Characteristics of Nubian Sandstone‐derived Soils

Singer, Arieh; Amiel, Abraham J.

doi:10.1111/j.1365-2389.1974.tb01127.x

Cited by 10 publications

(5 citation statements)

References 5 publications

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“…Its origin has been ascribed to neoformation (e.g. Singer & Norrish, 1974;Eswaran & Barzanji, 1974;Watts, 1976), alteration of montmorillonite (e.g. Yaalon & Wieder, 1976; Weaver & Beck, 1977) and to inheritance from palygorskiterich materials (e.g.…”

Section: Palygorskitementioning

confidence: 99%

“…Montmorillonite in weathering profiles may be detrital, or produced by weathering of primary minerals or neoformation (e.g. Singer & Amiel, 1974), migrating during pedogenesis by dispersion, physico-chemical fractionation and leaching (Millot, 1970, p. 108).…”

Section: Montmorillonitementioning

confidence: 99%

“…Their almost ubiquitous presence suggests that they play an integral role in calcrete formation. The occurrence of palygorskite in matted form discounts any possibilities of detrital origin (Singer & Norrish, 1974). The mineral is considered authigenic, formed either from alteration of montmorillonite (e.g.…”

Section: Origin Of Silicatesmentioning

confidence: 99%

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Quaternary pedogenic calcretes from the Kalahari (southern Africa): mineralogy, genesis and diagenesis

1980

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The calcretes of the Kalahari are amongst the thickest in the world representing pedogenic episodes in a semi‐arid climate during Pliocene to Recent times. The descriptive morphological terminology of Netterberg is used to describe the calcrete types and a differentiation into simple and composite profiles is made. A pedogenic/diagenetic scheme has been constructed using all available data. Early calcite cementation is induced by two mechanisms. Slow evaporation and/or CO2 loss causes the precipitation of low‐Mg calcite, whereas rapid evaporation and/or CO2 loss precipitates predominantly high‐Mg calcite, in thermodynamic disequilibrium with the low Mg/Ca ratio vadose water, and minor aragonite (which transforms rapidly to low‐Mg calcite). High‐Mg calcite is also precipitated from high Mg/Ca ratio vadose waters in calcretes developed on Mg‐rich host lithologies and by capillary rise from shallow groundwaters in saline depressions. Calcite precipitation may be passive (cement), displacive or replacive, in the latter released silica migrating down‐profile to precipitate length‐slow chalcedony, clinoptilolite (saline conditions), length‐fast chalcedony and megaquartz (non‐saline conditions). Displacive introduction of calcite takes place from highly supersaturated solutions due to rapid evaporation (with CO2 loss) of vadose waters. During low‐Mg calcite precipitation (in a ‘closed’ system) the Mg concentration of the resulting solution increases. This, combined with Mg released during high‐Mg to low‐Mg calcite transformation, induces precipitation of authigenic palygorskite, sepiolite and minor dolomite. Vadose dolomite is often present whilst some dolomite may be precipitated at the mixing‐zone of vadose and phreatic waters. The proposed model applies to the Kalahari calcretes, although it may perhaps be extrapolated to other areas. Further detailed studies, involving analyses of pore water chemistry, soil microclimate, and trace element and isotopic analyses of individual cements are necessary.

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Section: Palygorskitementioning

confidence: 99%

Section: Montmorillonitementioning

confidence: 99%

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Quaternary pedogenic calcretes from the Kalahari (southern Africa): mineralogy, genesis and diagenesis

1980

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“…Multiple genetic interpretations have been offered to explain the presence of palygorskite in the rock record. These include palygorskite as a primary detrital mineral (Singer & Amiel, ; Singer, ), a diagenetic replacement of detrital smectite (Weaver & Beck, ; Chen et al ., ; Xie et al ., ) and a direct precipitate from aqueous solutions (Weaver, ; Shadfan et al ., ; Çağatay, ; Botha & Hughes, ; Holail & Al‐Hajari, ; Xie et al ., ). Efforts to understand the fundamental controls on palygorskite formation have, however, been limited by an inability to synthesize it in the laboratory at earth surface conditions (Singer, , ).…”

