Showing papers on "Clay minerals published in 1978"

Diagenesis in first-cycle desert alluvium of Cenozoic age, southwestern United States and northwestern Mexico

Abstract: Petrographic studies of first-cycle desert alluvium of Cenozoic age in the southwestern United States and northwestern Mexico show that the mineralogy, texture, and chemical composition of the deposits have been changed diagenetically. The mineralogy has been changed by addition of mechanically infiltrated clay, partial removal of framework grains of feldspars and ferromagnesian silicates, and precipitation of authigenic potassium feldspar, zeolite, montmorillonite, quartz, hematite, and calcite. The texture has been changed by three processes: (1) infiltration of detrital clay and formation of authigenic montmorillonite, which form interstitial clayey matrix not present in the original sediment, (2) formation of voids where framework grains have been dissolved, and (3) in situ formation of silt and other fine-grained sizes. The chemical composition has been changed by infiltration of clay minerals that are richer in aluminum and lower in alkalis and alkaline earths than the original sediment and by removal in ground water of some of the ions released by dissolution and replacement of framework grains. These changes have significantly increased the mineralogical maturity and decreased the textural maturity of the sediments diagenetically. Four major conclusions are drawn from the studies. (1) Some or all of the diagenetic alterations observed in these deposits probably occurred in many analogous ancient first-cycle alluvial deposits at a comparable time in their history. (2) Prolonged movement of ground water through first-cycle deposits may cause unstable minerals to be removed completely, or nearly so, leaving no direct evidence that they were important original constituents of the deposits. (3) Ancient first-cycle alluvium probably rarely, if ever, has the same mineralogy, texture, or chemical composition that the sediments had when deposited. (4) The present mineralogy, texture, and chemical composition of ancient first-cycle alluvial deposits probably do not accurately reflect lithology and climate in the source area or the nature of depositional currents and other environmental factors in the depositional basin.

Synthesis of iron layer silicate minerals under natural conditions

Abstract: The low temperature synthesis of iron silicate minerals with clay structures is possible at surface temperatures only under reducing conditions. Under oxidizing conditions clay minerals could not be synthesized. Instead quartz and quartzine were found in these X-ray amorphous Fe III hydroxide-silica precipitates after 14 days at low temperatures (20 ~ and 3~ as well as geothite or X-ray amorphous iron hydroxides. Only from solutions containing Fe-II could the different iron-containing clay minerals be built up within days at low temperatures. The presence of Fe-II enables an octahedral layer of the hrucite-gibbsite type to be formed. This is necessary for the bidimensional orientation of SiO4-tetrahedra leading to clay mineral formation. The presence of Fe ~§ and/or Mg2+-ions is necessary for the formation of the A13+- and Fea+-containing octahedral layers. The reducing conditions were obtained in the experiments by addition of dithionite. With a high content of silica (ca. 20 ppm SiO2, 7 ppm Fe) nontronite and lembergite, the di-Fe-III and tri-Fe-II octahedral, three-layer silicates, were built up in several days at low temperatures. With a lower silica content, that is, a lower Si/Fe ratio (15 ppm SiO2 and 20 ppm Fe), the two-layer silicate minerals greenalite and chamosite could be synthesized. A higher Mg content and more reducing conditions in the solutions favored the tri- as well as dioctahedral chamosite synthesis. The conditions of formation of recent naturally formed nontronite fit well with the synthesis conditions. Chamosites in sedimentary iron ores are characterized by a low content of SiO2, between 15-30% SiO2. This low content of silica cannot be the result of primary precipitation from seawater. The iron and silica ratio in seawater or in river waters would lead to a precipitation of ~60% SiO2 in the iron hydroxide precipitates. A probable origin for chamosite iron ores, which explains the low SiO2 content, is diagenesis of the lateritic weathering crust. Indeed, investigations of recent tropical shoreline sediments and in particular their trace element content confirm that cliamosite minerals have formed diagenetically from lateritic panicles in reducing sediments.

