Person: Fernández Suárez, Javier
Universidad Complutense de Madrid
Faculty / Institute
Mineralogía y Petrología
Petrología y Geoquímica
Now showing 1 - 10 of 69
PublicationSelf-subduction of the Pangaean global plate(Nature Publishing Group, 2008) Gutiérrez Alonso, Gabriel; Fernández Suárez, Javier; Weil, Arlo B.; Murphy, J. Brendam; Nance, R. Damian; Corfu, Fernando; Johnston, Stephen T.One of the most striking and rare occurrences in the Earth's history is the amalgamation of most of the continental lithosphere into one supercontinent. The most recent supercontinent, Pangaea, lasted from 320 to 200 million years ago. Here, we show that after the continental collisions that led to the formation of Pangaea, plate convergence continued in a large, wedge-shaped oceanic tract. We súggest that plate strain at the periphery of the supercontinent eventually resulted in self-subduction of the Pangaean global plate, when the ocean margin of the continent subducted beneath the continental edge at the other end of the same plate. Our scenario results in a stress regime within Pangaea that explains the development of a large fold structure near the apex of the Palaeotethys Ocean, extensive lower crustal heating and continental magmatism at the core of the continent as well as the development of radially arranged continental rifts in more peripheral regions of the plate. PublicationGeochemistry and Sm–Nd isotopic sources of Late Ediacaran siliciclastic series in the Ossa–Morena Complex: Iberian–Bohemian correlations(Springer, 2021) Rojo-Pérez, Esther; Fuenlabrada Pérez, José Manuel; Linnemann, Ulf; Arenas Martín, Ricardo; Sánchez Martínez, Sonia; Díez Fernández, Rubén; Martín Parra, Luis Miguel; Matas, Jerónimo; Andonaegui Moreno, Pilar; Fernández Suárez, JavierThe Cadomian basement in central and southern Europe is composed by Ediacaran–Early Cambrian sequences that appear dismembered along the Variscan Orogen. These ancient series contain geochemical and isotopic keys related to their deposition in different basins located along the paleo margin of Gondwana. The southwest of Iberian Massif (Ossa–Morena Complex) contains an excellent representation of Cadomian basement. The oldest sedimentary succession of this region, the Serie Negra Group (c. 600–541 Ma), is composed by the Montemolín Formation which consists of metapelites, metagreywackes and abundant amphibolites; and the Tentudía Formation which consists of metagreywackes, black quartzites and metapelites. The whole-rock and Nd isotopic geochemistry of the Montemolín and Tentudía formations, are consistent with a deposition in a back-arc or fore-arc setting. Their Nd isotopic composition shows highly negative εNd(t) values in a range between − 6.9 and − 11.5, resulting in old Paleoproterozoic Nd model ages between 1.9 and 1.7 Ga. The Nd isotopic signatures obtained for the Cadomian basement in the Iberian Massif are almost identical to those obtained for equivalent sedimentary series in the Saxo-Thuringian Zone (Bohemian Massif), where Nd model ages range between 2 and 1.6 Ga. The limited variability of these Nd-TDM ages suggests that the southwestern Iberian and North Bohemian series shared a common source during Ediacaran times, which would be located close to the periphery of the West African Craton. The Nd isotopic data considered herein provide solid evidence about the peri-Gondwanan location and correlation between the Cadomian basement of southwestern Iberia and North Bohemia. PublicationIberian late-Variscan granitoids: Some considerations on crustal sources and the significance of “mantle extraction ages(Elsevier Science B.V., Amsterdam, 2011) Fernández Suárez, Javier; Gutiérrez Alonso, Gabriel; Johnston, Stephen T.; Jeffries, Teresa E.; Pastor Galán, Daniel; Jenner, G.A.; Murphy, J. BrendamA suite of post-tectonic granitoids (mostly peraluminous, broadly I-type granodiorites and monzogranites) and mafic rocks from NWIberia with crystallization ages between ca. 309 and 290 Ma has been investigated for Sm–Nd isotopes and inherited zircon content in order to constrain the nature of their source rocks. εNd values (at 300 Ma) vary from −0.2 to −5.9 and TDM values range from 1.01 to 1.58 Ga. Inherited (xenocrystic) zircons yielded ages ranging from 458 to 676 Ma, with 90% of data between 490 and 646 Ma, corresponding to Neoproterozoic(mostly Ediacaran), Cambrian andOrdovician ages. Only three highlydiscordant analyses yielded ages older than 650 Ma. Based on the data reported herein and relevant data fromthe literaturewe contend that post-tectonic granitoids of the Iberian Variscan Belt (with exception of the scarce anatectic S-type granitoids) were derived mostly from metaigneous lower crustal sources which in turn were ultimately derived from a subcontinental lithospheric mantle enriched between ca. 0.9 and 1.1 Ga. I-type