Metal speciation in fluid inclusions using microbeam X-ray absorption spectroscopy     

Julianne James-Smith  Joël Brugger  Jean Cauzid  Denis Testemale  Jean-Louis Hazemann  Weihua Liu  Olivier Proux 《Journal of Geochemical Exploration》2009

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Two-stage partial melting during the Variscan extensional tectonics (Montagne Noire,France)     

Poujol  Marc  Pitra  Pavel  Van Den Driessche  Jean  Tartèse  Romain  Ruffet  Gilles  Paquette  Jean-Louis  Poilvet  Jean-Charles 《International Journal of Earth Sciences》2017,106(2):477-500

International Journal of Earth Sciences - One of the striking features that characterise the late stages of the Variscan orogeny is the development of gneiss and migmatite domes, as well as...  相似文献   

Addressing ore formation and exploration     

Jean-Louis Vigneresse 《地学前缘(英文版)》2019,10(4):1613-1622

Common base and noble metals represent an important economic factor in the actual industrial development.For instance the world resources for copper are actually estimated for about the next 30 years only.The situation requires rethinking the way major ore deposits form,leading to new guides for exploration.The present paper briefly examines the processes leading to ore formation,in relation with granitic or granodioritic intrusions.It identifies the importance of metal enrichment during the magmatic stage.Within the magma chamber that forms porphyry intrusions,metals may incorporate to first formed crystals,becoming inert;concentrate into the residual melt of a mush;or segregate by diffusion into the exsolved magmatic volatile phase(MVP)into which they are transported and precipitated.A competition results between elements partitioning and diffusivity.Hence,a specific Peclet number for each metal(Cu,Au,Ag,Mo,W,Sn,and REE)controls the ratio between the diffusive and the advective flux.Metals diffusivity in the melt shows differential behavior relative to a threshold of about10 13 m2/s.Metals with slower diffusivity values(e.g.As)will not concentrate.Conversely,fast diffusive metals(Au,Ag,Cu)may rapidly incorporate the MVP,provided an adequate component(halogens or S)is attractive for metals.The chemistry of the MVP escaping the magma induces different alteration patterns.Their relative content in F,Cl or S,attested by the composition of biotites and apatites,links with the preferential content of metals in o re deposits,representing a valuable tool for exploration.Finally the model is replaced in a set of coupled mechanical-chemical instabilities,within a three phase material.  相似文献   

Modeling of cadmium speciation and dynamics in the Seine estuary (France)     

Jean-Louis Gonzalez  Benedicte Thouvenin  Catherine Dange  Annie Fiandrino  Jean-François Chiffoleau 《Estuaries and Coasts》2001,24(6):1041-1055

A complexation model (MOCO) was used to describe cadmium (Cd) speciation during estuarine transit in the Seine estuary. This model was developed from field data. Laboratory experiments based on the use of¹⁰⁹Cd enabled checking of certain model simplifications and hypotheses and evaluation of parameters which could not be measured directly. MOCO was coupled with a 3D multivariable hydrosedimentary model (SAM3D) to simulate Cd dynamics in the estuary. These results were compared with measurements (dissolved and particulate Cd) obtained during cruises representative of various hydrodynamic conditions. The purpose of this article is to present the modeling approach used, and its expected applications and limits.  相似文献   

Geometric Measurement Analysis Versus Fourier Series Analysis for Shape Characterization Using the Gastropod Shell ( Trivia ) as an Example     

Elisabeth Dommergues  Jean-Louis Dommergues  Françoise Magniez  Pascal Neige  Eric P. Verrecchia 《Mathematical Geology》2003,35(7):887-894

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The level of pollution of Kerguelen islands biota by organochlorine compounds during the seventies     

Jean-Louis Monod  Patrick M. Arnaud  Andr  Arnoux 《Marine pollution bulletin》1992,24(12):626-629

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Radiometric evidence for an Acadian tectonometamorphic event in Western Massif Central Français     

Jean Bernard-Griffiths  Jean-Marie Cantagrel  Jean-Louis Duthou 《Contributions to Mineralogy and Petrology》1977,61(2):199-212

Systematic Rb-Sr determinations on granites and orthogneisses in the Western part of Massif Central Français (Limousin) permit us to say that metamorphism and associated folding occured in this area during the Devonian (between 400 and 350 m.y.) with anatexis stated at 360 m.y. Two premetamorphic magmatic episodes are located in the upper Cambrian-early Ordovician (520-490 m.y.) and in the Ordovician (460-450 m.y.). This should be compared with very similar radiometric results from Rouergue to South Brittany; thus a South Brittany-Limousin-Rouergue axis may be easily related to the acadian part from Appalachian belt.  相似文献   

Long-term thermal evolution and effect of low power heating in an underground quarry     

Catherine Crouzeix  Jean-Louis Le Mouël  Frédéric Perrier  Patrick Richon  Pierre Morat 《Comptes Rendus Geoscience》2003,335(4):345-354