Catalytic Polymerization of Phenolic Compounds by Clay Minerals

Abstract: A solution of phenolic compounds was added separately to montmorillonite, illite, and kaolinite, each of which had been mixed with quartz in a 3:7 ratio, and to pure quartz. The oxidative polymerization took place at once and was allowed to proceed for 10 days. The humic and fulvic acids wer

Hydrothermal reactivity of smectite

Abstract: Hydrothermal experiments were conducted to explore the effects of changing chemistry, temperature, and pressure on the reaction of smectite, run I : I with pure water, to mixed-layer clay. At high temperatures trioctahedral smectites are more stable than dioctahedral smectites' For dioctahedral smectites, hydrothermal stabil ity is enhanced by saturation with interlayer cations of greater hydration energy than potassium, and by increased water pressute. Introduction Many of the unusual physical and chemical properties of the smectite group of clay minerals are related to the expandable interlayer region. These properties, which include swell ing, cation exchange capacity, catalytic activity, and thixotropy, are sometimes diminished or lost during hydrothermal treatment as the smectite reacts to form mixed-layer clay. It is of interest, therefore, from both a geologic and an industrial point of view, to determine the conditions under which smectites are least l ikely to react. Our experiments explore the effects of chemical composition, temperature, and pressure on the hydrothermal alteration of smectite to mixed-layer clay. Experimental techniques A direct comparison between the reactivity of dioctahedral and trioctahedral smectites was made by saturating each type of clay with various interlayer cations and then subjecting them to identical hydrothermal conditions. Trioctahedral starting materials included a natural saponite from Karolihof, Switzerland (<2 micron size fraction) saturated with K, Na, Ca, or Mg; u natural saponite from the Amargosa Valley, Nevada ((2 micron fraction); and gels of potassium and magnesium saponi te composi t ion, Mg.Sir..rAlo3aOr0(OH)rxilrr, where X+ is the exchangeable cation. Dioctahedral starting materials were the Wyoming bentonite ((2 micron fraction, Mol l e l a l . , 1975) saturated wi th K, Na, Ca, or Mg, and a gel of potassium montmor i l lon i te composi t ion, Alrsia 6?4.10 $Oro(OH)rKo.re. Gels were prepared by the method of Hami l ton and Henderson (1968). oo03-004x/78/0304-0401$02 00 401 Hydrothermal runs were prepared by introducing 30 mg of clay or gel and 30 pl of pure water into gold tubes (20 mm long, 2.5 mm I.D.) which were then welded shut. These charges were heated in large hotseal autoclave reaction vessels or in small cold-seal reaction vessels. The former generated maximum pressures of approximately 0.3 kbar, and the latter were maintained at 0.5 or 2 kbar by equil ibration with a large reservoir (see Eberl and Hower, 1976). All vessels were heated in resistance furnaces, and temperatures were controlled by on-off regulators attached to thermocouples located in wells near or in the base of the vessels. Run products were oriented on glass slides, glycolated, and X-rayed with a Norelco diffractometer, using Ni-fi l tered CuKa radiation. The expandabil ity of mixed-layer i l l i te/smectite was determined by comparison with the calculated patterns of Reynolds and Hower (1970). Experimental results The difference in reactivity between dioctahedral and trioctahedral smectite is clearly shown in Tables I and 2 and in F igures 1,2, and 3. At 400'C and autoclave pressure, the K-montmoril lonite gel (run I ) and the natural montmoril lonites saturated with K, Na, Ca, and Mg (runs 2-5) reacted extensively to lbrm regularly interstratif ied mixed-layer clay. The sraponites run under equivalent conditions did not react (runs l0-18). The effect of interlayer chemistry on the reaction of dioctahedral clays is also shown in Table l. Montmoril lonite with interlayer potassium (run 6) reacted at a lower temDerature than did mont402 EBERL ET AL.' REACTIVITY OF SMECTITE Table I Montmor i l loni te autoclave runs Run n o . Start ing mater i .a l Ternp. ( oc ) Time (days ) Run produc ts

