Exploration drilling and reservoir model of the Platanares geothermal system, Honduras, Central America     

Fraser Goff  Sue J. Goff  Sharad Kelkar  Lisa Shevenell  Alfred H. Truesdell  John Musgrave  Heinz Rüfenacht  Wilmer Flores 《Journal of Volcanology and Geothermal Research》1991,45(1-2)

Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ≥ 1.5 km in a region of active tectonism devoid of Quaternary volcanism. Large, artesian water entries of 160 to 165°C geothermal fluid in two core holes at 625 to 644 m and 460 to 635 m depth have maximum flow rates of roughly 355 and 560 l/min, respectively, which are equivalent to power outputs of about 3.1 and 5.1 MW(thermal). Dilute, alkali-chloride reservoir fluids (TDS ≤ 1200 mg/kg) are produced from fractured Miocene andesite and Cretaceous to Eocene redbeds that are hydrothermally altered. Fracture permeabillity in producing horizons is locally greater than 1500 and bulk porosity is ≤ 6%. A simple, fracture-dominated, volume-impedance model assuming turbulent flow indicates that the calculated reservoir storage capacity of each flowing hole is approximately 9.7 × 10⁶ l/(kg cm⁻²), Tritium data indicate a mean residence time of 450 yr for water in the reservoir. Multiplying the natural fluid discharge rate by the mean residence time gives an estimated water volume of the Platanares system of ≥ 0.78 km³. Downward continuation of a 139°C/km “conductive” gradient at a depth of 400 m in a third core hole implies that the depth to a 225°C source reservoir (predicted from chemical geothermometers) is at least 1.5 km. Uranium-thorium disequilibrium ages on calcite veins at the surface and in the core holes indicate that the present Platanares hydrothermal system has been active for the last 0.25 m.y.  相似文献   

Das Relief des Mars' Versuch einer zusammenfassenden Übersicht     

Dr. Heinz -Peter Jöns 《International Journal of Earth Sciences》1985,74(1):109-121

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Isothermal compression of low-cordierite to 30 kbar (25° C)     

P. W. Mirwald  M. Malinowski  Heinz Schulz 《Physics and Chemistry of Minerals》1984,11(3):140-148

The compression of cordierite (Mg, Fe)₂Al₄Si₅O₁₈·n (H₂O, CO₂; Na⁺, K⁺) has been studied up to 30 kbar (25° C) by volumetric measurements with a piston cylinder apparatus and by X-ray measurements with a diamond-anvil cell. Natural cordierite of intermediate Mg-Fe composition and synthetic Mg-cordierite served as samples. Two discontinuities at 2.2±0.3 and 9.0±0.6 kbar which are correlated with very small volume changes (0.3?0.05%) have been found. The X-ray data indicate, however, no symmetry change of the crystal structure. The two discontinuities are interpreted as phase transitions. The two discontinuities establish three pressure dependent phases referred to as low-pressure (LP)-, first high-pressure (HP1)- and second high-pressure (HP2)-phase. The gross compressibility of cordierite decreases from 1.1 Mbar^?1 at low pressure to 0.7 Mbar^?1 at 30 kbar for the intermediate Mg-Fe cordierite, and to 0.4 Mbar^?1 for Mg-cordierite. Depending on the pressure transmitting medium used in the two different compression techniques, two kinds of compression behavior are observed for cordierite. The measurements with the piston cylinder apparatus where lead is used as quasihydrostatic pressure medium indicate normal compression properties. The X-ray data, however, obtained with the diamond anvil cell where a methanol-ethanol mixture provides hydrostatic pressure conditions yield, e.g. for the HP1-phase a dramatic decrease in compressibility to almost zero. IR-spectra from samples of augmenting experiments with methanol, deuteromethanol and D₂O as pressure media indicate that pressure media of which the molecule size is comparable with the dimensions of the cordierite channels may be incorporated in the structure. This suggests that under such hydrostatic conditions the compression of cordierite is modified by a structure internal component which is acting via the channel system.  相似文献   

