bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-ray identification of randomly interstratified illite-smectite in mixtures with discrete illite
Authors: Środoń Jan 
Published: December 2006

AbstractProportions of the component layers in randomly interstratified illite-smectites can be determined precisely in the presence of discrete illite if two reflections (at 15–16 and 31–32°2θ Cu Kα) are strong enough to be measured accurately. The method takes into account the variable thickness of the smectite-ethylene glycol complex and involves a correction for the interference from illite reflections.
A mineralogical and geochemical study of turbidite sandstones and interbedded shales, Mam Tor, Derbyshire, UK
Authors: Spears D.A. , Amin M.A. 
Published: December 2006

AbstractEleven shales and fourteen turbidite sandstones from the Mam Tor Beds were analysed chemically and by XRD. The ratio of kaolinite to illite plus mixed-layer clay was higher in the sandstones than in the shales, size fractions demonstrating that this ratio decreased as the grain size decreased. Shales more basinal in character than those of the Mam Tor Beds contain more illite and mixed-layer clay and less kaolinite and it is suggested that there was a lateral variation in clay mineralogy with distance from the shore line due to particle size sorting and that the character of the clay mineral fraction was retained as the turbidity current transported sediment from a nearshore environment deeper into the basin. Support for this model was obtained from the geochemistry which showed that the sandstone matrix differed compositionally from the shales. Systematic variations occurred in the turbidite sandstones but not in the shales which are therefore considered to be non-turbiditic. Only minor mineralogical changes appear to have occurred during diagenesis.
Clay mineral diagenesis in Rotliegend aeolian sandstones of the southern North Sea
Authors: Rossel N. C. 
Published: December 2006

AbstractThe distribution of diagenetically-formed clay minerals in Rotliegend dune sandstones of the Southern North Sea Basin is closely related to the following factors: (i) the petrography of the sandstones, (ii) the paleoburial depth and tectonic setting of the area, (iii) the thickness of gas-generating Carboniferous strata underlying the Rotliegendes, and (iv) the facies distribution of the overlying Zechstein. The diagenetic clay minerals are mainly conversion products of feldspars and, to a lesser extent, of detrital clays and micaceous lithic fragments. Sandstones containing dominant drusy illitic and chloritic clay minerals have been buried to depths > 3000 m; if kaolinite is the dominant clay mineral, burial depths were less. Sandstones containing feldspars (detrital and authigenic) up to approximately 7% of bulk volume have permeabilities that are about four times higher than sandstones with similar amounts of kaolinite, and as much as 200 times higher than sandstones with similar amounts of illite and/or chlorite.
Surface-charge determination of crocidolite particles in suspension
Authors: Isherwood R. , Jennings B. R. 
Published: December 2006

AbstractThe translatory and rotatory diffusion coefficients, electrophoretic mobility, permanent dipole moment, electrical polarizability and optical anisotropy factor for a crocidolite sol have all been measured in a single optical apparatus. Electrophoretic light-scattering and electrically-induced birefringence were the methods used, these being rapid and well-suited to particles in the micron and sub-micron size-range, where conventional electrophoresis is difficult. Electric birefringence offers a fast means of sizing mineral particles in suspension and the electrical polarizability and electrophoretic mobility have a common origin in such sols. This is discussed in terms of the surface-charge and electric double-layer characteristics of the particles.
Reaction products of organic dye molecules with acid-treated montmorillonite
Authors: Fahn R. , Fenderl K. 
Published: December 2006

AbstractDuring the reaction of solutions of the leuco dyes crystal violet lactone and N-benzoyl leuco methylene blue with acid-treated montmarillonite (as occurs with carbonless copying papers), most of the offered dye is intercalated within the interlayers of the montmorillonite structure remaining after acid attack. This phenomenon was demonstrated by XRD and also by high-resolution transmission electron microscopy. During acid treatment, octahedral cations are dissolved from exposed edges of the montmorillonite lamellae and amorphous silica builds up in these areas. As a result, the BET(N2) specific surface area increases from ∼60 m2/g to ∼300 m2/g and, consequently, the theoretical reactivity towards leuco dyes. Nevertheless, only small quantities of the dye molecules are adsorbed onto the amorphous silica. The excellent colour intensity and, in particular, the resistance to fading in the light of the montmorillonite dye complexes may be explained by the protected position of the dye molecules within the interlayers of the montmorillonite.
Iron substitution in aluminosilicate sols synthesized at low pH
Authors: McBride M. B. , Farmer V. C. , Russell J. D. , Tait J. M. , Goodman B. A. 
Published: December 2006