The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl and Rhaetic of parts of England

Abstract: Hypotheses are reviewed on the origin of the magnesium-rich Triassic clays which characterize the Germanic facies of western Europe and north Africa. Relations between clay minerals, megafacies and stratigraphy are described from 28 localities in the Triassic Keuper Marl, Tea Green Marl and Rhaetic sediments of England. Two clay mineral assemblages are recognized: (1) a detrital assemblage of mica with minor chlorite which occurs throughout all the sediments investigated, and (2) a neoformed assemblage of magnesium-rich clay minerals with a limited occurrence related to certain megafacies cycles which resulted from the transgression and regression of the Alpine facies into the Germanic facies; this assemblage includes sepiolite, palygorskite, chlorite, smectite, corrensite and irregular mixed-layersmectite/mica$\dagger $ and smectite/chlorite minerals. The clay mineral neoformations resulted from reactions between the water masses in which the Germanic and Alpine facies were deposited. Controlling the distribution and types of minerals neoformed were the general and local variations in the chemistries of the Alpine and Germanic water masses, as well as competition for available magnesium from other mineral-forming reactions.

Alteration of glass as a possible source of clay minerals on Mars

Abstract: Thermodynamic calculations show that, under present Martian surface conditions, favorable gas-solid weathering products of feldspar glasses should include beidellites (clays of the montmorillonite series) + carbonates + quartz. The gas-solid weathering of mafic silicate glass ( of volcanic or impact origin) may similarly favor the production of metastable Fe-rich montmorillonite clays. Simple mass-balance calculations suggest that gas-solid weathering of Martian proto-regolith containing 10% glass could conceivably produce a global blanket of clays at a rate of at least 0.4 cm/b.y. The production rate should be expected to increase significantly with the glass content and rate of reworking of the proto-regolith and with the availability of water. Complete extraction of altered glass from a lunar-like proto-regolith might yield a global Martian clay blanket about 10-100 cm in thickness.

Relationships of specific surface area and clay content to shrink-swell potential of soils having different clay mineralogical compositions

Abstract: Data for 22 samples from 17 pedons were analyzed for relationships of specific surface area and amounts and kinds of clay to coefficient of linear extensibility, as determined by the paste method (COLErod), and to free swelling index (FSI). The soils were divided into three main groups according to their clay mineralogy. The clay of the first group was micaceous, that of the second group kaolinitic, and that of the third group montmorillonitic. Both clay contents and specific surface areas of the combined first and second groups of soils were closely related to COLErod (r2 = 0.81 and r2 = 0.91) with specific surface area giving the higher correlation. The correlation of clay content with COLErod decreased markedly, however, when the montmorillonitic soils were included (r2 = 0.56). In contrast, the correlation of specific surface area with COLErod remained high (r2 = 0.97), indicating that for the soils used in this study, specific surface area was more basic with respect to shrink–swell potential than wa...

Mineral matter in Australian bituminous coals

Abstract: The mineral matter has been isolated from a selection of Australian bituminous coals using low temperature (radio-frequency) oxidation or hydrogen peroxidation techniques and the species present identified by x-ray diffraction. Quartz, kaolinite, and a range of mixed layer clay minerals are the dominant constituents of the coals studied, with carbonate, sulphate, and phosphate minerals abundant in some samples. The clay bands that occur within these coal seams contain similar mineral assemblages to the coals themselves, but the lutites that form the inter-seam strata have a markedly different mineralogy, characterized by abundant quartz and illite and a low kaolinite content. The kaolinite is thought to have formed chiefly by interaction of silica and alumina in the waters of the coal swamp, aided by the catalytic action of organic acids, while most of the other clay minerals are probably detrital. The absence of illite from Australian coals is not fully understood, but it may reflect the action of organic acids on the detritus in the swamp, coupled with deposition in freshwater rather than marine conditions. Pyrite, although present in some coal samples when fresh, may undergo oxidation during storage to form a number of sulphate minerals, some of which may interact with any calcite present to form gypsum. The mineral matter assemblage in the coal determines to a great extent the fusion characteristics of the ash. Unless abundant carbonates are present, coals with kaolinite-rich assemblages have a very refractory ash, while those rich in chlorite or montmorillonite have ash fusion temperatures between 1000 and 1300/sup 0/C. The influence of the minerals on coal preparation and coking properties is also briefly discussed, as well as the potential of mineral matter studies in coal seam correlation.

