Modern beachrock formation in Durban, KwaZulu-Natal

We explored the recent cementation of modern beachrock on the seaward margin of the Durban Bluff, central KwaZulu-Natal. The low latitude and subtropical climatic setting is a unique context compared to the more commonly documented contemporary beachrock formation in the tropics. Geological field ma...

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Bibliographic Details
Published in:South African Journal of Science 2012-07, Vol.108 (7/8), p.1-1
Main Authors: Cawthra, Hayley, Uken, Ron
Format: Article
Language:English
Subjects:
carbonate cementation
Cement
Cementation
Cementing
Cements
clastic shoreline
Coastlines
Deposits
Diagenesis
Earth science
Geology
Grain size
Holocene
Interstitials
Iron oxides
Light microscopy
Marine
marine phreatic diagenesis
modern beachrock formation
Personal relationships
Pleistocene
recent sea level change
Sea level
Sea level changes
Sediment transport
Tropical environments
Voids
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Summary:We explored the recent cementation of modern beachrock on the seaward margin of the Durban Bluff, central KwaZulu-Natal. The low latitude and subtropical climatic setting is a unique context compared to the more commonly documented contemporary beachrock formation in the tropics. Geological field mapping was carried out and here we present results based on sedimentary facies of a clastic shoreline and carbonate diagenesis of interstitial cements using transmitted light microscopy. The beachrock was cemented by micrite and aragonite, and iron oxide infilled voids. The presence of human artefacts within the deposit showed evidence for cementation within the last century. The elevation (at Mean Low Water) and correlation to rates of sea level change for the east coast of South Africa showed that the beachrock is less than 72 years in age. In contrast to older local Pleistocene deposits, beachrocks have cemented along this stretch of coast during successive sea level highstands with similar climatic regimes - the last Interglacial, the Holocene High and the present. Here we report the most southerly documentation of modern beachrock in KwaZulu-Natal, which, to our knowledge, represents the youngest deposit reported in southern Africa. [PUBLICATION ABSTRACT]
ISSN:0038-2353
1996-7489
DOI:10.4102/sajs.v108i7/8.935