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The Eastern Galicia Magnetic Anomaly is the best studied anomaly of the Central Iberian Arc. This is due to its location, on the Lugo-Sanabria gneiss dome, and to the fact that its source rocks crop out in the Xistral Tectonic Window. Multiple studies of this anomaly have been carried out, but still, new results keep on shedding light on its understanding. This paper presents the first results on rock magnetic analyses, natural remanent magnetization, anisotropy of the magnetic susceptibility, X-ray diffraction, and stable isotopes geochemistry carried out on the source rocks of this anomaly. Results suggest that magnetization responds to the increase in oxygen fugacity underwent by rocks affected by late Variscan (330-300 Ma) extensional tectonics. Extensional detachments were the pathways that allowed the entrance of fluids that led to syntectonic crystallization of magnetite and hematite in metasediments and inhomogeneous S-Type granitoids derived from their partial melting. Accordingly, magnetization is not linked to lithologies, but to extensional structures developed in the late Carboniferous/earliest Permian, during the Kiaman reverse superchron. Systematic reverse magnetic remanence exhibited by hematite-bearing samples confirms the age of the magnetization and adds complexity to the interpretation of the anomaly. Understanding the EGMA contributes to the interpretation of other anomalies existing in the CIA, also located on thermal domes. The observed extension-related magnetization probably affected most of the NW Iberian Massif, thus hindering the study of previous tectonics by paleomagnetic techniques. This work aims to provide new hints to interpret magnetic anomalies located in extensional tectonic contexts worldwide., Projects SA065P17 and BU235P18, funded by the Regional Castilla-León Government, (2) Salamanca University through different lines of funding related to its support to research groups program, (3) projects CGL2016-78560-P and CGL2016-77560 of the Spanish Ministry of Economy, Industry and Competitiveness, and (4) project PID2019-108753GB-C21/AECI/10.13039/501100011033 of the Agencia Estatal de Investigación.

[EN] The 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., Research funded by Spanish project CGL2016-76438-P (Ministerio de Economía, Industria y Competitividad).

