Use of micro-XRF chemical analysis for mapping volcanogenic massive sulfide related hydrothermal alteration: Application to the subaqueous felsic dome-flow complex of the Cap d'Ours section,Glenwood rhyolite,Rouyn-Noranda,Québec,Canada     

Dominique Genna  Damien Gaboury  Lyndsay Moore  Wulf U. Mueller 《Journal of Geochemical Exploration》2011

A new analytical method using micro-X-ray fluorescence (XRF) is presented for the in situ analysis of major elements in rock samples. This approach has allowed for a separate study of hydrothermal alteration of matrix versus fragments in volcaniclastic material (i.e. flow breccia). This is particularly important for volcanogenic massive sulfide (VMS) exploration in subaqueous felsic dome-flow complexes, where brecciated facies are omnipresent and the imprint of hydrothermal alteration is typically heterogeneous. In this study, eleven elements are measured with a 1.7 by 1.3 mm window considered to be representative of each sample, based on replicate analyses. An average is calculated for the analyzed window and yields a nearly complete analysis with the exception of loss of ignition (LOI). Micro-XRF data were validated using whole rock XRF analyses performed on the same sample block. The application of this chemical method has been tested successfully on thin sections from the Cap d'Ours section of the Glenwood rhyolite in the Rouyn-Noranda region of Québec, Canada. With 58 samples spaced at approximately 50 m intervals, two styles of alteration zoning were recognized: (1) a lateral and concordant zoning expressed by vent-proximal silicification in the west grading toward vent-distal chlorite–sericite alteration to the east, and (2) vertical and discordant zoning expressed by stronger sericitization in the upper part of later volcanic quartz- and feldspar-phyric endogenous lobes. The former is typical of cooling induced by seawater interaction at the lava–water interface at temperatures greater than 400 °C, whereas the latter is related to lower temperature (< 300 °C) hydrothermal mineralization associated with endogenous lobe emplacement within the volcanic pile. The presented results clearly demonstrate the potential use of the micro-XRF data for characterizing weak to intense hydrothermal alteration in highly fragmented volcanic rocks.  相似文献   

Trophic status of earthen ponds used for semi-intensive shrimp (Litopenaeus stylirostris, Stimpson, 1874) farming in New Caledonia (Pacific Ocean)     

Pusceddu A  Della Patrona L  Beliaeff B 《Marine environmental research》2011,72(4):160-171

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Trophic ecology of mullets during their spring migration in a European saltmarsh: A stable isotope study     

Benoit Lebreton  Pierre Richard  Emmanuel P. Parlier  Gaël Guillou  Grard F. Blanchard 《Estuarine, Coastal and Shelf Science》2011,91(4):106

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Preliminary results From a partial LRTAP model based on an existing meteorological forecast model     

J. Pudykiewicz  R. Benoit  A. Staniforth 《大气与海洋》2013,51(3):267-303

Abstract

An existing state‐of‐the‐art regional meteorological model is coupled through appropriate constituent mass conservation equations to model the long‐range transport of atmospheric pollutants (LRTAP) under restrictive constraints on atmospheric chemistry and deposition. Particular emphasis is given to the importance of a good representation of turbulence and other sub grid‐scale processes in the planetary boundary layer (PBL), both in the formulation and in the interpretation of the results. The regional meteorological model provides not only forecasts of wind velocity and temperature, but also vertical diffusion profiles consistent with the evolution of its PBL. The transport in the LRTAP model is handled by computationally stable algorithms such that the time step may be chosen on the basis of accuracy rather than stability, and the chemistry is described by a simple four‐species model of the oxidation of sulphur dioxide and nitrogen dioxide. Results are presented of a sample 48‐h summer simulation over central and eastern North America, using real meteorological data and time‐averaged emission inventory data; parameters of the integration include a one‐hour time step, a horizontal resolution of 100 km and 15 variably spaced vertical levels, 10 of which are contained in the lower one third of the atmosphere. It is argued that despite the simplicity of the chemistry, the results are qualitatively realistic and the high impact of the PBL processes on LRTAP is evident. For this particular simulation, it is interesting to note the existence of a region over Nova Scotia where the deposition of sulphates is significantly greater than that which could be expected from local sources. This is interpreted as being due to the confluence of two flows that pass over two different centres of high emission ofSC>2, andas being evidence of the model's ability to qualitatively model LRTAP.  相似文献   

Thermal Conductivity of Argillaceous Rocks: Determination Methodology Using In Situ Heating Tests   总被引：1，自引：1，他引：0  

Benoit Garitte  Antonio Gens  Jean Vaunat  Gilles Armand 《Rock Mechanics and Rock Engineering》2014,47(1):111-129

