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Sin-le-Noble, France

In the upper part of the Chavanon sequence (Variscan French Massif Central), a widespread, high temperature, Devonian regional anatexis led to the genesis of a complex imbrication of cordierite-rich rocks. One striking type is characterised by a high modal (∼ 60-70%) amount of euhedral cordierite and its cumulative texture. The cordierite crystals contains inclusions of sillimanite needles that outlines the successive stages of cordierite growth in a melt. The estimated temperature range for the cordierite formation is 725-781 °C. The textural analysis of the rock, coupled with a crystal size distribution (CSD) diagram of cordierite, reveals crystallisation in equilibrium with melt. The complex imbrications between different migmatites types reveal several stages of melt expulsion and crystallisation. The different possibilities for the formation of this peculiar type of rock are also discussed. Source

Thiery V.,EM Douai | Green D.I.,University of Manchester
Computers and Geosciences | Year: 2012

The present paper provides a review of an imaging tool that is relatively underused in petrographic studies: the multifocus technique. Commonly used in macrophotography, and particularly in the imaging of minerals, it can also be applied to the imaging of thin sections where inclusions or other features that are present at different depths in the section can be combined into the same image. Improvements in computer performance and in image combination software make the technique simple and efficient. Its latest developments allow three-dimensional reconstructions of inclusions and other features of petrographic interest to be visualized. The difficulties of imaging under the optical microscope at high magnification are reviewed and demonstrations of the advantages of the multifocus technique are provided. Compared to more specialized and expensive imaging methods, such as confocal scanning microscopy and X-ray computed tomography, the multifocus technique offers an inexpensive and rapid approach, which is useful as an initial check as to whether more elaborate techniques are justified. © 2011 Elsevier Ltd. Source

Zri A.,University of Lille Nord de France | Abriak N.-E.,EM Douai | Zentar R.,EM Douai
European Journal of Environmental and Civil Engineering | Year: 2011

In a context of sustainable development, the management of sediment depends on their potential to induce pollution. The old management techniques used as immersion in the sea by overfflow, dumping or storage is restricted due to regulation which is increasingly rigid in terms of environmental protection. The new trend of all actors in the field of sediment management is moving ineluctably towards an alternative solution as the valorisation of the sediments as. Any valorisation requires a stage of characterisation in order to enhance the knowledge about the material: its various components, its potential to induce pollution and its mechanical behaviour. Our work consists, on the one hand, in carrying out a comparative study of mechanical and physical behaviours, between polluted and unpolluted sediment and on the other hand, to underline the evolution of the behaviour of polluted sediment following a lime treatment. The sediment in question is considered as a raw material as it has not been subject to any process of pretreatment. © 2011 Lavoisier, Paris. Source

Champenois J.-B.,CEA Marcoule Nuclear Site | Mesbah A.,CEA Marcoule Nuclear Site | Mesbah A.,Institute of Chemistry of Clermont-Ferrand | Cau Dit Coumes C.,CEA Marcoule Nuclear Site | And 7 more authors.
Cement and Concrete Research | Year: 2012

Crystal structures of boron-containing AFm (B-AFm) and AFt (B-AFt) phases have been solved ab-initio and refined from X-ray powder diffraction. 11B NMR and Raman spectroscopies confirm the boron local environment in both compounds: three-fold coordinated in B-AFm corresponding to HBO 3 2 - species, and four-fold coordinated in B-AFt corresponding to B (OH) 4 - species. B-AFm crystallizes in the rhombohedral R3̄c space group and has the 3CaO·Al 2O 3·CaHBO 3·12H 2O (4CaO·Al 2O 3·1/2B 2O 3·12.5H 2O, C 4AB 1/2H 12.5) general formulae with planar trigonal HBO 3 2 - anions weakly bonded at the centre of the interlayer region. One HBO 3 2 - anion is statistically distributed with two weakly bonded water molecules on the same crystallographic site. B-AFt crystallizes in the trigonal P3cl space group and has the 3CaO·Al 2O 3·Ca(OH) 2·2Ca(B (OH) 4) 2·24H 2O (6CaO·Al 2O 3·2B 2O 3·33H 2O, C 6AB 2H 33) general formulae with tetrahedral B (OH) 4 - anions located in the channel region of the structure. All tetrahedral anions are oriented in a unique direction, leading to a hexagonal c lattice parameter about half that of ettringite. © 2012 Elsevier Ltd. Source

This publication illustrates the imaging of both external and internal features of a single-garnet crystal using the multifocus imaging technique. Based on image stacks acquired using a standard optical microscope, it demonstrates that this easily implemented technique yields information on single grains and may in some cases provide more information than that obtainable from a conventional thin section. © 2012 Elsevier Ltd. Source

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