Section: Introductionmentioning

confidence: 99%

Dolomite dissolution: An alternative diagenetic pathway for the formation of palygorskite clay

2019

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Palygorskite is a fibrous, magnesium-bearing clay mineral commonly associated with Late Mesozoic and Early Cenozoic dolomites. The presence of palygorskite is thought to be indicative of warm, alkaline fluids rich in Si, Al and Mg. Palygorskite has been interpreted to form in peritidal diagenetic environments, either as a replacement of detrital smectite clay during a dissolutionprecipitation reaction or solid-state transformation, or as a direct precipitate from solution. Despite a lack of evidence, most diagenetic studies involving these two minerals posit that dolomite and palygorskite form concurrently. Here, petrological evidence is presented from the Umm er Radhuma Formation (Palaeocene-Eocene) in the subsurface of central Qatar for an alternative pathway for palygorskite formation. The Umm er Radhuma is comprised of dolomitized subtidal to peritidal carbonate cycles that are commonly capped by centimetre-scale beds rich in palygorskite. Thin section, scanning electron microscopy and elemental analyses demonstrate that palygorskite fibres formed on both the outermost surfaces of dissolved euhedral dolomite crystals and within partially to completely dissolved dolomite crystal cores. These observations suggest that dolomite and palygorskite formed sequentially, and support a model by which the release of Mg 2+ ions and the buffering of solution pH during dolomite dissolution promote the formation of palygorskite. This new diagenetic model explains the co-occurrence of palygorskite and dolomite in the rock record, and provides valuable insight into the specific diagenetic conditions under which these minerals may form.

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“…Hundreds of monuments were carved mainly in the mid and upper Cambrian Umm Ishrin Sandstone and the Ordovician Disi Sandstone, [1] also known as Nubian sandstone (quartzarenite). Regarding the soils derived from Nubian sandstone, Singer and Amiel [2] mention that these can contain carbonates and soluble salts, including gypsum. The weather in this region is very dry, and the rain is seasonal and torrential in winter.…”

Section: Introductionmentioning

confidence: 98%

Evaluation of Portable Raman for the Characterization of Salt Efflorescences at Petra, Jordan

López-Arce¹,

Zornoza-Indart²,

Vázquez-Calvo³

et al. 2011

Spectroscopy Letters

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The advantages of using portable Raman spectrometer equipment, such as avoiding sampling and providing a higher number of results, are contrasted with some of its shortfalls that make other analytical techniques necessary to characterize salt efflorescences on historic buildings. In-situ analyses of salt efflorescences were carried out with a portable Raman at both the so-called ''Silk Tomb'' and ''Monastery'' rock-cut façades at the Archaeological Park of Petra (Jordan). Samples were also taken to be analyzed in the laboratory with X-ray diffraction (XRD) and Environmental Scanning Electron Microscope with Energy-Dispersive X-ray spectroscopy and Cathodoluminescence (ESEM-EDS-CL). This research shows the pros and cons of these analytical techniques-and how they complement each other-to identify the occurrence and determine the origin of soluble salts, which are deeply damaging these rock-cut monuments by salt crystallization processes.

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Characteristics of Nubian Sandstone‐derived Soils

Cited by 10 publications

References 5 publications

Quaternary pedogenic calcretes from the Kalahari (southern Africa): mineralogy, genesis and diagenesis

Quaternary pedogenic calcretes from the Kalahari (southern Africa): mineralogy, genesis and diagenesis

Dolomite dissolution: An alternative diagenetic pathway for the formation of palygorskite clay

Evaluation of Portable Raman for the Characterization of Salt Efflorescences at Petra, Jordan

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