Clay mineral associations in melanic soils of South Africa

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 115 ◽  
Author(s):  
Gertruida M. E. van der Merwe ◽  
Michiel C. Laker ◽  
Christl Bühmann
Keyword(s):  
South African ◽  
Clay Mineral ◽  
Wide Spectrum ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Soil Classification ◽  
Large Degree ◽  
Mineral Associations ◽  
Investigative Technique ◽  
African Soil

The melanic horizon is 1 of 5 diagnostic topsoil horizons distinguished in the South African soil classification system. Melanic soils span a wide spectrum, ranging from those that intergrade with a vertic to those that intergrade with a humic horizon. Melanic soils are therefore expected to vary considerably with respect to a variety of physical, chemical, and clay mineralogical properties. The objective of the present study was to determine the clay mineral compositions of melanic horizons from 58 modal profiles and to establish to what extent melanic soil properties are related to clay mineralogy. Special emphasis was placed on the characterisation of the clay fraction in terms of group and species identification. X-ray diffractometry was employed almost exclusively as the investigative technique in mineral identification and quantification. Melanic A horizons showed a large degree of variation with regard to their clay mineral associations. More than half of the soils were dominated by smectite, 30% by kaolinite, and the rest by an association of about equal proportions of mica, kaolinite, and smectite. Talc and hydroxy-interlayered vermiculite occurred in a number of soils while one horizon was dominated by an illite/smectite interstratification. The smectite component was identified as belonging to either beidellite or vermiculite species, depending on the method employed. About a quarter of the smectitic soils contained montmorillonite as well but not as the dominant swelling phase. mollisols, clay mineralogy, layer charge.

Evaluating the paleoclimatic significance of clay mineral records from a late Pleistocene loess-paleosol section of the Ili Basin, Central Asia

2017 ◽  
Vol 89 (3) ◽  
pp. 660-673 ◽  
Author(s):  
Yue Li ◽  
Yougui Song ◽  
Mengxiu Zeng ◽  
Weiwei Lin ◽  
Rustam Orozbaev ◽  
...  
Keyword(s):  
Central Asia ◽  
Clay Mineral ◽  
Late Pleistocene ◽  
Sedimentary Rocks ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Metamorphic Rocks ◽  
Paleoclimatic Reconstruction ◽  
Paleoclimatic Significance ◽  
Wind Intensity

AbstractIn this study, we present clay mineral records from a late Pleistocene loess-paleosol sequence in the Ili Basin, Central Asia, and assess their significance for paleoclimatic reconstruction. The results show that the clay minerals are mainly illite (average 60%) and chlorite (28%), with minor kaolinite (9%) and smectite (3%). Illite was of detrital origin with no obvious modification to its crystal structure. Increases in illite content in the loess are ascribed to wind intensity rather than pedogenesis. High proportions of illite in the clay fraction, and of muscovite in the bulk samples of the paleosol units, may lead to an overestimation of the weathering intensity. Kaolinite was likely inherited from the sedimentary rocks, while chlorite might have been inherited from both sedimentary and metamorphic rocks. The paleoclimatic signals of kaolinite and chlorite were unclear, due to reworking by both fluvial and eolian systems. Smectite was more likely formed by the transformation of biotite and illite, and its variation in the loess sequence was also controlled by wind intensity; this was largely due to aggregation and is unlikely to reflect moisture changes. Although the interpretation of paleoclimate evolution may contain some uncertainties, clay mineralogy does provide the possibility of tracing dust provenance.