Vertical profiles of temperature have been monitored in the atmosphere of an underground quarry since June 2001. A long-term temperature increase of the order of 0.1 °C per year is observed. Three heating experiments with 100-W sources, performed to study plume dynamics, can also be used to investigate the effect of visits on this increase. Ten days after the 24-h heatings, the initial state is not restored. Artificial contributions to the observed long-term temperature trend, triggered by internal heat release, thus cannot be ruled out. This experiment defines strict criteria for the underground monitoring of global warming or the preservation of painted caves. To cite this article: C. Crouzeix et al., C. R. Geoscience 335 (2003).  相似文献   

Quantitative Zn speciation in a contaminated dredged sediment by μ-PIXE, μ-SXRF, EXAFS spectroscopy and principal component analysis     

Marie-Pierre Isaure  Agnès LaboudigueAlain Manceau  Géraldine SarretChristophe Tiffreau  Patrick TrocellierGéraldine Lamble  Jean-Louis HazemannDaniel Chateigner 《Geochimica et cosmochimica acta》2002,66(9):1549-1567

Dredging and disposal of sediments onto agricultural soils is a common practice in industrial and urban areas that can be hazardous to the environment when the sediments contain heavy metals. This chemical hazard can be assessed by evaluating the mobility and speciation of metals after sediment deposition. In this study, the speciation of Zn in the coarse (500 to 2000 μm) and fine (<2 μm) fractions of a contaminated sediment dredged from a ship canal in northern France and deposited on an agricultural soil was determined by physical analytical techniques on raw and chemically treated samples. Zn partitioning between coexisting mineral phases and its chemical associations were first determined by micro-particle-induced X-ray emission and micro-synchrotron-based X-ray radiation fluorescence. Zn-containing mineral species were then identified by X-ray diffraction and powder and polarized extended X-ray absorption fine structure spectroscopy (EXAFS). The number, nature, and proportion of Zn species were obtained by a coupled principal component analysis (PCA) and least squares fitting (LSF) procedure, applied herein for the first time to qualitatively (number and nature of species) and quantitatively (relative proportion of species) speciate a metal in a natural system.The coarse fraction consists of slag grains originating from nearby Zn smelters. In this fraction, Zn is primarily present as sphalerite (ZnS) and to a lesser extent as willemite (Zn₂SiO₄), Zn-containing ferric (oxyhydr)oxides, and zincite (ZnO). In the fine fraction, ZnS and Zn-containing Fe (oxyhydr)oxides are the major forms, and Zn-containing phyllosilicate is the minor species. Weathering of ZnS, Zn₂SiO₄, and ZnO under oxidizing conditions after the sediment disposal accounts for the uptake of Zn by Fe (oxyhydr)oxides and phyllosilicates. Two geochemical processes can explain the retention of Zn by secondary minerals: uptake on preexisting minerals and precipitation with dissolved Fe and Si. The second process likely occurs because dissolved Zn and Si are supersaturated with respect to Zn phyllosilicate. EXAFS spectroscopy, in combination with PCA and LSF, is shown to be a meaningful approach to quantitatively determining the speciation of trace elements in sediments and soils.  相似文献   

Apport de la modélisation géophysique pour la compréhension de la structuration du pas de Calais     

Bruno Minguely  Jean-Louis Mansy  Michel Everaerts  Geoffrey M. Manby  Olivier Averbuch 《Comptes Rendus Geoscience》2005,337(3):305-313

This study is based on an analysis of seismic, gravimetric and magnetic data to model the structure of the Dover Straits area. The Dover Straits are set in a transitional position within the Brabant para-autochthon, which lies between the Ardennes allochthon to the south and the Brabant Massif to the north. The seismic profiles show that this area is characterised by several superimposed Mesozoic basins, whose evolution has been controlled by the reactivation of Lower Palaeozoic faults. In common with the adjacent Weald–Wessex and southern North Sea basins, the Dover Straits area records a Jurassic extensional phase and a post-Cretaceous tectonic inversion. The geophysical modelling reveals the presence of a basement to these Mesozoic basins that exhibits Ordovician to Silurian structures, which cannot be detected on the seismic reflection profiles. In contrast to earlier interpretations, the modelling presented here suggests that the Brabant Massif continues southward beyond the Dover Straits and under the Brabant para-autochthon. Gravity data also provides evidence for the presence of granitic body at depth, in the vicinity of Km 27 on the seismic profile, which may have driven the uplift of the Silurian rocks in the area of the Straits. Similar granitic intrusions have been proposed to explain gravity anomalies along the Rhenohercynian Margin in Belgium, eastern and southern England. The geophysical modelling demonstrates the continuity of the basement and Mesozoic basin structures across the Dover Straits, suggesting a common geological evolution of the adjacent southern England–northern France regions. To cite this article: B. Minguely et al., C. R. Geoscience 337 (2005).  相似文献