La sidérurgie ancienne en Franche-Comté et dans l’est de la France : bilan d’une décennie de recherches

Le renouveau de la recherche en paléométallurgie a débuté dans l’Est dans les années 1970 ; mais les programmes pluridisciplinaires associant équipes de terrain et laboratoires n’ont été mis en place qu’à partir de 1981 en Bourgogne, 1983 en Franche-Comté et 1988 en Lorraine. Des résultats importants sont maintenant acquis et se traduisent par des publications, des soutenances de thèses et des programmes larges dans le cadre d’une Action thématique programmée du CNRS associant une vingtaine d..

Deciphering the nature and age of the protoliths and peak P−T conditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides

We present new constraints on the age, nature, and tectonic setting of mafic eclogite protoliths from the Maures-Tanneron Massif, southern Variscan belt. Whole-rock major and trace element geochemistry was combined with zircon dating using 206Pb/238U by LA‒ICP‒MS to improve the understanding of this key-target of the European Southern Variscides. Geochemical data show that protoliths of the mafic eclogites are typical MORBs, while REE and HFSE patterns suggest an E-MORB affinity. However, the geochemical study shows several signs of crustal contamination that increases with the degree of retrogression. A comparison with Sardinian eclogites, which belong to the same Variscan microplate, namely, “MECS” (Maures-Estérel-Corsica-Sardinia), demonstrates that the eclogites are included in migmatites, which is the case for the studied samples, are the most contaminated. The Maures-Tanneron mafic eclogites represent the remnant of an oceanic basaltic crust. Zircon cores display homogeneous Th/U ratios (0.3–0.4), which are consistent with a magmatic origin, and define an age peak at 499.5 ± 2.9 Ma that is interpreted as the most likely emplacement age of the basaltic protolith. This age suggests that this protolith was part of an oceanic floor that was older than the Rheic Ocean and located to the north of the Gondwana active continental margin as predicted by recent unified full plate reconstruction models. Although the studied eclogites are retrogressed, the study of mineral inclusions trapped in garnets combined with thermodynamic modelling yields a P−T range of 17.2–18.5 kbar and 640–660 °C, which is consistent with the standard oceanic subduction palaeo-geotherm. These new data suggest that eclogites recognized in the “MECS” Variscan microplate represent the closure of oceanic domains of different ages (Cambrian or Ordovician)

Le Massif des Rehamna (Meseta marocaine) : témoin d’un changement majeur de la dynamique des plaques au Carbonifère supérieur - Permien inférieur au sein de l’orogène varisque– alléghénien

L’absence d’étude moderne dans le varisque marocain associant étude structurale, métamorphique et géochronologique freine toute avancée significative sur son évolution tectonique et sur les corrélations géodynamiques avec les autres branches adjacentes de l’orogène varisque-alléghénien en Europe et en Amérique du Nord au Paléozoïque supérieur. Dans le massif des Rehamna (Meseta marocaine), trois épisodes tectoniques ont été mis en évidence. (1) Charriage vers le SSO de formations ordoviciennes sur le socle néoprotérozoïque à cambrien et ses bassins intracontinentaux dévono-carbonifères. Cet événement entraîne un cisaillement ductile horizontal et un métamorphisme prograde Barrovien au sein des roches enfouies. (2) Il résulte de ce raccourcissement la formation d’un dôme syn-convergent d’allongement ~E−O permettant l’extrusion des unités inférieures et le détachement des unités supérieures métamorphiques. Ces épisodes sont contraints à 310−295 Ma par les âges 40Ar/39Ar de refroidissement et de cristallisation métamorphique d’amphiboles et de micas. (3) Une convergence de direction ONO, orthogonal au précédent, permet l’accrétion finale de toutes les unités sur le socle continental plus à l’ouest. Les âges 40Ar/39Ar de refroidissement d’amphiboles d’un leucogranite syn-tectonique et de son encaissant, ainsi que les âges de cristallisation de muscovites d’une mylonite, démontrent que cet épisode prend place entre 295 et 280 Ma. La fin de l’orogène varisque dans cette partie de la Meseta marocaine est contrainte par l’âge de refroidissement d’un batholithe granitique post-tectonique à 275 Ma. Ces événements, confrontés d’abord à l’évolution de la Meseta marocaine, sont enfin mis en relation avec la géodynamique globale des continents Laurentia et Gondwana à la fin de l’orogène varisque–alléghénien, montrant le changement des contraintes aux limites dans la chaîne au Carbonifère supérieur−Permien inférieur au Maroc, en Europe et en Amérique du Nord (Appalaches).Non peer reviewe

