Allochthonous Units in the Variscan Belt of NW Iberia: Terranes and Accretionary History

Catalán, José R. Martı́nez; Arenas, Ricardo; García, Francisco Javier Puente; Abati, Jacobo

doi:10.1007/978-94-011-4800-9_5

Cited by 30 publications

(30 citation statements)

References 3 publications

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“…1 b) represents a more external section of the continental margin (Martinez Catalan et al, 1999). This domain occupied an intermediate position between the autochthonous sequences of the Central Iberian Zone and the allochthonous complexes.…”

Section: Sediments and Magmatismmentioning

confidence: 97%

“…The Neoproterozoic succession was deposited during the last pulses of the Cadomian cycle, whereas the overlying Lower-Middle Cambrian succession was not intruded by granitoids, and records, together with the lowermost ophiolitic units of NW Iberia, the development of a back-arc basin at the edge of Gondwana Dlez Fernandez et al, 201 0). This basin developed during the pulling apart of a continental voleanic arc (Abati et al, 1999;Andonaegui etal., 2002;Fuenlabrada etal., 2010), which was emplaced on top of the allochthonous pile of NW Iberia (e.g. G6mez and Europe (e.g.…”

Section: Sediments and Magmatismmentioning

confidence: 99%

See 1 more Smart Citation

Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

2012

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Section: Sediments and Magmatismmentioning

confidence: 97%

Section: Sediments and Magmatismmentioning

confidence: 99%

Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

2012

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“…1a, b), which constitutes the external part of the Iberian Massif in NW Spain and the core of the socalled Ibero-Armorican Arc. The Iberian Massif corresponds to the SW part of the European Variscan Orogen and was formed as a consequence of the collision between Laurentia and Gondwana during Devonian-Permian times (Matte 1991;Martínez Catalán et al 1999). The Cantabrian Zone is characterized by a complete Paleozoic succession with a low degree of metamorphism and aVected by thinskinned tectonics.…”

Section: Geological Settingmentioning

confidence: 99%

Transgressive–regressive sequence stratigraphy of Pennsylvanian Donezella bioherms in a foreland basin (Lena Group, Cantabrian Zone, NW Spain)

Corrochano

Barba

Colmenero

2011

Facies

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A well-preserved Pennsylvanian (early Moscovian) succession including Donezella mounds, which accumulated in a highly subsiding foreland basin (Cantabrian Zone, NW of Spain), is described and discussed. This succession has been interpreted as one 3rd-order sequence reaching a thickness up to 815 m and recording »2.3-My duration. It consists of four 4th-order transgressive-regressive (T-R) sequences (105-350 m thick and »0.6-My duration), each subdivided into several 5th-order (»70-ky duration) meter-scale cycles (23-m average thickness). Nearly all the Donezella mounds are present in the second and third 4th-order sequences deWned (Levinco Formation). They are up to »90 m in thickness and several hundreds of meters wide, showing lenticular to domal morphologies with steep slopes up to 35-40°. Bioherms are composed of micritic boundstones with heterogeneous microfabrics and a diverse biotic community, including the microproblematic Donezella, calcitornellid foraminifers, bryozoans, agglutinated worm tubes, crinoids, and calcareous algae (red Komia/Ungdarella, beresellids, dasycladaceans and phylloids). According to the biotic assemblage and sedimentological features, these Donezella-rich bioherms thrived in a relatively shallow and low-energy environment (below fair-weather wave-base), and resulted from the baZing and binding ability of Donezella and associated biota, and the in situ-precipitation of microbial micrite. The upward evolution of the succession mainly resulted from the interplay between high tectonic subsidence rates and high-frequency moderate-amplitude glacioeustatic sealevel changes. The mounds growth mainly occurred during the transgressive phase of the 3rd-order sequence (Vereian), whereas during the regressive phase (Kashirian), deltaic siliciclastics prograding westward gradually buried and prevented the buildup development.

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“…According to the data presented herein, these units might have undergone rapid exhumation after burial. The palaeogeography of this alleged arc in the context of the Laurentia Gondwana interactions during the Early Palaeozoic has been discussed by, for example, Martinez Catalan et al (1999) and Abati et al (1999). The present study does not (and did not aim to) furnish new data in this regard, but it does strengthen the hypothesis that the tectono thermal evolution of the upper units of the AC in NW Iberia is compatible with an (Early Palaeozoic) island arc scenario in which magmatism, burial metamorphism with high T gradients and fast exhumation are common features (e.g.…”

Section: The Early Ordovician Eventmentioning

confidence: 99%

U-Pb evidence for a polyorogenic evolution of the HP-HT units of the NW Iberian Massif

Fernández‐Suárez

Corfú²,

Arenas

et al. 2002

Contributions to Mineralogy and Petrology

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A isotope dilution thermal ionisation mass spectrometry U Pb geochronological study was carried out on the high-pressure and high-temperature units (HP HT units) overlying the oceanic suture in the Allo chthonous Complexes of the NW Iberian Variscan Belt. The rocks investigated are seven granulite-to eclogite facies paragneisses and one leucosome within mafi c high pressure granulites in the Ordenes and Cabo Ortegal Complexes of NW Spain. U Pb dating of zircon, monazite, titanite and rutile reveal the presence of a pervasive Early Ordovician metamorphic event at ca. 500 480 Ma and a later Early Devonian event at ca. 400 380 Ma. The U Pb ages, in conjunction with petrological and structural data, indicate that the high-pressure event recorded by these rocks is Early Ordovician in age. Monazite ages in the paragneisses suggest that peak metamorphic conditions were reached at ca. 500 485 Ma. Subsequently, the rock ensemble underwent exhumation accompanied by partial melting and zircon growth at ca. 485 470 Ma. Melting of mafi c granulites was coeval with this latter episode as indicated by zircon crystallisation age in the leucosomes dated at ca. 486 Ma. Based on these data and on the general features of magmatism and metamorphic evolution, it is proposed that this process took place at a convergent plate boundary within a peri Gondwanan oceanic domain. Monazite, titanite and rutile data in some of the samples studied show evidence of a second metamorphic episode that took place between ca. 400 and 380 Ma (with a peak at ca. 390 385 Ma). This Early Devonian event, at variance with the previous one, was not pervasive, but, rather, was localised in areas of intense Variscan tectonothennal reworking. It is claimed that this later metamorphic event was recorded by the U Pb system in areas where monazite and titanite growth was enhanced by fluid circulation in highly strained rocks (Variscan shear zones). According to previous structural studies and Ar Ar dating of fabrics, this Early Devonian episode took place as the HP HT units were deformed and thrusted upon the ophiolitic units in the early stages of the Variscan collision.

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Allochthonous Units in the Variscan Belt of NW Iberia: Terranes and Accretionary History

Cited by 30 publications

References 3 publications

Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

Transgressive–regressive sequence stratigraphy of Pennsylvanian Donezella bioherms in a foreland basin (Lena Group, Cantabrian Zone, NW Spain)

U-Pb evidence for a polyorogenic evolution of the HP-HT units of the NW Iberian Massif

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