granitoids and mantle-derived mafic rocks both underwent varying degrees of contamination by ametasedimentary lower crust depleted in pre-650 Ma zircon (through previousmelting episodes) with a time-integrated Sm–Nd evolution different to that of the metaigneous lower crust. Participation of this metasedimentary crust in the genesis of these granitoids may account for Nd isotopic variability and Nd model ages well in excess of 1.2 Ga. PublicationAmazonian Mesoproterozoic basement in the core of the Ibero-Armorican Arc: 40Ar/39Ar detrital mica ages complement the zircon’s tale(Geological Society of America, 2005) Gutiérrez Alonso, Gabriel; Fernández Suárez, Javier; Collins, Alan S.; Abad, Isabel; Nieto, FernandoThe 40Ar/39Ar age data on single detrital muscovite grains complement U-Pb zircon ages in provenance studies, as micas are mostly derived from proximal sources and record low-temperature processes. Ediacaran and Cambrian sedimentary rocks from northwest Iberia contain unmetamorphosed detrital micas whose 40Ar/39Ar age spectra suggest an Amazonian–Middle American provenance. The Ediacaran sample contained only Neoproterozoic micas (590–783 Ma), whereas the Cambrian sample contained three age groups: Neoproterozoic (550–640 Ma, Avalonian–Cadomian–Pan African), Mesoproterozoic-Neoproterozoic boundary (ca. 920–1060 Ma, Grenvillian-Sunsas), and late Paleoproterozoic (ca. 1580–1780 Ma, Rio Negro). Comparison of 40Ar/39Ar muscovite ages with published detrital zircon age data from the same formations supports the hypothesis that the Neoproterozoic basins of northwest Iberia were located in a peri-Amazonian realm, where the sedimentary input was dominated by local periarc sources. Tectonic slivering and strike-slip transport along the northern Gondwanan margin affected both the basins and fragments of basement that were transferred from Amazonian to northern African realms during the latest Neoproterozoic–earliest Cambrian. Exhumation and erosion of these basement sources caused shedding of detritus to the Cambrian basins, in addition to detritus sourced in the continental mainland. The apparent dominance of Rio Negro–aged micas in the Cambrian sandstone suggests the presence of unexposed basement of that age beneath the core of the Ibero-Armorican Arc. PublicationDetrital zircon ages and provenance of a Cambrian succession in the Sierra Albarrana Domain (SW Iberian Massif)(Elsevier, 2022-01) Solís Alulima, B.E.; Abati Gómez, Jacobo; López Carmona, Alicia; Gutiérrez Alonso, Gabriel; Fernández Suárez, Javier; Stockli, Daniel F.This study presents the first U-Pb geochronological data on detrital zircon grains from the metasedimentary successions of the Sierra Albarrana Domain (SW Iberian Massif) obtained by SHRIMP and LA-ICP-MS. We provide new information on the Maximum Depositional Ages (MDA) during the middle Cambrian through a systematic study, together with age comparisons of the successions, using Kernel Density Estimates (KDE) diagrams, Cumulative Age Distributions (CADs) and the Kolmogorov–Smirnov (K-S) test. On the other hand, the U-Pb zircon data presented in this study have been compared with all the existing data from detrital zircon grains in Neoproterozoic and Cambrian rocks of the Iberian Massif (20 samples, 2706 U–Pb zircon ages). For the comparison, in addition to the KDEs, CADs and K-S test, we apply 3D multidimensional scaling techniques (3D-MDS). The results, together with the geochemical and isotopic characterisation from previous studies, suggest that this domain is likely to be part of the autochthonous section of the Central Iberian Zone (CIZ). Zircon age patterns indicate a probable sedimentary provenance from the Saharan Metacraton with, or without, minor input from the Tuareg Shield. The most important local detrital source corresponds to Cadomian magmatism developed during a magmatic event (535–515 Ma) followed by back-arc extension and early Paleozoic rifting (535–460 Ma). The remaining Mesoproterozoic, Paleoproterozoic and Archean zircon grains would have been provided by the Paleoproterozoic basement and/or the older continental crust recycled in the western sections of the Gondwana margin. PublicationSignificance of detrital zircons in Siluro-Devonian rocks from Iberia(Geological Society of London., 2015) Gutiérrez Alonso, Gabriel; Fernández Suárez, Javier; Pastor Galán, D.; Johnston, S. T.; Linnemann, U.; Hofmann, M.; Shaw, J.; Colmenero, J. R.; Hernández, P.Seven samples of Siluro-Devonian sedimentary rocks from the Cantabrian and Central Iberian zones of the Iberian Variscan belt have been investigated for provenance and contain four main age populations in variable relative proportion: Ediacaran–Cryogenian (c. 0.55–0.8Ga), Tonian–Stenian (0.85–1.2Ga), Palaeoproterozoic (c. 1.8–2.2Ga) and Archaean (c. 2.5–3.3Ga). Five samples contain very minor