Abstract

The late Paleozoic to Tertiary stratigraphic record of much of the African plate reflects the effects of continental rifting and passive margin development. Several short-lived, but widespread and tectonically important, compressional or wrench-dominated events occurred, however, during the Permian to Recent evolution of Africa. We focus here on the best documented of these events, which occurred during the late Santonian. At that time, older sedimentary basins, mostly ENE-WSW trending, were folded and inverted, including some basins along the Tethyan margin from Morocco to the Syrian Arc and the intraplate Benue-southern Chad basins and the Lugh-Mandera basin. In Oman, ophiolites were obducted. Following the Santonian tectonism, an extensive phase of rifting occurred in Central and North Africa and northern Arabia, spanning from Campanian to Maastrichtian or Paleocene times. Rejuvenation or acceleration of subsidence occurred in several basins located along the Tethyan margin, along the Atlantic and Indian Ocean margins, as well as within the intraplate domain. Rifting was sometimes accompanied by magmatic activity, especially in offshore northern Libya and along the Indian Ocean margin. Compressional deformations rejuvenated or developed by latest Maastrichtian times along the Tethyan margin and locally within the intraplate domain. One of the most remarkable attributes of the Santonian tectonic event, which we consider representative of the major trans-African stress field changes, is the rapidity with which the change was reflected stratigraphically across North and Central Africa, and its short duration. The cause of the Santonian compressional event is directly linked to the change in poles of rotation for the opening of the Atlantic at ∼83–85 Ma, the end of the Cretaceous Normal Magnetic Quiet Zone. This was also synchronous with the obduction of ophiolites along the northeast margin of Arabia (Oman), the onset of separation between India and Madagascar with formation of the Mascarene oceanic basin, and the development of the European Alpine Chain. We interpret these phenomena as causally related aspects of a global tectonic event. The Santonian compressional event, as well as the Campanian-Maastrichtian rifting event and the end Cretaceous compressional event, illustrate the critical connection between intraplate tectonic histories and processes occurring at sometimes very distant plate boundaries.

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