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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Main Authors: Hayley Cawthra, Ron Uken
Format: Article
Language:English
Published: Academy of Science of South Africa 2012-07-01
Series:South African Journal of Science
Subjects:
Online Access:https://sajs.co.za/article/view/9814
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author Hayley Cawthra
Ron Uken
author_facet Hayley Cawthra
Ron Uken
author_sort Hayley Cawthra
collection DOAJ
description 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.
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spelling doaj-art-1425807ea8704f6bbc384b58268526412025-08-20T03:08:52ZengAcademy of Science of South AfricaSouth African Journal of Science1996-74892012-07-011087/85 Pages5 Pages8111Modern beachrock formation in Durban, KwaZulu-NatalHayley Cawthra0Ron Uken1Council for Geoscience, Marine Geoscience Unit, Cape TownSchool of Geological Sciences, University of KwaZulu-Natal, DurbanWe 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.https://sajs.co.za/article/view/9814modern beachrock formationcarbonate cementationmarine phreatic diagenesisrecent sea level changeclastic shoreline
spellingShingle Hayley Cawthra
Ron Uken
Modern beachrock formation in Durban, KwaZulu-Natal
South African Journal of Science
modern beachrock formation
carbonate cementation
marine phreatic diagenesis
recent sea level change
clastic shoreline
title Modern beachrock formation in Durban, KwaZulu-Natal
title_full Modern beachrock formation in Durban, KwaZulu-Natal
title_fullStr Modern beachrock formation in Durban, KwaZulu-Natal
title_full_unstemmed Modern beachrock formation in Durban, KwaZulu-Natal
title_short Modern beachrock formation in Durban, KwaZulu-Natal
title_sort modern beachrock formation in durban kwazulu natal
topic modern beachrock formation
carbonate cementation
marine phreatic diagenesis
recent sea level change
clastic shoreline
url https://sajs.co.za/article/view/9814
work_keys_str_mv AT hayleycawthra modernbeachrockformationindurbankwazulunatal
AT ronuken modernbeachrockformationindurbankwazulunatal