Stream profile analysis of the Koralm Range (Eastern Alps)   总被引：1，自引：0，他引：1  

Gerd Rantitsch  Gerald Pischinger  Walter Kurz 《Swiss Journal of Geoscience》2009,102(1):31-41

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Response of a River Catchment to Climatic Change: Application of Expanded Downscaling to Northern Germany   总被引：1，自引：1，他引：0  

Dirk-Ingmar Müller-Wohlfeil  Gerd Bürger  Werner Lahmer 《Climatic change》2000,47(1-2):61-89

We used the technique of expanded General Circulation Model (GCM) downscalingto derive time series of daily weather for the analysis of potential climaticchange impact on a river catchment in Northern Germany. The derived timeseries was then fed into a spatially distributed hydrological model tosimulate various water balance components and river discharge. All componentsof this modelling approach are known to provide fairly accurate results undernormal (current) climatic conditions. Hydrological time series, theirstatistics and spatial patterns of various water balance components, resultingfrom a `business-as-usual' emission scenario, were analysed. The simulationresults showed that if everything apart from climate is held constant, asignificant increase in river discharge may be expected in the coming decadesas a consequence of increased rainfall amounts. Although the modellingapproach provides an operational way of performing watershed climate changeimpact studies, many uncertainties still have to be considered.  相似文献   

Kohlendioxid-Messungen in einem Durchfluß-Meßsystem mit einem neu entwickelten CO₂-Sensor am Beispiel eines Hartwassersees (Willersinnweiher, Ludwigshafen am Rhein)     

Johannes Schmid  Wolfram Oelßner  Gerd Schukraft 《Limnologica》2002,32(4):338-349

The concentrations of free dissolved carbon dioxide in lake water were measured with a newly developed CO₂ sensor, which was installed in a through-flow measurement system. The results of measurements demonstrate the CO₂ dynamics in lake Willersinnweiher. The CO₂ concentrations showed a correlation with the oxidation of CH₄ in the metalimnion and caused shifts in the carbonate system, thus affecting the autochthonous precipitation and dissolution of calcite.

From the results of measurement appears that the CO₂ sensor is capable of very exact measurements of dissolved free CO₂ in lake water. At the same time, the parameter is easily determined in the field without large expenditures.  相似文献   

P-T-X conditions of hydrothermal fluids and precipitation mechanism of stibnite-gold mineralization at the Wiluna lode-gold deposits,Western Australia: conventional and infrared microthermometric constraints   总被引：15，自引：0，他引：15  

Steffen?Gerd?HagemannEmail author  Volker?Lüders 《Mineralium Deposita》2003,38(8):936-952

The Wiluna lode-gold deposits are located in the Archean Wiluna greenstone belt, in the northern sector of the Norseman-Wiluna belt in the Yilgarn Craton of Western Australia. They are hosted in subgreenschist facies meta-basalts, and controlled by the Wiluna strike-slip fault system and associated shear veins and breccias. The 13 individual lode-gold deposits have produced around 115 t Au from 1901 to 1946 and 1986 to today. Historically, they also produced 38.3 t As and 3.5 t Sb. Gold formed in two stages: stage 1 gold-pyrite-arsenopyrite is finely disseminated in the wallrock and breccia fragments, whereas stage 2 gold-stibnite is located in massive shear veins and breccia matrix, as fracture-fill and in banded-colloform textured veins. Stibnite-gold orebodies only occur in some of the deposits (e.g., Moonlight and northern part of the West Lode) and also display a restricted vertical extent, being preserved only in the uppermost 200 m of stibnite-bearing lodes.Petrographic, conventional, and infrared microthermometric and laser-Raman analysis on stibnite-bearing quartz veins and breccias reveal that the antimony- and gold-rich hydrothermal fluid was of mixed H₂O-NaCl-CO₂±CH₄ type. Microthermometric measurements reveal maximum homogenization temperatures of 340 °C (average 290±25 °C), and a wide range of salinities between 0.2 and 23 eq. wt% NaCl. Aqueous-carbonic fluid inclusions contain variable X_CO2+CH4 (0.03 to 0.82), with the carbonic phase containing a maximum X_CH4 of 0.21.Combined petrographic and microthermometric evidence suggests that the fluid inclusion properties reflect fluid immiscibility of a low-salinity, medium X_CO2+CH4, homogeneous parent fluid at about 290 °C and pressures between 700 and 1,700 bar. Fluid immiscibility was triggered by cyclic pressure release during fault-zone movement. The decompression (adiabatic cooling) of the hydrothermal fluids shifted the ore fluid to lower temperatures, significantly reduced the degree of stibnite undersaturation, and caused stibnite to precipitate. The deposition of stibnite reduced the ore-fluid H₂S concentration, thereby destabilized gold bisulfide complexes in solution, and caused gold precipitation locally. This mechanism explains the intimate spatial association of stibnite and gold in quartz veins and breccias in the stibnite-gold orebodies at Wiluna.Editorial handling: B. Lehmann  相似文献   

Observations of persistent pattern in the temperature field related to the North Atlantic Current     

Dr. Eberhard Fahrbach  Gerd Wegner 《Ocean Dynamics》1987,40(4):141-155

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Die Ultrabasitmassive im Präkambrium des Staates Goiäs/Brasilien     

Höhst Quade  Gerd -Andreas Stache 《International Journal of Earth Sciences》1973,62(3):864-887

The Brazilian state of Goiás and parts of Mato Grosso represent the centre of the Brazilian shield, between the Guaporé craton in the west and the São Francisco craton in the east. In contrast to opinions before, early Precambrian gneisses and migmatites form only small parts of the shield complex whereas middle and late Precambrian sequences dominate. From tectonic position, an eugeosynclinal central zone can be distinguished accompanied by younger miogeosynclinal series to the east and west. The ultrabasic massifs of Goiás can be differentiated into following types:

1. alpinotype serpentinised dunites and peridotites,
2. gabbro-pyroxenite-peridotite associations,
3. pyroxenite-metagabbro associations,
4. dunite-pyroxenite-alkalisyenite associations,
5. lamprophyre dykes.

