Thickening and exhumation of the Variscan roots in the Iberian Central System: Tectonothermal processes and 40Ar/39Ar ages

Pascual, Francisco J. Rubio; Arenas, Ricardo; Catalán, José R. Martı́nez; Fernández, L. R. Rodríguez; Wijbrans, J. R.

doi:10.1016/j.tecto.2012.10.005

Cited by 68 publications

(74 citation statements)

References 64 publications

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“…350-340 Ma (Dallmeyer et al, 1997;Martínez Catalán et al, 1996Gómez Barreiro et al, 2006López-Carmona et al, 2014). The emplacement of the allochthonous units was coeval with widespread recumbent folding and a subsequent thrusting event in the internal zones of the autochthonous units (Rubio Pascual, 2013;Martínez-Catalán et al, 2014). Given that the studied granitoids mostly intrude the parautochthonous unit around the allochthonous complexes (Fig.…”

Section: Discussionmentioning

confidence: 91%

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

et al. 2018

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In this study we report laser ablation-inductively coupled plasma-mass spectrometer U-Pb ages of granitoids from the so-called early granodiorites of the northwest Iberian Variscan belt. The U-Pb results attest to significant magmatic activity in Visean time (ca. 347-337 Ma) that generated a hitherto poorly constrained granitoid suite in the northwest Iberian tract of the western European Variscan belt realm. This early Carboniferous suite (ECS) is mainly composed of peraluminous cold and hot crustal granodiorites and monzogranites with minor associated mafic rocks that attest to minor involvement of mantle melting. Based on the geochronological and geochemical data, we compare the Visean granitoids with younger Variscan granitoids in northwest Iberia and, in view of the tectonothermal scenarios of the Variscan collision in northwest Iberia, propose a model for the genesis of the ECS in northwest Iberia that involves rapid melting upon fast exhumation of the thickened Gondwanan crust in the course of the protracted Variscan collision.

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Section: Discussionmentioning

confidence: 91%

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

et al. 2018

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“…Pervasive partial melting and late-to post-orogenic extension affected the hinterland of the orogen from ca. 340 Ma to 290 Ma (Burg et al, 1994;Faure, 1995;Fernández-Suárez et al, 2000;Faure et al, 2009;Gutiérrez-Alonso et al, 2011a;Rubio Pascual et al, 2013;Lardeaux et al, 2014;Gapais et al, 2015). The orogen has undergone reorganization from the late Carboniferous to the early Permian by the amplification of syntaxes and the activation of major transcurrent fault systems Matte, 1975, 1977;Matte and Ribeiro, 1975;Matte, 1986;Burg et al, 1994;Martínez-Catalán, 2011;Gutiérrez-Alonso et al, 2012;Dias et al, 2016).…”

Section: Geological Setting 21 Variscan Belt Of Southwestern Europementioning

confidence: 99%

Vertical strain partitioning in hot Variscan crust: Syn-convergence escape of the Pyrenees in the Iberian-Armorican syntax

Cochelin

Chardon

Denèle

et al. 2017

Bull. Soc. géol. Fr.

110

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-A new structural map of the Paleozoic crust of the Pyrenees based on an extensive compilation and new kinematic data allows for the evaluation of the mechanical coupling between the upper and lower crust of the abnormally hot foreland of the Variscan orogen of SW Europe. We document partitioning between coeval lower crustal lateral flow and upper crustal thickening between 310 and 290 Ma under an overall dextral transpressive regime. Partitioning also involved syn-convergence transtensional gneiss domes emplacement during this period. Late orogen-normal shortening of the domes and strain localization in steep crustal-scale transpressive shear zones reflects increasing coupling between the lower crust and the upper crust. The combination of dextral transpression and eastward flow in the Pyrenees results from the shortening and lateral escape of a hot buoyant crust along the inner northern limb of the closing Cantabrian orocline at the core of the Iberian-Armorican arc between ca. 305 and 295 Ma. Delamination or thermal erosion of the lithosphere enhanced orocline closure and explains (1) the switch from crust-to mantlederived magmatism in the Iberian-Armorican arc and (2) the abnormally hot and soft character of the Pyrenean crust that escaped the closing syntax.Keywords: Variscan / Pyrenees / syntax / orocline / gneiss dome / transpression / hot orogen Résumé -Partitionnement vertical de la déformation dans la croûte varisque chaude : échappement des Pyrénées de la syntaxe ibéro-armoricaine. Une nouvelle carte structurale harmonisée et une série de coupes de la croûte paléozoïque des Pyrénées sont présentées sur la base d'une compilation et de nouvelles observations de terrain. Cette carte permet d'évaluer les modalités du couplage mécanique entre la croûte supérieure et la croûte inférieure de l'avant-pays anormalement chaud de l'orogène varisque. La croûte inférieure a flué latéralement pendant l'épaississement de la croûte supérieure dans un contexte transpressif dextre entre 310 et 290 Ma. Dans ce contexte convergent et grâce à un couplage crustal partiel, la croûte inférieure a pu être partiellement exhumée dans des dômes gneissiques transtensifs. Le serrage tardif des dômes et la localisation progressive de la déformation dans des zones de cisaillement transpressives d'ampleur régionale attestent de l'augmentation du degré de couplage entre croûtes supérieure et inférieure pendant le refroidissement régional. La combinaison de la transpression dextre et du fluage latéral de la croûte des Pyrénées résulte du raccourcissement et de l'échappement du matériau piégé dans la syntaxe ibéro-armoricaine lors de son amplification et la fermeture de l'orocline cantabrique en son coeur entre 305 et 295 Ma. L'érosion thermique ou la délamination du manteau lithosphérique a permis (1) la transition entre un magmatisme crustal et un magmatisme mantellique ou hybride dans la syntaxe et (2) la fermeture de l'orocline et l'échappement contemporain du matériel pyrénéen chaud qu'elle contenait.

