Investigation of the Clay Fraction (<2 μm) of the Clay Minerals Society Reference Clays

The pedogeochemical maps present the spatial distribution of soils according to crystalochemical parameters (clay fraction) and physic-chemical aspects of the sorting complex (CEC and BS). These maps are adequate tool for environmental studies and particularly, for the analysis of the terrestrial ecosystem sensibility to acidic deposition. The pedogeochemical maps of the Brazilian soils, elaborated using FAO SoilWorld Map, allowed establishing the soil distribution according to 5 classes of vulnerability to acidic deposition, as defined by Stockholm Environmental Institute (SEI). From these maps, it is observed that about 50% of the Brazilian soils are high vulnerable to acidic deposition and can be included within the most sensitive class. This group is formed by well-developed and mature soils, constituted by clay minerals of kaolinite type associated with variable amount of gibbsite. About 8% of the soils can be considered as the least sensitive class. They correspond to Topomorphic Vertisols (Vertissolo, Embrapa 1999), Planosols (Planossolo, Embrapa 1999) and saline soils. Finally, the remaining soils represent the balanced media that dominate the northeastern semiarid zones and the south and northeastern subtropical zones.

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GENESIS AND PHYSICAL CHARACTERISTICS OF THE NEOGENE RED BEDS FROM THE CEDARHILS OF THESSALONIKI, MACEDONIA , GREECE

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.16801 ◽

2018 ◽

Vol 36 (2) ◽

pp. 708 ◽

Cited By ~ 1

Author(s):

A. Tsirambides

Keyword(s):

Clay Minerals ◽

Urban Forest ◽

Clay Fraction ◽

Eastern Mediterranean Region ◽

Physical Characteristics ◽

Coarse Grained ◽

Red Beds ◽

Primary Minerals ◽

In Situ Weathering

The genesis and the physical characteristics of the Neogene red beds of the cedar hills surrounding Thessaloniki are studied in this paper. The peri-urban forest, which covers these hills, has a 3,022 ha area. The topographic relief is smooth and is divided in eight small drainage basins, tapped through small creeks. The elevation of the surrounding hills varies between 85 and 560 m. The dominant land slopes vary between 20 and 55%. All the samples are coarse grained, poorly sorted and friable and present earthy lustre and red colour because of the extensive presence of iron oxides. Angular to sub-angular rock fragments derived from the metamorphic bedrock are very common. Petrographically, the studied red beds belong to the clayey sands. The extended presence (41-66%) of coarse silt and sand size grains (>20 pm) in the samples suggests a mild intensity of in situ weathering of the bedrock. X-ray diffraction analysis of the coarsest fractions 250-20 pm and 20-2 μιτι revealed in decreasing abundance the presence of quartz, feldspars, epidote, micas, chlorite, pyroxenes, amphiboles, and talc. These fractions contain the 2M polytype of mica, while in the fraction <2 pm the 1Μα polytype of illite predominates. In the clay fraction (<2 pm) illite, smectite, and chlorite predominate. The presence of mixed-layer minerals is limited, testifying the almost complete character of hydrolysis of the primary minerals. The formation of red beds took place on low relief land under alternating wet and dry seasons, which prevail in the eastern Mediterranean region since Neogene. The clay minerals are the in situ weathering products of the primary minerals of the greenschists, gneisses and gabbros predominating in the studied area. The extensive presence of clay size grains (11-26%) in the samples, their poor sorting, and their sub-angular morphology, indicate that the red beds are texturally immature. In addition, the abundance of feldspars and Fe-Mg minerals reflects mineralogical immaturity. The low relief and the long-lasting tectonic stability in the Thessaloniki district were essential for the significant thickness of the red beds. The oxygen isotope data of the <0.2 pm fraction (+18.2 to +18.8%o) confirm the pedogenic origin of the clay minerals present. The red beds studied present low plasticity with liquid limit (WÏ) 26.9 to 33.4% and plasticity index (lp) 9.1 to 17.3%. In addition, they have high consolidation index (lc) values (1.03 to 2.28). The swelling potential is low to medium and the activity varies between 0.5 and 1.0. The consolidation and induration degree of the samples analyzed is low, because of the great range of their mineralogical composition and the mild conditions of pressure and temperature to which they have been submitted. The studied red beds are not considered problematic for the foundation of various constructions on them.