Palaeozoic (Cambrian) zircons and six samples contain minor but significant zircons of Middle and Early Mesoproterozoic (Ectasian–Calymmian, 1.6–1.8) age. These data highlight the transition from an arc environment to a stable platform following the opening of the Rheic Ocean. Variations in detrital zircon populations in Middle–Late Devonian times reflect the onset of Variscan convergence between Laurussia and Gondwana. The presence of a high proportion of zircons of Tonian–Stenian age in Devonian sedimentary rocks may be interpreted as (1) the existence of a large Tonian–Stenian arc terrane exposed in the NE African realm (in or around the Arabian–Nubian Shield), (2) the participation, from the Ordovician time, of a more easterly alongshore provenance of Tonian–Stenian zircons, and (3) an increase in the relative proportion of Tonian–Stenian zircons with respect to the Ediacaran–Cryogenian population owing to the drift of the Avalonian–Cadomian ribbon continent, or the progressive burial of Ediacaran–Cryogenian rocks coeval with the denudation of older source rocks from the craton interior. PublicationNeoproterozoic-early Palaeozoic tectonostratigraphy and palaeogeography of the peri-Gondwanan terranes: Amazonianv. West African connections(Geological Society of London, 2008) Nance, R. Damian; Murphy, J. Brendan; Strachan, Rob A; Keppie, J. Duncan; Gutiérrez Alonso, Gabriel; Fernández Suárez, Javier; Quesada Ochoa, Cecilio; Linnemann, Ulf; D'Lemos, Richard; Pisarevsky, Sergei A.Within the Appalachian-Variscan orogen of North America and southern Europe lie a collection of terranes that were distributed along the northern margin of West Gondwana in the late Neoproterozoic and early Palaeozoic. These peri-Gondwanan terranes are characterized by voluminous late Neoproterozoic (c. 640-570 Ma) arc magmatism and cogenetic basins, and their tectonothermal histories provide fundamental constraints on the palaeogeography of this margin and on palaeocontinental reconstructions for this important period in Earth history. Field and geochemical studies indicate that arc magmatism generally terminated diachronously with the formation of a transform margin, leading by the Early-Middle Cambrian to the development of a shallow-marine platform-passive margin characterized by Gondwanan fauna. However, important differences exist between these terranes that constrain their relative palaeogeography in the late Neoproterozoic and permit changes in the geometry of the margin from the late Neoproterozoic to the Early Cambrian to be reconstructed. On the basis of basement isotopic composition, the terranes can be subdivided into: (1) Avalonian-type (e.g. West Avalonia, East Avalonia, Meguma, Carolinia, Moravia-Silesia), which developed on juvenile, c. 1.3-1.0 Ga crust originating within the Panthalassa-like Mirovoi Ocean surrounding Rodinia, and which were accreted to the northern Gondwanan margin by c. 650 Ma; (2) Cadomian-type (e.g. North Armorican Massif, Ossa-Morena, Saxo-Thuringia, Moldanubia), which formed along the West African margin by recycling ancient (c. 2.0-2.2 Ga) West African crust; (3) Ganderian-type (e.g. Ganderia, Florida, the Maya terrane and possible the NW Iberian domain and South Armorican Massif), which formed along the Amazonian margin of Gondwana by recycling Avalonian and older Amazonian basement; and (4) cratonic terranes (e.g. Oaxaquia and the Chortis block), which represent displaced Amazonian portions of cratonic Gondwana. These contrasts imply the existence of fundamental sutures between these terranes prior to c. 650 Ma. Derivation of the Cadomian-type terranes from the West African craton is further supported by detrital zircon data from their Neoproterozoic-Ediacaran clastic rocks, which contrast with such data from the Avalonian- and Ganderian-type terranes that suggest derivation from the Amazonian craton. Differences in Neoproterozoic and Ediacaran palaeogeography are also matched in some terranes by contrasts in Cambrian faunal and sedimentary provenance data. Platformal assemblages in certain Avalonian-type terranes (e.g. West Avalonia and East Avalonia) have cool-water, high-latitude fauna and detrital zircon signatures consistent with proximity to the Amazonian craton. Conversely, platformal assemblages in certain Cadomian-type terranes (e.g. North Armorican Massif, Ossa-Morena) show a transition from tropical to temperate waters and detrital zircon signatures that suggest continuing proximity to the West African craton. Other terranes (e.g. NW Iberian domain, Meguma) show Avalonian-type basement and/or detrital zircon signatures in the Neoproterozoic, but develop Cadomian-type signatures in the Cambrian. This change suggests tectonic slivering and lateral transport of terranes along the northern margin of West Gondwana consistent with the transform termination