The protolith nature of diamondiferous metamorphic rocks of the Kokchetav Massif     

Vladislav Shatsky  Emil Jagoutz  Olga Kozmenko  Alexey Ragozin  Sergei Skuzovatov  Nikolai Sobolev 《《地质学报》英文版》2018,92(Z1):173-173

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Hydrostatic compression of galenobismutite (PbBi<Subscript>2</Subscript>S<Subscript>4</Subscript>): elastic properties and high-pressure crystal chemistry     

Lars A. Olsen  Tonci Balic-Zunic  Emil Makovicky  Angela Ullrich  Ronald Miletich 《Physics and Chemistry of Minerals》2007,34(7):467-475

A single-crystal sample of galenobismutite was subjected to hydrostatic pressures in the range of 0.0001 and 9 GPa at room temperature using the diamond-anvil cell technique. A series of X-ray diffraction intensities were collected at ten distinct pressures using a CCD equipped 4-circle diffractometer. The crystal structure was refined to R1(|F₀| > 4σ) values of approximately 0.05 at all pressures. By fitting a third-order Birch-Murnaghan equation of state to the unit-cell volumes V ₀ = 700.6(2) ų, K ₀ = 43.9(7) GPa and dK/dP = 6.9(3) could be determined for the lattice compression. Both types of cations in galenobismutite have stereochemically active lone electron pairs, which distort the cation polyhedra at room pressure. The cation eccentricities decrease at higher pressure but are still pronounced at 9 GPa. Galenobismutite is isotypic with CaFe₂O₄ (CF) but moves away from the idealised CF-type structure during compression. Instead of the two octahedral cation sites and one bi-capped trigonal-prismatic site, PbBi₂S₄ attains a new high-pressure structure characterised by one octahedral site and two mono-capped trigonal-prismatic sites. Analyses of the crystal structure at high pressure confirm the preference of Bi for the octahedral site and the smaller one of the two trigonal-prismatic sites.  相似文献   

Simulation of long-term transient density-dependent transport in groundwater     

Emil O. Frind 《Advances in water resources》1982,5(2):73-88

A numerical model for the economical simulation of long-term transient response in density-dependent transport problems is introduced. Although a classical Galerkin finite element approach is used, emphasis on optimum efficiency throughout the development results in a scheme that is found to be significantly less costly than comparable existing schemes. This advantage in efficiency increases the scope of simulation problems that can be handled within the constraints of a limited research budget. Some distinctive aspects are the elimination of static quantities in the fluid continuity equation, achieved by the introduction of equivalent freshwater head, and the elimination of numerical integration, achieved by the deliberate choice of linear elements. As a result of this choice, fluid velocities are discontinuous across the element boundaries. It is shown, however, that the solution obtained with discontinuous velocities approaches that obtained with continuous velocities as the grid is refined, and that the two types of solutions give essentially the same results when the elements are in the same size range. The model is applied to simulate the complete transient response for a well-known problem of seawater intrusion in a confined aquifer. The simulation is performed with both the constant dispersion coefficient used by previous researchers, and a more physically realistic velocity-dependent dispersion coefficient. Responses are found to be substantially different for the two types of coefficients, with the velocity-dependent dispersion coefficient producing much slower convergence to a state of dynamic equilibrium, and a much more pointed saltwater toe, which at the bottom of the aquifer tends to a sharp interface at equilibrium. Finally, it is shown by means of large-scale applications that the model is capable of efficiently simulating the long-term transient response in systems of practical significance.  相似文献   

Cenozoic alkali basaltic magmas of western Germany and their products of differentiation   总被引：11，自引：0，他引：11  