AbstractThe procedure for synthesizing proto-imogolite (an acid-soluble hydroxy-aluminium orthosilicate complex) and imogolite (a tubular aluminosilicate mineral) was used to produce ferruginous aluminosilicates over a range of Al/Fe ratios to determine whether Fe3+ can be incorporated in the imogolite structure. Analysis of the synthesized products by transmission electron microscopy, electron diffraction, and IR spectroscopy indicated that, while imogolite was formed in the presence of iron, increased Fe3+ in the systems caused the formation of ferrihydrite and poorly-organized aluminosilicates resembling proto-imogolite allophane. Treatment of these materials with Na-citrate/dithionite/bicarbonate dissolved the ferrihydrite and poorly-organized aluminosilicate, and concentrated products with tubular morphology. Analysis of the structural Fe3+ by ESR spectroscopy suggested that little or no Fe3+ was incorporated in the structure of imogolite, although the less crystalline proto-imogolite allophane may have accommodated some structural Fe3+. A separate iron-rich product, identified as ferrihydrite, was formed at low Al/Fe ratios. Mössbauer spectroscopic analysis of 57Fe3+ doped at very low levels into proto-imogolite and imogolite indicated that the sites of substitution were better defined in the latter. At least part of this Fe3+ may have been incorporated in the structure of boehmite, an impurity formed during synthesis.
The influence of aluminium on iron oxides: IX. Dissolution of Al-goethites in 6 M HCl
Authors: Schwertmann U. 
Published: December 2006

AbstractThe rate of dissolution of synthetic Al-goethites with 0–10 mole% Al in 6 m HCl at 24°C decreases markedly with increasing extent of Al substitution. Most of the dissolution-time curves are S-shaped, suggesting some increase in surface area during the initial stages of dissolution. Based on electron microscopic examination, the increase in surface area is explained by preferential dissolution of less ordered ‘interdomainic’ zones and the consequent production of isolated ‘domains’. Thin sections of crystals provided some support for defect zones oriented parallel to the crystallographic c-direction. Stepwise multiple correlation analysis employing various properties of the goethites was used to investigate the large variation in half-dissolution time (1–96 h). 94% of the variation could be explained by the variation of the mean crystallite dimension perpendicular to the planes (110) and (111) (MCD110, MCD111). Inclusion of Al-substitution increased R2 to only 97%. As shown in a separate experiment, increasing Al concentration in the system retarded crystal growth. It is therefore believed that Al affects the dissolution rate of goethites not directly, but indirectly, by influencing crystal growth rate which, in turn, affects crystal size and order as measured by MCD110 and MCD111.
Weathering products of andesitic rocks from Sulawesi, Indonesia
Authors: Müller H. W. , Riedmüller G. , Schwaighofer B. 
Published: December 2006

AbstractMineralogical investigations of weathered andesitic bedrock and overburden on the valley flank of the Tondano river, Manado, Sulawesi, indicated that these had been subjected to different weathering conditions. The underlying andesite was completely altered to 7Å-halloysite and allophane. In the transported latosols of the overburden, 10Å- and 7Å-halloysites were found. The ratio of 10Å- to 7Å-halloysite increased linearly with depth in the profile. It is considered that weathering of the andesitic bedrock reflects a palaeoclimate with more strongly pronounced seasonal desiccation and lower annual rainfall. Neoformations by weathering of the overburden took place under the recent tropical climate.
The Mössbauer spectra of hydroxycarbonate green rusts
Authors: Murad E. , Taylor R. M. 
Published: December 2006

AbstractMössbauer spectra of Fe2+Fe3+ and Fe2+Al hydroxycarbonates taken in the paramagnetic state were fitted using two Fe2+ and Fe3+ doublets each. These spectra can be interpreted in terms of an ordered cation arrangement in the pyroaurite-type structure. The inner Fe2+ doublet seems to be the outcome of excess Fe3+ in the samples studied. The outer Fe2+ doublet (quadrupole splitting ∼2·8 mm s−1, FWHM = 0·26 mm s−1) is relatively well-defined and can, together with the fact that this doublet disappears on oxidation, possibly serve to identify these compounds in natural systems.
Fibrous silica gel obtained from sepiolite by HCl attack
Authors: Gozález L. , Ibarra L. M. , Rodríguez A. , Moya J. S. , Valle F. J. 
Published: December 2006

