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1
Oswald, P. « Fluage en cisaillement d'un smectique B ». Journal de Physique 46, no 7 (1985) : 1255–62. http://dx.doi.org/10.1051/jphys:019850046070125500.
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COLLIN, D., J. L. GALLANI et P. MARTINOTY. « COMPORTEMENT CRITIQUE DE LA VITESSE ET DE L'ATTÉNUATION DES ULTRASONS AU VOISINAGE D'UNE TRANSITION SMECTIQUE A - SMECTIQUE C ». Le Journal de Physique IV 02, no C1 (avril 1992) : C1–805—C1–808. http://dx.doi.org/10.1051/jp4:19921176.
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Oswald, P. « Modèle de couplage entre les défauts et un écoulement parallèle aux couches dans un smectique A ». Journal de Physique 47, no 6 (1986) : 1091–96. http://dx.doi.org/10.1051/jphys:019860047060109100.
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Barbarin, F., J. P. Chausse et J. P. Germain. « Modélisation du comportement conformationnel moléculaire dans un mélange de deux cristaux liquides thermotropes en phases nématique et smectique B ». Journal de Physique 51, no 14 (1990) : 1553–67. http://dx.doi.org/10.1051/jphys:0199000510140155300.
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Oswald, P. « Fluage d'un smectique B hexatique : lien entre la viscosité élongationnelle dans le plan des couches et la longueur de corrélation ξ // ». Journal de Physique 47, no 8 (1986) : 1279–83. http://dx.doi.org/10.1051/jphys:019860047080127900.
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Le Calvez, A., S. Montant, E. Freysz, R. Maleck-Rassoul et A. Ducasse. « Analyse femtoseconde et picoseconde de la rotation des molécules de cristaux liquides en phase smectique A autour de leur grand axe ». Annales de Physique 20, no 5-6 (1995) : 613–14. http://dx.doi.org/10.1051/anphys:199556037.
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Hillier, S. « Mafic phyllosilicates in low-grade metabasites. Characterization using deconvolution analysis — discussion ». Clay Minerals 30, no 1 (mars 1995) : 67–73. http://dx.doi.org/10.1180/claymin.1995.030.1.07.
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AbstractAny X-ray diffraction (XRD) pattern of mixed-layered maximum R1 ordered chlorite-smectite has an exact equivalent R0 smectite-corrensite or R0 chlorite-corrensite. The identification of a mineral as chlorite (0.8)-smectite R1 is, therefore, not evidence that the fundamental layers in such an interstratified structure are actually chlorite and smectite. Furthermore, there are no obvious differences between XRD patterns of R0 and R1 chlorite-smectite at high or low smectite contents. Therefore the frequently supposed identification of R0 chlorite-smectite with high smectite contents is also questionable. It follows that the identification of R1 chlorite (0.8)-smectite by Robinson & Bevins (1994) and of R0 chlorite (≈0.2)-smectite in an earlier publication (Robinson et al.,1993) cannot be used as evidence regarding the debate over the nature of the component layers in interstratified minerals intermediate between trioctahedral smectite and chlorite.Diffraction patterns of natural mixed-layer chlorite minerals from metabasites often show a strong reflection at 31 Å yet a lack of resolution of other mixed-layer peaks from those of discrete chlorite. These features cannot be matched by any single mixed-layer mineral consisting of layers of chlorite and smectite and were matched by Robinson & Bevins (1994) using a mixture of different chlorite-smectite minerals. However, they can be matched by a single chlorite-corrensite mineral in which there is an element of segregation of layer types. These different possibilities need to be investigated further.
8
Matsushita, Junichi, Seong Ho Yang et Geum Chan Hwang. « Absorption and Preservation of Bentonite Containing Smectite ». Materials Science Forum 569 (janvier 2008) : 241–44. http://dx.doi.org/10.4028/www.scientific.net/msf.569.241.
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The Na-bentonite with contained smectite was fabricated in order to observe their absorption and preservation about water. Absorption of fabricated specimens in the water and preservation of absorbed samples in the drying machine at 323 K was measured. It was obtained that absorption had been decreasing with increasing smectite. Absorption of As-received Na-bentonite was higher than absorption of As-received smectite. The preservation has been also decreased with increasing smectite was obtained. Na-bentonite with contained smectite were investigated the good absorption and preservation when the Na-bentonite containing smectite 5 mass %.
9
Koh, S. M., M. S. Song et T. Takagi. « Mineralogy, chemical characteristics and stabilities of Cetylpyridinium-exchanged smectite ». Clay Minerals 40, no 2 (juin 2005) : 213–22. http://dx.doi.org/10.1180/0009855054020167.
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AbstractCP (Cetylpyridinium)-exchanged smectite was manufactured by the cationic exchange reaction of Na-smectite with CP. The adsorption behaviour shows a typical L-type isotherm representing continuous and stable adsorption in excess of twice the cation exchange capacity of CP. CP-smectite shows a strong interlayer (d001) expansion to 40.2 Å when an amount of CP equivalent to 140% of the CEC is exchanged into smectite. CP-smectite is characterized by strong alkalinity (pH 9.3), low swelling (4.5 ml/2 g), low viscosity (3.9 mPa s), and strong and fast flocculation. These characteristics are in striking contrast to Na-smectite except for the alkalinity. CP-smectite shows no signs of desorption of the organic species under varying pH conditions (pH 2–12). Desorption is slight even when washed three times with DH2O (distilled water). Pyrolysis of CP-smectite begins at 250°C and ends at 400°C. These stable and persistent characteristics and the relatively low price of CP point to the likely increased use of CP-smectite as an organoclay.
10
Dong, Hailiang, Donald R. Peacor et Robert L. Freed. « Phase relations among smectite, R1 illite-smectite, and illite ». American Mineralogist 82, no 3-4 (1 avril 1997) : 379–91. http://dx.doi.org/10.2138/am-1997-3-416.
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Nakata, Eiji, Mei Yukawa, Hiroshi Okumura et Masaaki Hamada. « K-Ar dating by smectite extracted from bentonite formations ». E3S Web of Conferences 98 (2019) : 12015. http://dx.doi.org/10.1051/e3sconf/20199812015.
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We attempt to apply K-Ar dating to extracted smectite from bentonite formations collected by different age formations from Japan, China, and America. The results show that the K-Ar ages of smectite are younger than the expected geological age estimated from the stratigraphic data or other research data. The time differences increase with increased age, and K-Ar ages in this study also increase with increased age. For example, smectite in the old strata of bentonite has an older age than smectite in the young strata. K-Ar dating by smectite has the greatest potential for indicating the crystallized age of smectite.
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Eberl, D. D., B. Velde et T. Mccormick. « Synthesis of illite-smectite from smectite at Earth surface temperatures and high pH ». Clay Minerals 28, no 1 (mars 1993) : 49–60. http://dx.doi.org/10.1180/claymin.1993.028.1.06.
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AbstractIt is well known that illite-smectite can form from smectite at elevated temperatures in natural and experimental systems. However, the conversion of smectite to illite-smectite is also found in some natural systems that have never been heated. The present experiments show that illite layers can form from smectite by chemical reaction at 35° and 60°C at high solution pH. The rate of this reaction is accelerated by wetting and drying.
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Kuo, Shu-Lung, et Edward Ming-Yang Wu. « PHYSICOCHEMICAL CHARACTERISTICS AND PROPERTIES OF NANO-MODIFIED COUPLED SMECTITE CATALYSTS WITH AG+/ZN2+ ». EPH - International Journal of Applied Science 5, no 2 (27 juin 2019) : 7–13. http://dx.doi.org/10.53555/eijas.v5i2.118.
