Opposite subduction polarities connected by transform faults in the Iberian Massif and western European Variscides

Multiple crustal sources for post-tectonic I-type granites in the Hercynian Iberian Belt

“…Lithospheric fragments of the Rheic ocean were accreted to the Iberian micro-continent at around 390 Ma (Arenas et al 2007). On the other hand, the boundary between southern Central Iberian and Ossa-Morena zone is also interpreted as a suture of an oceanic realm that gently dips under the Central Iberian terrane (Simancas et al 2002). The closure of ocean basins in both boundaries suggests a local accretion or indentation of significant meta-basic layers under the Central Iberian zone (Fig.…”

Evidence for pre-orogenic, Early Devonian rifting in the Variscan belt: stratigraphy and structure of the Palaeozoic cover of the Mauges Unit (Upper Allochthon, Armorican massif, France)

“…Nevertheless, this geodynamic scenario is still a matter of debate as shown by the multiple alternative models recently proposed (e.g. Simancas et al 2002;Kroner et al 2007;Martínez Catalán et al 2009). The early history of the Variscan belt is still poorly understood, but various lines of evidence suggest that oceanic subduction could have started as early as Silurian and continental deformation as early as Devonian (for a discussion, see Ballèvre et al 2009;Faure et al 2009).…”

U–Pb dating of granodiorite and granite units of the Los Pedroches batholith. Implications for geodynamic models of the southern Central Iberian Zone (Iberian Massif)

“…In recent models on the lithosphere features of the southern Iberian Massif, it is generally considered that the main structural traits of the area are essentially the consequence of the Variscan orogenic activity (e.g., Simancas et al 2002Simancas et al , 2004. It is also a well established fact that preMesozoic outcrops of the Ossa-Morena Zone record the effects of two main orogenic events: firstly, the Cadomian or late-Pan African Orogeny, that extended from ca.…”

“…The models proposed generally include the closure of an oceanic basin along one of the plate boundaries, namely, the so-called Rheic Ocean between the South Portuguese and Ossa-Morena zones (e.g., Quesada et al 1994;Castro et al 1996;Simancas et al 2002). Yet, those models differ in such important aspects as: (1) the subduction direction, i.e., northward, southward or both, (2) the type of relative movement between plates, i.e., convergence and/or transpression, and (3) the timing of oceanic crust consumption and continental collision, either upper Devonian, lower Carboniferous or during both periods.…”

“…Conversely, the authors that minimize the influence of the Cadomian orogeny consider that the collision along the Ossa-Morena-Central Iberian boundary occurred during the upper Devonian , that is, while subduction was active along the opposite boundary (OssaMorena-South Portuguese), and involved the filling of basins generated by the resultant transtensive regime. Ensuing the subduction of the Rheic realm and the subsequent collision between the South Portuguese and OssaMorena plates (around 345-305 Ma), the Carboniferous deposits would also be folded in these models (e.g., Azor et al 1993;Simancas et al 2002Simancas et al , 2004. Julivert et al 1974) It appears evident therefore that whatever one considers it was the main orogenic period, Cadomian or Variscan, we are dealing here with a complex protracted Wilson cycle that extended from the mid-lower Cambrian to upper Carboniferous across the entire region of the southern Iberian Massif.…”