Experimental Evaluation of Factors Affecting Temporal Variability of Water Samples Obtained from Long-Screened Wells   总被引：4，自引：0，他引：4  

Thomas E. Reilly  Denis R. LeBlanc 《Ground water》1998,36(4):566-576

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Quantifying the Effects of Well Development in Unconsolidated Material     

Gilles Wendling  Robert P. Chapuis  Denis E. Gill 《Ground water》1997,35(3):387-393

A fully instrumented physical model was designed and built to reproduce development by surging and monitor its effects during surging and after development. The model simulates a horizontal layer in a confined aquifer with control of vertical overburden pressure. An automatic apparatus produced development by surging in successive phases up to 24 hours. Aquifer tests in steady-state conditions were performed between successive phases. The paper reports the main results of three experiments performed with Johnson screens 200 mm in diameter; they had slot sizes between the D₅₄ and D₇₀ of the aquifer soil. This soil was placed under controlled conditions, and initial homogeneity was obtained as confirmed by initial control tests. Pore pressures (and thus hydraulic heads) were continuously monitored during development phases and aquifer tests by 22 electronic piezometers at distances between 0 and 1 m from the screen. These piezometers measured water pressures every 0.1 s when required. Solid particles passing through the screen were recovered to study the solid yield and the gradation of particles. Positive and negative values of local gradients reached values up to 400 close to the screen at the beginning of development and decreased with time of development. These high values produced high seepage forces displacing particles in the aquifer. The well yield was increased by a factor of 6 after development. These model test results confirmed empirical criteria on entrance velocity, internal stability criteria, and field values of "sand" production by development. In addition, they enabled a quantification of skin effects to be considered in interpreting an aquifer test.  相似文献   

Automated Calibration of a Contaminant Transport Model for a Shallow Sand Aquifer     

K. John Holmes  Wen-sen Chu  Denis R. Erickson 《Ground water》1989,27(4):501-508

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Book review     

G. Leigh Anderson  Denis Marcotte 《Mathematical Geosciences》1986,18(5):511-515

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Petrogenesis of orthopyroxene-magnetite-ilmenite intergrowths from an ultramafic layer     

Denis Daval 《Contributions to Mineralogy and Petrology》1987,95(3):301-310

A new occurrence of myrmekitic orthopyroxene-magnetite-ilmenite intergrowth from a thin ultramafic layer within a heterogeneous noritic rock from the Frederiksdal area, South Greenland, was investigated chemically and texturally. Compositionally, the intergrown ilmenite and orthopyroxene show the lowest recorded MgO content from pyroxene-oxide mineral intergrowths. The magnetite-ilmenite intergrowth has skeletal morphology, consisting of sets of thinly tabular plates parallel to the (111) planes of the spinel structure. The orthopyroxene-oxide intergrowth is considered to be the result of a simultaneous magmatic crystallization, that of the oxide minerals being faster.  相似文献   

Fission-track dating of glass inclusions in volcanic quartz     

Denis Vincent  Roberto Clocchiatti  Yves Langevin 《Earth and Planetary Science Letters》1984,71(2):340-348

We have extended fission-track dating techniques to volcanic pyroclastic rocks, using quartz-bearing uranium-rich glass inclusions. We use both the glass itself and the surrounding quartz as track detectors, the latter having a much higher resetting temperature. We can thus derive the age of the last low-temperature thermal event, as well as that of the most recent deposition of quartz on the walls of the inclusions. This method has been applied to a Sardinian sample and to a Moroccan Precambrian sample.  相似文献   

Acceptance of the 2002 Distinguished Service Award     

Denis M. Shaw 《Geochimica et cosmochimica acta》2003,67(13):2319

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Seismological constraints on the crustal structure beneath the Zagros Mountain belt (Iran)   总被引：5，自引：0，他引：5  

Denis Hatzfeld  Mohammad Tatar  Keith Priestley  Mohsen Ghafory-Ashtiany 《Geophysical Journal International》2003,155(2):403-410

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Numerical modelling of the Storfjorden (Svalbard) polynya development due to wind stress: role of the sea ice rheology and damping forces     

Denis Zyryanov  Jörg Haarpaintner  Reinert Korsnes 《Polar research》2003,22(2):235-245

Remote sensing of the ice cover in Storfjorden (Svalbard) revealed the persistence and evolution of latent heat polynyas during the winter of 1997/98. Latent heat polynyas open mechanically under wind stress or ocean currents that transport the ice cover away. In the present work we used mathematical modelling to simulate the Storfjorden polynya size and geometry caused by wind stress, measured at the meteorological station on the island of Hopen in winter 1997/98. The dependence of the polynya outlines on the wind velocity is presented. Two approaches were used: quasi-static and dynamic. Quasi-static simulations are based on a time-independent, linear ice stress-strain relationship valid for the low strain rates only. Time dependence of the ice cover fracture is joined with stress-strain nonlinearity caused by ice delayed-elastic recovery and viscosity. Results are compared to satellite observations from the synthetic aperture radar (SAR) of ERS-2. The simulation results show that a northern wind opens a larger polynya (ca. 30%) than does a north-eastern wind with the same speed. The results also indicate that the bathymetry and geometry of the fjord might have a stronger influence on the polynya opening and development than the location of individual islands and reefs.  相似文献   

Datation Ar/Ar des leucogranites sous couverture du complexe plutonique de Charroux–Civray (Vienne)Ar/Ar dating of leucogranites in the sediment-covered Charroux–Civray complex (Vienne)     

Paul Alexandre  Christian Le Carlier de Veslud  Michel Cuney  Gilles Ruffet  Denis Virlogeux  Alain Cheilletz 《Comptes Rendus Geoscience》2002,334(16)

⁴⁰Ar/³⁹Ar dating on muscovites, performed on leucogranitic intrusions of Charroux–Civray plutonic complex, points out the existence of two peraluminous magmatic activities, whose equivalents are known in the Limousin: (1) garnet-bearing leucogranitic veins at ca. 340 Ma; (2) a specialised leucogranite associated with W ± Sn deposits at ca 310 Ma. However, available ⁴⁰Ar/³⁹Ar data do not allow us to provide further data concerning the age and the geometry at depth of a large leucogranitic body identified by geophysics. To cite this article: P. Alexandre et al., C. R. Geoscience 334 (2002) 1141–1148.  相似文献