K. Hans Wedepohl  Emil Gohn  Gerald Hartmann 《Contributions to Mineralogy and Petrology》1994,115(3):253-278

Analytical data on major elements and 31 trace elements in olivine nephelinites, nepheline basanites, basanitic alkali olivine basalts and their differentiates (tephrites, hawaiites, mugearites, benmoreites, latites, phonolites and trachytes) from Hegau, Kaiserstuhl, Rhön, Hessian Depression, Vogelsberg, Westerwald, Siebengebirge, E Eifel and Hocheifel are evaluated. They were based on 400 samples with new or unpublished data on about one third of the rocks. The Sr–Nd isotopic compositions for 78 rocks are included. The alkali basaltic volcanism is caused by adiabatic decompression of asthenospheric mantle updomed to a minimum depth of 50 km in connection with the Alpine continent collision. The chemical compositions of the primary basaltic melts from the different areas are similar containing about one hundred-fold enrichment of highly incompatible elements relative to the primitive mantle from partial melting of depleted and secondarily enriched peridotite. The elements Cs, K, Pb and Ti are specifically depleted in the basalts partly because of phlogopite being residual at partial melting. The Tertiary alkali basalts range in Nd-isotopic composition from 0.51288 to 0.51273 and in Sr-isotopic ratios from 0.7032 to 0.7042. These ranges indicate mixtures of HIMU, depleted and enriched mantle components in the metasomatically altered peridotite source which resembles that of certain ocean islands. The Nd-Sr-isotopic compositions of the Quaternary E Eifel are close to bulk Earth ratios. East and W Eifel plots differ distinctly from the Tertiary Hocheifel which is geographically intermediate. This isotopic difference, beside specific K/Na ratios, is probably caused by separate metasomatic pulses that immediately preceded the respective periods of volcanism. The metasomatically altered mantle had partly primitive mantle signatures (Nb/Ta, Zr/Sm and Th/U ratios) and partly ocean island (or MORB) source properties (Rb/Cs). A MORB source can be excluded because of the low K/Rb and high Th/U ratios. A correlation of D with ⁸⁷Sr/⁸⁶Sr in amphibole and phlogopite and a slightly larger ¹⁸O than in MORB is conformable with a seawater and crustal impact on the source of alkali basalts. Slightly higher than average water concentrations in the source of certain primary basaltic melts (indicated by amphibole phenocrysts in their basalts) are required for differentiation of these basalts in magma chambers of the upper crust. Model calculations are presented to explain compositions of differentiates which range from about 60% to about 20% residual melt. The latter are represented by phonolites and trachytes. The Nd- and Sr-isotopic signatures of the majority of differentiates indicate contamination by a granitic partial melt from the wall rocks of magma chambers. Olivine nephelinite magma was the common source of contaminated differentiates.  相似文献   

Ein Versuch zur quantitativen Bestimmung der Faltungskraft     

Walther Emil Petrascheck Jr. 《International Journal of Earth Sciences》1950,38(2):133-138

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Machine Learning Can Assign Geologic Basin to Produced Water Samples Using Major Ion Geochemistry     

Shelton  Jenna L.  Jubb  Aaron M.  Saxe  Samuel W.  Attanasi  Emil D.  Milkov  Alexei V.  Engle  Mark  Freeman  Philip A.  Shaffer  Christopher A.  Blondes  Madalyn S. 《Natural Resources Research》2021,30(6):4147-4163

Natural Resources Research - Understanding the geochemistry of waters produced during petroleum extraction is essential to informing the best treatment and reuse options, which can potentially be...  相似文献   

The role of iron in tetrahedrite and tennantite determined by Rietveld refinement of neutron powder diffraction data     

Jens Wenzel Andreasen  Emil Makovicky  Bente Lebech  Sven Karup Møller 《Physics and Chemistry of Minerals》2008,35(8):447-454

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12?xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12?xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I $ \ifmmode\expandafter\bar\else\expandafter\=\fi{4} Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12−xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12−xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1−S1–S2 triangle. In tetrahedrite, this split is about 0.6 ?, in tennantite about 0.7 ?. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression with Fe concentration as the independent variable.  相似文献   

Significance of Unsaturated Flow and Seepage Faces in the Simulation of Steady-State Subsurface Flow   总被引：3，自引：0，他引：3  

Connie G. Romanoa  Emil O. Frind  David L. Rudolph 《Ground water》1999,37(4):625-632

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Interactions between wind and tidally induced currents in coastal and shelf basins     

Benjamin Jacob  Emil Vassilev Stanev 《Ocean Dynamics》2017,67(10):1263-1281

This paper addresses the impact of atmospheric variability on ocean circulation in tidal and non-tidal basins. The data are generated by an unstructured-grid numerical model resolving the dynamics in the coastal area, as well as in the straits connecting the North Sea and Baltic Sea. The model response to atmospheric forcing in different frequency intervals is quantified. The results demonstrate that the effects of the two mechanical drivers, tides and wind, are not additive, yet non-linear interactions play an important role. There is a tendency for tidally and wind-driven circulations to be coupled, in particular in the coastal areas and straits. High-frequency atmospheric variability tends to amplify the mean circulation and modify the exchange between the North and the Baltic Sea. The ocean response to different frequency ranges in the wind forcing is area-selective depending on specific local dynamics. The work done by wind on the oceanic circulation depends strongly upon whether the regional circulation is tidally or predominantly wind-driven. It has been demonstrated that the atmospheric variability affects the spring-neap variability very strongly.  相似文献   

Evidence of sea level drawdown at the end of the Messinian salinity crisis and seismic investigation of the Nahr Menashe unit in the northern Levant Basin,offshore Lebanon     

Kyrre Heldal Kartveit  Heidrun Breiset Ulsund  Stle Emil Johansen 《Basin Research》2019,31(5):827-840

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