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This study used smectite clay as a carrier and exchanged Ag+ and Zn2+ onto the smectite via ion exchange. The coupled smectite-Ag/Zn catalysts at the nanolevel were formed after surface modification and high-temperature sintering. Various physicochemical experiments, such as Fourier-transform infrared spectroscopy (FT-IR) analysis, x-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) analysis, and thermal analysis, were conducted to further discuss the physicochemical properties of the smectite-Ag/Zn.
A function group analysis on the modified coupled smectite-Ag/Zn catalysts conducted via an FT-IR spectrum shows that the mineral structures of the catalysts remain intact after high-temperature sintering. In terms of the x-ray analysis, water tends to exist in the layer structure of the smectite, which is affected by humidity in the environment. After being modified by Ag and Zn, shrinkage occurs in layers of the smectite due to water loss. The spacing of layers is thereby narrowed. Moreover, a TEM observation of the coupled smectite-Ag/Zn catalysts after it was sintered at 350oC shows that the sizes of Ag+ and Zn+2 on the smectite-Ag/Zn are between 25-50 nm, respectively. This proves that Ag+ and Zn2+ do exist in the coupled smectite-Ag/Zn catalysts after they were exchanged, and that they are at the nanolevel. As for the thermal analysis, the findings show that significant melting occurs when the coupled smectite-Ag/Zn catalysts are sintered at 459oC, due to the oxidative pyrolysis of micromolecules or solvents.
14
Kuo, Shu-Lung, et Chiu-Jung Liao. « Photocatalytic Disinfection of Bacteria by Sodium Light with Smectite Catalysts ». Water Quality Research Journal 41, no 4 (1 novembre 2006) : 365–74. http://dx.doi.org/10.2166/wqrj.2006.040.
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Abstract In this study, modifications of Wyoming smectite clay minerals are conducted using four types of metallic cations that cover the surface with Ag+, Zn2+, Ti4+ and Ag+/Zn2+ to form smectite catalysts and destroy bacteria. When the smectite catalysts are illuminated with a sodium lamp, they reduce the number of viable bacteria in surface water and achieve a disinfecting effect. On the whole, smectite-Ti catalysts have the best disinfection efficiency, followed by coupled smectite-Ag/Zn catalysts, smectite-Ag catalysts and smectite-Zn catalysts. The higher quantity of catalysts there is, the easier it is for the shielding effect to take place. This causes a lower intensity of sodium light to react with the bacteria. When smectite-Zn catalysts are in the catalytic process, they produce intermediates that can compete for reaction sites with the OH free radicals. This can reduce the production of electrons and holes, and hence the reaction rate of objects on the surface of smectite-Zn catalysts. In smectite-Ag/Zn catalysts, coupled catalysts combine two types of semiconductor catalysts that have different energy gaps and energy band sites. These can separate electrons and holes more efficiently, increase the lifetime of electron carriers, and enhance disinfection efficiency. This study utilizes factor analysis of multivariate analysis to discuss the correlations between different catalysts, e.g., the four types of smectite catalysts and catalysts with different weight percentages, respectively. The results show two findings: (1) there is only one main factor influencing the disinfection efficiency of the four types of smectite catalysts—the photocatalytic competitiveness factor; and (2) only one main factor affects the disinfection efficiency of the four types of catalysts with different weight percentages—the concentration shielding effect factor.
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Hansen, Poul Lenvig, et Holger Lindgreen. « Structural investigations of mixed-layer smectite-illite clay minerals from North Sea oil source rocks ». Proceedings, annual meeting, Electron Microscopy Society of America 45 (août 1987) : 374–75. http://dx.doi.org/10.1017/s0424820100126664.
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The purpose of the present investigation is to identify mixed-layering between illite and smectite in oil source rocks with HREM and electron diffraction. Smectite and mica are both groups within the 2:1 type of layer silicates. Illite is a commonly used term for micas in the fraction less than 2 microns. Illite has a fixed d(001) spacing of 10A. Smectite is able to swell from 10A to more than 18A under uptake of water or organic polar molecules. Mixed-layer illite-smectite is built of alternating layers of illite and smectite. Smectite and illite layers are recognized by x-ray diffraction (XRD) from their swelling characteristics, but cannot be distinguished in this way in HREM, because smectite layers tend to contract to 10A by evaporation of water in the vacuum of the microscope. Illites are identified by HREM as small packets showing very regular lattice fringes and smectites as highly imperfect, anastomosing layers showing very irregular lattice fringes (1).
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Osacký, Marek, Miroslav Honty, Jana Madejová, Thomas Bakas et Vladimír Šucha. « Experimental interactions of Slovak bentonites with metallic iron ». Geologica Carpathica 60, no 6 (1 décembre 2009) : 535–43. http://dx.doi.org/10.2478/v10096-009-0039-7.
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Experimental interactions of Slovak bentonites with metallic ironThe experimental stability of four bentonites and one K-bentonite from Slovak deposits in the presence of iron was studied to simulate the possible reactions of clays (bentonite barrier) in the contact with Fe containers in a nuclear waste repository. The batch experiments were performed at 60 °C for 30 and 120 days in aerobic conditions. The reaction products were examined by XRD, FTIR, and Mössbauer spectroscopies and CEC (cation exchange capacities) were determined. Reaction solutions were analysed for selected elements using AAS (atomic absorption spectrometry). The results show that bentonites do not interact equally with metallic iron. Bentonites from the Jelšový Potok, Kopernica and Lieskovec deposits reacted similarly whereas the interaction between the bentonite from Lastovce and the iron was less intensive. The lower reactivity of the bentonite from Lastovce can be explained by its low content of smectite. During iron-clay interactions the iron was consumed and Fe oxides (magnetite, lepidocrocite) were formed. Decrease of the smectite diffraction peaks intensity and CEC values during the experiments show rather the rearrangement of the original smectite crystals than dissolution of smectite. In the K-bentonite from the Dolná Ves deposit where the mixed-layer illite-smectite is present instead of smectite, the dissolution of illite-smectite was observed along with the neoformation of smectite. The structure of illite-smectite deteriorated more than the structure of smectites which suggests that this mixed-layer illite-smectite is much less stable in the presence of iron than smectites.
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Walsh, Peter G., et Geoff S. Humphreys. « Inheritance and formation of smectite in a texture contrast soil in the Pilliga State Forests, New South Wales ». Soil Research 48, no 1 (2010) : 88. http://dx.doi.org/10.1071/sr09059.
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Smectite genesis is generally considered to require an alkaline environment, for in acid environments it is reportedly unstable. This study shows that smectite is forming in an acid, texture-contrast soil in the Pilliga State Forests in north-western New South Wales. Three modes of smectite genesis in the study soil are presented. The first mode involves direct inheritance from the underlying parent rock. The second and third modes involve precipitation of smectite from solution and its deposition from suspension, respectively. While the bulk of the smectite in the study soil is inherited from the transformation of labile primary minerals and rock fragments in the parent rock, restricted drainage coupled with a parent material capable of supplying the elemental constituents of smectite are also important factors in its genesis.
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Bergaya, F., et F. Kooli. « Acrylonitrile-smectite complexes ». Clay Minerals 26, no 1 (mars 1991) : 33–41. http://dx.doi.org/10.1180/claymin.1991.026.1.04.
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AbstractThe adsorption of acrylonitrile (AN) monomer vapour in the interlamellar space of smectites exchanged with different cations (Na or Y or hexylammonium) was monitored and used to yield macromolecular layers. Polymerization in the presence or absence of a free-radical initiator was obtained by heating at 100°C for 72 h. Cyclization can already be obtained at this stage, and is completed by heating the polyacrylonitrile (PAN)-complexes at 220°C for 48 h.