Tectonometamorphic evolution of the Rehamna dome (Morocco)

Volume: 42 Host publication title: The 2014 CETeG Conference "Lądek" Host publication sub-title: The Orlica-Śnieżnik Dome and the Upper Nysa Kłodzka Graben, the Sudetes 23-26 April 2014, Lądek Zdrój, Poland : Proceedings and Excursion GuideNon peer reviewe

Model-based pattern speed estimates for 38 barred galaxies

We have modelled 38 barred galaxies by using near-IR and optical data from the Ohio State University Bright Spiral Galaxy Survey. We constructed the gravitational potentials of the galaxies from $H$-band photometry, assuming constant mass-to-light ratio. The halo component we chose corresponds to the so called universal rotation curve. In each case, we used the response of gaseous and stellar particle disc to rigidly rotating potential to determine the pattern speed. We find that the pattern speed of the bar depends roughly on the morphological type. The average value of corotation resonance radius to bar radius, $\mathcal{R}$, increases from $1.15 \pm 0.25$ in types SB0/a -- SBab to $1.44 \pm 0.29$ in SBb and $1.82\pm 0.63$ in SBbc -- SBc. Within the error estimates for the pattern speed and bar radius, all galaxies of type SBab or earlier have a fast bar ($\mathcal{R} \le 1.4$), whereas the bars in later type galaxies include both fast and slow rotators. Of 16 later type galaxies with a nominal value of $\mathcal{R} > 1.4$, there are five cases, where the fast rotating bar is ruled out by the adopted error estimates. We also study the correlation between the parameter $\mathcal{R}$ and other galactic properties. The clearest correlation is with the bar size: the slowest bars are also the shortest bars when compared to the galaxy size. A weaker correlation is seen with bar strength in a sense that slow bars tend to be weaker. These correlations leave room for a possibility that the determined pattern speed in many galaxies corresponds actually that of the spiral, which rotates more slowly than the bar. No clear correlation is seen with either the galaxy luminosity or colour.Comment: 18 pages, 13 figures, accepted for publication in MNRA

The population of barred galaxies in the local universe I. Detection and characterisation of bars

(Abridge) Bars are very common in the centre of the disc galaxies, and they drive the evolution of their structure. A volume-limited sample of 2106 disc galaxies extracted from the Sloan Digital Sky Survey Data Release 5 was studied to derive the bar fraction, length, and strength as a function of the morphology, size, local galaxy density, light concentration, and colour of the host galaxy. The bars were detected using the ellipse fitting method and Fourier analysis method. The ellipse fitting method was found to be more efficient in detecting bars in spiral galaxies. The fraction of barred galaxies turned out to be 45%. A bar was found in 29% of the lenticular galaxies, in 55% and 54% of the early- and late-type spirals, respectively. The bar length (normalised by the galaxy size) of late-type spirals is shorter than in early-type or lenticular ones. A correlation between the bar length and galaxy size was found with longer bars hosted by larger galaxies. The bars of the lenticular galaxies are weaker than those in spirals. Moreover, the unimodal distribution of the bar strength found for all the galaxy types argues against a quick transition between the barred and unbarred statues. There is no difference between the local galaxy density of barred and unbarred galaxies. Besides, neither the length nor strength of the bars are correlated with the local density of the galaxy neighbourhoods. In contrast, a statistical significant difference between the central light concentration and colour of barred and unbarred galaxies was found. Bars are mostly located in less concentrated and bluer galaxies. These results indicate that the properties of bars are strongly related to those of their host galaxies, but do not depend on the local environment.Comment: 15 pages, 13 figures. Accepted for publication in A&

New Mediterranean biodiversity records (October 2015)

