Holocene environmental change along the southern Cape coast of South Africa: Insights from the Eilandvlei sediment record spanning the last 8.9 kyr

Michael Wündsch, Torsten Haberzettl, Hayley C. Cawthra, Kelly L. Kirsten, Lynne J. Quick, Matthias Zabel, Peter Frenzel, Annette Hahn, Jussi Baade, Gerhard Daut, Thomas Kasper, Michael E. Meadows, Roland Mäusbacher

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

This study investigates Holocene sediments from Eilandvlei, a coastal lake located within the Wilderness embayment at the southern Cape coast of South Africa. The evolution of the present estuarine/coastal lake system is reconstructed based on seismic data as well as a multi-proxy approach on a 30.5 m sediment core spanning the last ~8.9 kyr. Geochemical (Ca, TOC/S, Br/TOC) and micropalaeontological data (diatoms, foraminifera) reflect changes in the degree of marine influence at the core site. The embayment likely developed via distinct phases of connectivity to the Indian Ocean caused by sea level changes and dune progradation. Marine conditions prevailed at the core site from ~8900 to 4700 cal BP. The rapid sea level rise during the early Holocene caused the inundation of a palaeovalley that most likely had formed at lower sea levels during the Pleistocene. Towards the mid-Holocene the sea level exceeded its present height around ~7500 cal BP creating a marine embayment. At ~4700 cal BP, the embayment became distinctly more disconnected from the ocean turning into a lagoon system that persisted until ~1200 cal BP. Subsequently, the marine influence further decreased and the present estuarine/coastal lake system was established.

Grain size and geochemical data (Fe, Si/Al, chemical index of alteration (CIA)) further reflect changes in the deposition of terrigenous sediments at the core site. While the sedimentation of fine-grained (
Original languageEnglish
Pages (from-to)51-66
Number of pages16
JournalGlobal and Planetary Change
Volume163
Early online date4 Feb 2018
DOIs
Publication statusPublished - 1 Apr 2018
Externally publishedYes

Bibliographical note

© 2018 Elsevier B.V. All rights reserved.

Funder

(BMBF). The investigations were conducted within the collaborative project “Regional Archives for Integrated Investigations” (RAIN; grant no.: 03G0862B), which is embedded in the international research programme SPACES (Science Partnership for the Assessment of Complex Earth System Processes).

We are deeply grateful to South African National Parks (Garden Route National Park Scientific Services, Sedgefield) for the permission to conduct our fieldwork on Eilandvlei. We thank Sayed Hess, Richard Niederreiter and Bastian Reinwarth for their helping hands during the fieldwork as well as Stephanie Meschner, Sascha Fürstenberg, Nico Blaubach and Carmen Kirchner for their help during the data acquisition. Jacques Labrie is acknowledged for providing the modified version of the Gradistat 4.2 software. Finally, we thank Brian M. Chase for his comments on an earlier version of the manuscript.

Keywords

  • Coastal lake sediments
  • Sedimentary geochemistry
  • Palaeoclimate
  • Sea level change
  • El Niño-Southern Oscillation

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