Nº Especial: New developments in Geochemistry. A tribute to Carmen Galindo. - This work is a contribution to IGCP project 683 (Pre-Atlantic geological connections among northwest Africa, Iberia and eastern North America: Implications for continental confgurations and economic resources), [EN] Metasedimentary rock successions in Sierra Albarrana Group (SW Iberia Autochthonous Domain) were deposited during the Early Paleozoic influenced by the evolution of a peri-Gondwanan active margin. Their geochemical composition indicates dominant contributions from felsic igneous sources and an upper continental crust provenance. The high mineralogical and geochemical maturity, together with negative εNd(530), ranging from − 11.3 to − 4.5, and old Nd model ages (TDM: 1388–1897 Ma) imply reworked materials from old continental source areas with a limited juvenile contribution for the siliciclastic sedimentary rocks in Sierra Albarrana. Both, geochemical and isotope features were caused by the progressive denudation of rocks bearing the isotopic imprint from an old basement exposed along the Gondwanan margin. The paleobasin for the SW Iberia Autochthon probably occupied an outboard position across the peri-Gondwanan margin during Ediacaran–Cambrian times. In a convergent scenario, the interaction between the peri-Gondwanan trench and the external part of the continent generated tectonic uplift, giving way to exposure of crust formed during earlier stages of the Cadomian Orogeny and erosion. Sediment redistribution through Early Paleozoic times supplied recycled detrital materials, which likely filled a retro-arc basin formed after the switch from an extensional to a compressional regime in the upper plate of the Cadomian Orogen that is recorded throughout the peri-Gondwanan domain of Iberia. A subsequent extensional stage led to a progressive widening of its marginal basins, thus bringing the onset of a passive margin from the Cambro–Ordovician onwards. Nd model ages of the Sierra Albarrana Group overlap those of Early Cambrian series from the southernmost Central Iberian Zone, and are considered an indication for the paleogeographic closeness between all these sequences during Cambrian times, occupying eastern positions closer to Tuareg Shield and the Sahara Metacraton sections along the Gondwanan margin., [ES] Las series de rocas metasedimentarias en el Grupo Sierra Albarrana (Dominio Autóctono del SW de Iberia) se depositaron durante el Paleozoico Inferior, influidas por la evolución de un margen activo peri-Gondwánico. Su composición geoquímica indica una contribución dominante desde fuentes ígneas félsicas con afinidad con una corteza continental superior. La elevada madurez mineralógica y geoquímica, junto con valores negativos de εNd(530) (− 11.3 a − 4.5) y edades modelo de Nd relativamente antiguas (TDM: 1388–1897 Ma), implica materiales retrabajados desde áreas fuente continentales antiguas, con una contribución juvenil limitada para las rocas siliciclásticas estudiadas en el Grupo Sierra Albarrana. Sus características geoquímicas e isotópicas fueron fruto de una denudación progresiva de rocas con una composición isotópica afín a un basamento antiguo expuesto a lo largo del margen de Gondwana. Teniendo en cuenta la información disponible para el SW del Macizo Ibérico, la paleocuenca del Dominio Autóctono del SW de Iberia probablemente ocupó posiciones externas en el margen peri-Gondwánico durante la transición Ediacárico-Cámbrico. En un contexto de convergencia, la interacción entre la trinchera peri-Gondwánica y la parte externa del continente ocasionó probablemente un levantamiento tectónico pronunciado, dando lugar a la exposición y posterior erosión de la corteza continental peri-Gondwánica formada durante las etapas iniciales de la Orogenia Cadomiense. La redistribución de sedimentos durante el Paleozoico Inferior aportó materiales detríticos reciclados, que probablemente rellenaron una cuenca retro-arco, formada tras el cambio de un régimen compresivo a uno extensional en la placa superior del Orógeno Cadomiense y que se registra a lo largo de todo el dominio peri-Gondwánico de Iberia. El avance en la extensión condujo a un progresivo ensanchamiento de las cuencas marginales, marcando el inicio de un margen pasivo desde el periodo Cambro-Ordovícico en adelante. Las edades modelo de Nd del Grupo Sierra Albarrana se solapan con las obtenidas en series del Cámbrico Inferior del sur de la Zona Centro Ibérica, y se consideran indicadoras de una cercanía paleogeográfica entre estas secuencias durante el Cámbrico, ocupando posiciones relativamente orientales, cercanas al Escudo de Tuareg y al Metacratón del Sahara., Financial support has been provided by the Spanish project CGL2016-76438-P (Ministerio de Economía, Industria y Competitividad)

Normal incidence seismic data provide the best images of the crust and lithosphere. When properly designed and continuous, these sections greatly contribute to understanding the geometry of orogens and, together with surface geology, to unravel their evolution. In this paper we present an almost complete transect of the Iberian Massif, the westernmost exposure of the European Variscides. Despite the heterogeneity of the dataset, acquired during the last 30 years, the images resulting from reprocessing with a homogeneous workflow allow us to clearly define the crustal thickness and its internal architecture. The Iberian Massif crust, formed by the amalgamation of continental pieces belonging to Gondwana and Laurussia (Avalonian margin) is well structured in upper and lower crust. A conspicuous mid-crustal discontinuity is clearly defined by the top of the reflective lower crust and by the asymptotic geometry of reflections that merge into it, suggesting that it has often acted as a detachment. The geometry and position of this discontinuity can give us insights on the evolution of the orogen, i.e. of the effects and extent of the late Variscan gravitational collapse. Also, its position and the limited thickness of the lower crust in central and NW Iberia constraints the response of the Iberian microplate to Alpine shortening. This discontinuity is here observed as an orogeny-scale feature with characteristics compatible with those of the worldwide, Conrad discontinuity., The seismic data was reprocessed using the commercial seismic signal processing software Claritas. Funding for this research was provided by the Junta de Castilla y León (SA065P17), the Spanish Ministry of Science and Innovation (CGL2016-78560-P) and the Generalitat de Catalunya (grant 2017SGR1022).