Geological factors controlling clay mineral patterns across the Cretaceous-Tertiary boundary in Mediterranean and Atlantic sections

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483-500 ◽  
Author(s):  
M. Ortega ◽  
I. Palomo ◽  
F. Martinez ◽  
I. Gonzalez
Keyword(s):  
Rare Earth ◽  
Clay Mineral ◽  
Clay Mineralogy ◽  
Mineral Association ◽  
Mineral Associations ◽  
Uppermost Layer ◽  
Regional Tectonic ◽  
Geological Factors ◽  
The Mediterranean ◽  
Layered Clay

AbstractThe clay mineral associations in the Cretaceous-Tertiary Boundary (KTB) and in the Danian and Maastrichtian levels of sections from the Mediterranean and the Atlantic Domains have been studied. The Mediterranean sections have a single mineral association consisting of smectiteiltite and kaolinite, whereas the Atlantic sections have several associations: illite-chlorite, illite-R1 I-S-kaolinite and illite-R 1 I-S-chlorite. Data are presented relating to the influence of K-feldspars and Fe oxide sphemles on the clay mineral associations. Study of rare-earth elements shows that regional geological factors affect the clay mineralogy of the KTB, examples showing significant anthigenesis in the Mediterranean sections, and important detrital supply in all the Atlantic sections. We propose that the KTB studied in these marine sections is equivalent to the uppermost layer of the two-layered clay unit originating in a cloud of a vapourized bolide. Regional tectonic conditions have been responsible for differences in clay sedimentation in these geological domains and among the stratigraphic sections of the Atlantic Domain.

Clay mineralogy and pressure analysis from seismic information in Krishna‐Godavari basin, India

Geophysics ◽  
1990 ◽  
Vol 55 (11) ◽  
pp. 1447-1454 ◽  
Author(s):  
Saibal Basu
Keyword(s):  
Clay Mineral ◽  
Transit Time ◽  
East Coast ◽  
Clay Mineralogy ◽  
Seismic Velocities ◽  
Time Data ◽  
Mineral Associations ◽  
Sonic Logs ◽  
Godavari Basin ◽  
Pressure Analysis

Interval transit time data derived from seismic velocities have been analyzed to predict clay mineralogy and overpressures from compaction trends in the offshore areas of Krishna‐Godavari basin located on the east coast of India. Compaction trends from rms velocity fairly well match the trends obtained from sonic logs. This study has been extended to the undrilled part of the basin with the help of seismic information. Areal distribution of clay mineral types has been determined from the compaction trends. Prospective areas are identified on the basis of clay mineral distribution and overpressure zones related to the areas of different clay mineral associations.

The clay mineralogy of some soils derived from a biotite-rich quartz-gabbro in the Strathdon area, Aberdeenshire

Clay Minerals ◽  
1967 ◽  
Vol 7 (1) ◽  
pp. 91-100 ◽  
Author(s):  
M. J. Wilson
Keyword(s):  
Clay Mineral ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Plagioclase Feldspar ◽  
Soil Forming Processes ◽  
Mineral Constituents ◽  
Clay Mineral Composition ◽  
The Last Glacial

AbstractThree soils of the Strathdon area, Aberdeenshire, derived from a biotite-rich quartz-gabbro and representing well-drained, imperfectly drained and poorly drained types, were studied. The 50–200 µ fractions contained mainly plagioclase feldspar, amphibole (tremolite and hornblende), biotite and quartz and the following order of relative stability was established: quartz > amphibole > plagioclase feldspar > biotite. In all soils biotite was found to weather to a 14 Å aluminous vermiculite-chlorite with zones of kaolinite. The clay mineral composition of three soils was identical, consisting of trioctahedral vermiculite-chlorite, trioctahedral illite, kaolinite and gibbsite. These minerals originated in various ways through the decomposition of biotite which thus plays a key role in the origin of the clay fraction. It is suggested that the clay mineral constituents of the soils were formed in a regolith predating the last glacial period, and that post glacial soil-forming processes have modified them only slightly.

