Tectonic evolution of Variscan Iberia: Gondwana–Laurussia collision revisited

Abstract

An integrated interpretation of the late Paleozoic structural and geochronological record of the Iberian Massif is presented and discussed under the perspective of a Gondwana-Laurussia collision giving way to the Variscan orogen. Compressional and extensional structures developed during the building of the Variscan orogenic crust of Iberia are linked together into major tectonic events operating at lithosphere scale. A review of the tectonometamorphic and magmatic evolution of the Iberian Massif reveals backs and forths in the overall convergence between Gondwana and Laurussia during the amalgamation of Pangea in late Paleozoic times. Stages dominated by lithosphere compression are characterized by subduction, both oceanic and continental, development of magmatic arcs, (over-and under-) thrusting of continental lithosphere, and folding. Variscan convergence resulted in the eventual transference of a large allochthonous set of peri-Gondwanan terranes, the Iberian Allochthon, onto the Gondwana mainland. The Iberian Allochthon bears the imprint of previous interaction between Gondwana and Laurussia, including their juxtaposition after the closure of the Rheic Ocean in Lower Devonian times. Stages governed by lithosphere extension are featured by the opening of two short-lived oceanic basins that dissected previous Variscan orogenic crust, first in the Lower-Middle Devonian, following the closure of the Rheic Ocean, and then in the early Carboniferous, following the emplacement of the peri-Gondwanan allochthon. An additional, major intra-orogenic extensional event in the early-middle Carboniferous dismembered the Iberian Allochthon into individual thrust stacks separated by extensional faults and domes. Lateral tectonics played an important role through the Variscan orogenesis, especially during the creation of new tectonic blocks separated by intracontinental strike-slip shear zones in the late stages of continental convergence. Units, (6) Upper Allochthonous Units, (7) Beja-Acebuches Ophiolite, and (8) South Portuguese Zone. Gathering of 4, 5, and 6 will be also referred to as Iberian Allochthon (or simply Allochthon). A simple restoration of the cross-section shown in Figure 3 (Fig. 4a) reveals two major suture zones featured with ophiolitic units with different protolith ages. The NNE-dipping suture represented by the Beja-Acebuches Ophiolite (Bard and Moine, 1979; Munhá et al., 1986; Quesada et al., 1994) cuts the suture marked by the Allochthonous Ophiolitic Units (Arenas et al., 1986) and divides the Iberian Massif in two major blocks. The northern block comprises the Cantabrian Zone, and the Iberian Autochthon, Parautochthon and Allochthon, all of which have Gondwanan affinity

A pure dipole analysis of the Gondwana apparent polar wander path: Paleogeographic implications in the evolution of Pangea

“…[] documented that the early stages of the assembly of the Pangea supercontinent were dominated by dextral convergence. Lateral tectonics played an important role through the Variscan orogenesis [ Díez‐Fernandez et al ., ]. A continental‐scale dextral shear zone between Gondwana and Laurussia would have run across present‐day western Europe, acting as an intercontinental transform fault that included a series of en echelon shear zones, connected to the convergent boundaries of the Appalachians and the Urals [ Shelley et al ., ; Martínez Catalán et al ., ; Martinez Catalan , ].…”

“…Di ez-Fern andez Geochemistry, Geophysics, Geosystems 10.1002/2016GC006692 [Shelley et al, 2002;Mart ınez Catal an et al, 2007;Martinez Catalan, 2011]. Evidence of such large-scale dextral wrench and shear movements in the lithosphere is supported by paleomagnetic rotations [Aubele et al, 2012[Aubele et al, , 2014Edel et al, 2014Edel et al, , 2015, anisotropy of magnetic susceptibility [Denèle et al, 2008;Olivier et al, 2016], geochemistry and structural evidences [Mart ınez Catal an et al, 2007;Rabin et al, 2015;D ıez-Fernandez et al, 2016] that can be extended to Mexico [Dowe et al, 2005], and the Appalachians [Hatcher, 2002;Shelley et al, 2002]. The missing evidence to shed light on the complex evolution and formation of Pangea seems to have begun to appear over recent years.…”

Magnetic mineralogy of Variscan granites from northern Portugal: an approach to their petrogenesis and metallogenic potential

“…360-337Ma, e.g. Castiñeiras et al, 2008;Dallmeyer et al, 1997;Díez Fernández et al, 2016;Martínez Catalán et al, 2014;Pereira et al, 2018), and D 3 (ca. 321─300Ma, e.g.…”

Magnetotelluric Imaging of the Lithosphere Across the Variscan Orogen (Iberian Autochthonous Domain, NW Iberia)

“…The Variscan Orogen resulted from the collision of Laurussia and Gondwana during the assembly of Pangea supercontinent (e.g., Matte, ). The building of this orogenic belt took place during the Devonian and Carboniferous and, in the Iberian Massif, it was the result of successive stages of contractional and extensional deformation (Arenas et al, ; Díez Fernández et al, ; Martínez Catalán et al, ). In NW Iberia, the Iberian autochthonous domain (e.g., Central‐Iberian Zone) represents a section of the Gondwanan margin that experienced a complex geological history from Ediacaran to Carboniferous (e.g., Gutiérrez Marco et al, ; Martínez Catalán et al, ; Valladares et al, ) (Figure ).…”