Detrital zircon from a late Paleozoic accretionary complex of SW Iberia (Variscan Belt): History of crustal growth and recycling at the Rheic convergent margin

In this study we present new U-Pb ages of detrital zircons from greywackes and quartzites of the Pulo do Lobo Anticline (PLA) that have been interpreted to represent a Late Paleozoic accretionary complex in SW Iberia. The PLA separates the Ossa Morena Zone, which has a North- Gondwana affinity throughout Late Ediacaran and Early Paleozoic times, from the South Portuguese Zone, which is considered to be underlain by Laurussia basement. The PLA stratigraphy most likely represents a synorogenic basin that records the closure of the Late Paleozoic Rheic Ocean and the amalgamation of Pangaea. The youngest formations of the PLA contain upper Devonian microfossils.The results obtained indicate that the detrital zircons from the PLA represent a wide range of Precambrian and Paleozoic crystallization ages. Recycling of older sedimentary units of the Late Ediacaran active margin (Cadomian/Pan-African orogenies) as well as of the Early Paleozoic rifting and passive margin (Rheic Ocean) stages, accounts for the older populations with North-Gondwana affinity (Cambrian, Neoproterozoic, Paleoproterozoic and Archean, with a gap of Mesoproterozoic-age). However, the Mesoproterozoic detrital zircon ages found in the greywackes of the Pulo do Lobo Formation (< 7%) that do not correspond to any substantial source within North-Gondwana, could come from recycled sedimentary deposits or from denudation of Grenville-age basement (Laurussia?). The more recent formations present in the northern limb (Ferreira-Ficalho Group) of the PLA show a significant age cluster in the upper Devonian (c. 378 Ma), whereas on the southern limb (Chança Group), samples have from base to top of the stratigraphic sequence: a minor age cluster in the middle Devonian (c. 390 Ma), a significant age cluster in upper Devonian (c. 380 Ma) and very significant age cluster in the upper Devonian (c. 372 Ma). The presence of middle-upper Devonian detrital zircons in combination with very low abundances of Mesoproterozoic detrital zircon suggests that the PLA sedimentary rocks were not derived from exotic sources but rather have a North-Gondwanan origin. The zircon population in the interval c. 390-380 Ma has no identified corresponding magmatic or stratigraphic source in SW Iberia. Considering that, during the development of the upper Devonian basins of SW Iberia, Laurussia basement was not exposed and that there was no magmatic arc on the North-Gondwana margin, we suggest that the c. 390- 380 Ma detrital zircons are most probably derived from denudation of a (intra-oceanic) magmatic arc related to the closure of the Rheic Ocean

The mediating effect of satisfaction: Does is influences loyalty concerning online tourism purchases?

This paper intends to investigate the influence of relationship marketing dimensions on online tourism customer satisfaction and to analyze the mediating effect of e-satisfaction level, on the relation between these determinants and the formation of loyalty. A questionnaire was applied to regular online buyers and the statistical analyses were conducted within the Structural Equation Modeling framework. The most important results have shown that there are three dimensions that significantly influence e-customer satisfaction – understanding customer needs, service quality and personalization. Also show that there is a complete mediating effect of ecustomer satisfaction in the relationship between the relationship marketing dimensions and e-customer loyalty. Thus, research results provide an important insight into how e-companies can pursuit and use delight to highlight customersinfo:eu-repo/semantics/submittedVersio

Multiple Paleozoic magmatic-orogenic events in the Central Extremadura batholith (Iberian Variscan belt, Spain)

