Three profiles through the Central Pyrenees

Abstract

The Palaeozoic stratigraphic sequence of the Pyrenees, folded in Late Carboniferous time during the Variscan orogeny, consists of Cambro-Ordovician phyllites and quartzophyllites, Silurian carbonaceous shales, Devonian limestones, calcslates and slates with local sandstones, and Early Carboniferous shales. Igneous rocks consist of a pre-Variscan granite and late- to posttectonic granodiorites. Several generations of folds were formed during the Variscan orogenic period, of which the first two are responsible for most of the major structures. A large part of the folds shown on the profiles date from the second fold generation, usually called the main phase. These structures are accompanied by an axial-plane cleavage in low-grade rocks. In these rocks in the axial zone the cleavage forms half of a fan, which was formed by a late phase of tilting. In the high-grade infrastructure axial planes of folds and foliations are usually gently dipping. These structures were formed later and at the expense of earlier steep structures. Yet later fold generations have in general only resulted in small-scale structures.