This study focuses on the characterisation of thermal conductivity for three potential host rocks for radioactive waste disposal. First, the heat conduction process is reviewed on the basis of an analytical solution and key aspects related to anisotropic conduction are discussed. Then the existing information on the three rocks is summarised and a broad uncertainty range of thermal conductivity is estimated based on the mineralogical composition. Procedures to backanalyse the thermal conductivity on the basis of in situ heating tests are assessed and a methodology is put forward. Finally, this methodology is used to estimate the impact of experimental uncertainties and applied to the four in situ heating tests. In the three potential host rocks, a clear influence of the bedding planes was identified and anisotropic heat conduction was shown to be necessary to interpret the observed temperature field. Experimental uncertainties were also shown to induce a larger uncertainty on the anisotropy ratio than on the equivalent thermal conductivity defined as the geometric mean of the thermal conductivity in the three principal directions.  相似文献   

Modified Newtonian dynamics in the Milky Way     

Benoit Famaey  James Binney 《Monthly notices of the Royal Astronomical Society》2005,363(2):603-608

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The irradiation history of the Ghubara (L5) regolith breccia     

T. E. Ferko  M‐S. Wang  D. J. Hillegonds  M. E. Lipschutz  R. Hutchison  L. Franke  P. Scherer  L. Schultz  P. H. Benoit  D. W. G. Sears  A. K. Singhvi  N. Bhandari 《Meteoritics & planetary science》2002,37(3):311-327

Abstract— We measured cosmic‐ray products—noble gases, radionuclides, thermoluminescence, and nuclear tracks—and trace element contents and mineralogy of samples of three orthogonal and mutually intersecting cores (41–46 cm long) of a 101.6 kg Ghubara individual (1958,805) at The Natural History Museum, London. The xenoliths, like the host, have high concentrations of trapped solar gases and are heavily shocked. While contents of noble gases and degree of shock‐loading in this individual and three others differ somewhat, the data indicate that Ghubara is a two‐generation regolith breccia. Contents of cosmogenic ²⁶Al and ¹⁰Be and low track densities indicate that the Ghubara individuals were located more than 15 cm below the surface of an 85 cm meteoroid. Because of its large size, Ghubara's cosmic‐ray exposure age is poorly defined to be 15–20 Ma from cosmogenic nuclides. Ghubara's terrestrial age, based on ¹⁴C data, is 2–3 ka. Not only is Ghubara the first known case of a two‐generation regolith breccia on the macroscale, it also has a complicated thermal and irradiation history.  相似文献   

Geochemical evaluation of mineralization potential of the Somie-Ntem area within the Tikar plain,Cameroon: implication on petrogenesis     

Yannah  Mero  Fodoué  Yaya  Kwékam  Maurice  Mbassa  Benoit Joseph  Tifang  Juliana Amboh  Kagou  Armand Dongmo  Ayonghe  Samuel Ndonwi 《中国地球化学学报》2022,41(5):861-886

Acta Geochimica - Somie-Ntem area of the Tikar plain belongs to the western Cameroon Domain. The lithology of the plain has been characterized, and the mineral potential is still unclear despite...  相似文献   

Improving hydrogeological understanding through well-test interpretation by diagnostic plot and modelling: a case study in an alluvial aquifer in France     

Garin  Thibaut  Arfib  Bruno  Ladouche  Bernard  Goncalves  Julio  Dewandel  Benoit 《Hydrogeology Journal》2022,30(1):283-302

Hydrogeology Journal - The study of groundwater resources using pumping test data is usually carried out with the Theis solution, which enables the hydraulic parameters of porous aquifers such as...  相似文献   

Evaluating the genetic effects of the invasive Ocenebra inornata on the native oyster drill Ocenebra erinacea          下载免费PDF全文

Eric Pante  Pierre‐Yves Pascal  Vanessa Becquet  Amélia Viricel  Benoit Simon‐Bouhet  Pascale Garcia 《Marine Ecology》2015,36(4):1118-1128

Studies focusing on the effect of invasive species on the genetic diversity of native marine invertebrates remain scant. Here we report diversity among French populations of the intertidal gastropod Ocenebra erinacea (Linnaeus, 1758) sampled in the presence and absence of the invasive Ocenebra inornata (Recluz, 1851). Between 1999 and 2004, a total of 352 individuals of O. erinacea was collected from 15 sites (five of which had the invasive present) and was genotyped at the mitochondrial locus Cytochrome Oxidase 1 (cox1). No statistical difference was observed between polymorphism levels recorded within native populations exposed to the invasive, compared with populations sampled in the absence of O. inornata. No sign of native population decline was detected in response to the invader. While significant shifts in native O. erinacea population sizes have previously been reported in the literature, genetic effects may take longer to accumulate, or may be undetectable without a larger panel of genetic markers. By contrast, large genetic distances and significant population differentiation were recorded between Atlantic and Mediterranean O. erinacea samples, suggesting that these populations have distinct evolutionary histories. Comparison of genetic divergence within the closely related genus Nucella suggests that the Atlantic populations of O. erinacea and those from Thau Lagoon in the Mediterranean may belong to different species or subspecies.  相似文献