Neoformations and transformations of clay minerals in tectonic shear zones

Abstract: Neoformations and transformations of clay minerals in tectonic shear zones of the Penninikum (Hohe Tauern/Austria) were investigated by X-ray diffraction, optical and X-ray microanalytical methods The shear zones developed in granite-gneisses, gneiss-phyllonites and mica-schists Low-temperature solution transfers led to chemical alteration of the tectonically crushed rocks and to the formation of clay minerals in shear zones The distribution of clay minerals and the alteration sequences were evidence of three successive alteration stages These alteration stages can be characterized by kaolinization, illitization and montmorillonitization The argillation processes, together with tectonic compression, caused a decrease in permeability and were in this way the main controlling factor for the environment during the development of tectonic shear zones

Organic 14 C activity in an abyssal marine sediment

Abstract: ONE measure of transport rates and residence times of organic carbon within the various organic carbon pools in the ocean is to follow perturbations from the 1952–58 and 1961–62 atmospheric thermonuclear bomb tests on the natural 14C activities of living, detrital and dissolved organic matter. We report here our measurement of the 14C activity of the total sedimentary organic carbon (SOC) in an abyssal red clay, as no such data were available for this organic carbon pool. Ultimately, these sedimentary organic 14C activities may be compared with the 14C activity of the source organic material in the water column and estimates made of the magnitude of organic carbon consumption at the seawater–sediment interface. What was found, unexpectedly, was evidence for the penetration of recent organic carbon from the 4 cm mixed layer at the sediment–seawater interface down to at least 12 cm in the sedimentary column. This suggests a different and more rapid mechanism for the sedimentation of some fraction of the SOC other than direct association with clay minerals.

Quantitative clay mineralogical analyses from the bulk chemistry of sedimentary rocks

Abstract: A technique suitable for computer application has been developed whereby whole rock major element analyses are corrected for X-ray detectable nonclay minerals and used to set up simultaneous equations which are solved to give clay mineral abundances. A theoretical evaluation of the approach by graphical methods enables the intrinsic errors to be very clearly assessed. Errors are minimized when SiO2, A12O3, and K2O are used as variables but only slightly increased if total Fe2O3 + MgO is substituted for SiO2. Quartz and CO2 content are the only data normally required which cannot be determined by X-ray fluorescence. Results compare favorably with estimates obtained by XRD and other methods, being more accurate than XRD and equally precise provided the rock does not contain clay minerals other than the kaolin group, the mica group, and chlorite. Errors are large when the clay mineral phases comprise more than 35% chlorite and as yet undetermined when smectite exceeds 10%. The method is ideally suited to the analysis of large numbers of mudstones of fairly similar mineralogy especially where XRF equipment with direct output to a computer is available.

