The complex pattern of horsts and grabens in the Sirte Basin may have developed when Mesozoic drift of the African plate put north-central Libya over a fixed mantle hotspot in Early Cretaceous time (140 to 100 m.y. ago). Significant change in the motion of the plate during the prolonged residence above a hypothetical Cameroon plume may have produced stress that fragmented thinned and weakened lithosphere. Successive uplift and subsidence along a reconstructed track of the plume, as well as in the Sirte Basin, are compatible with predicted effects of the drift of northern Africa over a fixed mantle hotspot. This speculation suggests a plausible alternative to the possibility that rifting throughout northern Africa in Early Cretaceous time may have been produced along a wide zone of extension between two African plates when they were at rest relative to underlying plumes.

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