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The Occurrence of Authigenic Clay Minerals in Alkaline-Saline Lakes, Pantanal Wetland (Nhecolândia Region, Brazil)

Minerals ◽

10.3390/min10080718 ◽

2020 ◽

Vol 10 (8) ◽

pp. 718

Author(s):

Isis Armstrong Dias ◽

Leonardo Fadel Cury ◽

Bruno Guimarães Titon ◽

Gustavo Barbosa Athayde ◽

Guilherme Fedalto ◽

...

Keyword(s):

Electron Microscopy ◽

Clay Minerals ◽

Saline Lakes ◽

Clay Fraction ◽

Water Bodies ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Fine Clay ◽

Pantanal Wetland

Mg clay minerals are usually associated with carbonates in alkaline-saline environments, precipitated from solution and/or transformation from other minerals. The aim of this research is to identify the mineralogy and geochemistry of clay minerals in different alkaline lakes in the Nhecolândia region, the southernmost region of the Pantanal wetland (Brazil). Sediment samples were analyzed by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and transmission electron microscopy. Water samples were analyzed, determining their main cations and anions, in order to understand their relationship with the clays. The analyses allowed classifying the water bodies as saline, oligosaline and freshwater lakes. The sediments are composed mainly of quartz and a fine-clay fraction, dominated by illite, kaolinite and smectite. The XRD results showed illite and smectite mixed-layered in the saline lakes at Barranco Alto farm, whereas at Nhumirim farm, trioctahedral smectite was only observed in one lake. The smectite minerals were normally identified coupled with calcite at the top of the sequences, associated with exopolymeric substances (EPS) in the lakes, suggesting that these minerals are precipitating due to the physical-chemical and biological conditions of the water bodies.

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Physicochemical properties of protein-smectite and protein-Al(OH)x-smectite complexes

Clay Minerals ◽

10.1180/claymin.1995.030.4.06 ◽

1995 ◽

Vol 30 (4) ◽

pp. 325-336 ◽

Cited By ~ 30

Author(s):

A. Violante ◽

A. de Cristofaro ◽

M.A. Rao ◽

L. Gianfreda

Keyword(s):

Physicochemical Properties ◽

Clay Minerals ◽

Adsorption Isotherms ◽

Electrostatic Interactions ◽

Clay Fraction ◽

Electrostatic Forces ◽

Molecular Weights ◽

Protein Molecules ◽

Isoelectric Points ◽

Heating Treatment

AbstractProteins (catalase, albumin, pepsin and lysozyme with different molecular weights and isoelectric points) were differently adsorbed at pH 7.0 on the clay fraction of three raw Na-saturated smectites (Crook and Uri montmorillonites and one hectorite). The adsorption isotherms of proteins on clay minerals showed typical Langmuir characteristics. Lysozyme was adsorbed under the effect of electrostatic interactions between the opposite charges of clay surfaces and protein molecules, whereas catalase and albumin were adsorbed under the effect of non-electrostatic forces. Pepsin was held in relatively high amounts only on the surfaces of hectorite. Proteins were intercalated in the interlayers spaces of smectites, usually undergoing extensive unfolding. Protein-smectite complexes showed different behaviour to heating treatment. Some complexes remained practically unchanged after heating at 200°C. Presence of ‘wrecks’ of interlayered materials was found after heating at 500°C for two hours. The amounts of proteins adsorbed on the external and interlamellar surfaces of clay minerals, partially coated with OH-Al species, were much lower than those fixed on the clean clays. Only lysozyme was intercalated in chlorite-like complexes.