A Comparison of the Effectiveness of Eight Methods for the Removal of Organic Matter from Clay

Abstract: Organi c present in clayey sediments may act as a cement between the clay particles as well as a blocking agent for the swelling of clay minerals like montmorillonite. Removal of the organic matter is important when a clay sample is to be characterized by X-ray powder diffraction, or when it is to be separated into the composing minerals on the basis of differences in density. Eight different methods for the removal of organic matter from a North Sea clay sample have been studied. Of all methods tried bromine oxidation was found to be the most effective. EXPERIMENTAL METHODS To study the effectiveness of various methods for the removal of organic matter from a North Sea clay sam- ple, the carbon percentages and X-ray powder diffrac- tion patterns were compared before and after removal of the organic matter. Pretreatment of the clay The pretreatment of the clay sample consisted of the removal of carbonate in a sodium acetate-acetic acid buffer (pH = 5), followed by extraction of free iron with sodium dithionite and sodium citrate following Holmgren (1967). This pretreatment is necessary, be- cause carbonates and iron (as oxide and hydroxide) can act as a coating and as a cement. Moreover, organic carbon determinations cannot be made without such pretreatment. The fraction <0.5 p~ of the pretreated sample was separated with a centrifuge and freeze- dried. Methods for the removal of organic

The influence of organocation structure on the adsorption of mono- and of bipyridinium cations by expanding lattice clay minerals

Abstract: Adsorption isotherms, X-ray diffraction, and microcalorimetic techniques were used to study interactions in an aqueous environment between various pyridinium and bipyridinium cations and a Na+-montmorillonite clay preparation. All of these cations had high affinities for the clay, were adsorbed to 80–125% of its cation-exchange capacity (CEC) and the adsorption processes were exothermic. Where lamellar collapse onto flattened organocations was observed, bipyridinium cations were more energetically bound to the clay than were the monopyridinoum species. This can be attributed to additional stabilization arising from charge transfer complexes in the cases of the bivalent compounds. Although 4-phenylpyridinium compounds were not flattened in the interlamellar spaces, their interactions, per equivalent, with the clay were the most highly exothermic observed because of the van der Waals interactions between the interlamellarly adsorbed aromatic rings. Significant effects could be attributed to the quaternizing groups only in cases of adsorption of 2,2′-bipyridine derivatives, and there was no evidence to indicate that altering the species of halide counterion significantly influenced adsorption.

Attenuation of pollutants in municipal landfill leachate by clay minerals. Final report Dec 72-Aug 75

Abstract: The first part of this project was a laboratory column study of attenuation of pollutants in municipal solid waste landfill leachate by mixtures of sand and calcium-saturated clays K, NH4, Mg, Si, and Fe were moderately attenuated; and the heavy metals Pb, Cd, Hg, and Zn were strongly attenuated even in columns with small amounts of clay Precipitation was the principal attenuation mechanism for the heavy metals; cation exchange was responsible for any attenuation of the other elements The clays, in order of increasing attenuation capacity, were Kaolinite, Illite, Montmorillonite The second part of the project involved batch studies of adsorption of Cr, Cu, Pb, Cd, Hg, and Zn by Montmorillonite and Kaolinite from water solutions and from landfill leachate Adsorption of the cations Cr(III), Cu, Pb, Cd, Hg, and Zn increased with increasing pH; adsorption of the anions Cr(VI), As, and Se decreased with increasing pH Above pH about 53 precipitation of the cations was an important mechanism while adsorption was the principal mechanism for the anions over the pH range studied Because adsorption/mobility of any element was affected by other solutes in leachate, adsorption information on one leachate may not be directly applied to predicting adsorption of themore » same element at the same concentration in another leachate« less

Selective adsorption of liquid mixtures on organophilic clay minerals

Abstract: The selective adsorption properties of the clay minerals montmorillonite and kaolinite and their organophilic derivatives were studied, for alcoholbenzene mixtures. Adsorption excess isotherms were determined, and the adsorption capacities were calculated by the method of Schay-Nagy. It was found that the desaggregation of the clay minerals and their organophilic derivatives can be characterized quantitatively by the adsorption capacity. It could be shown how the shapes of the excess isotherms are affected by modification of the surfaces, and, in this connection, a new model isotherm equation was introduced.