UPb and LuHf isotope ratios measured in zircon crystals from magmatic and metamorphic rocks provide crucial information to understand the origin and tectonothermal evolution of allochthonous terranes, and can contribute to paleogeographic reconstructions and to the understanding of orogenic processes. We investigate the age of magmatic and tectonothermal events, and the provenance of a high-pressure unit from the Ossa-Morena Complex (SW Iberian Massif). Zircons for LA-ICP-MS analyses were separated form garnet-bearing amphibolites (retroeclogites) and quartzo-feldspathic gneisses from the Central Unit (Coimbra-Córdoba shear zone). Recent geological correlations propose that the high-pressure units cropping out in the Ossa Morena Complex of the SW Iberian Massif are equivalent to the Basal Allochthonous Units of NW Iberian Massif, and one of the objectives of the study is to check the validity of the proposed correlation. The new obtained ages presented in this study indicate that the high-pressure metamorphism of the Central Unit developed in the Variscan cycle. The metamorphic zircons reveal two distinct events: a younger one well constrained by an age of 339 ± 4 Ma and an older one of 377 ± 19 Ma. The former coincide with the age of the high-grade and post-high-P metamorphism described in other areas of the Ossa-Morena Complex, whereas the second one is interpreted as the age of the high-P metamorphism. The igneous ages of metabasites and metagranitoids (c.585–615 Ma and c.480–577 Ma, respectively) reveal a diachronism between magmatic events in Allochthonous Units from the SW and the NW Iberian Massif, suggesting that both domains were located in different parts of the North-Gondwanan margin. The magmatic ages of the metagranitoids resemble the evolution described for the lower paleozoic rifting in the Ossa-Morena Complex. The relatively juvenile character of the basic and acid Cadomian magmatism in the Central Unit, revealed by the new LuHf data, indicate limited mixing of mantle melts with crustal components, which is compatible with a generation in a continental magmatic arc. These similarities in the metamorphic and magmatic evolution support the correlation of the Basal Allochthonous Units from the SW and NW domains of the Iberian Massif., This work was financed by project CGL2016-76438-P(Ministerio de Economía, Industria y Competitividad, Spain).

A major event of plutonic activity occurred all across the Central Iberian Zone of the Iberian Variscan Belt at the end of Late Paleozoic Variscan collisional tectonism. The present study focuses on the western sector of the Viseu late-post-tectonic batholith (central Portugal), a large composite intrusion comprising three main plutonic units: (a) small bodies of mafic to intermediate composition preferentially concentrated along the northern border, (b) a wide ring of coarse porphyritic biotite monzogranite (Cota-Viseu granite) and (c) a more evolved medium porphyritic, biotite-muscovite monzogranite occupying the central part of the intrusion (Alcafache granite). The compositional zonation pattern of the whole batholith and the complex mixing/mingling relationships between the voluminous Cota-Viseu porphyritic granite and the mafic/intermediate rocks suggest that these melts were withdrawn from a lower crustal source region undergoing partial melting, invasion by mantle-derived mafic magmas, mixing and fractional crystallization. New CA-ID-TIMS U-Pb zircon ages indicate that pluton assembly via multipulse injection of successive magma batches took place between 299.4 ± 0.4 Ma and 296.0 ± 0.6 Ma. A detailed anisotropy of magnetic susceptibility (AMS) survey suggests that pluton emplacement occurred at the extensional termination of a regional-scale, ENE-WSW trending, sinistral D3 shear zone - the Juzbado-Penalva Shear Zone (JPSZ). A dilational opening model involving the development of “en-echelon” tensional gashes at the extensional termination of the fault, followed by progressive opening and widening of north-south trending fractures, provided the space into which the successive magma batches arriving from below were emplaced. Vertical inflation was accommodated by depression of the pluton floor. The proposed model is consistent with the asymmetric wedge-shaped geometry of the intrusion (steep root zone on the northern side, discordant subvertical walls and a shallowing pluton floor towards the south).