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Swelling clayey soils promote slope instability in the Muhunguzi watershed, western Burundi

10.5194/egusphere-egu2020-22030 ◽

2020 ◽

Author(s):

Bruno Delvaux ◽

Clairia Kankurize ◽

Gervais Rufyikiri

Keyword(s):

Clay Minerals ◽

Clay Fraction ◽

Slope Instability ◽

Atterberg Limits ◽

Intense Rainfall ◽

Angle Of Friction ◽

Red Soils ◽

Soil Cohesion ◽

Internal Angle ◽

Water Saturated

In Burundi, landslides are frequent on the western slope of the Congo-Nile ridge. Unfortunately, they are poorly studied and understood despite their deadly consequences. Previous reports have suggested that slope steepness, lithology and clay soils expose this slope to landslides, while heavy and intense rainfall is a trigger. However, the role of soil in the vulnerability of this specific slope to landslides is unknown. Here we investigate on soil characteristics involved in land sliding in this area.We selected and sampled black and red soils in two Muhunguzi landslides. We determined the soil plasticity from Atterberg limits as well as the particle size distribution. In addition, we measured the soil weathering stage, and further identified the clay minerals from measuring the cation exchange capacity of the clay fraction and analyzing clay samples with X-ray diffraction (XRD).Both the black and red soils are moderately weathered since TRB values in the B horizons range between 330 and 425 cmol(+) kg-1. The soils are loamy clayey to clayey (% clay: 33-55%), and contain high charge clay minerals. They do not differ in their Atterberg limits, which classify the soils as medium plasticity soils in the Casagrande plasticity diagram. Our data further show that both soils have a medium swelling potential. XRD show that the clay fraction consists of kaolinite and smectite and/or vermiculite. The latter 2:1 clay minerals are expandable and swelling clays, respectively. They give these two soils their plasticity and swelling properties. These two properties play an important role in the mechanical behavior of water-saturated soils. Indeed, swelling reduces soil cohesion while the plasticity index and the liquidity limit vary inversely with the internal angle of friction of the soil; cohesion and internal angle of friction being the fundamental parameters of the soil shear resistance. In addition, the soil mantle covers a hard schistose rock whose declivity is parallel to the soil surface slope. Thus, after intense rainfall during the wet season, the water-saturated soil reaches a level of liquidity sufficient to favor a landslide, all the more easily if the slope of the hard rock is inclined in the direction of the gravity flow.gru

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Evolution with depth from detrital to authigenic smectites in sediments from AND-2A drill core (McMurdo Sound, Antarctica)

Clay Minerals ◽

10.1180/claymin.2012.047.4.07 ◽

2012 ◽

Vol 47 (4) ◽

pp. 481-498 ◽

Cited By ~ 12

Author(s):

F. Iacoviello ◽

G. Giorgetti ◽

F. Nieto ◽

I. T. Memmi

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Clay Minerals ◽

Clay Fraction ◽

Drill Core ◽

Mcmurdo Sound ◽

Volcanic Material ◽

The Core ◽

Diagenetic Processes ◽

Scanning Electron

AbstractWe have examined the nature and origin of smectites in glaciomarine sediments of the AND-2A drill core (McMurdo Sound, Antarctica) by means of X-ray diffraction (XRD) analyses on the clay fraction, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. Relying on the smectite variation throughout the drill core it was possible to split the sequence into three units. Smectites throughout the core are either detrital or authigenic. Detrital smectites are close to montmorillonite-beidellite in composition while newly-formed smectites frequently have higher Fe-Mg contents and intermediate compositions between the saponite and nontronite field, with lower amounts in the montmorillonite-beidellite field. In the upper sedimentary sections (Unit I, and Unit II, 36-440 mbsf, 0.7-16.5 Ma) smectites are interpreted to be predominantly detrital, whereas in the lower portion of the core (Unit III, 440-1123.20 mbsf, 16.5-20.2 Ma) authigenic smectites are the most common feature. The predominance of mica, the abundance of chlorite, and the nature of smectites in the upper units indicate physical weathering under cold and dry climate, and a dominant provenance for the clay minerals from the Transantarctic Mountains. Smectites in the lower unit are considered mostly authigenic and they are most likely to be the result of early diagenetic processes, being formed from the alteration of volcanic material (glass, pyroxenes and feldspars) and/or through precipitation from fluids of a possible hydrothermal origin. Our survey attests to the importance of discriminating between a detrital and authigenic nature of smectites as the occurrence of authigenic clay minerals in ancient sedimentary successions might lead to incorrect palaeoclimatic interpretations, since they can be affected by diagenetic processes, thus obliterating the climatic signal.