Physical, Chemical, and Mineralogical Properties of Fluvial Unconsolidated Bottom Sediments in Northwestern Ohio

Abstract: Fluvial unconsolidated bottom sediments that have the potential to become part of the suspended sediment load in the Maumee River Basin, Ohio, ranged in texture from sandy loams to clays. Particle size analysis by water dispersion and electrolyte dispersion procedures revealed that an average of 34% of the total clay fraction was aggregated into the silt and sand-sized range, indicating that the coarser fraction of bottom sediments may be physically-chemically active. The water-dispersible clay was lower in mica but higher in expandable 14A (smectite) and quartz constituents than the electrolyte-dispersible clay. The mineralogy of clay-sized bottom sediments (mica, 65 ± 5%; chlorite-vermiculite, 12 ± 5%; quartz, 14 ± 5%; expandable 14A (smectite) and kaolinite, 5 ± 5%) from upstream agricultural drainage ditches, major Basin tributaries, and from the Maumee River are essentially identical. The 2- to 50-µm fraction was dominated by quartz with secondary amounts of mica, kaolinite, feldspars, and carbonates. Mean calcite, dolomite, and calcium carbonate equivalent values were 4.1, 3.4, and 7.8%, respectively. Calcite dissolution in transport is probable on the basis of observed calcite-dolomite ratios. Organic matter content of the fluvial bottom sediments (3 to 7%) was analogous to Lake Erie bottom sediments and Maumee River suspended sediments. CEC values ranged from 39 to 55 meq/100 g for the total clay fraction collected by electrolyte and water dispersion procedures. Enrichment of heavy metals of bottom sediments over surficial soil materials occurred for Cu, Ni, Zn, Ca, and Pb by factors of 1.6, 2.0, 2.3, 3.5, and 3.0, respectively. Traces of herbicides (atrazine, 2-4-D) and insecticides (DDT metabolites, endosulfan) were detected in the filtered stream water samples and bottom sediment materials. Downstream trends in selected physical, chemical, and mineralogical properties could not be related to increased urban influences or increased stream discharge.

Mineralogy, genesis and classification of ferruginous soils of the eastern mysore plateau, india

Abstract: Summary The relationship of geomorphic and climatic history and formation of the ferruginous soils, formed on the acidic Peninsular Gneiss, of the Mysore Plateau, India, is discussed. The profiles studied are found on two different land systems. The soils of the older, fairly smooth landscape are composed of colluvium over truncated laterite profiles, with a gravel layer and a prominent kaolin layer over the weathered rock. These soils show an accumulation of pedogenic haematite grains in the sand fraction and have considerable kaolinite and amorphous ferri-aluminosilicate minerals in the clays. The soils of the younger, rugged landscape have similar clay mineralogy, but do not have a gravel layer, or haematite grains. The influence of the coarse-grained parent rock is seen in the large amounts of quartz gravel. The absence of granulation is attributed to lack of accumulation of iron. The soils have been formed in an earlier, more humid climate than prevails today. The original laterite profiles were formed on a plane surface, and subsequent change in climate has led to change in the land forms and dissection. Truncation of the profiles was followed by deposition of red colluvium over the resistant ferruginous layer. These ancient soils do not fit the criteria for Oxisols in the U.S. classification, but fit well in the French system as ‘Sols Ferrallitiques’, subclass ‘fiablement desatures en (B)’. The soil from a low lying area, formed from colluvium under hydromorphic conditions. is classified as‘Vertisols et Paravertisols'.

Stabilization of heavy clay with potassium chloride

Abstract: Some basic considerations of clay mineralogy suggest that potassium chloride, which is readily available in Israel from the Dead Sea, may significantly improve the engineering properties of heavy clay. This paper describes the results of a laboratory investigation into the effect of potassium chloride on the engineering properties of an Israeli heavy clay. The investigation indicated that the addition of potassium chloride results in a significant decrease in the activity of the clay and apparently in a change in its mineral structure. The overall stabilizing effect appears to be a result of this mineralogical change together with the increase of electrolyte concentration. /Author/TRRL/