Das Relief des Mars' Versuch einer zusammenfassenden Übersicht     

Dr. Heinz -Peter Jons 《International Journal of Earth Sciences》1986,75(2):461-493

The analysis of the martian relief leads to the conclusion that some of the most important relief elements are either concentrically or radially arranged with respect to a central structure and hence form aureoles. In this paper four different types of aureoles are identified and described:

1. impact aureoles (as result of extradynamics),
2. volcanic aureoeles (as result of lava flow through vents),
3. tectonic aureoles (as result of isostatic adjustment and/or settlement),
4. permafrost-related aureoles and mega-aureoles (as result of migration above thawing permafrost in areas with high relief).

The spatial distribution of these different types of aureoles indicates the predominant type of relief-forming dynamics in the area of their distribution (impact-related aureoles occur predominantly in the area of the Southern Uplands; volcanic, tectonic and permafrost-related aureoles in the area of large-scale updomings-TaNoVa, Elysiumand their volcanic provinces).  相似文献   

A deuterium-hydrogen fractionation mechanism in magnesium oxide     

Friedemann Freund  Heinz Wengeler  Reinhard Martens 《Geochimica et cosmochimica acta》1982,46(10):1821-1829

Water dissolved in a nominally anhydrous oxide like MgO forms not only OH^? ions, as is usually assumed, but also molecular H₂ and peroxy anions O₂^2?. The specific lattice site where this reaction occurs has been identified for the model-type MgO structure: it is the fully OH^? compensated cation vacancy. In partially deuterated synthetic MgO, molecular D₂ forms preferentially to H₂, by a factor of the order of 4. Three methods have been used to study this very large D/H fractionation experimentally: mass spectrometry, electron spin resonance and infrared spectroscopy. All give consistent results and confirm that internal D/H fractionation occurs and is a function of the temperature. Theoretically the D/H fractionation is explained by the lower zeropoint energy of D₂ with respect to H₂, amplified by secondary processes through which the molecular hydrogen species become mobilized and eventually lost via diffusion. The possible consequences of such internal D/H fractionation processes are indicated for the interpretation of water and hydrogen release patterns, with varying D/H ratios, from terrestrial and extraterrestrial samples.  相似文献   

Velocity constraints for the inner core inferred from long-period PKP amplitudes     

Heinz Häge 《Physics of the Earth and Planetary Interiors》1983,31(2):171-185

Long-period PKP amplitudes from 16 earthquakes in the distance range 110– 170° are compared with theoretical amplitudes which are derived from synthetic seismograms calculated for 56 systematic modifications of Earth model 1066B in the inner core. A suitable normalization procedure allows for the common representation of all observed amplitudes as a function of epicentral distance. Using the theoretical amplitude distributions it can be shown that the parameters of a regression line through the logarithmic and normalized amplitudes between 110 and 134° are related to the velocity and density jump at the inner-core boundary (ICB). The analysis shows that the dominant influence on the PKP amplitudes is the P-velocity jump which can be restricted to 0.64 ± 0.05 km s^?1. There exists a trade-off between the S-velocity jump and the density jump. Restricting the latter to the reasonable range 0–1.2 g cm^?3 the S-velocity jump at the ICB can be inferred to be 2.5–3.0 km s^?1. A rather strong S-velocity gradient below the ICB follows from the condition that the S-wave travel-time through the inner core agrees with that implied by free oscillation observations. This leads to central S-velocities between 3.81 and 4.15 km s^?1, assuming a parabolic velocity law.  相似文献   

Anthropogenic effects on sedimentary facies in Lake Baldeney,West Germany     

Peter Neumann-Mahlkau  Heinz Theo Niehaus 《Environmental Geology》1983,5(4):169-176