Nos. 1, 2 and 3 are of Precambrian age whereas 4 and 5 are surely of post-Devonian, probably of Cretaceous age and can be attributed to the phase of Paraná volcanism. The most economic types at the moment (Nos. 1 and 2) yield Ni, Cu and Co in lateritic enrichment, Cr, Pt and related elements as primary constituents. Latest, the types 4 and 5 cause special interest. From their association with carbonatites they are related to the Araxá complex of Minas Gerais and anticipate mineralizations of Nb, Ta, Ti and P.  相似文献   

Sea surface-water salinities observed during the Deutsches hydrographisches institut's North Sea radiological surveys 1969–1973     

Dipl.-Ozeanogr. Gerd Becker 《Ocean Dynamics》1973,26(6):247-250

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Generation of a consistent absolute phase-center correction model for GPS receiver and satellite antennas   总被引：26，自引：16，他引：10  

Ralf Schmid  Peter Steigenberger  Gerd Gendt  Maorong Ge  Markus Rothacher 《Journal of Geodesy》2007,81(12):781-798

The development and numerical values of the new absolute phase-center correction model for GPS receiver and satellite antennas, as adopted by the International GNSS (global navigation satellite systems) Service, are presented. Fixing absolute receiver antenna phase-center corrections to robot-based calibrations, the GeoForschungsZentrum Potsdam (GFZ) and the Technische Universität München reprocessed more than 10 years of GPS data in order to generate a consistent set of nadir-dependent phase-center variations (PCVs) and offsets in the z-direction pointing toward the Earth for all GPS satellites in orbit during that period. The agreement between the two solutions estimated by independent software packages is better than 1 mm for the PCVs and about 4 cm for the z-offsets. In addition, the long time-series facilitates the study of correlations of the satellite antenna corrections with several other parameters such as the global terrestrial scale or the orientation of the orbital planes with respect to the Sun. Finally, completely reprocessed GPS solutions using different phase-center correction models demonstrate the benefits from switching from relative to absolute antenna phase-center corrections. For example, tropospheric zenith delay biases between GPS and very long baseline interferometry (VLBI), as well as the drift of the terrestrial scale, are reduced and the GPS orbit consistency is improved.  相似文献   

On the radiation characteristics of Antarctic Sea Ice     

Gerd Wendler  Blake Moore  Dorte Dissing  John Kelley 《大气与海洋》2013,51(2):349-366

Abstract

Radiative measurements were carried out continuously during a cruise from Australia to Antarctica during austral summer 1995/96. Both shortwave and longwave radiative fluxes were measured. Some of the results are:

• The incoming solar radiation had a mean value of 217 W m^–2; this was a relatively weak value due to the large amount of fractional cloud cover observed. The sun was, for a large part of the trip, above the horizon for 24 hours a day.

• The reflectivity varied widely, not only as a function of sea‐ice concentration, but also as a function of ice type.

• Snow covered pack ice gave the highest albedo values (<70%), while flooded sea ice and thin ice reflected much less (<30%).

• For each sea‐ice type, short term observations showed a good relationship between albedo and ice concentration.

• The albedo increased with decreasing solar elevation.

• The net longwave radiation was negative (mean –27 W m–2); this small absolute value is due to a high amount of fractional cloud cover. There was a weak diurnal variation with a maximum loss (–33 W m^–2) in the early afternoon.

• On the average, the net radiation was positive for 17 hours, and negative for 7 hours a day. However, the duration of a positive balance depended strongly on the surface albedo.

• For the observed albedo values, modelling results showed that the net radiation was always positive when averaged over a day. The magnitude, however, depended strongly on the surface albedo, varying by more than the factor of three.

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Towards a Higher Comparability of Geothermometric Data obtained by Raman Spectroscopy of Carbonaceous Material. Part I: Evaluation of Biasing Factors   总被引：1，自引：0，他引：1  

Nils K. Lünsdorf  Istvan Dunkl  Burkhard C. Schmidt  Gerd Rantitsch  Hilmar von Eynatten 《Geostandards and Geoanalytical Research》2014,38(1):73-94

Raman spectroscopy of carbonaceous material (RSCM) is frequently used to determine metamorphic peak temperatures from the structural order of carbonaceous material enclosed in metasediments. This method provides a quick, robust and relatively cheap geothermometer. However, the comparability of the RSCM parameter is low as there are at least three major sources of biasing factors. These sources are the spectral curve‐fitting procedure, the sample characteristics itself and the experimental design including the used Raman system. To assess the impacts of the biasing factors on RSCM, a series of experiments was performed. The experiments showed that curve‐fitting is strongly influenced by individual operator‐bias and the degrees of freedom in the model, implying the need for a standardised curve‐fitting procedure. Due to the diversity of components (optics, light detection device, gratings, etc.) and their combinations within the Raman systems, different Raman instruments generally give differing results. Consequently, to estimate comparable metamorphic temperatures from RSCM data, every Raman instrument needs its own calibration. This demands a reference material series that covers the entire temperature calibration range. Although sample heterogeneity will still induce some variation, a reference material series combined with standardised curve‐fitting procedures will significantly increase the overall comparability of RSCM data from different laboratories.  相似文献