Fold Structures in the Iberian Pyrite Belt

Abstract

Cleavages and minor folds are developed in the Devonian and Carboniferous strata of the Iberian Pyrite Belt. We used these minor structures to analyze fold structures, and recognized three stages of folding. The first stage folds (F₁) are generally tight overfolds with associated slaty cleavages or schistosities (S ₁). The second stage folds (F₂) are commonly open to gentle folds with associated crenulation cleavages (S ₂). The third stage folds (F₃) are recognized only in a limited area, with an additional associated crenulation cleavage (S ₃). The lithological successions of the Tharsis mine (Filon Norte), the Aznalcollar mine, and the Pomarao area are folded by the first stage folding, which form slaty cleavages (S₁). In the Vulcano mine (Tharsis area), the Sotiel mining area, and the Corte do Pinto area the first stage folds (F₁) are refolded by the second stage folding which form crenulation cleavages (S ₂).