Morphology, composition and genesis of argillans and organans in soils

Ranst, Éric Van; Righi, D.; Coninck, Fr. De; Robin, Anne-Marie; Jamagne, M.

doi:10.1111/j.1365-2818.1980.tb04154.x

Cited by 16 publications

(6 citation statements)

References 4 publications

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“…Conditions for clay translocation of this type are relatively infrequent (Gombeer & D'Hoore, 1971;Federoff, 1972) and continuously-oriented ferri-argillans form by the slow sedimentation of very thin layers of fine clay (Van Ranst et al, 1980). Consequently, their high frequency in the fragipans of the Milfield Plain suggests illuviation under well-drained conditions over a long period.…”

Section: Clay Migration Under Well-drained Conditionsmentioning

confidence: 95%

“…The uniform colour of ferri-argillans in the strongest parts of the fragipan horizons and in the underlying 2BCt horizons indicates clay dispersion and translocation from the well-drained Eb horizons and deposition in an oxidizing environment. Conditions for clay translocation of this type are relatively infrequent (Gombeer & D'Hoore, 1971;Federoff, 1972) and continuously-oriented ferri-argillans form by the slow sedimentation of very thin layers of fine clay (Van Ranst et al, 1980). Consequently, their high frequency in the fragipans of the Milfield Plain suggests illuviation under well-drained conditions over a long period.…”

Section: Clay Migration Under Well-drained Conditionsmentioning

confidence: 99%

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Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. II. Post Devensian developmental processes and the origin of fragipan consistence

Payton

1993

Journal of Soil Science

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SUMMARY Pedogenetic processes following a permafrost stage of development in four argillic brown earths with fragipans (Glossic and Ochreptic Fragiudalfs) are investigated by soil microscopy, including SEM observations of unimpregnated soil material, and by determination of clay mineralogy. Micromorphology of the apparently massive fragipan confirms both the presence of subhorizontal fissures infilled with illuvial deposits separating dense lenticular structures formed by ice‐lens growth, and former vertical fissures formed by dessication on freezing with subsequent widening by ice‐vein development. The firmness and brittle failure of the fragipans are attributed to a closely‐packed, well‐graded matrix of skeleton grains bonded by clay bridges consisting of non‐swelling illite and chlorite and to weak interconnection of macrovoids. Weak cementation is rejected as an explanation of fragipan consistence. Sequential stages of particle translocation have been critical to fragipan formation. High bulk density is attributed not only to irregular compression and contraction of the soil matrix under permafrost conditions but also to the infilling of voids by illuvial silt and clay. The full development of the fragipans has depended on Flandrian clay migration which has contributed to clay‐bridge formation, void infilling and localized seasonal impedance of drainage resulting in eluviation of iron oxides, the development of grey polygonal patterning, and processes of degradation at the pan surface leading to glossic features.

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Section: Clay Migration Under Well-drained Conditionsmentioning

confidence: 95%

Section: Clay Migration Under Well-drained Conditionsmentioning

confidence: 99%

Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. II. Post Devensian developmental processes and the origin of fragipan consistence

Payton

1993

Journal of Soil Science

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“…The SEM-EDS results show that the clay fraction separation provides distinct particles of aluminosilicates and entities in which iron and organic compounds are preferentially located. The latter are described as organans (Van Ranst et al, 1980). The removal of SOM by wet oxidation (NaOCl treatment) leads to a removal of Fe (Fig.4b) presumably in the form of suspended oxide nanoparticles.…”

