Trend detection in hydrological series: when series are negatively correlated     

Christine Rivard  Harold Vigneault 《水文研究》2009,23(19):2737-2743

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Reply to comment by M. D. Sacchi and T. J. Ulrych on 'Simultaneous time-domain deconvolution with application to the computation of receiver functions'     

Harold Gurrola  G. Eli Baker  J. Bernard Minster 《Geophysical Journal International》1996,127(1):255-255

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Behavior and effects of phosphorus in the system Na2O−K2O−Al2O3−SiO2−P2O5−H2O at 200 MPa(H2O)   总被引：1，自引：1，他引：1  

David London  George B. Morgan VI  Harold A. Babb  Jennifer L. Loomis 《Contributions to Mineralogy and Petrology》1993,113(4):450-465

The addition of phosphorus to H₂O-saturated and initially subaluminous haplogranitic (Qz–Ab–Or) compositions at 200 MPa(H₂O) promotes expansion of the liquidus field of quartz, a marked decrease of the solidus temperature, increased solubility limits of H₂O in melt at low phosphorus concentrations, and fractionation of melt out of the haplogranite plane (projected along an Or₂₈ isopleth) toward a peralkaline, silica-poor but quartz-saturated minimum composition. The partition coefficient for P₂O₅ between aqueous vapor and melt with an ASI (aluminum saturation index, mol Al/[mol Na+K])=1 is negligible (0.06), and consequently so are the effects of phosphorus on other melt-vapor relations involving major components. Phosphorus becomes more soluble in vapor, however, as the concentration of a NaPO₃ component increases via the fractionation of melt by crystallization of quartz and feldspar. The experimental results here corroborate existing concepts regarding the interaction of phosphorus with alkali aluminosilicate melt: phosphorus has an affinity for alkalis and Al, but not Si. Phosphorus is incorporated into alkali feldspars by the exchange component AlPSi_-2. For subaluminous compositions (ASI=1), the distribution coefficient of phosphorus between alkali feldspar and melt, D[P]Af/m, is 0.3. This value increases to D[P]Af/m=1.0 at a melt ASI value of 1.3. The increase in D[P]Af/m with ASI is expected from the fact that excess Al promotes the AlPSi_-2 exchange. With this experimental data, the P₂O₅ content of feldspars and whole rocks can reveal important facets of crystallization and phosphorus geochemistry in subaluminous to peraluminous granitic systems.  相似文献   

Gravity changes accompanying volcanic activity at Pacaya volcano, Guatemala     

Albert Eggers  Jeffery Krausse  Harold Rush  James Ward 《Journal of Volcanology and Geothermal Research》1976,1(3):229-236

Gravity changes of up to 1.2 ± 0.1 mgal (1 standard deviation) were measured at three points within 400 m of an active vent on Pacaya volcano, Guatemala during eleven days of January, 1975. For five continuous days gravity varied inversely with the average muzzle velocity of ejecta, the frequency of volcanic explosions, and the frequency of volcanic earthquakes. The gravity changes are most reasonably interpreted as the product of intravolcanic movements of magma with masses one to two orders of magnitude larger than any flow ever erupted from the volcano. However, elevation changes and/or combination of elevation and mass distribution changes could also have been an important factor in effecting the observed gravity variations. Because we lack elevation control on the gravity stations, we are unable to unequivocally conclude which factor or which combination of factors produced the gravity changes. The study indicates the possibility of gravity monitoring of hazardous volcanoes as a predictive tool, and as an added means for investigating the internal mechanism of volcanic eruptions.  相似文献   

Spectroscopic evidence for aqueous alteration products on the surfaces of low-albedo asteroids     

Michael A. Feierberg  Larry A. Lebofsky  Harold P. Larson 《Geochimica et cosmochimica acta》1981,45(6):971-981

High-resolution IR spectra (0.9–2.5 μm) and narrowband photometry (3.0–3.5 μm) are presented for asteroids 1 Ceres, 2 Pallas and 324 Bamberga. Laboratory experiments with hydrated minerals indicate that the 3 μm absorption feature observed on asteroids is largely due to interlayer water molecules in clay minerals, with a possible contribution from water molecules bound to salts. The depth of the 3 μm band as a function of 2.2 μm albedo is a useful measure of the amount of hydrated mineral present on these asteroids. 1 Ceres must consist mostly of a clay mineral like that in CM chondrites, with some contribution to the strength of the 3 μm band by hydrated salts. These salts, which are products of aqueous alteration, may also be responsible for Ceres' high albedo relative to other C-type asteroids. 2 Pallas must have a low abundance of hydrated minerals relative to 1 Ceres, with the bulk of its composition being spectrally featureless minerals such as the iron-free silicates in CM chondrules. 324 Bamberga probably contains clay minerals, but their abundance cannot be determined at present. The spectrum of Bamberga below 2.5 μm shows evidence for abundant magnetite, which can be a product of aqueous alteration. The presence of magnetite on Bamberga and possibly other C-type asteroids may be responsible for their low albedos. The spectra of C-type asteroids may be reconcilable with those of carbonaceous chondrites if the asteroids surfaces have undergone alteration by aqueous or other analogous processes.  相似文献   

Spectroscopic evidence for two achondrite parent bodies: asteroids 349 Dembowska and 4 Vesta     

Michael A. Feierberg  Harold P. Larson  Uwe Fink  Howard A. Smith 《Geochimica et cosmochimica acta》1980,44(3):513-524

