The relation between geosynclinal folding phases and foreland movements in Northwest Spain

Abstract

The Palaeozoic in NW Spain is discussed in terms of palaeogeographic zones as distinguished by LOTZE (1945). These are from west to east: the Galician-Castilian Zone, the West Asturian-Leonese Zone, and the Cantabrian Zone. The latter represents a foreland spur around which successive folds have been molded in an arcuate structure. The first two zones mentioned represent the internal parts of a géosynclinal complex which terminates and fuses in the western part of the Iberian Peninsula and which strikes eastwards under the Mesozoic and Tertiary cover. The evidence is examined for tectonic movements in different parts of the orogen, and it is concluded that these occurred in seven major phases which can be correlated from one part of the orogen to another, although the intensity differs in the different areas. The older tectonic phases deformed strongly the more internal parts of the géosynclinal complex, while producing uplift on the foreland. Later phases hardly affected the cratonised internal parts but folded quite strongly the tardigeosynclinal basins which became established on the former foreland area.