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Mineralogical Study of Levels with Magnesian Clay Minerals in the Santos Basin, Aptian Pre-Salt Brazil

Minerals ◽

10.3390/min11090970 ◽

2021 ◽

Vol 11 (9) ◽

pp. 970

Author(s):

Maurício Dias da Silva ◽

Márcia Elisa Boscato Gomes ◽

André Sampaio Mexias ◽

Manuel Pozo ◽

Susan Martins Drago ◽

...

Keyword(s):

Clay Minerals ◽

Clay Fraction ◽

Total Sample ◽

Petrographic Analysis ◽

X Ray Diffraction ◽

X Ray ◽

Mineralogical Study ◽

Original Rock ◽

Mixed Layers

The object of this study is magnesian clay minerals present in carbonate rocks of the post-rift phase of the pre-salt in the Santos Basin. These rocks developed in an Aptian-age alkaline lacustrine environment. This study summarizes the formation of clay minerals associated with different lithotypes in a range of 19 m and a depth of more than 5100 m. They were characterized from petrographic analysis by optical microscopy, X-ray diffraction (total sample and clay fraction), and modeling by Newmod®; and examined and analyzed by scanning electron microscopy. An approach based on identifying lithotypes and characterization of microsites allowed us to understand the occurrence of different clay minerals. Kerolite was the most abundant mineral in the sampled range. It occurs in lamellar aggregates under greater preservation of the original rock lamination and in association with spherulites and shrubs. The Stv/Ker mixed layers occurs in the same association, and formed finer unlaminated aggregates associated with the more intense dolomitization and silicification processes. Saponite occurs associated with detrital minerals forming clayey levels intercalated with microcrystalline carbonates. Fluids with a high Mg/Si and pH < 9 favor the precipitation of kerolite. The increase in pH during diagenesis may be responsible for the formation of Stv/Ker mixed layers.

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Mineralogical composition and physical characteristics of marly soils from Heraklion Crete

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17097 ◽

2001 ◽

Vol 34 (3) ◽

pp. 851

Author(s):

Α. ΤΣΙΡΑΜΠΙΔΗΣ ◽

Θ. ΠΑΠΑΛΙΑΓΚΑΣ

Keyword(s):

Clay Minerals ◽

Clay Fraction ◽

Soil Classification ◽

Mineralogical Composition ◽

Liquid Limit ◽

Silty Clay ◽

High Plasticity ◽

Degree Of Consolidation ◽

Very High

The mainly white-yellow marly soils studied present medium degree of consolidation and induration. The predominant grain size of the non - carbonate constituents is that of silt varying from 34 to 64%. According to the textural classification of soils of the SSDS the samples are mainly silty-clay loams with moisture capacity 30-40%. In the untreated samples in decreasing abundance the following minerals predominate: calcite (31-59%), clay minerals (20-34%) and quartz (12-20%). In the clay fraction (<2μπι) in decreasing abundance the following clay minerals (in discrete and interstratified phases) predominate: illite, smectite and vermiculite. Chlorite and kaolinite are missing. Mineralogically the marly soils are immature, because of the extended presence of Fe-Mg minerals (i.e. amphiboles, pyroxenes and clay minerals). According to the Unified Soil Classification System of the ASTM the studied marly soils mainly belong to the groups MH and CH (inorganic silts and inorganic clays respectively with high plasticity and liquid limit >50%), as well as to the group CL (inorganic clays with low plasticity and liquid limit <50%). The degree of consolidation and induration, as well as of compaction of these soils is medium. They contain significant amounts of discrete or interstratified smectite and mainly present high to very high swelling potential and activity between 0.5 and 2.0. It is concluded that specific precautions must be taken into account, when it is unavoidable the foundation of various constructions on these marly soils, because they swell and shrink extensively.

