Imprint of the Reguibat Promontory (West Africa) on the Appalachian, Mauritanide and Souttoufide Belts During the Assembly of Pangaea

Abstract

During the course of the Carboniferous to Permian, large parts of eastern Laurentia and northern Gondwana were affected by the Variscan Orogeny accompanying the assembly of Pangea. Here, we concentrate on the Appalachian belt of eastern Laurentia and the Mauritanide of western Gondwana. Owing to the irregular shapes of the craton margins, the collision between Laurentia and the West African Craton provides several conjugate promontories and embayments alongside both cratons. Among others, the coupled pair formed by the African Reguibat promontory and its counterpart in North America, the Pennsylvania embayment, is the principal subject of this study. The western movement of the Reguibat Shield had initially imprinted the West African belts but finally also affected the Appalachians. Acting as a “hallmark”, it produced two specific lobes (stacks of nappes) on both sides of the promontory. The southern NW-SW lobe (Akjoujt nappes) is long known. However, the northern lobe of the “Adrar Souttouf Massif” has not been identified previously, owing to being partially covered and also to its N-S alignment instead of an expected symmetrical SW-NE direction. Furthermore, the Adrar Souttouf Massif is partially covered by allochthonous terranes (Western Thrust Belt, TB, or Appalachians). This new discovery supports a classical impingement model for the deformation of the North American and African belts by westward displacement of the Reguibat Shield.