Background The Central Extremadura batholith located in the southeast part of the Central Iberian Zone (e.g. Iberian Autochthonous domain of the Iberian Variscan belt) was originally thought to have been generated entirely during Carboniferous igneous activity. However, some recent geochronological work has shown the existence of Ordovician plutonic rocks. Purpose The aim of this study is to re-examine the age of granitic rocks in the Central Extremadura batholith and complement this information with new field and geochemical data. This data set is used: to constrain the relative timing of plutons emplacement, as well as deformation and metamorphism preserved in the host rocks; to track deep crustal rocks and granitic magma sources; and to discuss prevailing tectonic evolutionary models for the Paleozoic evolution of the Iberian Variscan belt. Methods We use geochemical and SHRIMP U-Pb zircon geochronology data of three granitic plutons (Ruanes, Plasenzuela and Albalá) from the Central Extremadura batholith to track magmatic sources and provide a better understanding of temporal and spatial relationships between deformation and magmatism in the Iberian Variscan belt. Results Ruanes tonalite dated at 464 ± 2 Ma is peraluminous, magnesian and calc-alkaline, as typical of a magmatic arc setting. We report, for the first time, the occurrence of a Middle Ordovician intrusion spatially and temporally related to host deformed rocks of the Central Iberian Zone (e.g. the Iberian Autochthonous domain), which reached high-grade metamorphic conditions. Plasenzuela two-mica leucogranite is strongly peraluminous and of anatectic origin and includes a Neoproterozoic and Ordovician population of inherited zircon grains. This granite possibly derived from the partial melting of a crustal source composed of Neoproterozoic metapelites and metagreywackes (Schist-Greywacke Complex) and/or Lower Ordovician gneisses (Ollo de Sapo Formation), both including greywackes of volcano-sedimentary origin and peraluminous composition. The crystallization age of 330 ± 7 Ma obtained for the syn-kinematic Plasenzuela two-mica leucogranite constrains the functioning of D2 dextral strike-slip shear zones within the Iberian Autochthonous domain. The age of 309 ± 2 Ma obtained for the Albalá cordierite-bearing monzogranite matches the age interval of the calc-alkaline magmatic suite post-dating the main Variscan D1–D3 structures in the Iberian Autochthonous domain. Conclusion The new data presented in this study make it possible to recognize multiple Paleozoic magmatic-orogenic events (e.g. Caledonian, Variscan and Cimmerian) in the Central Extremadura batholith. During the Ordovician, the emplacement of intermediate magmas at shallow depths gave rise to extensive metamorphism due to heat transfer to the host rocks. The onset of this Ordovician plutonic–metamorphic complex in the Iberian Autochthonous domain is contemporaneous with the development of an active continental margin probably related to the subduction of the Iapetus–Tornquist Ocean (i.e. the Caledonian orogeny). During the Lower Carboniferous, these D2 strike-slip domains acted as lateral margins of largescale gravitational collapses associated with the SE-direct transport of low-angle extensional shear zones (i.e. the Variscan cycle). The emplacement of Upper Carboniferous arc type granitic rocks is interpreted in the context of the amalgamation of Pangaea and the spatial proximity of Iberia relative to the Eurasian active margin in the course of Paleotethys subduction (i.e. the Cimmerian orogeny)

Application of commercial disinfectants to improve chestnut fruit sanitation

Fresh European chestnut (Castanea sativa Mill.) gas intermediate perisability charactyeristics between fresh and dried fruitsFoundation for Science and Technology (FCT, Portugal) - national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020).info:eu-repo/semantics/publishedVersio

Optical von Neumann measurement

We present an optical scheme that realizes the standard von Neumann measurement model, providing an indirect measurement of a quadrature of the field with controllable Gaussian state-reduction. The scheme is made of simple optical elements, as laser sources, beam splitters, and phase sensitive amplifiers, along with a feedback mechanism that uses a Pockels cell. We show that the von Neumann measurement is achieved without the need of working in a ultra-short pulsed regime.Comment: One latex figure. Accepted on Phys. Lett.

U-Pb geochronology of the El Jadida rhyolite and relation to possible Lower Cambrian recycling (Coastal block, Moroccan Meseta).

The El Jadida (Mazagan) dome, whose existence was reported as early as 1934 by Yovanovitch and Freys, constitutes one of the first outcrops of the Moroccan Meseta where the Precambrian (PIII?)-Paleozoic (Lower Cambrian?) boundary was established (Gigout, 1951; Cornée et al., 1984). Since then, it is listed as one of the few locations where the basement of the Moroccan Variscan belt can be observed (Hoepffner et al.. 2005; Michard et al., 2010).Despite, the absence of geochronological and biostratigraphic precise data to constrain the time interval recorded here, there are stratigraphic similarities that allow a correlation with the Ediacaran-Cambrian geological record of Anti-Atlas belt (Cornée et al., 1984). In this study, we developed a petrographic, geochemical and U-Pb geochronological study using zircon extracted from: (i) the El Jadida rhyolite with the aim of characterizing the magma source and estimate the age of crystallization; (ii) a microbreccia sampled at the base of the El Jadida Dolomitic Formation for determining provenance

Photon Green’s functions theory for Coulomb correlated quantum well lasers

A photon Green’s function theory is used to incorporate Bethe-Salpeter-like many body corrections in the computations of output spectra of semiconductor quantum well lasers. Coulomb, quantum-confinement, multiple valence band coupling and cavity resonator effects are consistently included in the theory. Numerical results are presented for multiple quantum wells, under different design, and excitation conditions

Time-space distribution of silicic plutonism in a gneiss dome of the Iberian Variscan Belt: The Évora Massif (Ossa-Morena Zone, Portugal)