Sepiolite is an Mg-silicate with fibrous morphology. Its structure consists of talc-like ribbons parallel to the fibre axis. Although the tetrahedral sheets are continuous, the apices in adjacent ribbons point in opposite directions, each ribbon alternating with an open channel along the fibre axis. Tetrahedral positions are normally filled with Si atoms. The width of the ribbons corresponds to eight octahedral positions, which are, normally occupied by Mg atoms, and the channel cross-section is 3·8 x 9·4 Å. This structure gives the mineral a high adsorptive capacity and molecular sieve capability. The ideal mineralogical formula is (OH2)4(OH)4Mg8Si12O30.8H2O (Brauner & Preisinger, 1956).Activation of sepiolite by acid attack has been extensively studied (Fernández-Alvarez, 1972; Jiménez-López et al., 1978; Rodríguez-Reinoso et al., 1981). This note describes the changes undergone by sepiolite during dissolution of the octahedral Mg-sheet by HCl attack, silica gel being the end-product. This process was followed by IR spectroscopy, study of Mg-extraction kinetics, and morphological observations by SEM and TEM.
Ferrihydrite in pyrophosphate extracts of podzol B horizons
Authors: Kassim J. K. , Gafoor S. N. , Adams W. A. 
Published: December 2006

The amount of Fe and Al extracted from soil by 0·1 M pyrophosphate (Fep, Alp) has long been used as a criterion in the designation of spodic horizons of podzols (Avery, 1973). Although Adamset al.(1980) showed that in a group of podzolic soils developed from Lower Palaeozoic sedimentary (LPS) rocks Fepwas very closely correlated with the quantities of Fe eluviated and illuviated, such evidence validating the use of pyrophosphate is not generally available. Recently there has been renewed interest in the identification of forms of Fe and Al extracted by pyrophosphate in order that greater confidence might be gained in the use of Fepand Alpin soil classification (McKeague & Schuppli, 1982).Our interest in pyrophosphate extraction was stimulated when Nto (1981) discovered that Fepwas an excellent predictor of P sorption in soils developed from LPS rocks. Indeed, the level of predictability was not improved by the inclusion, in multiple regressions, of either Fe or Al extracted by any other of the commonly used selective extractants.
The adsorption of quadrivalent cerium by kaolinite
Authors: Laufer F. , Yariv S. , Steinberg M. 
Published: December 2006

AbstractThe adsorption of cerium(IV) by both natural and Na-exchanged kaolinite from aqueous solutions of ceric ammonium nitrate was studied in equilibrium systems. Cerium may be adsorbed either as a monomeric species or as a polymeric hydroxy cation. The species adsorbed depends on the concentration of cerium in the stock solution, the age of this solution prior to the preparation of the equilibrium system and on the equilibration period. Adsorbed cations undergo polymerization on the surface of the kaolinite; the resulting polymeric species forms strong bonds with the clay surface—it is not desorbed by sulphuric acid—and may be considered fixed. Adsorption of cerium reaches a maximum in solutions containing 0·15 M sulphuric acid.
Influence de la lyophilisation sur la structure d'une argile sensible du Québec
Authors: Delage P. , Pellerin F. M. 
Published: December 2006

ResumeL' étude de la structure d' une argile sensible du Québec est abordée en porosimétrie au mercure après lyophilisation et en microscopie électronique à balayage sur une surface obtenue par fracture de l' échantillon congelé (système Cryoscan). On observe une structure en agrégats définissant deux classes de pores. A grande vitesse de congélation, la cristallisation de la glace semble surtout affecter les points faibles de la structure, qui sont les ponts de plaquettes reliant les agrégats les uns aux autres.
Relation entre surface specifique taille et morphologie des particules: applications a la kaolinite
Authors: Cambier P. 
Published: December 2006

