Skip to main content

The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers, South Africa

Journal Article


Abstract


  • Barrier systems contain lengthy, but complex, records of long-term environmental fluctuations. The

    Wilderness embayment, South Africa, contains a system of shore-parallel barriers reaching up to 200 m

    above modern sea level. This study reports the results of chronological, topographical (both on- and offshore),

    sedimentological and micromorphological analyses within the Wilderness embayment. Sixty-one

    new luminescence ages from sixteen sites in unconsolidated dunes and three separate barriers are

    presented which, when combined with previously published luminescence ages from the area, provide

    a high-resolution chronological framework for the emplacement and evolution of the barrier system. The

    preserved barriers have been constructed within at least the last two glacialeinterglacial cycles with

    notable phases between 241e221 ka, 159e143 ka, 130e120 ka, 92e87 ka and post 6 ka. Multiple phases

    of barrier construction occurred during sea-level highstands, with sediment deposition on each individual

    barrier occurring over at least two interglacials. Holocene evolution of the system sheds light on

    earlier events, with dune preservation occurring only during early regression from the Mid-Holocene

    highstand. Tectonic stability at Wilderness allowed glacio-eustatically formed shorelines to occupy

    similar positions on multiple occasions. This, in conjunction with a relatively humid climate and a wellvegetated

    landscape, enabled deflated sediment from beaches to form dunes which stacked upon each

    other to form an extensive and complex vertical accretionary sequence. Repeated erosion and recycling

    of pre-existing barriers as well as barrier construction on what is currently the off-shore platform during

    still-stands in sea-level regressional cycles, when sea levels dropped below ca 50 m from the present

    day, has added to the complexity of the preserved terrestrial barrier record. The Wilderness barrier

    system contrasts with barriers developed elsewhere in the world where higher rates of crustal uplift

    have allowed preservation of a more complete and more widely spaced palaeorecord. This research also

    shows the utility of integrating off-shore topography as revealed by bathymetry, with terrestrial topographic

    data for the better understanding of the evolution of palaeo-coastlines and the preserved dune

    record found on present-day coastal plains. Local variation in the topography of the continental shelf at

    Wilderness has generated spatial and temporal complexity within the sedimentary records of individual

    barriers as well as having a significant influence on preservation.

Authors


  •   Bateman, Mark D. (external author)
  •   Carr, Andrew S. (external author)
  •   Dunajko, Adam D. (external author)
  •   Holmes, Peter J. (external author)
  •   Roberts, David L. (external author)
  •   McLaren, Sue J. (external author)
  •   Bryant, Robert G. (external author)
  •   Marker, Margaret E. (external author)
  •   Murray-Wallace, Colin V.

Publication Date


  • 2011

Citation


  • Bateman, M. D., Carr, A. S., Dunajko, A. C., Holmes, P. J., Roberts, D. L., McLaren, S. J., Bryant, R. G., Marker, M. E. & Murray-Wallace, C. V. (2011). The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers, South Africa. Quaternary Science Reviews, 30 (1-2), 63-81.

Scopus Eid


  • 2-s2.0-78650518377

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5226

Number Of Pages


  • 18

Start Page


  • 63

End Page


  • 81

Volume


  • 30

Issue


  • 1-2

Place Of Publication


  • http://www.elsevier.com/wps/find/journaldescription.cws_home/636/description#description

Abstract


  • Barrier systems contain lengthy, but complex, records of long-term environmental fluctuations. The

    Wilderness embayment, South Africa, contains a system of shore-parallel barriers reaching up to 200 m

    above modern sea level. This study reports the results of chronological, topographical (both on- and offshore),

    sedimentological and micromorphological analyses within the Wilderness embayment. Sixty-one

    new luminescence ages from sixteen sites in unconsolidated dunes and three separate barriers are

    presented which, when combined with previously published luminescence ages from the area, provide

    a high-resolution chronological framework for the emplacement and evolution of the barrier system. The

    preserved barriers have been constructed within at least the last two glacialeinterglacial cycles with

    notable phases between 241e221 ka, 159e143 ka, 130e120 ka, 92e87 ka and post 6 ka. Multiple phases

    of barrier construction occurred during sea-level highstands, with sediment deposition on each individual

    barrier occurring over at least two interglacials. Holocene evolution of the system sheds light on

    earlier events, with dune preservation occurring only during early regression from the Mid-Holocene

    highstand. Tectonic stability at Wilderness allowed glacio-eustatically formed shorelines to occupy

    similar positions on multiple occasions. This, in conjunction with a relatively humid climate and a wellvegetated

    landscape, enabled deflated sediment from beaches to form dunes which stacked upon each

    other to form an extensive and complex vertical accretionary sequence. Repeated erosion and recycling

    of pre-existing barriers as well as barrier construction on what is currently the off-shore platform during

    still-stands in sea-level regressional cycles, when sea levels dropped below ca 50 m from the present

    day, has added to the complexity of the preserved terrestrial barrier record. The Wilderness barrier

    system contrasts with barriers developed elsewhere in the world where higher rates of crustal uplift

    have allowed preservation of a more complete and more widely spaced palaeorecord. This research also

    shows the utility of integrating off-shore topography as revealed by bathymetry, with terrestrial topographic

    data for the better understanding of the evolution of palaeo-coastlines and the preserved dune

    record found on present-day coastal plains. Local variation in the topography of the continental shelf at

    Wilderness has generated spatial and temporal complexity within the sedimentary records of individual

    barriers as well as having a significant influence on preservation.

Authors


  •   Bateman, Mark D. (external author)
  •   Carr, Andrew S. (external author)
  •   Dunajko, Adam D. (external author)
  •   Holmes, Peter J. (external author)
  •   Roberts, David L. (external author)
  •   McLaren, Sue J. (external author)
  •   Bryant, Robert G. (external author)
  •   Marker, Margaret E. (external author)
  •   Murray-Wallace, Colin V.

Publication Date


  • 2011

Citation


  • Bateman, M. D., Carr, A. S., Dunajko, A. C., Holmes, P. J., Roberts, D. L., McLaren, S. J., Bryant, R. G., Marker, M. E. & Murray-Wallace, C. V. (2011). The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers, South Africa. Quaternary Science Reviews, 30 (1-2), 63-81.

Scopus Eid


  • 2-s2.0-78650518377

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5226

Number Of Pages


  • 18

Start Page


  • 63

End Page


  • 81

Volume


  • 30

Issue


  • 1-2

Place Of Publication


  • http://www.elsevier.com/wps/find/journaldescription.cws_home/636/description#description