19
Volzone, C. « Hydroxy-Chromium Smectite ». Clays and Clay Minerals 41, no 6 (1993) : 702–6. http://dx.doi.org/10.1346/ccmn.1993.0410608.
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Šucha, V., J. Środoń, N. Clauer, F. Elsass, D. D. Eberl, I. Kraus et J. Madejová. « Weathering of smectite and illite- smectite under temperate climatic conditions ». Clay Minerals 36, no 3 (septembre 2001) : 403–19. http://dx.doi.org/10.1180/000985501750539490.
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AbstractWeathering profiles developed on the top surface of a bentonite (containing Al-Mg montmorillonite) and a K-bentonite (containing mixed-layer illite-smectite (I-S)) under Central European temperate conditions were studied by XRD, HRTEM, FTIR, K-Ar and chemical analyses. Weathering of montmorillonite results in the decrease of cation exchange capacity (CEC), total surface area and Mg content. The process is interpreted as montmorillonite dissolution and precipitation of amorphous SiO2. Weathering of I-S produces an increase in CEC and total surface area. The XRD data suggest dissolution of I-S and appearance of smectite as a separate phase at intermediate depths. The fixation of ammonium is documented in the topmost sample. In both profiles, abundant aeolian contaminants, including mica, were identified and their migration was traced using K-Ar dating.
21
Mikloš, D., et B. Čičel. « Development of Interstratification in K-and NH4-Smectite from Jelšový Potok (Slovakia) Treated by Wetting and Drying ». Clay Minerals 28, no 3 (septembre 1993) : 435–43. http://dx.doi.org/10.1180/claymin.1993.028.3.07.
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AbstractA K+-saturated and an NH4+ -saturated smectite from Jelgov 37 Potok (Slovakia) was analysed by X-ray diffraction (XRD) after a series of I to 150 wetting and drying (WD) cycles, and the corresponding distribution functions were calculated using the Dyakonov method. From these data the thicknesses and proportions of different layers were determined. Three kinds of layers (A- 1-00 nm, B-1.26 nm and C-1-52 nm) were detected in the original samples. After 15 WD cycles only A and B type layers were identified in the K-smectite, whereas all three varieties were present during the whole WD treatment in the NH4-smectite. After initial changes the mutual proportion of layers seems to be stable. The 1.00 nm layer is the major layer type in the K-smectite and the 1.26 nm layer is the major layer type in the NH4-smectite. The layer thicknesses evolved during the WD experiments. The systematic changes observed for the NH4-smectite were greater than those for the K-smectite.
22
Ben Salah, M., H. Souli, P. Dubujet, M. Hattab et M. Trabelsi Ayadi. « Experimental study of the electrokinetic behaviour of kaolinite–smectite mixtures ». Soil Research 55, no 8 (2017) : 743. http://dx.doi.org/10.1071/sr16267.
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The evolution of the behaviour of kaolinite–smectite mixtures was studied using mechanical and electrokinetic tests. Oedometric tests showed that the compression index of the mixtures increases with increasing smectite percentage and that the curves feature a double slope in the [log σv,e] (where σv is the vertical mechanical stress and e is the void ratio) coordinate system when the percentage of smectite is strictly higher than 25%. Electrokinetic tests show that, of smectite the electrical conductivity and electro-osmotic flow tend towards that of the smectite. Measurements performed after the electrokinetic tests showed that the pH and conductivity are constant when the amount of smectite is lower than 25%. For higher smectite content, acidification of the medium is not totally obtained and the electrical conductivity is higher near the anode because of the slow diffusion of H+ ions in the structure. The tests also highlight that the electro-osmotic permeability is affected by the hydraulic permeability, although the variation in electro-osmotic permeability remains small compared with that of hydraulic permeability.
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Churchman, GJ, PG Slade, PG Self et LJ Janik. « Nature of interstratified kaolin-smectites in some Australian soils ». Soil Research 32, no 4 (1994) : 805. http://dx.doi.org/10.1071/sr9940805.
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The clay minerals in the < 2 �m, and finer, size fractions of several horizons from each of five Australian soils of different types and from different locations have been analysed by X-ray diffraction, infrared spectroscopy, transmission electron microscopy and X-ray fluorescence. Samples from each profile contained a phase in which layers of smectite and of kaolin (positively identified as kaolinite) were randomly interstratified with each other. The relative proportions of the two types of layers varied widely. One interstratified phase contained 70% smectite. This value for smectite content of kaolin-smectites is as high as any reported in the literature. The charges associated with the interstratified smectite layers also differed substantially. Discrete kaolinite commonly occurred along with interstratified kaolinite-smectite, Towards the surfaces of the soils, the proportions of kaolinite in the interstratified phases increased at the expense of smectite.
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Xie, Haixia, Shuai He, Chuanqin Huang et Wenfeng Tan. « Origin of Smectite in Salinized Soil of Junggar Basin in Xinjiang of China ». Minerals 9, no 2 (10 février 2019) : 100. http://dx.doi.org/10.3390/min9020100.
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In this paper, salinized soils with different degrees of salinity are sampled in Junggar Basin of Xinjiang of China. The X-ray diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry are employed to investigate the morphology and distribution characteristics of smectite in salinized soil profiles. In the salinized soil profiles of this region, crystals of smectite are poor where lattice fringes are not parallel. In all soil layers, the content of smectite in the soil increases with the decrease in content of illite, which has demonstrated significant negative correlation (r = 0.79, n = 50, p < 0.01) between illite and smectite. This phenomenon has demonstrated that illite may be transformed into smectite in salinized soils of studied regions. In general, the transformation process of illite to smectite is affected by climate condition. The δ18O values of secondary carbonate in the 0–10 cm soil layers is higher than that in deep soil layers, which indicates that δ18O concentrates in surface soil and reflects temperature rise during soil layer formation. The δ13C values of secondary carbonate and soil organic matter in 0-10cm soil layers are higher than that in deep soil layers. It indicates that C4 plants were the main plants, which reflects that the climate was relatively dry during the formation of the surface soil. Thus, the climate during the surface soil formation is arid, which is not conducive for leaching K+ from illite of the 0–10 cm soil to form smectite. As a result, the content of the smectite becomes lowest in the soil surface. In the relative humid condition of deep soil layers, the K+ of the illite of the soil would be relative easily leached and more smectite may be formed. Furthermore, the presence of salt in the salinized soil would promote the formation of smectite in Junggar Basin of Xinjiang. A lot of Ca2+, Na + and Mg2+ in the soil solution of salinized soils would enter into the illite and occupy K+ positions. The studied result shows that the amount of smectite would increase with the increase of salt below 10cm of the soil layer, where the amount of smectite would be significantly correlated with soil electrical conductivity (r = 0.64, n = 39, p < 0.01). In the Junggar Basin in Xinjiang, therefore, the salinized soil below 10 cm would have the necessary water conditions and chemical components for illite transformation to smectite.
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Lindgreen, Holger. « Elemental and structural changes in illite/smectite mixed-layer clay minerals during diagenesis in Kimmeridgian- Volgian (- R yazanian) clays in the Central Trough, North Sea and the Norwegian Danish Basin ». Bulletin of the Geological Society of Denmark 39 (25 octobre 1991) : 1–82. http://dx.doi.org/10.37570/bgsd-1991-39-01.
