Terranes affinity and Variscan transpressional evolution of Rheic-related units in SW Iberia

Abstract

The Rheic Ocean closure led to the Variscan collision between Laurussia and Gondwana and concluded with the formation of the Pangea supercontinent in late Paleozoic time. Other minor terranes were also involved in the Variscan Cycle, e.g. Avalonia and Armorica. This Thesis deals with the Variscan tectonometamorphic evolution of the SW Iberian Variscides, constituted by the southern Central Iberian Zone (CIZ), the Ossa-Morena Zone (OMZ) and the South Portuguese Zone (SPZ). The main focus is put on the OMZ/SPZ boundary, which is interpreted as the Rheic Ocean suture and attests the collision of Avalonia (SPZ) with a north-Gondwanan terrane (OMZ). Three tectonics units have been classically related to the OMZ/SPZ suture: (i) the Beja-Acebuches amphibolites (BAA), a metamafic unit interpreted as a Rheic ophiolite; (ii) the Pulo do Lobo unit, a lowgrade metasedimentary unit with minor MORB-like metabasalts, considered as the remnant of a Rheic subduction-related accretionary prism; and (iii) the allochthonous Cubito-Moura unit, which appears emplaced onto the southern OMZ and contains Ordovician? MORBfeatured rocks and Devonian? high-pressure metamorphic assemblages.