Oroclines and pseudo-oroclines

Abstract In the last few decades, a variety of mechanisms have been proposed for the genesis of oroclines and pseudo-oroclines. “Poinconnement” (P. Tapponnier, for the Alpine-Himalayan chain); plate bending on a vertical axis (H.P. Laubscher in the Mediterranean Sea); change of the thrust direction (L.B. Harris in Corsica); axial plunge of a nonplane thrust surface (R. Sacchi in Mozambique); “whirl” tectonics (M. Gidon, for the Western Alps); large-scale ductile shear (M.P. Coward and M.C. Daly, for the Lufilian Arc of Zambia); tear faulting (J. Goguel, for the Western Alps); high strain at boundaries of polygonal miniplates (M.B. Katz, for Precambrian Africa); differential displacement connected with different thermal regimes (M.P. Coward, for the Damara orogenic system); Mesozoic basin pattern inheritance (E.V. Artyushkov and M.A. Baer in the Alpine-Carpathyan region) and large-scale shearing of weakened continental margins (W.M. van der Linden in the Mediterranean area) have all been proposed. Several combinations of these models have also been suggested. After a brief review, the criteria of recognition of some models are discussed. The importance of the distribution pattern of the minor structures is stressed by drawing inspiration from some of the ideas of Hans Laubscher (especially the emphasis laid on the uncoupling of the “surficial peels” from the rest of the crust). As an example two case histories are reported from the Western Alps and from Southern Africa.