Short Paper: Kinematics of the Alpine arc

Abstract

Is there a continuous sweep in direction of Alpine orogenic displacements around the Alpine arc, or does the overlap of a few distinct directions give this impression? The thrust evolution of the SW Alps, which supports the latter view, does not accord with the hypothesis of indenter-induced body forces. Two displacement realms, one with directions determined by intraplate configuration and another with directions related simply to the body forces, maycoexist within the orogen, but this is not yet established. One of the longest-standing disagreements in Alpine geology concerns the nature of the radial pattern of orogenic displacements outwards from the Alpine arc. In one view, there is a continuum of displacement directions sweeping from approximately southward in the Maritime Alps, through west and northwest to approximately northward in Austria. In the other view, there is no continuum, but a small number of distinct directions of orogenic displacements, each dominating a particular sector, which relay one to another around the Alpine arc. Recent papers mark a significant development in both sides of this argument, which is given additional importance by the attempt of Platt et al. (1989 a ) to use displacement data to constrain plate motions. This paper is intended as a contribution to the discussion and suggests one possible resolution of the argument. Sophisticated syntheses of Alpine structure have for a long time accepted the possibility that both of the above views have some validity, and Goguel (1963) is a good starting point for discussion. His displacements of crystalline basement of