Oxic and Related Materials

Marcelino, Vera de Melo; Schaefer, C. E. G. R.; Stoops, Georges

doi:10.1016/b978-0-444-63522-8.00023-1

Cited by 18 publications

(9 citation statements)

References 73 publications

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“…Although the microgranular structure has long been recognized in latosols, no consensus has yet been reached to explain its origin [Marcelino et al, 2018]. Two main origins have been proposed: either that it results mainly (i) from physico-chemical processes combining mechanical fragmentation of a compact soil material due to alternating wetting and drying in relation to change in physico-chemical interactions between kaolinite and iron oxyhydroxides [e.g.…”

Section: Origin Of the Microgranular Structurementioning

confidence: 99%

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Morphology, chemical composition and origin of 2:1 phyllosilicates in Bw horizons of latosols of the Brazilian Central Plateau: contribution to the discussion of the microgranular structure origin

Bruand¹,

Reatto²

2022

Comptes Rendus. Géoscience

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Polished sections of two Bw horizons collected in latosols located on the South American Surface (LSAS) and the Velhas Surface (LVS) in the Brazilian Central Plateau were studied using backscattered scanning images (BESI) in scanning electron microscopy and energy dispersive spectroscopy (EDS). BESI showed areas with a strong microgranular structure associated with areas having a weak to moderate microgranular structure. BESI at high magnification also showed the presence of

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Section: Origin Of the Microgranular Structurementioning

confidence: 99%

“…Cooper et al, 2005, Karathanasis et al, 1983, Melfi and Pédro, 1977, 1978, Volkoff and Melfi, 1980, or (ii) from bioturbation processes related to long term soil faunal activity, particularly termite activity [e.g. Jouquet et al, 2016, Marcelino et al, 2018, Reatto et al, 2009, Schaefer, 2001.…”

Section: Origin Of the Microgranular Structurementioning

confidence: 99%

Morphology, chemical composition and origin of 2:1 phyllosilicates in Bw horizons of latosols of the Brazilian Central Plateau: contribution to the discussion of the microgranular structure origin

Bruand¹,

Reatto²

2022

Comptes Rendus. Géoscience

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“…However, FP not only experienced hydrolysis, but also fersiallitization, before it was reworked. Indeed, FP contains not only primary silicate minerals, but also clays (essentially kaolinite with a minor proportion of smectite) and Fe oxyhydroxides, which point to the typical features of fersiallitization observed in thin sections (Diaz et al, 2016a; Marcelino et al, 2018).…”

Section: Discussionmentioning

confidence: 82%

Calcium transfer and mass balance associated with soil carbonate in a semi‐arid silicate watershed (North Cameroon): An overlooked geochemical cascade?

Dietrich

Diaz

Deschamps

et al. 2021

The Depositional Record

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Calcium is a key element of the Earth system and closely coupled to the carbon cycle. Weathering of silicate releases Ca, which is exported and sequestered in oceans. However, pedogenic calcium carbonate constitutes a second Ca‐trapping pathway that has received less attention. Large accumulations of pedogenic calcium carbonate nodules, associated with palaeo‐Vertisols, are widespread in North Cameroon, despite a carbonate‐free watershed. A previous study suggested that a significant proportion of Ca released during weathering was trapped in palaeo‐Vertisols but the pathways involved in the transfer of Ca from sources (the granite and the Saharan dust) to a temporary sink (the carbonate nodules) remain unclear. This study aims to compare the distribution of elements in carbonate nodules and their associated past and present compartments for Ca in the landscape. These compartments are all characterised by a distinctive geochemical composition, resulting from specific processes. Three end members have been defined based on geochemical data: (a) the granite and its residual products, dominated by K2O and Na2O, Ti and Zr, HREE, and a positive Ce anomaly; (b) the soil parental material and the Saharan dust, dominated by Al2O3, Fe2O3 and MgO, V, HREE, and a positive Ce anomaly; and finally (c) the carbonate nodules, which are dominated by CaO, a depletion in V, Ti and Zr, and an enrichment in REE with a negative Ce anomaly. Mass balance calculations in soil profiles demonstrated that the accumulation of Ca in carbonate nodules exceeds the Ca released by chemical weathering of the parental material, because of a continuous accumulation and contribution from lateral transfers. Consequently, at the landscape scale, carbonate nodules associated with palaeo‐Vertisols constitute a temporary sink for Ca. Such a spatial relationship between sources and transient compartments opens an avenue to the new concept of ‘geochemical cascade’, similar in terms of geochemistry, to the concept of ‘sediment cascade’ developed by continental sedimentologists.

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“…Loose infillings composed of silt and fine sand, result from deposition of fine material in open voids by surface and percolating water. Other types of infilling are interpreted as faunal voids filled with grains transported by soil animals such as termites (for example, passage feature; Kooistra & Pulleman, 2010;Marcelino et al, 2018;Figs 14C and 15C). Clay illuviation and low preservation of organic matter suggest generally oxidizing conditions.…”

Section: Micromorphological Features Of Well-drained Floodplain (Wfp)...mentioning

confidence: 99%

Compositional, micromorphological and geotechnical characterization of Holocene Tiber floodplain deposits (Rome, Italy) and sequence stratigraphic implications

et al. 2022

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This study reports a high-resolution micromorphological characterization of floodplain deposits to investigate the relationships among compositional, textural and geotechnical data, and integrate soil micromorphology with sequence stratigraphy. Compositional and textural characterization of facies associations and soil features are calibrated against geotechnical parameters. The latter, obtained from cone penetration and pocket penetrometer tests from a borehole advanced 60 m into the Tiber channel belt and floodplain, show that depositional features and post-depositional modifications are intrinsically associated with cone penetration test parameters: cone resistance; sleeve friction; and friction ratio. Petrographic and micromorphological features document pedogenetic modifications across stratigraphic markers evidenced by faunal and plant activity, accumulation of peat, and typified by precipitation of heavy metals, iron oxides and secondary carbonates. All of these features developed in correspondence with alluvial flooding surfaces that are correlated with non-marine and marine flooding surfaces recognized in the transgressive and highstand coastal and lagoonal deposits of the Tiber Depositional Sequence. These observations may serve as a model to reconstruct the sequence-stratigraphic evolution of ancient relict soils. Nevertheless, additional criteria (for example, their stratigraphic position and correlative surfaces) are necessary to adequately interpret the genesis of such low-rank stratigraphic surfaces. This work demonstrates that a combination between sedimentological and stratigraphic observations and soil micromorphology can be critical to supplement field observations and determine the relative effect of pedogenic and depositional processes on the organization, composition and texture, and geotechnical properties of floodplain in urban areas.

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Oxic and Related Materials

Cited by 18 publications

References 73 publications

Morphology, chemical composition and origin of 2:1 phyllosilicates in Bw horizons of latosols of the Brazilian Central Plateau: contribution to the discussion of the microgranular structure origin

Morphology, chemical composition and origin of 2:1 phyllosilicates in Bw horizons of latosols of the Brazilian Central Plateau: contribution to the discussion of the microgranular structure origin

Calcium transfer and mass balance associated with soil carbonate in a semi‐arid silicate watershed (North Cameroon): An overlooked geochemical cascade?

Compositional, micromorphological and geotechnical characterization of Holocene Tiber floodplain deposits (Rome, Italy) and sequence stratigraphic implications

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