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., Financial support has been provided by the Spanish project CGL2012-34618, funded by Ministerio de Economía y Competitividad (Spain).

The Calzadilla Ophiolite is an ensemble of mafic and ultramafic rocks that represents the transition between lower crust and upper mantle of a Cadomian (peri-Gondwanan) fore arc. Mapping and structural analysis of the ophiolite demonstrates that it was obducted in latest Ediacaran times, because the Ediacaran-Early Cambrian sedimentary series (Malcocinado Formation) discordantly covers it. The ophiolite and emplacement-related structures are affected by Variscan deformation (Devonian-Carboniferous), which includes SW verging overturned folds (D1) and thrusts (D2), upright folds (D3), extensional faults (D4), and later faults (D5). These phases of deformation are explained in the context of Variscan tectonics as the result of the progressive collision between Gondwana and Laurussia. Qualitative unstraining of Variscan deformation reveals the primary geometry of Ediacaran-Cambrian structures and uncovers the generation of east verging thrusts as responsible for the primary obduction of the Calzadilla Ophiolite. Restoration of planar and linear structures associated with this event indicates an Ediacaran, east directed obduction of the ophiolite, that is, emplacement of the Cadomian fore arc onto inner sections of the northern margin of Gondwana. According to regional data, the obduction separates two extension-dominated stages in the tectonic evolution of the African margin of northern Gondwana preserved in southern Europe. Preobduction extension brought about the onset and widening of fore-arc and back-arc basins in the external part of the continent, while postobduction extension facilitated the formation of extensional migmatitic domes, an oceanward migration of back-arc spreading centers across peri-Gondwana, and the eventual opening of a major basin such as the Rheic Ocean. ©2018. American Geophysical Union. All Rights Reserved., Financial support has been provided by the Spanish project CGL2016‐76438‐P (Ministerio de Economía, Industria y Competitividad). This work is a contribution to IGCP project 648 (Supercontinent Cycle and Global Geodynamics).

The Sierra Bermeja Pluton (similar to 60 km(2) surface area) exemplifies a type of controversial granites of the Iberian Massif (European Variscan Belt), the cordierite-bearing 'Serie Mixta' (mixed series) monzogranites. The pluton is included almost completely in the Cornalvo Natural Park (Badajoz, Spain), a relevant target area in Roman times. The geological mapping summarised in the presented map at 1:10,000 scale has revealed a complex intrusive assemblage. Three main cordierite-bearing monzogranite types that show local varieties constitute most of the massif. Monzogranite intrusions are younger towards the centre of the pluton and gave rise to outstanding mappable mingling/mixing zones in some areas. A NE-SW trending reduced dyke complex composed by vaugnerite series rocks, lamprophyres, aplites and quartz dykes, completes the lithological assemblage of the pluton. An inventory of Geologic Points of Interest to promote the geological knowledge of this remarkable protected area and its geoconservation is also presented. The authors thank the financial support of the Spanish Ministerio de Economia y Competitividad Ciencia e Innovacion (MINECO, grant CGL2015-63530-P) and the University of the Basque Country (UPV/EHU, Grupo Consolidado project GIU15/05).