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. The literature on the diagenetic conversion of smectite layers to illite layers in mixed-layer illite/smectite is reviewed. According to this smectite layers are converted to illite layers during diagenesis at temperatures above 55°C and illite/smectites become IS ordered at about 100°C and at illite percentages of about 80%. Charge and elemental composition seem, beside temperature, to be of importance in the process. Investigations from metamorphic and hydrothermal areas have also found a conversion of smectite to illite layers with increasing temperature. In hydrothermal experiments, the process has been found to occur at temperatures of 250°C and above. Investigations from metamorphic areas have shown that the increase in amount of illite layers in _illite/smectite during short lived heating events is very slow compared to the increase in vitrinite reflectancy. The elemental changes during illite layer formation are a substitution of AIH for Si4+ in the tetrahedral sheet and a fixation of K• between 2: 1 units. Some investigations have also found substitution of AlH for Mg2+ and Fe and a reduction of FeH in the octahedral sheet. The changes seen during the hydrothermal experiments and in hydrothermal areas are different from the diagenetic changes in that higher negative charges are created and Na+ and Ca2+ are fixed under hydrothermal conditions. Two models have been proposed for the diagenetic formation of illite layers from smectite layers: 1) A solid-state AlH for Si4+ substitution in the tetrahedral sheets of smectite layers and subsequent fixation of K+ and interlayer collapse, giving illite layers; and 2) A dissolution of smectite layers and crystallization and growth of illite crystals. K+ supply is the main control on the formation of illite layers from smectite. Even in systems with sufficient K+ available, other cations such as Mg>+, Ca2+, and Na+ may inhibit K•- fixation and illite layer formation. The release of clay transformation water and its possible role in petroleum migration has been the subject of several investigations. There seems in most cases to be a coincidence between collapse of interlayer space (assumed to release interlayer water) and the generation of petroleum. But the role of the water released during clay diagenesis is not clear. The geology of the Central Trough and the Norwegian-Danish Basin is shortly reviewed. The source of the Upper Jurassic clays was probably mainly the Fennoscandian Shield. In addition volcanic material including ash has probably been sedimented in the North Sea region during Upper Jurassic. Cores and hand-picked cuttings samples from the Manda!, Farsund and Haugesund Formations in the Central Trough and from the Sauda, Tau, B0rglum and Bream Formations in the Norwegian-Danish Basin have been investigated. Intact bulk rock samples were ion-milled and investigated by high resolution transmission electron microscopy (HRTEM). The samples were also ultrasonically and chemically treated and the mixed-layer illite/smectite isolated by centrifuging. The illite/smectite samples thus obtained were investigated by HRTEM, by transmission electron microscopy (TEM) ort shadowed specimens, by X-Ray diffraction (XRD), by 27AI and 29Si magic angle spinning, nuclear-'magnetic resonance spectroscopy (mas-nmr), by infrared spectroscopy (IR), and by chemical al):\lysi_s for elements and NH,+. lllite percentages and ordering in illite/smectite were estimated by computer simulation of XRD patterns by the NEWMOD program for two-component systems and by a program for three component systems. The interpretations of the HRTEM images of illite/smectite structures in intact bulk rock were supported by computer simulations. The results of XRD on coarse clay fractions indicated that the main source area for the Upper Jurassic claystones was the Fennoscandian Shield. XRD supported by computer simulations showed that the amount of illite layers in illite/smectite was between 40% and 80% illite layers in randomly ordered or I-S segregated illite/smectite, between 80% and 90% in mainly IS ordered illite/smectite, and about 95% illite layers in ISII ordered illite/smectite. 10--14 A distances were seen in lattice fringes by HRTEM on intact bulk rock and are probably due to smectite layers with non-contracted interlayer space, whereas 10 A lattice fringes can be due to illite or collapsed smectite and 14 A distances to chlorite_ or non-collapsed smectite. 10 A lattice fringes with periodically enhanced contrast were observed by HRTEM on intact bulk rock in all Central Trough samples investigated. Regular 20 A period sequences of such enhanced contrast were most frequent but also 30 A period sequences and sequences with enhanced contrast occurring randomly along c* were seen. These particles are MacEwan illite/smectite particles. The specimens prepared for HRTEM from dispersed illite/smectite contained a large amount of thin particles with 10 A period in contrast but also, in IS ordered illite/smectite, a large number of particles with 20 A periodically enhanced contrast, MacEwan particles. It is concluded that the thin particles seen by HRTEM and TEM on specimens prepared from dispersed illite/smectite have probably formed by dispersion of the thick particles seen by HRTEM in intact bulk rock. The illite/smectite from the Norwegian-Danish Basin, with 65--75% illite layers and randomly ordered or 1-S segregated, is probably detrital. Similar illite/smectite at shallow depth (less than about 3 km) and low temperatures (less than about l00°C) in the Central Trough is probably also detrital, but at larger depths and higher temperatures it is diagenetically changed to predominantly IS ordered illite/smectite with 80--95% illite layers. This change occurs at a vitrlnite reflectancy of about 0.65%, i.e. at about oil generation. Chemical analysis and mas-nmr showed that the formation of illite layers is accompanied by an increase in tetrahedral Al arid a minor increase in octahedral Al, by a decrease in tetrahedral Si and by a minor decrease in octahedral Mg and Fe. Analysis of pore water from Upper Jurassic claystone cores gave ratios for K+/NH4 + in pore water similar to those in illite/smectite from the same depth, indicating that the relative amounts of K+ and NH/ control the fixation of these cations in illite/smectite. The ordering of illite and smectite layers in MacEwan particles in intact bulk rock, observed in images as 20 A (and sometimes 30 A) periods of enhanced contrast, can only have formed during solid-state smectite to illite formation, the polarization effect probably being responsible. The chemical analyses show that the illite layers have charges of about -0.8, less than the ideal -1.0 of mica. Such low charge illite layers can form during a solid-state transformation. It is concluded that the formation of illite layers from smectite layers in the Upper Jurassic claystones is a solid-state transformation.
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Manapat, Jill, Ivyleen Arugay, Johanna Michelle Ambait, Mitch Irene Galvan et Leslie Joy Diaz. « Electrophoretic Characterization of Clay Mineral Systems for Smectite Recovery ». Key Engineering Materials 654 (juillet 2015) : 280–84. http://dx.doi.org/10.4028/www.scientific.net/kem.654.280.
Texte intégralRésumé :
A novel technique that makes use of electrophoretic deposition (EPD) in upgrading the quality of Philippine clay, specifically for smectite recovery, was explored in this study. Focus was given on understanding the electrophoretic behavior of smectite and kaolinite to effectively control colloidal stability during EPD. Zeta potential measurements showed that pH has negligible effect on the electrophoretic mobility of smectite, but has an appreciable effect on the mobility of kaolinite with the isoelectric point (IEP) of kaolinite recorded around pH 5. Knowing this behavior, EPD of a 3.5wt% smectite-kaolinite slurry was carried out at pH 5 and pH 10. Separation of clay minerals was expected only at pH 5 where kaolinite is almost immobile. However, analysis of deposits using XRD showed some degree of separation (~60% smectite recovery) for both pH values when EPD was performed using stainless steel electrodes at a specific applied voltage and electrode gap, for twenty minutes, without stirring. Further investigation of EPD design is needed to improve smectite recovery.
27
Wei, H., E. Roaldset et M. Bjorøy. « Parallel reaction kinetics of smectite to illite conversion ». Clay Minerals 31, no 3 (septembre 1996) : 365–76. http://dx.doi.org/10.1180/claymin.1996.031.3.07.
Texte intégralRésumé :
AbstractA parallel reaction model is developed for describing the conversion of smectite to illite. Each reaction represents a group of similar smectite layers that require the same activation energy and have the same illitization rate. The model considers that the rate-determining reactant is smectite itself which follows first-order Arrhenius kinetics. By modelling the data from hydrothermal illitization experiments and from a Gulf Coast well, the activation energies are found to be distributed in the range of 11–24 kcal/mol with a maximum reaction at 18 kcal/mol, which involves 65% of reactive smectite. A frequency factor in the order of 10−3–10−4/s, obtained from the data fitting, appears to be adequate for modelling natural diagenesis in sedimentary basins. The distribution pattern of activation energies is considered to be controlled by the degree of heterogeneity of the initial smectite and the degree of electrostatic interactions between smectite layers and the newly formed illite layers during reaction.
