The geochemical cycle of boron: Constraints from boron isotope partitioning experiments between mica and fluid   总被引：8，自引：0，他引：8  

Bernd Wunder  Anette Meixner  Rolf L. Romer  Richard Wirth  Wilhelm Heinrich 《Lithos》2005,84(3-4):206-216

The fractionation of boron isotopes between synthetic boromuscovite and fluid was experimentally determined at 3.0 GPa/500 °C and 3.0 GPa/700 °C. For near-neutral fluids Δ¹¹B_(mica-fluid) = δ¹¹B_(mica) − δ¹¹B_(fluid) is − 10.9 ± 1.3‰ at 500 °C, and − 6.5 ± 0.4‰ at 700 °C. This supports earlier assumptions that the main fractionation effect is due to the change from trigonal coordination of boron in neutral fluids to tetrahedrally coordinated boron in micas, clays and melts. The T-dependence of this effect is approximated by the equation Δ¹¹B_{(mica,clay,melt–neutral fluid)} = − 10.69 · (1000/T [K]) + 3.88; R² = 0.992, valid from 25 °C for fluid–clay up to about 1000 °C for fluid–silicate melt. Experiments at 0.4 GPa that used strongly basic fluids produced significantly lower fractionations with Δ¹¹B_{(mica–fluid)} of − 7.4 ± 1.0‰ at 400 °C, and − 4.8 ± 1.0‰ at 500 °C, showing the reduced fractionation effect when large amounts of boron in basic fluids are tetrahedrally coordinated. Field studies have shown that boron concentrations and ¹¹B/¹⁰B-ratios in volcanic arcs systematically decrease across the arc with increasing distance from the trench, thus reflecting the thermal structure of the subducting slab. Our experiments show that the boron isotopic signature in volcanic arcs probably results from continuous dehydration of micas along a distinct P–T range. Continuous slab dehydration and boron transport via fluid into the mantle wedge is responsible for the boron isotopic signature in volcanic arcs.  相似文献   

The impact of different spatial land cover data sets on the outputs of a hydrological model - a modelling exercise in the Ucker catchment, North-East Germany   总被引：1，自引：0，他引：1  

M. Wegehenkel  U. Heinrich  V. Dunger 《Physics and Chemistry of the Earth》2006,31(17):1075-1088

The spatial distribution of forests, meadows, arable land, water bodies and settlements in a catchment influences the spatial and temporal dynamics of evapotranspiration, surface runoff, soil moisture and ground water recharge. Four digital data sets from different sources were available for land cover distribution to be applied in a regional case study in the Ucker catchment with an area of about 2415 km². The first data set was obtained from the German digital topographic data set “Atkis” and the second one from the federal German biotope mapping procedure “Biotoptypenkartierung”. In addition, Corine land cover data and a land cover obtained from a supervised, multitemporal classification of three Landsat-TM5-scenes from the year 2000 were used in our study. These data sets differ in spatial resolution and in information content and this leads to different areal proportions of the main land cover classes forests, meadows, arable land, water bodies and settlements. This has to be considered as an uncertainty in the land cover data. In our case study, we analyzed how and to which extent this uncertainty influences the outputs of a hydrological catchment model such as evapotranspiration and discharge. For the time period 1996-2001, meteorological time series were obtained from four meteorological stations and five additional precipitation stations. Measured daily discharge rates were available from two gauges located in the catchment. In the different land cover data sets, the proportions of arable land ranged from 52.7% to 61.7% of the catchment area and for forests from 19.5% to 24.6%. These different proportions showed only minor impacts with small differences below ±10 mm y⁻¹ on the simulated annual rates of evapotranspiration and ground water recharge. In contrast, the simulated surface runoff rates showed a strong correlation to the amount of the settlement areas in the catchment. The highest proportion of settlements with 4.9% of the catchment area in comparison to the lowest proportion of 2.9% leads to an increase in the simulated surface runoff of 70%.  相似文献   

Numerical Simulation of the 1969 Portuguese Tsunami by a Finite Element Method   总被引：2，自引：0，他引：2  

