Modern beachrock formation in Durban, KwaZulu-Natal

Authors

  • Hayley Cawthra Council for Geoscience, Marine Geoscience Unit, Cape Town
  • Ron Uken School of Geological Sciences, University of KwaZulu-Natal, Durban

Keywords:

modern beachrock formation, carbonate cementation, marine phreatic diagenesis, recent sea level change, clastic shoreline

Abstract

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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Author Biographies

Hayley Cawthra, Council for Geoscience, Marine Geoscience Unit, Cape Town

Hayley Cawthra is a geologist in the Marine Geoscience Unit, Council for Geoscience

Ron Uken, School of Geological Sciences, University of KwaZulu-Natal, Durban

Professor Ron Uken is a lecturer in the School of Geological Sciences, University of KwaZulu-Natal

Published

2012-07-11

How to Cite

Cawthra, H., & Uken, R. (2012). Modern beachrock formation in Durban, KwaZulu-Natal. South African Journal of Science, 108(7/8), 5 Pages. Retrieved from https://sajs.co.za/article/view/9814

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