts, and Side Pistol Lake (SPL) and Sargent Mountain Pond (SMP), Maine, USA. SP is a kettle seepage lake in granitic sand and gravel. SMP is a drainage pond on granite with little soil in the small watershed. SPL is a drainage lake in granitic till. The three cores were analyzed for total Cd. For SP and SMP, maximum concentrations of 1.7 and 3.9 mg/kg, four and eight times background concentrations, respectively, occur in the late 1960s. Accumulation rates reach maximum values concurrently with concentration and are 0.054 and 0.016 μg/cm²/a, more than 10 times background. Concentration and accumulation rate age relationships in SMP and SP are similar for background values, timing and magnitude of increase to peak values, and the decrease nearly to background values since about 1975. The chemical response to decreased atmospheric deposition lags in SPL sediment. Kettle-like lakes more clearly indicate changes in atmospheric deposition than drainage lakes.  相似文献   

On the natural variability of the pre-industrial European climate     

Lennart Bengtsson  Kevin I. Hodges  Erich Roeckner  Renate Brokopf 《Climate Dynamics》2006,27(7-8):743-760

We suggest that climate variability in Europe for the “pre-industrial” period 1500–1900 is fundamentally a consequence of internal fluctuations of the climate system. This is because a model simulation, using fixed pre-industrial forcing, in several important aspects is consistent with recent observational reconstructions at high temporal resolution. This includes extreme warm and cold seasonal events as well as different measures of the decadal to multi-decadal variance. Significant trends of 50-year duration can be seen in the model simulation. While the global temperature is highly correlated with ENSO (El Nino- Southern Oscillation), European seasonal temperature is only weakly correlated with the global temperature broadly consistent with data from ERA-40 reanalyses. Seasonal temperature anomalies of the European land area are largely controlled by the position of the North Atlantic storm tracks. We believe the result is highly relevant for the interpretation of past observational records suggesting that the effect of external forcing appears to be of secondary importance. That variations in the solar irradiation could have been a credible cause of climate variations during the last centuries, as suggested in some previous studies, is presumably due to the fact that the models used in these studies may have underestimated the internal variability of the climate. The general interpretation from this study is that the past climate is just one of many possible realizations and thus in many respects not reproducible in its time evolution with a general circulation model but only reproducible in a statistical sense.  相似文献   

Lithology‐controlled evolution of stream bed sediment and basin‐scale sediment yields in adjacent mountain watersheds,Idaho, USA          下载免费PDF全文

Erich R. Mueller  M. Elliot Smith  John Pitlick 《地球表面变化过程与地形》2016,41(13):1869-1883

The composition, grain‐size, and flux of stream sediment evolve downstream in response to variations in basin‐scale sediment delivery, channel network structure, and diminution during transport. Here, we document downstream changes in lithology and grain size within two adjacent ~300 km² catchments in the northern Rocky Mountains, USA, which drain differing mixtures of soft and resistant rock types, and where measured sediment yields differ two‐fold. We use a simple erosion–abrasion mass balance model to predict the downstream evolution of sediment flux and composition using a Monte Carlo approach constrained by measured sediment flux. Results show that the downstream evolution of the bed sediment composition is predictably related to changes in underlying geology, influencing the proportion of sediment carried as bedload or suspended load. In the Big Wood basin, particle abrasion reduces the proportion of fine‐grained sedimentary and volcanic rocks, depressing bedload in favor of suspended load. Reduced bedload transport leads to stronger bed armoring, and coarse granitic rocks are concentrated in the stream bed. By contrast, in the North Fork Big Lost basin, bedload yields are three times higher, the stream bed is less armored, and bed sediment becomes dominated by durable quartzitic sandstones. For both basins, the geology‐based mass balance model can reproduce within ~5% root‐mean‐square error the composition of the bed substrate using realistic erosion and abrasion parameters. As bed sediment evolves downstream, bedload fluxes increase and decrease as a function of the abrasion parameter and the frequency and size of tributary junctions, while suspended load increases steadily. Variable erosion and abrasion rates produce conditions of variable bed‐material transport rates that are sensitive to the distribution of lithologies and channel network structure, and, provided sufficient diversity in bedrock geology, measurements of bed sediment composition allow for an assessment of sediment source areas and yield using a simple modeling approach. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Fossil sulphate-reducing bacteria in the Bleiberg lead-zinc deposit, Austria   总被引：1，自引：0，他引：1  

Henryk Kucha  Erich Schroll  Eugen F. Stumpfl 《Mineralium Deposita》2005,40(1):123-126

