Propos sur les geosynclinaux

Abstract

Abstract Geosynclinal theory began with the characteristics found in the geosynclinal chains of the Alpine cycle in Europe, then, after much research, was modified to include Prealpine chains, the Hercynian (Variscan), Caledonian, and Precambrian. The fundamental organization is found to be the eugeosynclinal-miogeosynclinal couple. These couples are repeated in two types of symmetry, centrifugal and centripetal, in the manner of centrifugally-symmetrical bicouples. The classic chain's double character, with the median zone either an intermediate massif of the Zwischenberg type, an intermediate trough, or eugeanticlinal and eugeosynclinal folds, influences the orogenic, magmatic and metamorphic gradients toward the exterior. The eugeosynclinal-miogeosynclinal couple itself is defined by the paleogeography, the polarity, and the tectonic structures. Geosynclinal, tardigeosynclinal, and postgeosynclinal periods are recognized, but seem to be of lesser importance with greater age of the geosynclinal development.