Resumen de The Ordovician succession from the western Iberian Ranges (NE Spain)
Pedro Herranz Araújo, Juan Carlos Gutiérrez Marco, Agustín Pieren Pidal, Michel Robardet, Miguel A. de San José Lancha, Isabel Rábano Gutiérrez del Arroyo, Graciela N. Sarmiento
Calymenoid trilobites from the western Iberian Ranges (= Castilian branch of the Cordillera Ibérica) were already described as early as the middle of the eighteenth century, being the first Ordovician fossils reported from Spain. However, systematic studies on the Paleozoic rocks started a century later with discontinuous progress until the main contributions by Riba Arderiú (1959), Sacher (1966) and Villena (1976). Afterwards, studies on the Lower Paleozoic from the Castilian branch decreased drastically, because interest for Ordovician rocks had moved to the eastern or Aragonian branch, where the Paleozoic succession is more complete and displays very good outcrops. It resulted that the better known Ordovician sequence from the easternmost Iberian Range was generally considered as the type succession for the whole region, without detailed mentions of the western Ordovician occurrences (for instance see Liñán et al., 1996). However, the previous studies mentioned above, together with the systematic mapping at 1:50,000 scale published by the Geological Survey of Spain (IGME) as well as some personal research by the authors, support the existence in the Castilian branch of pronounced stratigraphical and paleontological singularities with regard to the Aragonian branch.
The aim of our research is to establish a composite Ordovician succession based on several key areas of the Castilian branch (Figure 1), that includes stratigraphical refinements and a number of new fossil localities (Figure 2) which can be very useful for correlation and paleogeographical purposes.