Polished ore samples from the world-class Bleiberg lead-zinc deposit in Austria were studied by Field Emission Scanning Electron Microscopy (FESEM) at magnifications in the range of 10⁵–10⁶. The zinc ore shows nano-sized sphalerite filaments and spherules which are morphologically similar to recent biofilms of sulphate-reducing bacteria. The activity of sulphate-reducing bacteria is suggested by a large ³⁴S difference of ~40 between coeval seawater sulphate (+16 ) and sulphide sulphur (< –25 ) in the Bleiberg ores, and by variable sulphur valences. Peloids of sphalerite, Zn-bearing calcite and pyrite have features typical of bacterial colonies. Combined with geological and mineralogical evidence, a significant role of bacteria during ore deposition at Bleiberg is likely.Eugen F. Stumpfl deceasedEditorial handling: B. Lehmann  相似文献   

Über die hydrographische Situation in der Deutschen Bucht während des Eiswinters 1962/1963     

Erich Goedecke 《Ocean Dynamics》1963,16(6):249-263

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Zur Bestimmung der Tonminerale mit dem Elektronennikroskop     

Erich Neuwirth 《Mineralogy and Petrology》1956,5(4):347-361

Inhalt Einleitung — Beschreibung der Untersuchungsmethoden — Ihre Anwendung bei der Bestimmung der wichtigsten Tonminerale.Mit 15 Textabbildungen  相似文献   

Neues über den Basalt von Kollnitz im Lavanttal Kärnten     

Erich Johann Zirkl  O. Braitsch  F. Hofer  Erentraud Kahler 《Mineralogy and Petrology》1962,8(1):96-139

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Analytic theory of Titan’s Schumann resonance: Constraints on ionospheric conductivity and buried water ocean     

Christian Béghin  Orélien Randriamboarison  Michel Hamelin  Erich Karkoschka  Christophe Sotin  Robert C. Whitten  Jean-Jacques Berthelier  Réjean Grard  Fernando Simões 《Icarus》2012,218(2):1028-1042

This study presents an approximate model for the atypical Schumann resonance in Titan’s atmosphere that accounts for the observations of electromagnetic waves and the measurements of atmospheric conductivity performed with the Huygens Atmospheric Structure and Permittivity, Wave and Altimetry (HASI–PWA) instrumentation during the descent of the Huygens Probe through Titan’s atmosphere in January 2005. After many years of thorough analyses of the collected data, several arguments enable us to claim that the Extremely Low Frequency (ELF) wave observed at around 36 Hz displays all the characteristics of the second harmonic of a Schumann resonance. On Earth, this phenomenon is well known to be triggered by lightning activity. Given the lack of evidence of any thunderstorm activity on Titan, we proposed in early works a model based on an alternative powering mechanism involving the electric current sheets induced in Titan’s ionosphere by the Saturn’s magnetospheric plasma flow. The present study is a further step in improving the initial model and corroborating our preliminary assessments. We first develop an analytic theory of the guided modes that appear to be the most suitable for sustaining Schumann resonances in Titan’s atmosphere. We then introduce the characteristics of the Huygens electric field measurements in the equations, in order to constrain the physical parameters of the resonating cavity. The latter is assumed to be made of different structures distributed between an upper boundary, presumably made of a succession of thin ionized layers of stratospheric aerosols spread up to 150 km and a lower quasi-perfect conductive surface hidden beneath the non-conductive ground. The inner reflecting boundary is proposed to be a buried water–ammonia ocean lying at a likely depth of 55–80 km below a dielectric icy crust. Such estimate is found to comply with models suggesting that the internal heat could be transferred upwards by thermal conduction of the crust, while convective processes cannot be ruled out.  相似文献   

Aqueous–solid solution thermodynamic model of U(VI) uptake in C–S–H phases     

Xavier Gaona  Dmitrii A. Kulik  Nathalie MacéErich Wieland 《Applied Geochemistry》2012

Reliable thermodynamic models assessing the interaction of radionuclides with cementitious materials are important in connection with long-term predictions of the safe disposal of radioactive waste in cement-based repositories. In this study, a geochemical model of U(VI) interaction with calcium silicate hydrates (C–S–H phases), the main component of hardened cement paste (HCP), has been developed. Uranium(VI) sorption isotherms on C–S–H phases of different Ca:Si ratios (C:S) and structural data from spectroscopic studies provided the indispensable set of experimental data required for the model development. This information suggested that U(VI) is neither adsorbed nor incorporated in the Ca–O octahedral layers of the C–S–H structure, but rather is located in the interlayer, similar to Ca²⁺ and other cations. With a view to the high recrystallisation rates and the cryptocrystalline ‘gel-like’ structure of the C–S–H phases, these observations indicated a U(VI) uptake driven by the formation of a solid solution.  相似文献