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MINERAL COMPOSITION OF SOME LATGALE LAKE SEDIMENTS

Environment Technology Resources Proceedings of the International Scientific and Practical Conference ◽

10.17770/etr2019vol1.4146 ◽

2019 ◽

Vol 1 ◽

pp. 304

Author(s):

Rasma Tretjakova ◽

Andris Karpovičs

Keyword(s):

Grain Size ◽

Lake Sediments ◽

Size Distribution ◽

Clay Minerals ◽

Mineral Composition ◽

Grain Size Distribution ◽

Sandy Loam ◽

Clay Fraction ◽

Fine Grained ◽

Two Samples

Our research is focused on sedimentological conditions and postdepositional changes of recent fine grained lake sediments. We used bulk sediment mineralogical composition and grain size distribution as indicators to identify sediment source areas and possible changes during Holocene. We analysed fine grained (clayey) sediments from three Latgale lakes - Zeili, Pauguļi and Plusons, situated in Latgale upland. Lake sediments cover Late Pleistocene glacial deposits – loam and sandy loam. Bulk mineral composition of 6 sediment samples was determined by X-ray diffraction (XRD). Sediments contained typical minerals found in surrounding glacial sediments: rock-forming minerals as quartz, plagioclase, albite, enstatite, dolomite, calcite, and clay minerals - illite, kaolinite. To identify postdepositional changes in lake sediments of Holocene age clay minerals in clay fraction (<2 mkm) should be analysed. Particularly illite, smectite mixed layered minerals - illite/smectite (I/Sm) and chlorite. Additionally, grain size distribution of studied lake sediments was analysed. Accordingly, our studied sediments are clays, silty clays and clayey silts with bimodal particle distribution, except two samples from Zeiļi and Plusons with unimodal distribution.

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Mineral matter composition of drained floodplain soils in north-eastern Poland

Soil Science Annual ◽

10.2478/ssa-2018-0019 ◽

2018 ◽

Vol 69 (3) ◽

pp. 184-193 ◽

Cited By ~ 1

Author(s):

Jacek Długosz ◽

Barbara Kalisz ◽

Andrzej Łachacz

Keyword(s):

Organic Matter ◽

Clay Minerals ◽

Clay Fraction ◽

Mineral Matter ◽

Oxbow Lakes ◽

Floodplain Soils ◽

North Eastern ◽

Clay Fraction Content ◽

Mineral Soils ◽

River Valleys

Abstract Soils in two river valleys (Rozoga and Omulew) in north-eastern Poland were investigated. The valleys are located on a sandy outwash plain formed during the Vistulian (Weichelian) Glaciation. The soils are drained, used as meadows and classified as Fluvic Umbric Gleysol, Fluvic Mollic Gleysol, and Eutric Fluvic Histic Gleysol (IUSS Working Group WRB 2015). The aim of the study was to identify the composition of mineral matter and to determine the types of clay minerals and intermediate stages of clay minerals by means of the X-ray diffraction (XRD). The studied floodplain soils are rich in organic matter and contain considerable mineral alluvial admixtures. The content of clay fraction (< 2.0 μm) is low (0.02–5.61% of total mineral matter). Higher content of clay fraction was noted in soils with elevated content of organic matter, which can be evidence of simultaneous accumulation of both components. In deeper depressions occurring in river valleys (oxbow lakes), a specific deposit termed silty telmatic mud (16–24% TOC, 50–75% silt, 3.1–5.6% clay fraction content) was accumulated. On the other hand, in shallow depressions, a muddy deposit was accumulated (5.7–7.7% TOC, sandy texture). The main identified clay minerals were smectite, vermiculite, illite and kaolinite as well as variety of mixed-layer clays. Alluvial clay admixture in studied soil formations showed mineralogical similarity to typical floodplain mineral soils (Fluvisols). Mineral fraction of studied soils is mostly of allochthonous origin.

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