Mineral inclusions in fibrous diamonds: constraints on cratonic mantle refertilization and diamond formation   总被引：1，自引：0，他引：1  

Christine E. Miller  Maya Kopylova  Evan Smith 《Mineralogy and Petrology》2014,108(3):317-331

We analyzed mineral microinclusions in fibrous diamonds from the Wawa metaconglomerate (Superior craton) and Diavik kimberlites (Slave craton) and compared them with published compositions of large mineral inclusions in non-fibrous diamonds from these localities. The comparison, together with similar datasets available for Ekati and Koffiefontein kimberlites, suggest a general pattern of metasomatic alteration imposed on the ambient mantle by formation of fibrous diamond. Calcium and Fe enrichment of peridotitic garnet and pyroxenes and Fe enrichment of olivine associated with fibrous diamond-forming fluids contributes to refertilization of the cratonic mantle. Saline—carbonatitic—silicic fluid trapped by fibrous diamonds may represent one of the elusive agents of mantle refertilization. Calcium enrichment of peridotitic garnet and pyroxenes is expected in local mantle segments during fibrous diamond production, as Ca in the carbonatitic fluids is deposited into the surrounding mantle when oxidized carbon is reduced to diamond. Harzburgitic garnet evolves towards Ca-rich compositions even when it interacts with Ca-poor saline fluids. An unusual trend of Mg enrichment to Fo_95–98 is observed in some olivine inclusions in Wawa fibrous diamonds. The trend may result from the carbonatitic composition of the fluid that promotes crystallization of magnesian olivine and preferentially oxidizes the fayalite component. We propose a generic model of fibrous and non-fibrous diamond formation from carbonatitic fluids that explains enrichment of the mantle in mafic magmaphile and incompatible elements and accounts for locally metasomatized compositions of diamond inclusions.  相似文献   

Are we modelling impacts of climatic change properly?     

Slobodan P. Simonovic  Evan G. R. Davies 《水文研究》2006,20(2):431-433

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20-Year Anniversary     

Evan K. Nyer 《Ground Water Monitoring & Remediation》2006,26(2):36-46

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Plaintiff Lawyers and Environmental Litigation     

Evan Nyer  Joe Darby 《Ground Water Monitoring & Remediation》2005,25(4):30-43

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MICROBIOCLIMATE: ONE TOOL FOR ENVIRONMENTAL ASSESSMENT     

Steven A. Carlson  Evan Denney 《The Professional geographer》1978,30(1):42-47

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Treatment of Herbicides in Ground Water     

Evan K. Nyer 《Ground Water Monitoring & Remediation》1988,8(3):54-59

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Subhaloes in scale-free cosmologies     

Pascal J. Elahi  Robert J. Thacker  Lawrence M. Widrow  Evan Scannapieco 《Monthly notices of the Royal Astronomical Society》2009,395(4):1950-1962

We explore the dependence of the subhalo mass function on the spectral index n of the linear matter power spectrum using scale-free Einstein-de Sitter simulations with   n =−1  and −2.5. We carefully consider finite volume effects that may call into question previous simulations of   n < −2  power spectra. Subhaloes are found using a 6D friends-of-friends algorithm in all haloes originating from high-σ peaks. For   n =−1  , we find that the cumulative subhalo mass function is independent of the parameters used in the subhalo finding algorithm and is consistent with the subhalo mass function found in Λ cold dark matter (ΛCDM) simulations. In particular, the subhalo mass function is well fit by a power-law with an index of  α=−0.9  , that is the mass function has roughly equal mass in subhaloes per logarithmic interval in subhalo mass. Conversely, for   n =−2.5  , the algorithm parameters affect the subhalo mass function since subhaloes are more triaxial with less well-defined boundaries. We find that the index α is generally larger with  α≳−0.75  . We infer that although the subhalo mass function appears to be independent of n so long as   n ≳−2  , it begins to flatten as   n →−3  . Thus, the common practice of using  α≈−1.0  may greatly overestimate the number of subhaloes at the smallest scales in the CDM hierarchy.  相似文献   

Radio-continuum study of the Nearby sculptor group galaxies. Part 1: NGC 300 at λ=20 cm     

Timothy J. Galvin  Miroslav D. Filipović  Evan J. Crawford  Graeme Wong  Jeff L. Payne  Ain De Horta  Graeme L. White  Nick Tothill  Danica Drašković  Thomas G. Pannuti  Caleb K. Grimes  Benjamin J. Cahall  William C. Millar  Seppo Laine 《Astrophysics and Space Science》2012,340(1):133-142

A series of new radio-continuum (λ=20 cm) mosaic images focused on the NGC?300 galactic system were produced using archived observational data from the VLA and/or ATCA. These new images are both very sensitive (rms?=60 μJy) and feature high angular resolution (<10?″). The most prominent new feature is the galaxy’s extended radio-continuum emission, which does not match its optical appearance. Using these newly created images a number of previously unidentified discrete sources have been discovered. Furthermore, we demonstrate that a joint deconvolution approach to imaging this complete data-set is inferior when compared to an immerge approach.  相似文献   

Erratum to: Petrology and tectonic significance of seamounts within transitional crust east of Orphan Knoll,offshore eastern Canada     

Georgia Pe-Piper  Shawn Meredyk  Yuanyuan Zhang  David J. W. Piper  Evan Edinger 《Geo-Marine Letters》2014,34(6):567-568

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Static and dynamic conceptual model of a complexly fractured crystalline rock aquifer     

Evan Earnest  David Boutt  Larry Murdoch  William P. Clement 《水文研究》2019,33(20):2691-2710

A conceptual model of anisotropic and dynamic permeability is developed from hydrogeologic and hydromechanical characterization of a foliated, complexly fractured, crystalline rock aquifer at Gates Pond, Berlin, Massachusetts. Methods of investigation include aquifer‐pumping tests, long‐term hydrologic monitoring, fracture characterization, downhole heat‐pulse flow meter measurements, in situ extensometer testing, and earth tide analysis. A static conceptual model is developed from observations of depth‐dependent and anisotropic permeability that effectively compartmentalizes the aquifer as a function of foliation intensity. Superimposed on the static model is dynamic permeability as a function of hydraulic head in which transient bulk aquifer transmissivity is proportional to changes in hydraulic head due to hydromechanical coupling. The dynamic permeability concept is built on observations that fracture aperture changes as a function of hydraulic head, as measured during in situ extensometer testing of individual fractures, and observed changes in bulk aquifer transmissivity as determined from earth tides during seasonal changes in hydraulic head, with higher transmissivity during periods of high hydraulic head, and lower transmissivity during periods of relatively lower hydraulic head. A final conceptual model is presented that captures both the static and dynamic properties of the aquifer. The workflow presented here demonstrates development of a conceptual framework for building numerical models of complexly fractured, foliated, crystalline rock aquifers that includes both a static model to describe the spatial distribution of permeability as a function of fracture type and foliation intensity and a dynamic model that describes how hydromechanical coupling impacts permeability magnitude as a function of hydraulic head fluctuation. This model captures important geologic controls on permeability magnitude, anisotropy, and transience and therefor offers potentially more reliable history matching and forecasts of different water management strategies, such as resource evaluation, well placement, permeability prediction, and evaluating remediation strategies.  相似文献