Los diques clásticos de Filón Norte (Tharsis). Interpretación en relación con la crisis finidevónica de la cuenca de la Faja Pirítica Ibérica

Abstract

Basic rocks from the Filón Norte open pit (Tharsis, Iberian Pyrite Belt) are hydrothermally altered and crosscutted by a stockwork which is composed by carbonate filled veins and clastic dikes. Both, dykes and veins, show carbnonate selvages. Clastic dykes include black shale, basic rock and siliceous fragments that exhibit angular to lobulate shape and grain size up to 40 cm in diameter. Palynomorphs recovered from black shales of the clastic dykes give an uppermost Devonian age (LN Biozone). Dykes and veins belong to a fracture system representing the escape pathways of fluids trapped within the footwall muddy sediments when the basic sill was intruded. Black shale sedimentation, emplacement of the basic sills, fracturation and carbonate alteration, and filling of veins and dykes constitute a succession of nearly coeval events, all of them related with the uppermost Devonian crisis of the South Iberian Basin.