ResumeLa relation entre la surface développée par les particules d'une poudre et leur paramètre de taille et de morphologie est abordée de façon théorique, rigoureuse et générale. A l'aide d'un nouveau choix des grandeurs mesurées, il est possible de ne prendre en compte qu'une seule distribution statistique, de l'un des paramètres, les autres paramètres n'apparaissant dans la formulation qu'à travers leurs moyennes arithmétiques. Dans le cas de plaquettes, le problème est analysé de façon théorique et expérimentale. La formulation est encore simplifiée et on voit que la formule la plus simple consistant à négliger surfaces latérales et distribution de taille est finalement parmi les meilleures, les deux approximations se compensant.
Transformation of an aluminosilicate gel into pre-kaolinitic and pre-zeolite structures: effects of the solution media
Authors: De Kimpe C. R. , Kodama H. 
Published: December 2006

Rodrique et al. (1972) reported that kaolinite was formed at 200°C from gels with an A12O3/(A12O3 + SiO2) weight ratio ⩽0·315 and pH values ranging from 4·8 to 5·8. At this temperature and using a gel with an A12O3/(A12O3 + SiO2) weight ratio >0.315, boehmite and pseudoboehmite, were obtained at pH values of up to 5·8. The latter minerals were also observed in the products formed under similar conditions at 175°C.Unlike the situation under acidic conditions, where gel composition is important, the gel/solution ratio becomes critical under alkaline conditions. When the gel/solution ratio is low, zeolites are produced from a gel with a weight ratio between 0·3 and 0·5 in the presence of NaOH at 130-170°C (De Kimpe, 1976). When the gel/solution ratio is high, kaolinite instead of zeolites is formed under similar conditions (De Kimpe, 1969, 1976). For an intermediate gel/solution ratio, smectite is produced from a gel with a weight ratio of 0.4 in the presence of NaOH at 175°C In the presence of KOH, however, kaolinite is the only crystalline product formed under similar pH and temperature conditions (De Kimpe et al., 1981).
Early carbonate diagenesis within Phanerozoic shales and sandstones of the NW European Shelf
Authors: Gluyas J. G. 
Published: December 2006

AbstractContinuous nodular limestone beds in north-west European shale sequences developed during early diagenesis via anaerobic, bacterial catabolysis of organic matter which yielded both carbonate and sulphide. The high carbonate content of the nodular limestones (50–90%) demonstrates that they developed in the upper tens of metres of the sediment column. In addition, each of the nodular limestones displays a centrifugal decrease in carbonate, indicating that growth was synchronous with compaction of the host ooze. The chemistry of the carbonate changed with time, becoming more rich in magnesium and iron and reflecting a progressive change in the porewater chemistry from its initially marine composition. The earliest precipitate was calcite containing < 1 mole% MgO; later precipitates contained several percent MgO and ultimately dolomite was precipitated. Similarly, iron content of the carbonate increased as precipitation continued and sulphate reduction, and thus pyrite production, declined. The early diagenetic cementation of many marine sandstones followed a pattern similar to that of nodular limestones and much of the carbonate was also derived from organic matter via bacterial oxidation. Thus, early diagenetic bacterial oxidation of organic matter may not only reduce the source potential of shales but also reduce the reservoir potential of associated sandstones, or those more distant which lie along compactional-fluid pathways.
Diagenesis, porosity and permeability in the Corallian Beds (Upper Oxfordian) from the Harwell Research Site, South Oxfordshire, UK
Authors: Milodowski A. E. , Wilmot R. D. 
Published: December 2006

AbstractThe Corallian Beds beneath the Harwell Research Site, south Oxfordshire, are a highly variable sequence of sandstones, mudstones and limestones. The more permeable lithologies of the upper part of the sequence constitute an important local aquifer. Diagenetic and post-lithification processes have strongly influenced the porosity, permeability and mineralogy of the aquifer rocks. Calcite cementation reduced the porosity and permeability of the sandstones and limestones in the upper part of the aquifer. Cementation occurred in at least three stages ranging from early diagenesis to post-compactional diagenesis. Late-stage dissolution of calcite took place along fractures and bedding discontinuities, restoring the porosity and permeability of these sediments and developing secondary porosity and permeability where original clastic carbonate was removed. Invasion of the Corallian porewaters by waters charged with CO2 is postulated as a mechanism by which calcite was removed. At the base of the aquifer, early diagenetic dissolution of biogenic silica created a high secondary porosity. Silica was reprecipitated in the dissolution voids and matrix as opal-CT. Authigenic smectite and zeolites are also associated with opal-CT. These phases are believed to have precipitated from pore-waters rich in ions derived from the alteration of volcanogenic detritus associated with the Corallian sediments.
Diagenetic influences on reservoir properties of the Sherwood Sandstone (Triassic) in the Marchwood geothermal borehole, Southampton, UK
Authors: Knox R. W. O'B. , Burgess W. G. , Wilson K. S. , Bath A. H. 
Published: December 2006