In the Iberian Variscan Belt, polyphasic deformation has been recognized as comprising an early phase of crustal thickening, followed by an intermediate phase of crustal extension and doming, and a later phase of shortening. The Évora Massif is a gneiss dome of the westernmost domains of the Ossa-Morena Zone (SW Iberia), which provides a remarkable insight into the late Paleozoic deep crustal structure of the Variscan continental crust of northern Gondwana. In this study, we bring new structural and geochronological U-Pb data for the northern hanging-wall of the Évora Massif. We describe the existence of low-dipping D2 extensional shear zones associated with Buchan-type metamorphism (M2); this enables three tectono-metamorphic units to be distinguished: the Lower Gneiss Unit, the Intermediate Schist Unit, and the Upper Slate Unit. D2-M2 structures experienced sub- horizontal shortening (D3) and were transposed by low-plunging folding, thrusting and strike-slip faulting. Zircon grains extracted from Pavia quartz-feldspathic gneiss of the Lower Gneiss Unit yielded a crystallization age of ca. 521 Ma (Cambrian Stage 2–3), which establishes a correlation with tectono-metamorphic units of the footwall and southern hanging-wall of the Évora Massif. U-Pb zircon dating of Divôr foliated quartz-diorite (339 ± 7 Ma), Malarranha weakly foliated biotite-rich granite (322 ± 3 Ma), and undeformed porphyritic granite of the Pavia pluton (314 ± 4 Ma) constrain the timing of emplacement of granitic magmas synchro- nously with doming. Carboniferous magmatism initiated with doming (ME1 - ca. 343–335 Ma), continued through D2-M2 (ME2 - ca. 328–319 Ma), and lasted until the waning stage of crustal extension (ME3 - ca. 317–313 Ma). The Évora Massif gneiss dome probably formed as result of the combined effect of gravitational collapse of the thickened crust and buoyancy-driven gravitational instability developed in the partially molten continental crust influenced by the transfer of heat from rising mantle-derived (i.e. dioritic-gabbroic) magmas rocks found in the footwall of the Évora Massif

Sedimentary provenance of siliciclastic rocks from the Lalla Mouchaa Calcschists Formation (Coastal Block, Western Rehamna): Evidence of denudation of ca. 2 Ga basement in the Moroccan Meseta.

Paleoproterozoic basement rocks (ca. 2Ga) are scarce along the European and North African Paleozoic mountain chains (Fig.1a). In Morocco, ca. 2.2-2Ga granitic rocks (Gasquet et al., 2008; Kouyaté et al., 2013) have been exclusively reported in the Western Anti-Atlas at southwest of the Anti-Atlas Major Fault, (Choubert, 1963). In Eastern and Central Anti-Atlas and in the Moroccan Meseta, the existence of a Paleoproterozoic basement has only been recognized through indirect evidence (Gasquet et al., 2008; Michard et al., 2010). In the Anti- Atlas belt, ca. 2Ga detrital zircon grains are found in the Ediacaran siliciclastic rocks of the Bou Salda, Saghro and Taghdout groups (Abati et al., 2010). In the Moroccan Meseta, Paleoproterozoic (ca. 2Ga) zircon grains were extracted from gneiss and granitic xenoliths found in Triassic lamprophyre dykes, and from Carboniferous granophyric microgranite intrusions of central Jebilet (Dostal et al., 2005, Essaifi et al., 2003). Recently, a porphyritic rhyolite from the Rehamna Massif was dated at ca. 2.05Ga (Pereira et al., 2015), demonstrating for the first time, the exposure of the Eburnian basement in the Western Meseta. These Eburnian arc-related magmatic rocks, which are exposed to the south of the Permian Sebt Brikiyine granite in the core of anticlines from the Lalla Mouchaa Anticlinorium, are allegedly unconformably overlained by transgressive siliciclastic and carbonate beds (Corsini, 1988; Pereira et al., 2015). At north of the Sebt Brikiyine granite the probable Lower Cambrian sequence (Lalla Mouchaa Calcschists Formation; Guezou & Michard, 1976; Corsini, 1988) comprises a basal unit of microbreccias, arkosic sandstones and siltstones (lower member) that pass towards the top to centimeter-thick beds of calcschists interbedded with limestones and dolomites (upper member) that are conformably overlain by the “Paradoxides Shale Formation” composed of siltstone, greywacke and sandstone with Middle Cambrian fauna. In order to study the potential sources of the Lalla Mouchaa Calcschists Formation (probable Lower Cambrian), we have sampled a microbreccia at the Koudiat El Hamra region, for U-Pb geochronology on detrital zircon. This foliated microbreccia is composed of elongated Kfeldspar and quartz phenocrysts surrounded by a fine-grained matrix. Detrital zircon grains gave 206Pb/238Ub ages that in the Probability density plot curve are distributed by two main age peaks at ca. 2.05Ga and ca. 2.03Ga (Fig.1b), yielding a 206Pb/238U age-weighted mean of ca. 2.04Ga (El Houicha et al., 2018). The obtained U-Pb results point to a provenance from a Paleoproterozoic source, suggesting a possible contribution from rocks of the same age of the 2Ga porphyritic rhyolite exposed at south of the Sebt Brikiyine granite. Thus, there is a possibility that the Paleoproterozoic basement extends bellow the Paleozoic and Neoproterozoic sequences of the Rehamna massif