Late Cretaceous—Palaeocene mid-latitude climates: inferences from clay mineralogy of continental-coastal sequences (Tremp-Graus area, southern Pyrenees, N Spain)

Clay Minerals ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 105-126 ◽  
Author(s):  
J. Arostegi ◽  
J. I. Baceta ◽  
V. Pujalte ◽  
M. Carracedo
Keyword(s):  
Clay Mineral ◽  
Chemical Weathering ◽  
Clay Mineralogy ◽  
Source Area ◽  
Climatic Conditions ◽  
Sem Images ◽  
Climatic Trend ◽  
Mineral Associations ◽  
Continental Basin ◽  
Mixed Layers

AbstractThe origin and distribution of late Maastrichtian–early Palaeocene clay mineral associations were investigated in the Tremp-Graus basin (South Pyrenees, Spain) to assess palaeoclimate changes during that period. The studied succession is made up of expanded continental and transitional terrigeneous and carbonate deposits accumulated in a coastal plain setting. X-ray diffraction, SEM-EDX and TEM-AEM analysis reveal that the main clay components are illite and smectite, but kaolinite, chlorite and illite-smectite mixed layers are present, although irregularly distributed, all of them showing a platy morphology typical of a detrital origin. Persistence of the chemical features of the Al-dioctahedral smectites throughout the whole succession demonstrates the persistence of the same source area during the interval studied. Palygorskite occurs in the late Danian and Selandian, within carbonate tidal flats as sabkha-like facies. In SEM images, the palygorskite displays straight fibre morphologies, both coating and branched curling out, a clear proof of authigenic origin.Physical or chemical weathering (PhW/ChW) determined as illite + chlorite/smectite + kaolinite ratio, smectite/kaolinite ratio and palygorskite distribution have been used as clay proxies for palaeoclimate reconstructions. Such data suggest a shift from temperate subhumid (perennial) conditions in late Maastrichtian times to a warm seasonal climate during early Palaeocene times. This trend, however, was dramatically altered during the late Danian–Selandian interval, when prevailing warm and semi-arid to arid climatic conditions caused intense evaporation and the development of an alkaline environment in which the palygorskite authigenesis took place.The proposed climatic trend partly concurs with that established for earliest Danian time by Domingoet al.(2007), also in the Tremp-Graus basin, from isotopic and geochemical proxies, as well as with the reconstruction of Cojan & Moreau (2006), in which a semiarid Danian phase for the near continental basin of Aix-en-Provence is postulated. However, it is at odds with the notion of a humid Danian state in the Pyrenees, as inferred by Gawendaet al.(1999) from clay mineral proxies of deep marine successions.

scholarly journals Quantitative clay mineralogy as a tool for lithostratigraphy of Neogene Formations in Belgium: a reconnaissance study

2020 ◽  
Vol 23 (3-4) ◽  
Author(s):  
Rieko ADRIAENS ◽  
Noël VANDENBERGHE
Keyword(s):  
Detailed Analysis ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Natural Radioactivity ◽  
Mineral Content ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Soil Material ◽  
Lithostratigraphic Units ◽  
Borehole Logs

Although the main stratigraphic frame of the Neogene in North Belgium is well established still several issues remain. This is in particular the case at the boundaries of lithostratigraphic units and where lateral facies have developed. Not only are more biostratigraphic data needed but also the commonly used geophysical well logging needs a better information on the precise influence of the variable mineralogy in the sediments. In particular glauconite, muscovite and clay mineralogy need a detailed analysis. Such an analysis is carried out on the Antwerp Member of the Berchem Formation, the Diest Formation, the Kasterlee Formation and the Mol Formation with particular emphasis on the boundary intervals between these units. Clay minerals, glauconite, feldspars and muscovite are analyzed. Interstratified glauconite/smectite appears to be common in the low abundant dispersed clay fraction of sand rich in glauconite pellets. Marine units generally consist of detrital smectite-rich assemblages while kaolinite becomes more abundant in units under more continental influence. The presence of Fe-rich vermiculite in a clayey top facies of the Diest Formation indicates the influx of soil material containing weathered glauconite. It is common to find that the basal sediments of a new unit contain the mineralogical heritage of the underlying unit. The clay mineral content has helped to differentiate between units, to locate the boundaries between units and to understand the reworking that occurred at the base of new stratigraphic units. The mineralogical information can also be used to interpret the natural radioactivity and resistivity signals in the borehole logs.