LA-MC-ICP-MS U–Pb zircon ages and wholerock geochemical data obtained from volcanic rocks erupted in the northern margin of Gondwana provide new insights on the polyphase magmatic evolution of the NW Iberian domain during the establishment of passive margin conditions in Lower Paleozoic times. The U–Pb data show crystallization ages of ca. 455 Ma for two calc-alkaline rhyolites sampled in the Upper Parautochthon of the eastern Galicia—Trás-os-Montes Zone (GTMZ) and for an intraplate basalt intruded into Middle Ordovician slates of the autochthonous series of the Central Iberian Zone (CIZ). Together with previous data, the ages obtained reveal a periodic magmatic activity across the northern Gondwana margin during the Lower Paleozoic, which is comparable to that observed in NE Iberia and in other massifs of the Mediterranean realm. Both geochronological and geochemical data reinforce paleontological and stratigraphic evidences for paleogeographic proximity between these domains and contribute to the recognition of extensional-related magmatism along the northern margin of Central Gondwana associated with the opening of the Rheic Ocean., Instituto Dom Luiz, Universidade de Lisboa, Portugal, Departamento de Geociências, Instituto Dom Luiz, Universidade de Évora, Portugal, Department of Geological Sciences, University of Florida, Estados Unidos, Unidad de Salamanca, Instituto Geológico y Minero de España, España

The Mississippian volcano-sedimentary complex in the Toca da Moura – Cabrela areas represents remnants of intra-volcanic marine sedimentary basins, formed during the collision between the Ossa Morena Zone with the South Portuguese Zone. These rock units are unconformably overlain by the Pennsylvanian intramontane coal-bearing Santa Susana Basin. Vitrinite reflectance determinations from rocks of these two basins indicate two episodes of thermal maturation. During the first episode, the Toca da Moura – Cabrela volcano-sedimentary complexes attained high maturation levels, equivalent to anthracite coal rank (3.0–3.5% R oran ), which pre-dates the middle Moscovian Santa Susana Basin. The Santa Susana Basin attained moderate maturation levels equivalent to bituminous coal rank (1.35–1.5% R oran ) recording a second episode of thermal maturation. Here, peak thermal conditions did not overprint the first maturation episode. The observed effects of magmatic intrusion on the thermal maturity and the lack of any increase in vitrinite reflectance with depth through c. 400 m of section in borehole SDJ-1 indicate high geothermal gradients during the first maturation episode. A contemporaneous magmatic event associated with the c. 335–320 Ma Cuba-Alvito Gabbros/Diorites of the Beja Massif was the possible cause for the high geothermal gradients postulated for the first maturation episode. Burial under a post-upper Moscovian sedimentary cover was the most likely process to account for the maturation levels determined for the Santa Susana Basin and for the second episode of thermal maturation.

We present here a comprehensive and updated review on the gneissic Ollo de Sapo Formation (OSF) in the Iberian Massif and discuss multiple aspects (lithostratigraphy, petrography, geochemistry, geochronology, and partial melting relationships) of its evolution through time. These aspects arise from the superposition of a multi-magmatic Cambro-Ordovician assemblage and a complex Variscan metamorphic overprint. The OSF comprises plutonic, subvolcanic, volcanic, and volcaniclastic units of fel and peraluminous compositions and calcalkaline affinity of the Upper Cambrian to the Lower Ordovician age (495–470 Ma), which crops out at the core of a 600-km-long antiform in the Ollo de Sapo Domain of the Iberian Massif and are overlain by the Armorican Quartzite. The most striking petrographic features of the OSF are the large phenocrysts of K-feldspar, plagioclase, and blue quartz, giving the name “Ollo de Sapo” (toad's eyes), and the large fraction of inherited zircons of Ediacaran or older ages. Geochemical and petrographic indicators point to a medium-P, high-T melting event of Neoproterozoic metasedimentary rocks, most probably the Schist and Greywacke Complex, and a subsequent rapid ascent of melts. Augen gneisses of mostly plutonic origin, of similar age, petrography, and geochemistry and emplaced in the same sedimentary sequences in the Iberian Massif but in lower stratigraphic levels than the classical Ollo de Sapo Domain, also exist. These plutonic augen gneisses are considered to be genetically related to the OSF. The magmatic event that produced the OSF and the equivalent augen gneisses in the Iberian Massif, as well as other augen gneisses present in the European Variscan Belts, has been supposedly related to the opening of the Rheic Ocean in the northern margin of Gondwana. The Variscan metamorphism affected the OSF and the equivalent augen gneisses to variable degrees, from low-grade to anatectic conditions, in a clockwise P-T-t path, that produced its characteristic gneissic foliation. No model for the generation of the OSF has been unanimously accepted yet because of several, and often contradictory, geodynamic scenarios suggested by the petrographic and geochemical characteristics, further complicated by current debates on the paleogeography of northern Gondwana terranes. The stepwise investigation of this complex formation allows at present a general review of its evolution through time, a review that is presented here., Departamento de Geociencias, Universidad de Los Andes, Colombia, Unidad de Salamanca, Instituto Geológico y Minero de España, España, Departamento de Petrología y Geoquímica, Universidad Complutense de Madrid, España

