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Pliocene-Pleistocene stratigraphy and sea-level estimates, Republic of South Africa with implications for a 400 ppmv CO2 world
  • +3
  • Paul Hearty,
  • Alessio Rovere,
  • Michael Sandstrom,
  • Michael O'Leary,
  • David Roberts (deceased),
  • Maureen E. Raymo
Paul Hearty
Jackson School of Geosciences, University of Texas at Austin

Corresponding Author:[email protected]

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Alessio Rovere
Universität Bremen,Lamont-Doherty Earth Observatory, Columbia University
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Michael Sandstrom
Columbia University
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Michael O'Leary
The University of Western Australia,University of Western Australia
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David Roberts (deceased)
Council for Geosciences, Cape Town and Faculty of Natural and Agricultural Sciences, University of the Free State, 205 Nelson Mandela Drive, Bloemfontein, 9300, Republic of South Africa.
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Maureen E. Raymo
Columbia University
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Abstract

Hearty, P. J., Rovere, A., Sandstrom, M. R., O’Leary, M. J., Roberts, D., & Raymo, M. E. (2020). Pliocene‐Pleistocene stratigraphy and sea‐level estimates, Republic of South Africa with implications for a 400 ppmv CO2 world. Paleoceanography and Paleoclimatology, 35, e2019PA003835. https://doi.org/10.1029/2019PA003835 The Mid-Pliocene Warm Period (MPWP, 2.9 to 3.3 Ma), along with older Pliocene (3.2 to 5.3 Ma) records, offers potential past analogues for our 400-ppmv world. The coastal geology of western and southern coasts of the Republic of South Africa expose an abundance of marine deposits of Pliocene and Pleistocene age. In this study, we report differential GPS elevations, detailed stratigraphic descriptions, standardized interpretations, and dating of relative sea-level indicators measured across ~700 km from the western and southern coasts of the Cape Provinces. Wave abrasion surfaces on bedrock, intertidal sedimentary structures, and in situ marine invertebrates including oysters and barnacles provide precise indicators of past sea levels. Multiple sea-level highstands imprinted at different elevations along South African coastlines were identified. Zone I sites average +32 ± 5 m (6 sites). A lower topographic Zone II of sea stands were measured at several sites around +17 ± 5 m. Middle and late Pleistocene sites are included in Zone III. Shoreline chronologies using 87Sr/86Sr ages on shells from these zones yield ages from Zone I at 4.6 and 3.0 Ma, and Zone II at 1.04 Ma. Our results show that polar ice sheets during the Plio-Pleistocene were dynamic and subject to significant melting under modestly warmer global temperatures. These processes occurred during a period when CO2 concentrations were comparable to our current and rapidly rising values above 400 ppmv.