A Fourier spectrometer was used to obtain IR spectra of asteroids 349 Dembowska and 4 Vesta (0.8–2.5μm; 25cm ^?1 resolution). The spectrum of Dembowska shows olivine and pyroxene (Fs_{24 ± 8}) with an olivine/pyroxene abundance ratio greater than 2, and possibly as high as 10. This is probably an unsampled achondritic composition, similar to the unique achondrite ALHA 77005. Similar olivine-rich compositions have also been proposed for the mantles of basaltic achondrite parent bodies. Dembowska's mineralogy therefore appears related in some way to the achondrites. but a direct link cannot as yet be made. Our IR observations of Vesta have more complete spectral coverage than those first obtained by Larson and Fink (1975b). Pyroxene (Fs_{50 ± 5}) and plagioclase feldspar are both seen, with a pyroxene/feldspar abundance ratio between 1.5 and 2.0. Vesta's mineralogy is consistent with a mixture of eucrites and howardites on its surface. Time-resolved observations over one-half of the rotation period show no spectral variations at the 2% level, indicating compositional homogeneity. Both 349 Dembowska and 4 Vesta can be considered as candidates for the parent bodies of igneous meteorites.  相似文献   

Potassium-argon dating of polyhalite in southeastern New Mexico     

Douglas G. Brookins  Joseph K. Register  Harold W. Krueger 《Geochimica et cosmochimica acta》1980,44(5):635-637

Polyhalite, K₂Ca₂Mg (SO₄)₄-2H₂O, is an important mineral in many evaporites. Although its use for K-Ar dating has never been investigated, our results indicate that it is a very useful mineral for dating events ranging from the time of potash mineralization to any younger events which may have affected the evaporite. Five K-Ar dates on pure polyhalite, including two from included material and from beds distorted by the formation of a rubble chimney, yield dates between 198 and 216 Myp, in good agreement with Rb-Sr dates and the diagenetic age of the potash deposits from the same rocks. Two polyhalites mixed with sylvite gave lower dates (154 and 174 Myr) which is to be expected because of radiogenic ⁴⁰Ar loss from the sylvite phase. One polyhalite, formed after the intrusion of a 31 Myr lamprophyre dike, yielded 21 Myr. Collectively our results indicate that pure polyhalite is satisfactory for K-Ar dating and may provide critical age information in studies of the geologic history of the evaporite sequences.  相似文献   

The territorial production complex as an industrial sub-system in the United States     

Gerald J. Karaska  Harold Moody 《Geoforum》1977,8(3):141-143

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Unbiased station grid for study of the kinetic energy balance of the atmosphere     

Harold C. Walker 《Pure and Applied Geophysics》1970,81(1):313-322

Summary For the past several years observational studies of the northern hemisphere kinetic energy balance and related subjects have been performed by the Planetary Circulation Project of the Massachusetts Institute of Technology. Numerous integrals required were recently evaluated directly from a five-year period of observations using a network of nearly 800 stations. The stations, however, are concentrated primarily over temperate latitude continents, and the data from maritime and tropical areas were comparatively sparse. The question then arises whether the results are representative. The problem discussed in this paper is to select a subset of more uniformly spaced stations and to recompute the zonal kinetic energy balance. This is accomplished and the results are presented herewith.The research reported in this paper was sponsored by the U.S. National Science Foundation under Grant No. GA-1310X.  相似文献   

Mobility of arsenic in a Bangladesh aquifer: Inferences from geochemical profiles, leaching data, and mineralogical characterization   总被引：3，自引：0，他引：3  

Christopher H. Swartz  Nicole Keon Blute  Borhan Badruzzman  Daniel Brabander  Jenny Jay  James Besancon  Harold F. Hemond 《Geochimica et cosmochimica acta》2004,68(22):4539-4557

Aquifer geochemistry was characterized at a field site in the Munshiganj district of Bangladesh where the groundwater is severely contaminated by As. Vertical profiles of aqueous and solid phase parameters were measured in a sandy deep aquifer (depth >150 m) below a thick confining clay (119 to 150 m), a sandy upper aquifer (3.5 to 119 m) above this confining layer, and a surficial clay layer (<3.5 m). In the deep aquifer and near the top of the upper aquifer, aqueous As levels are low (<10 μg/L), but aqueous As approaches a maximum of 640 μg/L at a depth of 30 to 40 m and falls to 58 μg/L near the base (107 m) of the upper aquifer. In contrast, solid phase As concentrations are uniformly low, rarely exceeding 2 μg/g in the two sandy aquifers and never exceeding 10 μg/g in the clay layers. Solid phase As is also similarly distributed among a variety of reservoirs in the deep and upper aquifer, including adsorbed As, As coprecipitated in solids leachable by mild acids and reductants, and As incorporated in silicates and other more recalcitrant phases. One notable difference among depths is that sorbed As loads, considered with respect to solid phase Fe extractable with 1 N HCl, 0.2 M oxalic acid, and a 0.5 M Ti(III)-citrate-EDTA solution, appear to be at capacity at depths where aqueous As is highest; this suggests that sorption limitations may, in part, explain the aqueous As depth profile at this site. Competition for sorption sites by silicate, phosphate, and carbonate oxyanions appear to sustain elevated aqueous As levels in the upper aquifer. Furthermore, geochemical profiles are consistent with the hypothesis that past or ongoing reductive dissolution of Fe(III) oxyhydroxides acts synergistically with competitive sorption to maintain elevated dissolved As levels in the upper aquifer. Microprobe data indicate substantial spatial comapping between As and Fe in both the upper and deep aquifer sediments, and microscopic observations reveal ubiquitous Fe coatings on most solid phases, including quartz, feldspars, and aluminosilicates. Extraction results and XRD analysis of density/magnetic separates suggest that these coatings may comprise predominantly Fe(II) and mixed valence Fe solids, although the presence of Fe(III) oxyhydroxides can not be ruled out. These data suggest As release may continue to be linked to dissolution processes targeting Fe, or Fe-rich, phases in these aquifers.  相似文献