A complete Ediacaran–Early Cambrian stratigraphic transition can be observed in the southern part of the Central Iberian Zone (Iberian Massif). Two different stratigraphic units, underlying Ordovician series, display geochemical and Sm–Nd isotopic features in agreement with an evolving geodynamic setting. Pusa Shales (Early Cambrian) rest unconformably on greywackes of the Lower Alcudian Formation (Late Ediacaran). Both sequences present minor compositional variations for major and trace element contents and similar REE patterns, close to those of PAAS (Post Archean Australian Shale). Trace element contents and element ratios suggest mixed sources, with intermediate to felsic igneous contributions for both units. Tectonic setting discrimination diagrams for the Ediacaran greywackes indicate that these turbiditic series were deposited in a sedimentary basin associated with a mature active margin (volcanic arc). However, the compositions of the Cambrian shales fit better with a more stable context, a back-arc or retro-arc setting. εNd(T) and TDM ages are compatible with dominance of a similar cratonic source for both sequences, probably the West Africa Craton. εNd565 values for the Ediacaran greywackes (− 3.0 to − 1.4) along with TDM ages (1256–1334 Ma) imply a significant contribution of juvenile material, probably derived from the erosion of the volcanic arc. However, εNd530 values in the Cambrian shales (− 5.2 to − 4.0) together with older TDM ages (1444–1657 Ma), suggest a higher contribution of cratonic isotopic sources, probably derived from erosion of the adjacent mainland. Coeval with the progressive cessation of arc volcanism along the peri-Gondwanan realm during the Cambrian, there was a period of more tectonic stability and increasing arrival of sediments from cratonic areas. The geochemistry of the Ediacaran–Cambrian transition in Central Iberia documents a tectonic switch in the periphery of Gondwana, from an active margin to a more stable context related to the onset of a passive margin., Financial support has been provided by the Spanish projects CGL2012-34618 and CGL2013-48877 (Ministerio de Economía y Competitividad).

The existence of a large allochthonous nappe pile emplaced onto the hinterland of the Iberian Massif and covering most of the basement of NW and SW Iberia proposed by Díez Fernández and Arenas has been called into question on the basis of structural, geophysical, and regional data from SW Iberia. The discussion provided here is based on a revision of the fundamentals of the Variscan geology of NW Iberia and on a more detailed presentation of the geology of SW Iberia. Our counterarguments reveal the reasoning of Simancas et al. against the verisimilitude of the large allochthonous pile as inconclusive, incomplete, or erroneous in some cases. Therefore, we maintain that our structural correlation and its implications remain fully valid for the case of the Iberian Massif., Financial support has been provided by the Spanish project CGL2012-34618 (granted by Ministerio de Economía y Competitividad).