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“…The present structure of the Central Iberian Zone is the result of (1) Paleozoic transference of peri-Gondwanan terranes onto the adjacent margin of Gondwana and associated crustal thickening (D 1 ), followed by (2) syn-and late-orogenic collapse of the orogenic belt synchronous with the development of intracontinental strike-slip systems and oroclinal bends (D 2 -D 4 ). In the autochthon, folds and thrusts produced initial crustal thickening (D 1 ; Bellido et al, 1981;Capote et al, 1981;Díez Balda, 1986;Macaya et al, 1991;Rubio Pascual et al, 2012). The subsequent development of extensional shear zones and magmatic activity accompanied thermal and gravitational re-equilibration during crustal thinning (D 2 ; Doblas, 1991;Doblas et al, 1994;Escuder Viruete et al, 1994;Barbero, 1995;Díez Balda et al, 1995;Díez Montes et al, 2010;Rubio Pascual et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…In the autochthon, folds and thrusts produced initial crustal thickening (D 1 ; Bellido et al, 1981;Capote et al, 1981;Díez Balda, 1986;Macaya et al, 1991;Rubio Pascual et al, 2012). The subsequent development of extensional shear zones and magmatic activity accompanied thermal and gravitational re-equilibration during crustal thinning (D 2 ; Doblas, 1991;Doblas et al, 1994;Escuder Viruete et al, 1994;Barbero, 1995;Díez Balda et al, 1995;Díez Montes et al, 2010;Rubio Pascual et al, 2012). Extension was accompanied and followed by transcurrent shear zones and upright folds (D 3 ;Martínez Catalán, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The Variscan collisional crust here displays a three-layer crustal section. The upper layer includes upper-crustal rocks deformed under low-to medium-grade conditions (syn-D 1 to syn-D 2 Barrovian metamorphic zonation formed by the chlorite, biotite, garnet, and staurolite zones; Rubio Pascual et al, 2012). The middle layer preserves some higher-grade D 1 Barrovian mineral associations (kyanite, staurolite, almandine, garnet) but is mainly overprinted by D 2 penetrative deformation under medium-to high-grade metamorphic conditions (staurolite and sillimanite zones).…”

Section: Introductionmentioning

confidence: 99%

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Large-scale flat-lying isoclinal folding in extending lithosphere: Santa María de la Alameda dome (Central Iberian Massif, Spain)

2013

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The exhumation mechanisms of deep-seated continental crust can be constrained by analyzing the structural and metamorphic imprints left in lithological ensembles. The Santa María de la Alameda dome formed during the collision of Gondwana and Laurussia in late Paleozoic time and is located in the Central Iberian Zone of the Iberian Massif (Spain). Rocks of the dome are part of the autochthonous Gondwanan sections of the Variscan belt, and they occur in the Variscan hinterland. The lithostratigraphy of the dome consists of metasedimentary rocks alternating with orthogneiss massifs showing irregular and sinuous structure. The metamorphic record indicates peak pressures indicative of lower-crust depths followed by isothermal decompression to middle-upper-crust levels. Exhumation resulted in the exposure of different crustal levels (represented by subsolidus vs. supersolidus mineral assemblages). The exhumation was accompanied by initial layer-parallel stretching and subsequent large-scale isoclinal folding developed in a heterogeneous, fl at-lying shear zone with top-to-the-SE kinematics. SE-directed shearing and lateral extensional fl ow occurred in response to thermomechanical disequilibrium of previously thickened orogenic crust, probably assisted by coeval accretion of tectonic slices and lithospheric bending about a vertical axis. Positive feedback among partial melting, exhumation, and crustal attenuation resulted in the formation of a NE-SW-trending, migmatite-cored dome, and in refolding of early isoclinal folds and an associated axial surface regional foliation. The dome formed beneath a set of extensional detachments and was reshaped by WNW-ESE upright folds during later convergent deformation. The latter event brought in further instabilities throughout the belt, triggering in this region the development of a late extensional detachment under low-grade metamorphic conditions (top-to-the-S kinematics). The development of a regional train of fl at-lying isoclinal folds is presented here as the macrostructural expression of the combination of vertical and lateral extensional fl ow, both of which are particularly common in orogens worldwide.

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Thickening and exhumation of the Variscan roots in the Iberian Central System: Tectonothermal processes and 40Ar/39Ar ages

Abstract: Keywords:Variscan metamorphism Barrovian to low-P evolution 4.°Arp9Ar geochronology Iberian Massif

Cited by 68 publications

References 64 publications

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

Vertical strain partitioning in hot Variscan crust: Syn-convergence escape of the Pyrenees in the Iberian-Armorican syntax

Large-scale flat-lying isoclinal folding in extending lithosphere: Santa María de la Alameda dome (Central Iberian Massif, Spain)

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