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Title: Pliocene‐Pleistocene Stratigraphy and Sea‐Level Estimates, Republic of South Africa With Implications for a 400 ppmv CO 2 World
Abstract

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 exposes 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 (six 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 using87Sr/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 CO2concentrations were comparable to our current and rapidly rising values above 400 ppmv.

 
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NSF-PAR ID:
10456318
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Paleoceanography and Paleoclimatology
Volume:
35
Issue:
7
ISSN:
2572-4517
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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