Clay mineralogy effects on sodium fluoride pH of non-allophanic tropical soils

Soil Research ◽  
2004 ◽  
Vol 42 (8) ◽  
pp. 865 ◽  
Author(s):  
M. E. Alves ◽  
A. Lavorenti
Keyword(s):  
Agricultural Soils ◽  
Ammonium Oxalate ◽  
Clay Fraction ◽  
Chemical Properties ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Soil Classification ◽  
Tropical Soils ◽  
Oh Groups ◽  
Soil Weathering

Soil pH measured in 1 m NaF (pHNaF) can be a useful tool for soil classification and to provide better advice on the chemical management of agricultural soils in the tropics. In this study, we verified the effects of clay mineralogy on pHNaF values of non-allophanic soils of São Paulo State, Brazil. Fourteen subsurface soil samples were characterised for chemical properties, clay content, clay mineralogy, and for pHNaF values, which were measured in the whole soil and in both natural and deferrified (dithionite-treated) clay fractions. Regression and correlation analyses showed that both ammonium-oxalate-extractable Al (Alo) and gibbsite contents have positive relationships with both clay and soil pHNaF values. On the other hand, kaolinite is inversely related to the pHNaF measured in the clay and has nonsignificant effect on soil pHNaF. X-ray diffraction patterns of dithionite-treated clays did not show disruption of kaolinite or gibbsite after the treatment with 1 m NaF, suggesting that the displacement of surface OH groups by F– seems to be the main mechanism associated with the pH increase verified in the NaF solution after its contact with the deferrified clay fraction. The smaller influence of hematite on pHNaF seems to be due to its correlation to Alo. Goethite and ammonium-oxalate-extractable Fe (Feo) exert no effect on pHNaF. Finally, the relationships observed in the present study strongly suggest that pHNaF values <10.3 measured in non-allophanic kaolinitic soils with low levels of non-humified organic matter are essentially due to their smaller Alo and gibbsite contents, which agrees with the direct correlation verified between pHNaF and soil weathering degree.

A study of clay mineralogy and particle size

1957 ◽  
Vol 8 (1) ◽  
pp. 45 ◽  
Author(s):  
JS Hosking ◽  
ME Neilson ◽  
AR Carthew
Keyword(s):  
Particle Size ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mineral Content ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Coarse Sand ◽  
Reverse Effect ◽  
Chemical Alteration ◽  
Intermediate Particle

A study of the mineralogy of the clay, silt, and sand fractions of 24 soils has shown that the clay minerals are distributed through all fractions of the soils. In granitic and other soils which are characterized by kaolinite, with mica, illite, or montmorillonoids sometimes present though subsidiary, the clay mineral content of the silts may be as high as in the clay fraction though on the average it is about 50 per cent.; in the sands, however, clay minerals are negligible. In basaltic or basic soils which are characterized by halloysite or nontronite or both, with other types subsidiary, the clay mineral content of the silts is somewhat less than that in granitic soils, but persists a t an average of 20 per cent, in the sands. The higher concentration of kaolinite in the silt fractions reflects the larger particle size of this mineral. The concentration of halloysite or nontronite in the sand fractions, and even the concentrations reached in the silts of soils containing these minerals, reflect their fibrous nature which allows the formation of stable interlaced aggregates. Overall the two types of mineral, altered (authigenic) and residual (allogenic), vary continuously with particle size; the former, constituting the bulk of the colloids, decrease to small amounts in the coarse sand, while the latter necessarily show the reverse effect. The silts contain both types of mineral in about equal amounts and thus represent the intermediate particle size of mechanical breakdown and chemical alteration.

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