of arc magmatism. In the early Palaeozoic, several peri-Gondwanan terranes (e.g. Avalonia, Carolinia, Ganderia, Meguma) separated from West Gondwana, either separately or together, and had accreted to Laurentia by the Silurian-Devonian. Others (e.g. Cadomian-type terranes, Florida, Maya terrane, Oaxaquia, Chortis block) remained attached to Gondwana and were transferred to Laurussia only with the closure of the Rheic Ocean in the late Palaeozoic. PublicationDating of lithospheric buckling: 40Ar/39Ar ages of syn-orocline strike–slip shear zones in northwestern Iberia(Elsevier, 2015-03-07) Gutiérrez Alonso, Gabriel; Collins, Alan S.; Fernández Suárez, Javier; Pastor Galán, Daniel; González Clavijo, Emilio; Jourdan, Fred; Weil, Arlo B.; Johnston, Stephen T.Abstract Orogenic curvature is a ubiquitous feature of mountain belts, and the plate tectonic and geodynamic setting responsible for the development of curved orogens is a subject of debate. In order to distinguish between different models of orocline formation it is necessary to tightly constrain the absolute timing of oroclinal development. However, determining the absolute (isotopic) timing of oroclinal bending is challenging. The most direct method available to constrain the time interval during which an orocline formed is to obtain absolute age constraints on fabrics generated within syn-orocline strike–slip shear zones that accommodated rotations around a vertical axis during the development of crustal or lithospheric scale orogenic curvature. Here we present a data set of 40Ar/39Ar ages obtained from five shear-zones, some of which display curved traces parallel to the Cantabrian Orocline structural grain in NW Iberia and are interpreted to have been generated coevally to it. The 40Ar/39Ar ages were obtained by laser-rastering induced step-heating on single muscovite crystals that grew synkinematically during shearing. All five samples yielded ages that cluster tightly at 308 ± 3 Ma providing direct evidence for the age of oroclinal bending. This age is consistent with the age constraints obtained from paleomagnetic and structural data that place the onset of oroclinal bending in Moscovian times. Our 40Ar/39Ar age determinations therefore provide a reliable absolute constraint on the age of buckling of the Variscan orogen around a vertical axis and provide further evidence that oroclinal bending is unrelated to Variscan convergence/collision or the subsequent extensional collapse of the mountain belt. PublicationMagmatism and early-Variscan continental subduction in the northern Gondwana margin recorded in zircons from the basal units of Galicia, NW Spain(Geological Society of America, 2010) Abati Gómez, Jacobo; Fernández Suárez, Javier; Arenas Martín, Ricardo; Whitehouse, Martín J.; Díez Fernández, RubénIn situ uranium-lead dating (LA-SF-ICPMS and SIMS) and Lu-Hf isotope analyses (LA-MC-ICP-MS) of zircon from eclogite facies rocks from the basal units of the Variscan Belt in Galicia constrain their magmatic and metamorphic evolution and give some clues about the nature and origin of the involved basement. The samples studied are two felsic gneisses, two eclogites, and one eclogitic gneiss of intermediate composition (metatonalite). Oscillatory-zoned zircon cores from the felsic samples gave a main clustering of U-Pb ages at 493 ± 2 and 494 ± 2 Ma, and some older ages that represent inherited cores. Zircon grains from the intermediate and one of the mafic rocks show no inherited cores and yielded ages of 494 ± 3 and 498 ± 6 Ma, respectively, interpreted as time of protolith crystallization. Variably developed homogeneous zircon rims in one felsic gneiss yielded an age of 372 ± 3 Ma, and very tiny zircons of one eclogite gave 350 ± 2 Ma, both of which we interpret as metamorphic ages. The new age data demonstrate that the calc-alkaline magmatic suite described in the basal unit is ca. 20 Ma older than the alkaline to peralkaline plutonic suite of the same unit (dated at 472 ± 2 Ma; Rodríguez et al., 2007), and thus probably represents a distinct geologic event. Overgrowth rims are interpreted as metamorphic on the basis of their Lu/Hf and Th/U ratios. The 372 ± 3 age is considered as dating the high-pressure (high-P) metamorphism, and is essentially in agreement with previous Ar-Ar and Rb-Sr data. This high-P metamorphism marks the initial early-Variscan subduction of the Gondwana margin. The inherited zircon ages and Hf isotopic composition of zircons point to a considerable input of crustal material with West African Craton provenance to the felsic magma. PublicationExhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?(Geological Society of America, 2018-02-09) Gutiérrez-Alonso, Gabriel; Fernández Suárez, Javier; López Carmona, Alicia; Gärtner, AndreasIn 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.