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Table of Contents - Memoir 201 (MWR201)

The African Erosion Surface: A Continental-Scale Synthesis of Geomorphology, Tectonics, and Environmental Change over the Past 180 Million Years

by Kevin Burke and Yanni Gunnell

Abstract 1
The Unique Tectonic Identity of the African Continent: Expected Effects on the History of Its Eroding Land Surface 2
General Characteristics of the African Surface 6
What Is the African Surface? 6
  The African Surface: A Composite Surface 6
  Tectonic Evolution of Afro-Arabia and Its Controls on the History of the African Surface 7
  Structures That Influenced Local Relief on the African Surface during Its Evolution 10
  The African Surface in Basins That Experienced Marine Incursions between 100 Ma and 34 Ma 11
Regional Characteristics of the African Surface 13
  The African Surface in Its Type Area: Southern Africa 13
      History of the Concept of the African Surface 13
      Recent Interpretations of the African Surface 15
      The African Surface in Southern Africa: A Summary 19
  West Africa: From Senegal to Cameroon 20
  Central Africa 24
  East Africa: The Great Swell and the Rift System 27
  Northeastern Africa and Arabia 29
  Summary: Regional Age Brackets for the African Surface 31
Bauxite Occurrences as Indices of the African Surface: Their Value and Limitations 31
  Bauxites … and Bauxites 31
  Examples of Orthobauxites and Laterites in Afro-Arabia Inherited from the Last Great Bauxite-Forming Interval, 70–40 Ma 32
  Staircases of Bauxite- and Laterite-Capped Surfaces in Their Key Area: West Africa 32
  Bauxites in Africa That May Have Formed since the End of the Main Bauxite-Forming Interval, i.e., after 40 Ma 35
  Synthesis on Bauxites and Laterites 36
The Imprint of Continental-Scale Paleoclimatic Variations in Afro-Arabia 37
  Cretaceous Times, 140–65 Ma 37
  Earlier Cenozoic Times, 65–34 Ma 38
  Early Oligocene to Late Pliocene Times, 34–2.8 Ma 39
  Late Pliocene and Quaternary Times, since 2.8 Ma 40
The African Surface in the Post–30 Ma Basin-and-Swell Reference Frame 40
  Burial of the African Surface in Africa’s Active Continental Basins 40
  Topographic Uplift of the African Surface on Africa’s Swells 40
      Volcanism or Absence Thereof: Its Relevance to the African Surface 40
      The African Surface on Africa’s Swells: General Characteristics 42
      The Great Swell of South Africa 44
Implications of the Cenozoic Swell Model for the History of the Great Escarpments at Africa’s Continental Margins 46
  Long-Lived Escarpments Close to Rifted Continental Margins? A Return to the Historical Type Area of the African Surface in Southern Africa 46
  A New Perspective on the Great Escarpment of Southern Africa 52
Summary and Conclusions 57
Acknowledgments 59
References Cited 59