EPeirogenic motions of Africa as inferred from Cretaceous shoreline deposits

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  • DSDork Sahagian
    Dork Sahagian
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Abstract
Epeirogenic motions can be quantified if paleodatum planes can be recognized. These motions have been determined for the time interval mid‐Cretaceous (Cenomanian) to recent in continental Africa using the vertical displacement of ancient shoreline sediments and other nearshore or low‐elevation deposits that are inferred to represent a Cenomanian sea level datum plane. The Cretaceous Trans‐Saharan seaway brought shoreline sediments deep into the African continental interior, and additional data suggest that most of the remaining terrestrial regions were also low‐lying during the Cenomanian. The present elevations of the sea level sediments indicate that large portions of Africa have undergone epeirogenic uplift since the Cenomanian. The character of the motions in north Africa can be described as small‐scale high‐amplitude (3 km) doming separated by relatively flat‐lying areas of deposition. The largest single epeirogenic feature is the uplift associated with Red Sea and East African Rift development. The timing of post‐Cenomanian epeirogenic motions can be further constrained using paleontologic, K‐Ar, faulting, paleodrainage and sedimentary data. The most likely causal mechanism for African epeirogeny may be hot spot activity reflective of the mantle convection regime underlying the African lithosphere.

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