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A sand budget for the Alexandria coastal dunefield, South Africa (1988)

ILLENBERGER, WERNER K. ; RUST, IZAK C.

Oxford, UK : Blackwell Publishing Ltd

Sedimentology 35 (1988), S. 0

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ISSN: 1365-3091

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences

Notes: The sand in the Alexandria coastal dunefield is derived from the sandy beach which forms the seaward boundary of the dunefield. Sand is blown off the beach onto the dunefield by the high-energy onshore-directed dominant wind. The dunefield has been forming over the past 6500 years.Sand transport rates calculated from dune movement rates and wind data range from 15 to 30 m3 m -1 yr-1 in an ENE direction. The sand transport rate decreases with increasing distance from the sea due to a reduction in wind speed resulting from the higher drag imposed upon the wind by the land surface. Aeolian sand movement rates of this order are typical of dunefields around the world.The total volume of sand blown into the dunefield is 375 000 m3 yr-1. Sand is being lost to the sea by wave erosion along the eastern third of the dunefield at a rate of 45 000 m3 yr -1. The dunefield thus gains 330 000 m3 of sand per year. This results in dunefield growth by vertical accretion at about 1.5 mm yr-1 and landward movement at about 0.25 m yr-1. The dunefield is a significant sand sink in the coastal sand transport system.The rate of deposition in coastal dunefields can be 10 times as high as rates of deposition in continental sand seas. The higher rate of deposition may result from the abundant sand supply on sandy beaches, and the higher energy of coastal winds.Wind transport is slow and steady compared to fluvial or longshore drift transport of sediment, and catastrophic aeolian events do not seem to be significant in wind-laid deposits.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-3091.1988.tb01001.x

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Upper Ordovician chitinozoans from the Cedarberg Formation of South Africa. Preliminary note (1974)

Cramer, Fritz H. ; Rust, Izak C. ; Díez de Cramer, M. d. C. R.

Springer

International journal of earth sciences 63 (1974), S. 340-345

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ISSN: 1437-3262

Keywords: Soom Shale ; Cedarberg Formation ; Ordovician ; chitinozoans ; organic eometamorphism

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences

Description / Table of Contents: Abstract Chitinozoans bracket the geological age of the Soom Shale at the base of the Cedarberg Formation of South Africa as Lower Silurian to Upper Ordovician whereby the oldest age is the more probable. On account of the organic eometamorphism the most likely maximum depth of burial of the Soom Shale was slightly in excess of 5000 meters.

Abstract: Resumen La edad geológica de las pizarras Soom (base de la formatión de Cedarberg, áfrica del Sur) es determinada por los quitinozoos como SilÚrico inferior a Ordovícico superior, siendo esta Última la más probable. Por medio del nivel de eometamorfismo orgánico se estima que las pizarras Soom se hallaban cubiertas por terrenos de mas de 5000 metros de espesor.

Notes: Zusammenfassung Das Alter der Soom-Schiefer an der Basis der Cedarberg-Formation in Südafrika wurde mit Hilfe von Chitinozoen als unteres Silur bis oberes Ordovizium bestimmt, wobei das höchste Alter am wahrscheinlichsten ist. Die Höhe des organischen Eometamorphismus in den Soom-Schiefern würde einem Gebirgsdruck von wenig mehr als 5000 Metern entsprechen.