Montmorillonitic Soils Developed in Nile River Sediments

El-Attar, H. A.; Jackson, M. L.

doi:10.1097/00010694-197309000-00007

Cited by 21 publications

(9 citation statements)

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“…Briner and Jackson (1970) proposed a SiOJR20 3 molar ratio method of calculation to eliminate the interference by other iron-rich phyllosilicates such as partially chloritized montmorillonites which may be dehydroxylated along with kaolinite. El-Attar and Jackson (1973) reported that large quantities of silica and alumina were dissolved from 2:1 layer silicates by the 0.5 N NaOH extraction after dehydroxylation of the clay fractions of montmorillonitic soils in Nile River sediments. This was reflected in the high SiO2/ R203 molar ratios of 2.44-3.34 obtained by them.…”

Section: Resultsmentioning

confidence: 99%

Isomorphous Substitution of Iron for Aluminium in Some Soil Kaolinites

Rengasamy

1975

Clays and clay miner.

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Abstract--Clay ( < 2 ttm) and fine silt (~20/~m) fractions of twenty seven soil samples from eight tropical ferruginous profiles of the Mysore Plateau (India) were analysed for kaolinite by dehydroxylation and selective dissolution. The considerable amounts of iron extracted by the procedure and the closeness of the SiO2/R203 molar ratios (2.00-2.18) to the ideal value of 2.00 indicated that iron was a structural constituent of the kaolinites, The calculated unit cell cation composition of the kaolinites showed a substitution of 0.114).82 atoms of Fe(III) for A1 in every four octahedral sites. The kaolinites in these soils appear to be products of crystallization from weathering solutions.

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Section: Resultsmentioning

confidence: 99%

Isomorphous Substitution of Iron for Aluminium in Some Soil Kaolinites

Rengasamy

1975

Clays and clay miner.

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“…Petrographic, heavy‐mineral and isotopic data after Garzanti et al. (); clay‐mineral data after Buursink (), El‐Attar and Jackson (), de Vivo et al. (), and Nyakairu and Koeberl ()…”

Section: Propagation Of Detrital Signals In a Segmented River Systemmentioning

confidence: 99%

“…This indicates that not even the finest sediment fraction can pass the marshlands. Smectite represents the dominant clay mineral from Ethiopia and Sudan to the Mediterranean sea floors (El-Attar & Jackson, 1973;Stanley & Wingerath, 1996).…”

Section: Discontinuous Propagation Of Other Provenance Signalsmentioning

confidence: 99%

The zircon story of the Nile: Time‐structure maps of source rocks and discontinuous propagation of detrital signals

et al. 2018

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A new dimension has recently been added to provenance analysis by the rapid development of detrital‐geochronology techniques. The application of any dating method to sediments allows the definition of a unique age pattern of parent rocks, a “time structure” that represents an essential complement to the information on their lithological structure obtained by traditional petrographic and mineralogical methods. This detrital‐geochronology study illustrates the distribution of U‐Pb zircon ages in all parts of the Nile catchment from its equatorial headwaters to the Delta, and surveys how the provenance signal is formed, transmitted, and modified along this huge sediment‐routing system. Age‐spectra obtained by targeting specific parts of zircon grains after cathodo‐luminesce imaging and by our Automated Phase Mapping + LAICPMS “blind‐dating strategy” were compared. The former approach emphasises specific magmatic or metamorphic events in source areas, whereas the latter aims at minimising selection bias and focuses on consistency among samples. Grain‐size and hydraulic‐sorting controls were also checked, but found to have only a minor effect on zircon‐age distributions. The trimodal age spectrum of Kagera zircons sourced from the rift highlands of Burundi and Rwanda, characterised by prominent late Neoarchean (Aruan) and mid‐Mesoproterozoic (Kibaran) peaks with a wider mid‐Palaeoproterozoic (Ubendian) cluster, is lost in the Lake Victoria sediment sink. The sharp unimodal Aruan peak displayed by zircon grains in both Victoria and Albert Nile is supplemented and finally superseded by Neoproterozoic grains across the vast marshlands of South Sudan, where detritus produced in equatorial regions is eventually stored. All Nile tributaries in Sudan and Egypt carry zircon grains yielding predominantly Neoproterozoic ages, with a major peak around 0.6 Ga associated with clusters around 0.8 and 1.0 Ga. A few Oligocene zircons represent the key diagnostic feature of Ethiopian provenance, the Ariadne's golden thread that allowed retracing the palaeo‐Nile to its Ethiopian sources back in the Oligocene. The Nile presents a text‐book case of discontinuous transmission of provenance signals along a segmented ultra‐long drainage system. Zircon‐age fingerprints as well as all other detrital signatures are lost repeatedly in large Ugandan lakes, reconstituted or replaced, lost again in the vast marshlands of South Sudan, and finally homogenised downstream from Ethiopia and Sudan to the Mediterranean Sea.

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“…Greater packing stability develops with time and depth, resulting in porosities of 50% or less. Such dewatering and compaction phases are also affected by certain features attributed to specific clay types in the argillaceous deposits, especially the smectite (montmorillonite) species that dominate and account for about 70% of the clay components in the Holocene sections of the Nile Delta (El-Attar and Jackson, 1973;El Sabrouti and Sokkary, 1982;Fayed and Hassan, 1970;Stanley and Wingerath, 1996;Stanley, Mart, and Nir, 1997;Weir, Ormerod, and El-Mansey, 1975). This group of clay minerals is characterized by very fine-grained particles and expansion perpendicular to the layers because of interlayer water absorption.…”

Section: Introductionmentioning

confidence: 99%