|
Resumen:
|
The boundary between the Central-Iberian Zone and the Ossa-Morena Zone of the Hesperian Massif has long been placed either in Los Pedroches batholith or in the Badajoz-Cordoba shear zone, using different arguments. Here, based on mainly stratigraphic and paleogeographic criteria, we propose that this boundary is in fact a new zone of the Hesperian Massif, the Lusitan-Marianic Zone, and not just a simple lineament. The northern limit of this zone is at present concealed by the Variscan “Los Pedroches” batholith, and the southern one is the “Malcocinado Fault”. The main distinctive geological features of this zone are: 1) The Proterozoic-Lower Cambrian basement rocks are similar to those of the Ossa-Morena Zone. This basement cannot be correlated with Precambrian rocks outcropping north-eastwards of the Los Pedroches batholith, even if the Alcudian-type sediments might have a Central-Iberian equivalent. 2)The Paleozoic sequences younger than Middle/Upper Cambrian, outcropping between the Malcocinado fault and the Pedroches batholith, display however clear Central-Iberian affinities, and have nothing in common with those of SW Ossa Morena. Excepting the Silurian, a persistent paleogeographic high existed in the south of the Lusitan-Marianic Zone that migrated transversally through time. The proposed new Lusitan-Marianic Zone shows more distinctive properties to be recognised as an independent entity, than other traditionally distinguished zones, e.g., the Cantabrian Zone, West Asturian-Leonese Zone or Central-Iberian Zone, whose boundaries do not correspond to paleogeographic features as significant as those described here.
|
