Electromagnetic Image of a Fault in the South Portuguese Zone

The South Portuguese Zone (SPZ) represents the southerrn brench of the Iberian variscides outcropping in Portuguese mainland (Fig. 1). The SPZ consists mainly in Upper Paleozoic ante volcanic lowgrade sediments, and is separated from the Lower Paleozoic metasediments and abundant granitic intrusions of the Ossa Morena Zone (OMZ), by an hercynian suture that contains Ophiolitic sequences (8eja-Acebuches ultramafics). According to the accepted model for the formation and evolution of the SW variscan foldbelt, the South Portuguese "terrain" and the Iberia terrain crustal structures would be the result of a continent-continent collision with a NE to E subduction.