28
Ko, J., G. H. Lee, H. S. Moon et Y. Song. « Alkylammonium characterization of smectite alteration in the Tertiary basins of southeast Korea ». Clay Minerals 33, no 2 (juin 1998) : 243–54. http://dx.doi.org/10.1180/000985598545606.
Texte intégralRésumé :
AbstractThe layer charge characteristics of smectite from the Tertiary basins in the Pohang area, Korea have been studied in detail using the alkylammonium method. On the basis of layer charges, the smectite in the Pohang area can be classed as normal and high-charge (hc) smectite. The layer charge of the normal smectite averages 0.3, and ranges from 0.25 to 0.38/half unit-cell. The hcsmectite collapses on K saturation to become illite-like material and shows 10 Åseries reflections on X-ray diffraction. The layer charge of the hc-smectite ranges from 0.5 to 1. The layer charges do not appear to be related to stratification or to basins of occurrence. The diagenetic trend that may have existed in the region was probably disturbed by later volcanic activity. A systematic change in layer charge and geochemistry of smectite in Waeup illustrates that the heat and solutions associated with the volcanic activity may have played a role in the development of layer charge.
29
Fellah, Imen, Ridha Djellabi, Hédi Ben Amor, Noureddine Hamdi, Marcela Frias Ordonez et Claudia L. Bianchi. « Enhanced Photocatalytic Kinetics Using HDTMA Coated TiO2-Smectite Composite for the Oxidation of Diclofenac under Solar Light ». Catalysts 13, no 1 (27 décembre 2022) : 51. http://dx.doi.org/10.3390/catal13010051.
Texte intégralRésumé :
Slow kinetics is one of the capital issues of photocatalytic technology because of its heterogeneous nature, which involves multi-step processes. Herein, we show that the simple modification of the sol-gel-based TiO2-smectite composite by hexadecyltrimethylammonium bromide (HDTMA) significantly boosts adsorption and photocatalytic efficient sol-gel-based light towards the removal of diclofenac from water. Three photocatalysts were prepared, including TiO2, TiO2-smectite, and HDTMA-TiO2-smectite. The materials were characterized to understand the surface interaction and crystal characteristics. In terms of photoactivity, it was found that the addition of HDTMA to TiO2-smectite improved the removal rate by twice. HDTMA changes the functional groups to TiO2-smectite composite allowing enhanced adsorption and photoactivity through the so-called Adsorb and Shuttle process. The recycling tests show that HDTMA-TiO2-smectite can be used up to four times with good performance. This modification approach could intensify the removal of pollutants from water instead of using complicated and costly techniques.
30
Roonwal, G. S., et S. K. Srivastava. « Clay Mineralogy of the Pelagic Sediments : Along a West-East Transect in the Indian Ocean ». Journal Geological Society of India 38, no 1 (1 juillet 1991) : 37–54. http://dx.doi.org/10.17491/jgsi/1991/380105.
Texte intégralRésumé :
Abstract The clay fraction of the sediments contain illite, chlorite, kaolinite, montmorillonite and iron-smectite with minor amounts of goethite. The siliceous sediments contain both montmorillonite and iron-smectite, while the calcareous sediments show only montmorillonite. This suggests that montmorillonite is formed by the alterations of ridge basalts, palagonite and volcanic glass. Iron-smectite is probably formed during low temperature diagenesis by the chemical combination of iron and silicon. High biogenic sedimentation in the calcareous sediments inhibited the formation of iron-smectite.
31
Ross, G. J., et H. Kodama. « X-ray diffraction characteristics and related properties of Smectites in some Canadian soils ». Canadian Journal of Soil Science 73, no 1 (1 février 1993) : 93–102. http://dx.doi.org/10.4141/cjss93-009.
Texte intégralRésumé :
The X-ray diffraction (XRD) peak intensities of smectites in Chernozemic and related soils of Western Canada are generally low, in contrast to the high peak intensities of smectites in Podzolic soils of Eastern Canada and those of standard smectite samples. Consequently, X-ray quantitative analysis based on standard smectite samples may underestimate the amount of smectite and overestimate the amount of noncrystalline material in western Canadian soils. This study was undertaken to find the reasons for the weak XRD peak intensities of western soil smectites in terms of their purity and crystallinity. The Tiron dissolution method extracted only small amounts of noncrystalline material from the western soil clays and had little effect on XRD characteristics. The cation exchange capacity (CEC) hysteresis (or pH dependent CEC) between pH 3.5 and 11.0 of the western soil clays was also relatively small which confirmed the absence of significant amounts of noncrystalline material in these soil clays. Observed deviations of XRD positions from true basal spacings indicated that the western soil smectite particles were consistently thinner than the eastern soil smectite and Wyoming montmorillonite particles. Electron microscope observations supported these results. Because the diffraction intensity is proportional to the square of the particle thickness, the thinness of the western soil smectite particles appears to be a major factor in reducing their peak intensities. Thus, to obtain comparable peak intensity data from different soil smectites, particle thickness should be taken into account. Since it is often not practical to measure particle thickness, a procedure for quantifying smectite in soils that avoids this measurement is proposed. Key words: Peak intensity, crystallinity, particle size, particle thickness, Chernozemic smectite, Podzolic smectite
32
Ekіncі Şans, B., F. Esenlі, S. Kadir et W. C. Elliott. « Genesis of smectite in siliciclastics and pyroclastics of the Eocene İslambeyli Formation in the Lalapaşa region, NW Thrace, Turkey ». Clay Minerals 50, no 4 (septembre 2015) : 459–83. http://dx.doi.org/10.1180/claymin.2015.050.4.04.
Texte intégralRésumé :
AbstractThe Eocene İslambeyli Formation in the Lalapaşa region (NW Thrace, Turkey) consists predominantly of siliciclastic clayey clastics at the bottom and of claystone, tuff and tuffaceous claystone/ sandstone/limestone in the middle and uppermost parts of this formation. Some tuff-tuffaceous beds of the middle–upper parts of the formation are economically viable bentonite depoits. The İslambeyli Formation exhibits vertical variations in the mineralogy, elemental compositions, and smectite-forming processes. Smectite was formed by weathering and diagenetic processes in the fluvial-shore environments in the lower part and by diagenetic alteration in a shallow-marine environment in the middle–upper parts of the formation. Ca-smectite flakes were formed by two processes: direct precipitation; and by means of a dissolution-precipitation mechanism from feldspar and mica. Dissolution-precipitation was most prevalent in the siliciclastic lower part of the formation. The amounts of Al, Fe, Mg and Ca required to form smectite and accessory illite were supplied mainly from the alteration of feldspars, mica and glass shards. The origin of smectite can also be explained by the inferred solution compositions given the parent phases in this formation, and the devitrification of glass shards in pyroclastic-rich middle–upper parts of the formation. In the upper beds, the observed decrease of K and Fe in the smectite structure coincided with both the increase in the amount of smectite and the increase in solution pH suggesting that precipitation of smectite developed over a prolonged period and under arid conditions.
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Day-Stirrat, Ruarri J., et L. Taras Bryndzia. « Hydration behavior by X-ray diffraction profile fitting of smectite-bearing minerals ». E3S Web of Conferences 205 (2020) : 04009. http://dx.doi.org/10.1051/e3sconf/202020504009.
