Person:
Novo Fernández, Irene

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First Name
Irene
Last Name
Novo Fernández
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https://hdl.handle.net/20.500.14352/81525
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Universidad Complutense de Madrid
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Ciencias Geológicas
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Mineralogía y Petrología
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2021 - 20234
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Author: Díez Fernández, Rubén × Subject: 551.24(460) ×

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    Single subduction zone for the generation of Devonian ophiolites and high‐P metamorphic belts of the Variscan Orogen (NW Iberia)
    (Terra Nova, 2021) Díez Fernández, Rubén; Arenas Martín, Ricardo; Sánchez Martínez, Sonia; Novo Fernández, Irene; Albert Roper, Richard
    Within the Variscan Orogen, Early Devonian and Late Devonian high‐P belts separated by mid‐Devonian ophiolites can be interpreted as having formed in a single subduction zone. Early Devonian convergence nucleated a Laurussia‐dipping subduction zone from an inherited lithospheric neck (peri‐Gondwanan Cambrian back‐arc). Slab‐retreat induced upper plate extension, mantle incursion and lower plate thermal softening, favouring slab‐detachment within the lower plate and diapiric exhumation of deep‐seated rocks through the overlying mantle up to relaminate the upper plate. Upper plate extension produced mid‐Devonian suprasubduction ocean floor spreading (Devonian ophiolites), while further convergence resulted in plate coupling and intraoceanic ophiolite imbrication. Accretion of the remaining Cambrian ocean heralded Late Devonian subduction of inner sections of Gondwana across the same subduction zone and the underthrusting of mainland Gondwana (culmination of NW Iberian allochthonous pile). Oblique convergence favoured lateral plate sliding, and explained the different lateral positions along Gondwana of terranes separated by Palaeozoic ophiolites.
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    On the Rootless Nature of a Devonian Suture in SW Iberia (Ossa-Morena Complex, Variscan Orogen): Geometry and Kinematics of the Azuaga Fault
    (Tectonics, 2021) Díez Fernández, Rubén; Fernández Rodríguez, Carlos; Arenas Martín, Ricardo; Novo Fernández, Irene
    Suture zones are key to understand collisional orogens, but not all the remains of subduction leading to collision occur in the root of the suture. The Azuaga Fault bounds a Devonian suture zone known as Central Unit. This fault is a steeply NE-dipping, Variscan strike-slip fault with left-lateral and reverse oblique slip components formed during sinistral transpression in the Pennsylvanian. Motion along this fault was coeval with folding and fabric development in both its hanging wall and footwall, and also with the Matachel Fault. Tectonic flow associated with the Azuaga Fault shows high-vorticity, explaining the exhumation of a flat-lying Devonian suture zone via WNW-plunging extrusion from the upper-middle crust under inclined triclinic transpression during ENE-WSW convergence. The exposed basal contact of the Central Unit is not the root zone of a Variscan suture zone, but instead is a NE-dipping breaching fault that cuts across the suture zone that is contiguous to the SW under the upper section of the footwall. The peri-Gondwanan terrane between the Central Unit and the South-Portuguese Zone of the Iberian Massif (most of the Ossa-Morena Zone) is underlain by a Devonian suture, implying it is a continental allochthon. Variscan suture zones in Europe are affected by strike-slip faults. In our case, this pattern implies the location of suture zone exposures and location of its root are different. Suture zones and strike-slip faults are common in orogens and analysis of their relationships may lead to relocation of suture zone roots and re-thinking of upper and lower plates.
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    Reply to Comment by Azor et al. on “On the Rootless Nature of a Devonian Suture in SW Iberia (Ossa-Morena Complex, Variscan Orogen): Geometry and Kinematics of the Azuaga Fault”
    (Tectonics, 2022) Díez Fernández, Rubén; Fernández Rodríguez, Carlos; Arenas Martín, Ricardo; Novo Fernández, Irene
    Geological mapping, structural data, and analytical modeling by Díez Fernández et al. (2021), https://doi.org/10.1029/2021tc006791 supported that the Central Unit belonged to a rootless Devonian suture zone contiguous to the SW of its exposure and under the upper section of the footwall to the Azuaga Fault. Late exhumation of the Central Unit was via extrusion from the upper-middle crust under inclined triclinic sinistral transpression, which favored upright folding of the suture zone. Azor and coworkers argue that the upright folds that affect the Central Unit are local, despite geological maps and structural data demonstrate they are km-scale and occur all across the Central Unit. Besides ignoring structural data regarding the kinematics of the Azuaga Fault, Azor et al. (2022), https://doi.org/10.1029/2021TC006982 fail to recognize the net upthrown movement of the NE side of the Azuaga Fault, as the Central Unit in that side is juxtaposed against syn-orogenic strata that rest unconformably onto other metamorphic units in the SW side of the fault. Seismic data that image the Central Unit as a NE-dipping rock package is used as an argument against the proposal by Díez Fernández et al. (2021), https://doi.org/10.1029/2021tc006791. However, the section of the Central Unit those data account for, are from a different part of the Central Unit, the real dip of some structures in the seismic image is not properly interpreted, and the model by Díez Fernández et al. (2021), https://doi.org/10.1029/2021tc006791 is compatible with a Central Unit that also dips to the NE. Overall, the model proposed by Díez Fernández et al. (2021), https://doi.org/10.1029/2021tc006791 remains valid.
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    Building and collapse of the Cadomian Orogen: A plate-scale model based on structural data from the SW Iberian Massif
    (Tectonics, 2023) Moreno Martín, Diana; Díez Fernández, Rubén; Arenas Martín, Ricardo; Rojo Pérez, Esther; Novo Fernández, Irene; Sánchez Martínez, Sonia
    The Cadomian Orogeny produced a subduction-related orogen along the periphery of Gondwana and configured the pre-Variscan basement of the Iberian Massif. The architecture of the Cadomian Orogen requires detailed structural analysis for reconstruction because of severe tectonic reworking during the Paleozoic (Variscan cycle). Tectonometamorphic analysis and data compilation in SW Iberia (La Serena Massif, Spain) have allowed the identification of three Cadomian deformation phases and further constrained the global architecture and large-scale processes that contributed to the Ediacaran building and early Paleozoic dismantling of the Cadomian Orogen. The first phase (DC1, prior to 573 Ma) favored tabular morphology in plutons that intruded during the building of a continental arc. The second phase (DC2, 573–535 Ma) produced an upright folding and contributed to further crustal thickening. The third phase of deformation (DC3, ranging between ∼535 and ∼480 Ma) resulted in an orogen-parallel dome with oblique extensional flow. DC1 represents the crustal growth and thickening stage. DC2 is synchronous with a period of crustal thickening that affected most of the Gondwanan periphery, from the most external sections (Cadomian fore-arc) to the inner ones (Cadomian back-arc). We explain DC2 as a consequence of flat subduction, which was followed by a period dominated by crustal extension (DC3) upon roll-back of the lower plate. The Ediacaran construction of the Cadomian Orogen (DC1 and DC2) requires ongoing subduction beneath Gondwana s.l., whereas its dismantlement during the Early Paleozoic is compatible with oblique, sinistral convergence.