Analysis of well logs of Lake Baldeney, a reservoir of the Ruhr River, yields four facies factors that reflect the effect of anthropogenic processes on the sediment. First, the sedimentation rate is directly related to the subsidence caused by mining. The extent of the subsidence was such that the sediment load of the river could not compensate for the sinking of the lake bottom. Discharged sediment filled about one-fifth of the basin within 40 years. In certain areas of the basin the sedimentation rate reached up to 10 cm per year. Second, the grain-size distribution of the sediment was influenced by long-term and short-term events. During the subsidence, grain-size distribution remained relatively constant. The destruction of the Möhne River dam during World War II resulted in the presence of an extremely large grain size as evidenced by the so-calledMöhnelage. The filling of the lake after 1961 was accompanied by a continual increase in medium grain size. Third, until 1975, the mode of the lake sediment reflects the effect of mining in the vicinity of the lake. High coal content can be traced to its origin. The introduction of modern production processes, modernization of coal dressing, and hydraulic hauling is documented in the sediment. Finally, the heavy metal content of the sediment corresponds to the industrial development in the drainage area the Ruhr River. The accumulation of Cd reached an extreme concentration, exceeding the natural content by a thousand times. Variation in concentration reflects an increase in industrial production, as well as measures undertaken to restore water quality.  相似文献   

Flood Events in the Rhine Basin: Genesis,Influences and Mitigation   总被引：4，自引：1，他引：4  

Disse  Markus  Engel  Heinz 《Natural Hazards》2001,23(2-3):271-290

The paper analyses the hydrological regime of the Rhine catchment,the genesis of recent floods,and recommends some research and practical activities to mitigate flood damage. The catchment of the Rhine River can be divided into four main subcatchments: the alpine region with the Aare River as its main tributary and downstream the lower mountain regions of the tributaries Neckar, Main and Moselle. These four basins generate very different hydrographs. Due to the geographical conditions, the average discharge maximums shift from summer to winter downstream the Rhine. Moreover, the spatial and temporalprecipitation patterns of each river have a strong influence on the individual flood events. Some recent extraordinary floods are used to illustrate the parameters that have influenced these events.A strong relationship between recent climate change observationsand the occurrence of flood levels cannot be proven. However, the consequences of human interventions and the resulting changes to the river system (the Rhine and its tributaries) for the hydrograph can be quantified precisely.The influences of different land-use and climatic scenarios on flood conditions in the Rhine basin have not yet been separately identified. Thus, the Dutch-German project LAHoR was established. The primary aim of this project is to giveadvice for the ``Action Plan on Flood Defence' of the International Commission for the Protection of the Rhine (IKSR). In this plan a multidisciplinary approach to mitigating floods is suggested.It is anticipated that the plan willgenerate synergistic effects between flood prevention, water management, regional planning, agriculture, forestry and ecological demands.  相似文献   

Evidence for vertical ozone redistribution since 1967     

R. Furrer  W. Döhler  H. -J. Kirsch  P. Plessing  U. Görsdorf 《Surveys in Geophysics》1993,14(2):197-222

Long-term measurements of the ozone concentration in the vicinity of the city of Berlin have been performed with ground based Dobson spectrophotometers and balloon borne systems. The respective experiments cover the past 24 years. All data have been reevaluated and corrected towards uniform calibration standards, leading to the longest European data set of total column density, altitude-dependent ozone partial pressures and the corresponding temperatures. Smoothing algorithms unravel significant long-term trends.The analysis shows an increase of ozone concentration within the middle stratosphere (below 31 km height) as well as in the troposphere over the past 24 years. On the contrary, ongoing ozone depletion in the lower stratosphere has been found.The large scale vertical redistribution of atmospheric ozone in the troposphere and the lower stratosphere seems to be in agreement with model calculations and trend predictions that have their roots in changes of the chemical composition and the ozone photochemistry due to anthropogenically induced trace gas concentrations.Deutscher Wetterdienst, Meteorologisches Observatorium Potsdam.Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg.  相似文献   

Editorial     

Gerhard Furrer  Bernhard Wehrli  Heinz Gamsjäger 《Aquatic Sciences - Research Across Boundaries》1993,55(4):229-229

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