Guesmia  M.  Heinrich  Ph.  Mariotti  C. 《Natural Hazards》1998,17(1):31-46

On 28 February 1969, the coasts of Portugal, Spain and Morocco were affected by sea waves generated by a submarine earthquake (Ms = 7.3) with its epicenter located off Portugal. The propagation of this tsunami has been simulated by a finite element numerical model solving the Boussinesq equations. These equations have been discretized using the finite element Galerkin method and a Crank–Nicholson scheme in time. The model is validated by investigating the propagation of a solitary wave over a flat bottom. The grid sizes for the 1969 event have been determined by one-dimensional tests offshore and in shallow water regions. The two-dimensional simulation of the 1969 tsunami is carried out using the hydraulic source calculated from the geophysical model of Okada and seismic parameters of Fukao. The modeled waves are compared with the recorded ones with respect to travel times, maximum amplitudes and periods of the signal. The comparison between Boussinesq and shallow-water models shows that the effects of frequency dispersion are minor. Good agreement is found for most of the studied gauges.  相似文献   

Chemical mass transfer modelling of ore-forming hydrothermal systems: current practise and problems     

C. A. Heinrich  J. L. Walshe  B. P. Harrold 《Ore Geology Reviews》1996,10(3-6)

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Derivatives of silicic acids as model compounds for silicates     

Edith Bertling  Heinrich C. Marsmann 《Physics and Chemistry of Minerals》1988,16(3):295-297

Silicon-29 chemical shifts of methyl, ethyl, chloro and trimethylsilyl derivatives of silicic acids are compared to those of silicic acid anions found in aqueous solutions. Although the chemical shifts of the silicate anions vary with pH and concentration, a good correlation is obtained for the chloro and alkoxi derivatives. The chemical shifts of the trimethylsilyl esters are of limited comparability to the data of the silicates only.  相似文献   

Experimental investigation of the kinetics of the reaction 1 tremolite+11 dolomite⇌8 forsterite+13 calcite+9 CO2+1 H2O     

Wilhelm Heinrich  Paul Metz  Matthias Gottschalk 《Contributions to Mineralogy and Petrology》1989,102(2):163-173

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Neuere veröffentlichungen     

Hartmut Heinrich 《Ocean Dynamics》1985,38(4):191-192

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Quantitative multi-element analysis of minerals, fluid and melt inclusions by laser-ablation inductively-coupled-plasma mass-spectrometry   总被引：7，自引：0，他引：7  

C.A. Heinrich  T. Pettke  M. Aigner-Torres  D. Günther  D. Bleiner  M. Guillong 《Geochimica et cosmochimica acta》2003,67(18):3473-3497

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Volcanic gases, black smokers, and the great oxidation event   总被引：3，自引：0，他引：3  

Heinrich D. Holland 《Geochimica et cosmochimica acta》2002,66(21):3811-3826

This paper proposes that gradual changes in the composition of volatiles that have been added to the atmosphere-ocean system are responsible for the Great Oxidation Event (G.O.E.) ca. 2.3 Ga. Before ca. 2.3 Ga, the composition of these volatiles was probably such that 20% of the carbon gases could be reduced to organic matter and all of the sulfur gases could be reduced to pyrite. Since 2.3 Ga, the composition of these volatiles has been such that 20% of the carbon gases could be reduced to organic matter, but only a fraction of the sulfur gases could be reduced to pyrite. This change led to the oxygenation of the atmosphere and to a large increase in the SO₄⁻² concentration of seawater. A considerable body of observational data supports these proposals.  相似文献   

Modelling of submarine landslides of rock and soil     

C. Mariotti  P. Heinrich 《国际地质力学数值与分析法杂志》1999,23(4):335-354

Landslides and their hydraulic effects are studied by numerical and experimental means. A two-dimensional model based on Navier–Stokes equations has been developed considering the sediments and water as a mixture. A Bingham law written in effective stress and an erosion–diffusion law at the water–sediment interface have been introduced into the model. Laboratory experiments consisting in the sliding of a block, a coarse gravel and a fine sand have been carried out. The results are compared with the numerical model. These experiments show the importance of sediment rheology and interstitial pressure in slide velocity and water wave generation. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献