Section: Colloidal Constituents: Nature and Distributionmentioning

confidence: 99%

Sub-micrometer distribution of Fe oxides and organic matter in Podzol horizons

et al. 2018

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The spatial distribution of soil constituents at the micrometer scale is of great importance to understand processes controlling the formation of micro-aggregates and the stabilization of organic carbon. Here, the spatial distribution of organic and mineral constituents in Podzol horizons is studied by concerted measurements of (i) the content of various forms of Fe, Al, Si and C determined by selective extraction in the fine earth fraction of soil (f < 2 mm); (ii) the elemental composition of the clay fraction (f < 2 μm) with lateral resolution using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and with surface selectivity using X-ray photoelectron spectroscopy (XPS); (iii) the specific surface area (SSA) of fine earth and clay fractions by krypton physisorption. The SSA of the fine earth in illuvial horizons is predominantly due to finely divided Fe oxides, including goethite, characterized by an equivalent particle size of about 10 nm. Kaolinite platelets of about 2 μm size account for a large volume proportion in the clay fraction but have a minor contribution to SSA. Fe oxides and organic matter (OM) are intimately associated. Heterogeneity at the μm scale is created by local variations in the relative amounts of kaolinite and Fe-OM associations. These two kinds of physical entities are in random mixture. Moreover, variation of C/Fe atomic ratios reveals sub-μm scale heterogeneity. The latter is due to variation in the relative proportion of organic compounds and Fe oxides, indicating that aggregation of nanoparticles, and not only mere adsorption or pore filling, plays a role in these associations. In this regard, our results highlight that OM associated with Fe protects Fe oxides against physical displacement and that part of this associated OM is oxidizable by NaOCl treatment. These findings demonstrate that the concept of OM stabilization through association with Fe must be revisited when considering the sub-μm scale level because fine Fe oxide particles can be easily dispersed during oxidation of associated carbon. Combination of physical fractionation and microanalysis (e.g. SEM-EDS, vibrational spectroscopy) offer promising perspectives to clarify the relationship between chemical composition and sub-μm scale architecture, and to better understand soil processes.

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“…yr B.P. The translocation of clay under undisturbed natural woodland is a slow process that requires sufficient leaching and acidification to allow the soil pH to fall in the range 6.5–5.0 and results in limpid, yellowish brown illuvial clay coatings with strong yellowish interference colors in XPL and continuous orientation of clay particles (Van Ranst et al., ; Payton, ; Nicosia et al., ). It is certainly possible, from evidence reported elsewhere in Britain (Weir, Catt, & Madgett, ), that argillic horizons could have developed by the Early Bronze Age, and that the anomalously high soil pH values (7.9–8.4) relate to the postburial influx of exchangeable calcium leached from the overlying dune sand.…”

Section: Discussionmentioning

confidence: 99%

Soil Paleocatenas, Prehistoric Land Use, and Coastal Landscape Dynamics at Druridge Bay, Northeast England

Payton

2016

Geoarchaeology

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Coastal erosion of sand dune systems along Druridge Bay, northeast England, has progressively exposed parts of the subdune mid‐Holocene landscape, including paleocatenas, indicating former soil hydrosequences with localized wetland habitats, and archaeological evidence of human activities and land use from the Late Mesolithic to the Romano‐British period. Archaeological investigations and pedostratigraphic studies of paleosols provide a unique spatial–chronological framework to interpret soil and land use change over several millennia in the context of a changing coastal environment. Evidence includes dating of archaeological remains, the stratigraphy, morphology and micromorphology of buried soils and sediments, and the palynology and radiocarbon dating of subdune peats. Early Bronze Age burial sites were preferentially located on well‐drained hillocks also used for grazing. Adjacent wetland depressions provided areas of marshy grassland and swamp over deep fen peat soils that started to develop c. 5435 cal. yr B.P. in response to a rising groundwater table stimulated partly by slow sea‐level rise. The backslopes of the paleocatena were occupied by imperfectly to poorly drained soils that supported open oak‐hazel woodland with evidence for progressive clearance and use for agriculture. Windblown sand started to accumulate on the study site sometime between 3930 and 3670 cal. yr B.P., well before the Little Ice Age date for dune formation suggested by previous researchers.

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Morphology, composition and genesis of argillans and organans in soils

Cited by 16 publications

References 4 publications

Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. II. Post Devensian developmental processes and the origin of fragipan consistence

Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. II. Post Devensian developmental processes and the origin of fragipan consistence

Sub-micrometer distribution of Fe oxides and organic matter in Podzol horizons

Soil Paleocatenas, Prehistoric Land Use, and Coastal Landscape Dynamics at Druridge Bay, Northeast England

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