The Collective Article “New Mediterranean Biodiversity Records” of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article has adopted a country-based classification and the countries are listed according to their geographic position, from west to east. New biodiversity data are reported for 7 different countries, although one species reported from Malta is new for the entire Mediterranean basin, and is presumably also present in Israel and Lebanon (see below, under Malta). Italy: the rare native fish Gobius kolombatovici is first reported from the Ionian Sea, whilst the alien jellyfish Rhopilema nomadica and the alien fish Oplegnathus fasciatus are first reported from the entire country. The presence of O. fasciatus from Trieste is concomitantly the first for the entire Adriatic Sea. Finally, the alien bivalve Arcuatula senhousia is reported for the first time from Campania (Tyrrhenian Sea). Tunisia: a bloom of the alien crab ortunus segnis is first reported from the Gulf of Gabes, where it was considered as casual. Malta: the alien flatworm Maritigrella fuscopunctata is recorded in the Mediterranean Sea for the first time, on the basis of 25 specimens. At the same time, web searches include possible unpublished records from Israel and Lebanon. The alien crab P. segnis, already mentioned above, is first formally reported from Malta based on specimens collected in 1972. Concomitantly, the presence of Callinectes sapidus in Maltese waters is excluded since based on misidentifications. Greece: the Atlantic northern brown shrimp Penaeus atzecus, previously known from the Ionian Sea from sporadic records only, is now well established in Greek and international Ionian waters. The alien sea urchin Diadema setosum is reported for the second time from Greece, and its first record from the country is backdated to 2010 in Rhodes Island. The alien lionfish Pterois miles is first reported from Greece and concomitantly from the entire Aegean Sea. Turkey: the alien rhodophyte Antithamnion hubbsii is first reported from Turkey and the entire eastern Mediterranean. New distribution data are also provided for the native fishes Alectis alexandrina and Heptranchias perlo. In particular, the former record consists of a juvenile measuring 21.38 mm total length, whilst the latter by a mature male. Cyprus: the rare native cephalopod Macrotritopus defilippi, and the alien crab Atergatis roseus, sea slug Plocamopherus ocellatus and fish Cheilodipterus novemstriatus are first recorded from the entire country. Lebanon: the alien crabs Actaea savignii and Matuta victor, as well as the alien fish Synanceia verrucosa, are first recorded from the entire country. In addition, the first Mediterranean record of A. savignii is backdated to 2006, whilst the high number of M. victor specimens observed in Lebanon suggest its establishment in the Basin. The Atlantic fishes Paranthias furcifer and Seriola fasciata, and the circumtropical Rachycentron canadum, are also first reported from the country. The P. furcifer record backdates its presence in the Mediterranean to 2007, whilst S. fasciata records backdate its presence in the eastern Mediterranean to 2005. Finally, two of these latter species have been recently ascribed to alien species, but all three species may fit the cryptogenic category, if not a new one, better.peer-reviewe

“New Alien Mediterranean Biodiversity Records” (November 2021)

This Collective Article includes records of 29 alien and cryptogenic species in the Mediterranean Sea, belonging to eight Phyla (Rhodophyta, Ochrophyta, Cnidaria, Annelida, Mollusca, Arthropoda, Echinodermata, and Chordata) and coming from 11 countries. Notes published here can be divided into three different categories: occupancy estimation for wide areas, new records for the Mediterranean Sea, and new records of species expanding within the Mediterranean Sea. The first category includes a visual survey held along the coastline of Peloponnese (Greece), which yielded records of 15 species. The second category includes the first Mediterranean records of the Coho salmon Oncorhynchus kisutch (Greece) and of the Arabian monocle bream Scolopsis ghanam (Tunisia). The third category includes new records for countries (Ganonema farinosum in Malta, Cassiopea andromeda in Libya, Cingulina isseli in Greece, Okenia picoensis in Italy, Callinectes sapidus in Slovenia, Charybdis cf. hellerii in Malta, Urocaridella pulchella in Cyprus, Ablennes hians and Aluterus monoceros in Lebanon, and Fistularia petimba in Greece and Lebanon), new records for MSFD areas or regional seas (Septifer cumingii in the Greek Ionian Sea and F. petimba in the Marmara Sea), and confirmation of old, doubtful, or spurious records/statements (Branchiomma luctuosum in Tunisia, Thalamita poissonii in the Saronikos Gulf, and Pterois miles in Albania). Noteworthy, the three new records of F. petimba suggest that it may soon spread further in the Mediterranean Sea, as already happened for its congeneric Fistularia commersonii. Distributional data reported here will help tracing colonization routes of alien species in the basin and may facilitate the development of mitigation measures