Correlation of a group of allochthonous terranes (referred to as basal, ophiolitic and upper units) exposed in the NW and SW of the Iberian Massif, is used to propose a new geotectonic zone in the southern branch of the Variscan Orogen: the Galicia–Ossa-Morena Zone. Recent advances in SW Iberia identify most of the former Ossa-Morena Zone as another allochthonous complex of the Iberian Massif, the Ossa-Morena Complex, equivalent to the Cabo Ortegal, Órdenes, Malpica-Tui, Bragança and Morais complexes described in NW Iberia. The new geotectonic zone and its counterparts along the rest of the Variscan Orogen constitute an Internal Variscan Zone with ophiolites and units affected by high-P metamorphism. The Galicia–Ossa-Morena Zone includes a Variscan suture and pieces of continental crust bearing the imprint of Ediacaran–Cambrian events related to the activity of peri-Gondwanan magmatic arcs (Cadomian orogenesis). In the Iberian Massif, the general structure of this geotectonic zone represents a duplication of the Gondwanan platform, the outboard sections being juxtaposed on top of domains located closer to the mainland before amalgamation. This interpretation offers an explanation that overcomes some issues regarding the differences between the stratigraphic and paleontological record of the central and southern sections of the Iberian Massif. Also, equivalent structural relationships between other major geotectonic domains of the rest of the Variscan Orogen are consistent with our interpretation and allow suspecting similar configurations along strike of the orogen. A number of issues may be put forward in this respect that potentially open new lines of thinking about the architecture of the Variscan Orogen., Financial support has been provided by the Spanish project CGL2012-34618 (Ministerio de Economía y Competitividad).

The Viseu area is located in the Central Iberian Zone of the Iberian Variscan Belt and hosts numerous post-thickening, collision-related granitoids intruded into upper and middle crustal levels. The present paper reports high precision U-Pb zircon and monazite ages for four plutons of the Viseu area: The syn-kinematic granitoids of Maceira (314±5 Ma), Casal Vasco (311±1 Ma) and Junqueira (307.8±0.7 Ma) and the late-kinematic biotite monzogranites of Cota (306±9 Ma). This points to a synchronous emplacement of the different syn-kinematic plutons shortly followed by the intrusion of the late-kinematic granites and shows that the Upper Carboniferous plutonism occurred within a short time span of ca. 10 million years. The ascent of granite magmas took place after an extensional tectonic event (D2) and is coeval with dextral and sinistral crustal-scale transcurrent shearing (D3). Field and petrographical evidence suggest a narrow time-span between peak T metamorphic conditions and the intrusion of granitic melts which implies very fast uplift rates accommodated through active tectonic exhumation. Magma compositions evolve through time, reflecting an increasing involvement of mid-crustal sources and the underplating effect of an upwelling asthenospheric mantle at the base of a thinning and stretching continental crust. © 2005 Elsevier B.V. All rights reserved.

Integrated in the national inventory of geological heritage in Portugal, the “Iberian Massif Landscape and Fluvial Network” was selected as one of the geological frameworks with international relevance. Taking into account the diversity of geomorphological and stratigraphic elements occurring in the Portuguese Iberian Massif, 38 geosites were selected in order to represent five themes related to the main geomorphological elements of the Iberian Massif Landscape: major residual landforms, granite landforms, tectonic landforms, correlative sediments, and fluvial landforms. For each theme, some sub-themes were defined, together with key-areas that were considered for the selection of geosites. A quantitative assessment of the scientific value and vulnerability of all geosites was undertaken using a methodology that numerically scores a set of criteria. Results highlight the Vilariça geosite with top-priority for management based on its high scientific value and high vulnerability, and the key-area of Miranda do Corvo-Lousã Basin because of the high concentration of geosites. The quantitative evaluation shows that seven geosites have high vulnerability and that special attention should be paid to sedimentary sections. These results allow the establishment of priorities for the management of geosites under the scope of a national geoconservation strategy., This paper results of the research done at the University of Minho and at the Geology Centre of the University of Porto, both partially founded by the Foundation for Science and Technology (strategic project with reference PEst-OE/CTE/UI0039/2014), and IMAR-CMA – University of Coimbra, sponsored by the Foundation for Science and Technology (Portugal)., info:eu-repo/semantics/publishedVersion