Texte intégralRésumé :
Clay mineral hydration and dehydration processes are reversible at temperatures <100 °C and strongly affect wellbore stability, fines migration, permeability, and dispersion of pore pressure. The hydration behavior of smectite-rich material as a function of relative humidity (activity of water, aw, controlled by salinity) and temperature was studied using in situ X-ray diffraction on a material retrieved from coring in the Gulf of Mexico. X-ray diffraction profile fitting was used to explore the competition for water between hydratable phases across a range of relative humidity, 2 % to 90 %, and temperature, 25°C to 95°C, conditions. X-ray diffraction profile fitting employed a modified multi-specimen approach in which proportions of minerals were modelled using Ca-exchanged preparations in air-dried and ethylene glycol solvated states. Across the range of hydration states, the mineral proportions and crystallographic parameters remained constant from the multi-specimen approach and only the number of water layers in hydratable phases varied. Quantitative clay mineralogy showed a natural material with a discrete smectite component and a mixed-layered illite-smectite, both capable of hydration/dehydration. Results of this study showed the discrete smectite component and the mixed-layered illite-smectite hydrated at different rates with discrete smectite up-taking more water at lower relative humidity than the mixed-layered illite-smectite. Over geological time this study highlights the non-static nature of smectite hydration with implications of long-term creep and permeability behavior.
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Pardo, Laura, Juan Cecilia, Cristina López-Moreno, Víctor Hernández, Manuel Pozo, María Bentabol et Francisco Franco. « Influence of the Structure and Experimental Surfaces Modifications of 2:1 Clay Minerals on the Adsorption Properties of Methylene Blue ». Minerals 8, no 8 (19 août 2018) : 359. http://dx.doi.org/10.3390/min8080359.
Texte intégralRésumé :
In this work the adsorption capacities of methylene blue on Mg-smectite and sepiolite and its derived material obtained after acid treatment and/or the addition of Fe at its surfaces are studied. Natural smectite with high Mg-content in its octahedral sheet (Mg-smectite) displays higher adsorption capacity than the sepiolite due to the ability of Mg-smectite to expand the basal spacing to accommodate methylene blue cations between adjacent layers and the inability of sepiolite to adsorb these cations within the structural channels. The acid-activation of Mg-smectite causes a clear decrease in the adsorption capacity attributed to the partial loss of the interlayer positions by the loss of the octahedral sheet and subsequent formation of amorphous silica. Moreover, the adsorption of the Mg-smectite decreases even more when iron oxohydroxides species are incorporated in its interlayer spacing making inaccessible the interlayer active sites for the adsorption of methylene blue cations. On the contrary, the microwave-assisted acid treatment of sepiolite causes a slight increase in the adsorption capacity related with the dispersion of fibers. Nevertheless, contrary to that observed with Mg-smectite, higher increasing of adsorption capacities are obtained after the formation of new adsorption centers due to the incorporation of iron oxohydroxides species at the external surfaces of sepiolite.
35
Delvaux, B., M. M. Mestdagh, L. Vielvoye et A. J. Herbillon. « XRD, IR and ESR study of experimental alteration of Al-nontronite into mixed-layer kaolinite/smectite ». Clay Minerals 24, no 4 (décembre 1989) : 617–30. http://dx.doi.org/10.1180/claymin.1989.024.4.05.
Texte intégralRésumé :
AbstractThe formation of kaolinite from Al hydroxy interlayered Garfield nontronite has been carried out at 225°C in hydrothermal conditions. The kaolinitization process, which proceeds through mixed-layer kaolinite/smectite intermediates, was followed by XRD, IR and ESR spectroscopy, chemical analysis and charge properties. The smectite content of the clay products decreases regularly with the duration of the hydrothermal treatment. The CEC and the structural Fe content of the deferrated products show a similar trend. IR features specific to nontronite disappear and are barely detectable as the smectite content of the mixed-layer clay falls below 30%. In contrast, the ESR spectrum of nontronite is characterized by a broad g2 signal that remains even after prolonged hydrothermal treatment. The calibration of the g2 ESR signal, due to Fe-smectite, shows that the synthetic kaolinites have low Fe contents (∼ 1% Fe2O3) indicating that the kaolinitization process involves destruction of the 2:1 layers and the subsequent neoformation of kaolinite and Fe oxides. As illustrated by the study of deferrated soil clay samples, representing a weathering sequence Fe-smectite → kaolinite + Fe oxides, ESR spectroscopy proved to be a powerful Fe probe for detecting Fe-rich smectite in kaolinite/Fe-smectite mixed-layer clays.
36
Li, Yuting, Peter D. Clift, Richard W. Murray, Elise Exnicios, Thomas Ireland et Philipp Böning. « Asian summer monsoon influence on chemical weathering and sediment provenance determined by clay mineral analysis from the Indus Submarine Canyon ». Quaternary Research 93 (2 octobre 2019) : 23–39. http://dx.doi.org/10.1017/qua.2019.44.
Texte intégralRésumé :
AbstractClay minerals from the Indus Canyon and eastern clinoform since ~12 ka are uniformly rich in smectite and illite, similar to those from the Holocene Indus flood plains. A systematic enrichment of smectite in the proximal delta compared to the canyon and eastern clinoform argues for preferential capture of smectite close to the river mouth since ~12 ka. There is a rapid shift to a more smectite-rich assemblage in the canyon and eastern clinoform after ~5 ka. This change is probably caused by a change in sediment source, with less direct flux from the Himalaya and more erosion of older, weathered, smectite-rich sediment from the Indus River flood plains, driven by incision of the Indus and its tributaries into the floodplain as summer monsoon rains weakened. This influx of smectite is consistent with lower kaolinite/smectite values since ~5 ka. The onset of large-scale agricultural activities since ~5 ka, especially starting with the Harappan Civilization, may also have enhanced incision and erosion of floodplain sediments over the same time period. This study reports for the first time how monsoon strength variations since ~12 ka affected the clay mineral assemblages and sediment provenance in a major submarine canyon.
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Chahi, A., N. Clauer, T. Toulkeridis et M. Bouabdelli. « Rare-earth elements as tracers of the genetic relationship between smectite and palygorskite in marine phosphorites ». Clay Minerals 34, no 3 (septembre 1999) : 419–27. http://dx.doi.org/10.1180/000985599546325.
Texte intégralRésumé :
AbstractDetrital smectite in a sandy claystone and a phosphorite, and authigenic palygorskite in a dolomitic marl and a porcellanite from Cretaceous-Tertiary phosphorite deposits of the Ganntour Basin (Morocco) were purified using cation exchange resin, leached with dilute acid, and analysed for the contents and distribution patterns of their REE before and after acid treatment. The normalized patterns confirm a detrital origin for the smectite in the sandy claystone, whereas the origin of the smectite from the phosphorite is obscured by the addition of REE from the phosphogenic environment. The normalized REE patterns of the palygorskite suggest formation in non-oxidizing restricted environments. The Al2O3/ΣREE ratio of the two clay types suggests formation of diagenetic palygorskite (and mixed-layer illite-smectite) from Al-bearing detrital smectite by a dissolution-crystallization process.
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Mosser-Ruck, Regine, Jacques Pironon, Michel Cathelineau et Alain Trouiller. « Experimental illitization of smectite in a K-rich solution ». European Journal of Mineralogy 13, no 5 (27 septembre 2001) : 829–40. http://dx.doi.org/10.1127/0935-1221/2001/0013/0829.
Texte intégral
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Robinson, D., et V. P. Wright. « Ordered illite-smectite and kaolinite-smectite : pedogenic minerals in a Lower Carboniferous paleosol sequence, South Wales ? » Clay Minerals 22, no 1 (mars 1987) : 109–18. http://dx.doi.org/10.1180/claymin.1987.022.1.09.
