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GEOREF RECORD

Aeolian and marine deposits of the Tabakbaai Quarry area, Western Cape, South Africa

Giuliana Franceschini and John S. Compton
Aeolian and marine deposits of the Tabakbaai Quarry area, Western Cape, South Africa
South African Journal of Geology (December 2004) 107 (4): 619-632

Abstract

The Prospect Hill Formation is well exposed in the Tabakbaai Quarry near Saldanha Bay and represent the southern portion of a 200 km long fossilised dune cordon oriented north-northeastward. The Prospect Hill Formation consists of basal sandy beach deposits conformably overlain by up to 70 m of aeolian sands. Carbonate shell fragments, foraminiferal tests, echinoderm spines and barnacle plates make up 90% of the sand-size fraction, well -rounded quartz grains make up the remaining 10%. Previously proposed ages for the Prospect Hill Formation range from middle Miocene ( approximately 10 to approximately 12 Ma), based on eggshell of an extinct ostrich species, to latest Pliocene/early Pleistocene based on foraminiferal biostratigraphy. Strontium isotope stratigraphy of various biogenic components from this study, however, indicates a latest Miocene/early Pliocene age for the Prospect Hill Formation, making these dunes the oldest coastal dune system in the Western Cape. Our strontium ages are consistent with the global sea-level highstand at the Mio/Pliocene boundary and appear to correlate with the terrestrial fauna at Langebaanweg Quarry. A reconstruction of the palaeoshoreline in the Saldanha Bay area demonstrates that coastal progradation was dominant in the area up until the latest Miocene/early Pliocene, when sea level was 25 m above present day, and strong southerly winds formed the carbonate dune cordon. Evidence of a 23 to 24 m highstand during the early Pleistocene is recorded by a coquina bed deposited on a wave cut terrace, similar to other marine terraces preserved along the west and east coasts of southern Africa.


ISSN: 1012-0750
EISSN: 1996-8590
Coden: TGSAA3
Serial Title: South African Journal of Geology
Serial Volume: 107
Serial Issue: 4
Title: Aeolian and marine deposits of the Tabakbaai Quarry area, Western Cape, South Africa
Affiliation: University of Cape Town, Department of Geological Sciences, Rondebosch, South Africa
Pages: 619-632
Published: 200412
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 51
Accession Number: 2005-056819
Categories: StratigraphySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map, 1 table, sect.
S33°00'00" - S33°00'00", E17°55'00" - E17°55'00"
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200520
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