AbstractPetrological studies of the Sherwood Sandstone of the Marchwood Borehole show that the formation is made up of two units of differing primary lithological character: a lower unit with lithic sandstone and conglomerate, and an upper unit with arkosic sandstone. A combination of compaction and calcite cementation (early and late) has severely reduced porosity and permeability in the lower unit. In the upper unit compaction is again important, but several beds have largely escaped cementation, and their primary porosity has been enhanced by leaching of feldspars. The secondary porosity reaches 7% in some samples. Oxygen and carbon isotope data for the early (calcrete) cements indicate isotopic equilibrium with typical freshwater compositions. The later cements yield more variable values, indicating precipitation under a wider range of conditions.
Authigenic chlorites: problems with chemical analysis and structural formula calculations
Authors: Curtis C. D. , Ireland B. J. , Whiteman J. A. , Mulvaney R. , Whittle C. K. 
Published: December 2006

AbstractAnalytical transmission electron microscopy was applied to some authigenic chlorites occurring as grain coatings in sandstones. Compositional variation proved to be relatively slight: all were magnesian chamosites. The coating chlorites were often intimately mixed with extremely fine-grained (0·01–0·2 µm) hematite but analytical ‘contamination’ was avoided because of the very high resolution of both observation (spot location) and analysis. One example of a water-sensitive (‘swelling chlorite’) coating was also studied. This proved to have a very much more variable composition even within a single section. The coating appeared to include both chloritic and vermiculitic components. The effect of this on structural formulae is discussed and a model proposed in which the ‘talc’ layer may be common to both components.
The soil clays of Great Britain: I. England and Wales
Authors: Loveland P. J. 
Published: December 2006

AbstractThe mineralogy of the clay fractions (<2 µm) of the major soils of England and Wales is reviewed, and the data presented in terms of the 1:250 000 National Soil Map. Most soils developed in pre-Rhaetic sediments are dominated by mica with lesser amounts of chlorite and kaolin. Exceptions are soils developed in calcareous Coal Measure shales which have significant smectite contents, and freely drained soils in Keuper Marl which contain swelling chlorite, sepiolite and palygorskite. Soils developed in post-Triassic sediments are dominated generally by expansible minerals, except for those developed in Lower Lias and Estuarine Series rocks (Jurassic) which are dominated by mica and kaolin respectively. The presence of loess in soils seems to be associated with the occurrence of a complex interstratified mineral with X-ray diffraction properties akin to vermiculite. Weathering of soil clays is most marked in the wetter uplands, but over most of lowland England is detectable only by slight changes in non-exchangeable potassium content and cation-exchange capacity towards the soil surface. Applications of soil clay mineralogy in the fields of plant nutrition and soil mechanics are discussed, in particular the production of maps showing mineralogical provinces.
The soil clays of Great Britain: II. Scotland
Authors: Wilson M. J. , Bain D. C. , Duthie D. M. L. 
Published: December 2006

AbstractThe soils of Scotland are relatively young, being developed mainly on glacial drift deposited some 10 000 years ago. Only a small number of genetic soil types are represented, but this is more than compensated for by the wide variety of parent materials from which the drift ultimately derives. The major parent materials include granite and granitic gneiss, gabbro, basalt/andesite, mica-schist and related metamorphic rock types, Lower Palaeozoic greywackes and shales, Old Red Sandstone sediments, Carboniferous sediments, fluvioglacial sands and gravels, and estuarine silts and clays. The clay mineralogy of the soil associations developed on these parent materials is described and the origin of the clay minerals is interpreted. It is concluded that the influence of inheritance is predominant, but that the effects of pre-glacial weathering and Holocene pedogenesis can also be discerned. Inheritance has contributed a wide variety of clay minerals to the soils, including illite, kaolinite, chlorite, smectite and a number of interstratified minerals, pre-glacial weathering has resulted in the widespread formation of kaolinite and halloysite, irrespective of soil parent material or drainage class, and recent pedogenesis has brought about the transformation of inherited layer silicates by vermiculitization processes, with concomitant interlayer alumination, particularly in surface horizons.