Texte intégralRésumé :
AbstractMixed-layer clay minerals of illite-smectite, having smectite contents ∼25% and IS ordering, kaolinite-smectite, and a three-component variety with kaolinite-smectite-chlorite-like material are described from a Carboniferous paleosol in South Wales. The clays, which are restricted to particular horizons, are unusual occurrences in a pedogenic sediment and pose particular problems as to their genesis. Positive geological evidence, principally in the form of mineralogical and organic thermal maturation data, demonstrates that the rocks of the region cannot have reached diagenetic temperatures > 100°C. This would appear to suggest a pedogenic rather than a diagenetic origin for these clays. In these sediments the only plausible mechanism of illitization to produce the illite-smectite would be by repeated wetting and drying cycles causing irreversible K fixation. Such cycles would be entirely realistic for a vertisol-like paleosol formed on overbank deposits in a floodplain environment subject to strong seasonal moisture contrasts. If this interpretation is correct, this illite-smectite represents the most illitic yet recorded from a non-burial or non-hydrothermal environment.
40
Buatier, M. D., K. Ouyang et J. P. Sanchez. « Iron in Hydrothermal Clays from the Galapagos Spreading Centre Mounds : Consequences for the Clay Transition Mechanism ». Clay Minerals 28, no 4 (décembre 1993) : 641–55. http://dx.doi.org/10.1180/claymin.1993.028.4.11.
Texte intégralRésumé :
AbstractGlauconite and Fe-smectite, which can be distinguished by their peculiar morphology and stacking sequences, coexist in the Galapagos Spreading Centre hydrothermal mounds. Analytical electron microscopy (AEM) data suggest that Fe is entirely in octahedral sites in Fe-smectite whereas glauconite is K-rich with Fe in tetrahedral and octahedral sites. However, the Mossbauer spectra, recorded at various temperatures for samples containing both smectite and glauconite, were satisfactorily analysed with three overlapping doublets corresponding to Fe in octahedral sites. The contradictory results obtained with the two methods are explained by the presence of small particles of iron oxide intimately associated with glauconite. These particles were detected in Mossbauer spectra obtained at 77 K and 4·2 K and were observed by transmission electron microscopy. Iron oxide is a secondary phase formed by alteration of smectite. These data are in good agreement with the hypothesis that the smectite-glauconite reaction, which occurs at 30 m and low temperature in the Galapagos hydrothermal mounds, is a dissolution-precipitation process, dissolution of Fe-rich smectite being followed by precipitation of glauconite and iron oxides.
41
Christidis, G. E., et N. Skarpelis. « CLAY MINERALOGY OF THE SEDIMENTARY IRON-NICKEL ORE OF AGIOS IOANNIS, NE BOEOTIA : NEW DATA AND IMPLICATION FOR DIAGENETIC MODIFICATIONS Christidis G. » Bulletin of the Geological Society of Greece 43, no 5 (31 juillet 2017) : 2553. http://dx.doi.org/10.12681/bgsg.11662.
Texte intégralRésumé :
The clay mineralogy of the sedimentary Fe-Ni deposit of Agios Ioannis and a Ni lateritic profile from Pavlos, both in Lokris area, Greece, is investigated. The clay fraction of samples from Agios Ioannis consists mainly of Fe-rich chlorite and Fe-smectite, with minor serpentine, hematite and goethite. Locally, disordered talc (kerolite and/or pimelite), illite, R1 mixed layer illite/smectite and gibbsite are identified. The lateritic profile has different composition and contains mainly Fe-rich smectite (nontronite and/or ferruginous montmorillonite) with minor serpentine, goethite, magnetite, and talc, whereas chlorite is absent. It is suggested that in the Agios Ioannis deposit chlorite has formed from smectite via R0 mixed layer chlorite/smectite with >80% chlorite layers. The source of Al is probably the diagenetic transformation of pedogenic goethite to hematite during burial. The lack of chlorite in the lateritic profile of Pavlos is attributed to the limited presence of goethite. Smectite is believed to be a major mineralogical constituent of the Fe-Ni ores of the broader Lokris area.
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Christidis, G. E., P. Katsiki, A. Pratikakis et G. Kacandes. « RHEOLOGICAL PROPERTIES OF PALYGORSKITE-SMECTITE SUSPENSIONS FROM THE VENTZIA BASIN, W. MACEDONIA, GREECE ». Bulletin of the Geological Society of Greece 43, no 5 (31 juillet 2017) : 2562. http://dx.doi.org/10.12681/bgsg.11663.
Texte intégralRésumé :
In this contribution we examine the rheological properties of palygorskite rich clays from the Ventzia Basin, W. Macedonia, Greece. The clays consist of palygorskite and/or dioctahedral Fe-rich smectite (nontronite) and quartz as main components, and serpentine, amphibole and sepiolite as minor constituents. The apparent and plastic viscosity and yield point increase with increasing concentration of clay in the suspension. Flow is Newtonian for 1% suspensions, becoming gradually Bingham plastic (3% clay suspensions) and then pseudoplastic with yield point described by the Herschel Bulckley flow model. In the case of suspensions cf smectite-free clays Bingham plastic flow behaviour was not observed. Addition of 1M NaCl electrolyte deteriorates the rheological behaviour of the smectite-bearing palygorskite clays but it does not affect significantly the smectite-free, palygorskite rich clays. The different rheological properties of the palygorskite compared to smectite is due to the different morphological and crystal-chemical properties of these two minerals. It is suggested that the palygorskite-rich clays can be used successfully as drilling muds in seawater based drilling fluids, in which smectite-based drilling muds tend to flocculate.
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Andrews, Julian E. « Jurassic clay mineral assemblages and their post-depositional alteration : upper Great Estuarine Group, Scotland ». Geological Magazine 124, no 3 (mai 1987) : 261–71. http://dx.doi.org/10.1017/s0016756800016289.
Texte intégralRésumé :
AbstractClay minerals from Middle Jurassic lagoonal mudrocks, siltstones and silty fine-grained sandstones of the upper Great Estuarine Group (Bathonian) are divided into four assemblages. Assemblage 1, the most common assemblage, is rich in mixed-layer illite–smectite with attendant illite and kaolinite. Assemblage 2 is dominated by smectitic clay. These assemblages are indicative of primary Jurassic deposition. Illite and kaolinite were probably derived from the weathering of older rocks and soils in the basin hinterland and were deposited in the lagoons as river-borne detritus. The majority of smectite and mixed-layer illite–smectite is interpreted as the argillization product of Jurassic volcanic dust, also deposited in the lagoons by rivers. Near major Tertiary igneous intrusions these depositional clay mineral assemblages have been altered. Assemblage 3 contains smectite-poor mixed-layer illite–smectite, whilst Assemblage 4 contains no smectitic clay at all. Destruction of smectite interlayers occurred at relatively shallow burial depths (< 2500 m) due to enhanced geothermal gradients and local convective hot-water circulation cells associated with the major Tertiary igneous intrusions.
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Bouchet, A., D. Proust, A. Meunier et D. Beaufort. « High-charge to low-charge smectite reaction in hydrothermal alteration processes ». Clay Minerals 23, no 2 (juin 1988) : 133–46. http://dx.doi.org/10.1180/claymin.1988.023.2.02.
Texte intégralRésumé :
AbstractIllite/smectite mixed-layered minerals (I/S) occurring in hydrothermally altered dacite from the island of Martinique were studied using X-ray powder diffraction, electron microprobe and CEC measurement techniques. Microprobe analyses and X-ray identification of high- and low-charge smectite layers indicate that the I/S hydrothermal alteration operates from wall-rock to hydrothermal veins, with conversion of high-charge to low-charge smectite and formation of illite layers. The overall alteration reaction can be expressed as: mixed-layered high-charge smectite + Si4+ + K+ → mixed-layered low-charge smectite + illite. This reaction requires Si and K from external sources and differs from the currently invoked mechanisms for diagenetic illitization where Si is released. The proposed reaction appears, therefore, to be the first step of I/S alteration under low-temperature hydrothermal conditions, prior to the crystallization of newly-formed I/S.
45
Lee, S. Y., et S. J. Kim. « Dehydration behaviour of hexadecyltrimethylammonium-exchanged smectite ». Clay Minerals 38, no 2 (juin 2003) : 225–32. http://dx.doi.org/10.1180/0009855033820091.
Texte intégralRésumé :
AbstractThe dehydration of hexadecyltrimethylammonium (HDTMA)-exchanged smectites has been studied using X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The basal spacing of hydrated HDTMA-smectites changed with temperature. The 2.5 HDTMA-smectite (i.e. smectite treated with HDTMA equivalent to 2.5 times the CEC) showed a continuous increase in its basal spacing during dehydration up to 200ºC, while the 1.2 HDTMA-smectite showed a significant decrease in basal spacing. It is assumed that the less ordered alkyl chains in the wet state in the interlayer region may be rearranged to ordered chains (e.g. all-trans conformation) during sequential dehydration. This results in a decrease in interlayer spacing in the phase with low organic packing density and a flat-lying array (i.e. 1.2 HDTMA-smectite), and a gradual increase in the basal spacing when the chains have a vertical configuration (2.5 HDTMA-smectite).
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MILES, N., et C. R. DE KIMPE. « APPLICATION OF GLYCEROL/ETHANOL SOLUTIONS FOR SOLVATION OF SMECTITES DRIED ON GLASS SLIDES ». Canadian Journal of Soil Science 65, no 1 (1 février 1985) : 229–32. http://dx.doi.org/10.4141/cjss85-025.
Texte intégralRésumé :
Glycerol/ethanol solutions with various glycerol concentrations were used for the solvation of smectite on glass slides. The effects of concentration and standing time before X-ray analysis were considered. A 14% glycerol solution in ethanol applied to the clay with a glycerol/clay weight ratio of 31% produced after 10 min standing time high intensity and maximum expansion of the basal spacing of smectite from 1.4 to 1.78 nm. The procedure described may be especially useful for the identification of smectite when present in small percentages. Key words: Glycerol solvation, basal spacing expansion, smectite characterization
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Karasa, J., J. Kostjukovs, A. Palaša et A. Actiņš. « Advanced Research of the Triassic Clay from the Baltic Region ». Latvian Journal of Chemistry 51, no 4 (1 décembre 2012) : 376–82. http://dx.doi.org/10.2478/v10161-012-0023-x.
Texte intégralRésumé :
A procedure of smectite containing clay enrichment has been optimized, and the process of sedimentation has been studied. The new enrichment based method for quantitative determination of clay fraction in smectite containing sediment was developed. A new method for obtaining organoclays from enriched smectite clays has been investigated. The method is based on solid-state reaction between smectite and organic compounds, where organic molecules can be intercalated in dried clay mineral (montmorillonite) by solid-state reactions, without or with use of solvents. The enriched clay and the obtained organoclay samples were characterized with X-ray powder diffraction (PXRD).
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Baker, Julian C., Philippa J. R. Uwins et Ian D. R. Mackinnon. « SWELLING BEHAVIOUR OF MIXED-LAYER CLAYS IN HYDROCARBON RESERVOIRS ». APPEA Journal 34, no 1 (1994) : 366. http://dx.doi.org/10.1071/aj93033.
Texte intégralRésumé :
The freshwater sensitivity of a variety of mixed-layer illite/smectite and chlorite/smectite clays has been studied with an Environmental Scanning Electron Microscope (ESEM) in order to determine whether all hydrocarbon reservoirs hosting these clays should be regarded as freshwater sensitive. Experimental procedures involved closely comparing in situ mixed-layer clay within selected areas at high magnification before and after prolonged freshwater treatments.The response of smectite-rich illite/smectite (two samples; 10–20 per cent illite interlayers) to freshwater immersion varied greatly. One sample rapidly swelled to many times its original volume to form a pervasive gel that greatly reduced porosity and permeability, whereas the other sample underwent only a subtle morphological change that had little or no adverse effect on reservoir quality. Illite-rich illite/smectite (three samples; 65—>85 per cent illite interlayers) and chlorite-rich chlorite/smectite (two samples; 50 per cent and >70 per cent chlorite interlayers) underwent no morphological change when immersed in freshwater for up to three months, indicating that these clays in sandstones are unlikely to cause formation damage due to swelling if exposed to freshwater-based fluids.
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Deconinck, J. F., A. Strasser et P. Debrabant. « Formation of illitic minerals at surface temperatures in Purbeckian sediments (Lower Berriasian, Swiss and French Jura) ». Clay Minerals 23, no 1 (mars 1988) : 91–103. http://dx.doi.org/10.1180/claymin.1988.023.1.09.
Texte intégralRésumé :
AbstractThe clay-mineralogical assemblages of Purbeckian carbonate sediments of the Swiss and French Jura Mountains are often composed of illite and interstratified illite-smectite. These illitic minerals occur mainly in thin layers of green marls which show evidence of subaerial exposure and mark the top of shallowing-upward sequences. X-ray diffraction, chemical and thermal analyses coupled with transmission electron microscopy suggest that the Purbeckian illitic minerals replaced smectite in intermediate continental-marine environments. The transition from smectite to illite and interstratified illite-smectite probably resulted from repeated cycles of wetting by marine waters and subsequent drying in hypersaline environments, under a hot Purbeckian climate.
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López-Quirós, Adrián, Antonio Sánchez-Navas, Fernando Nieto et Carlota Escutia. « New insights into the nature of glauconite ». American Mineralogist 105, no 5 (1 mai 2020) : 674–86. http://dx.doi.org/10.2138/am-2020-7341.
Texte intégralRésumé :
Abstract Glauconite must be assessed as mica-rich mica-smectite R3 interstratified mineral, with the pure end-member mica also having intrinsic K-deficient chemical characteristics (K+ ~ 0.8 apfu). This assertion is in accordance with our X-ray diffraction (XRD) and high-resolution tranmission electron microscopy (HRTEM) studies and chemical analyses by electron probe microanalysis (EPMA) of mature glauconites in Cenozoic Antarctic sediments that indicate that: (1) It consists of a glauconite-smectite (R3 ordered) mixed-layer silicate, composed mainly of mica-type layers (>90%), but displaying slightly different proportions of Fe(III)-smectite layers (<10%). (2) More mature glaucony grains are characterized by major K+ and VIFe2+ (mica layers) and minor VIFe3+ (smectite layers) content in the interstratified glauconite-smectite. (3) Potassium is stabilized at the interlayer site by the octahedrally coordinated Fe2+. (4) Microtexture of the glauconite crystals are comparable with those of other micas and illite minerals, with straight, defect-free lattice fringes of ~10 Å spacings glauconite packets characteristic of mica with minor interstratified poorly crystalline smectite layers. In addition, our new findings give insights into the glauconitization process and at the same time investigate the potassium-deficient character of the dioctahedral mica “glauconite.” These findings show that glauconite crystallizes by a layer-growth mechanism at the expense of a poorly crystalline smectite precursor and that smectiteto-glauconite transformations are accompanied by a gradually higher octahedral charge deficiency (Fe2+/Fe3+) stabilized by K+ uptake into the interlayer sheet.