Literatura académica sobre el tema "Fossiles calcaires"

Two new echinoid genera and species, Salvaster roberti gen. et sp. nov. and Pygolampas edita gen. et sp. nov. are de-scribed. They were collected in the Calcaires à Spatangues Formation (CSF) that consists of limestone and clay sedimentsdeposited in the southeast of the Paris Basin (France) during the Early Hauterivian (Early Cretaceous). The CSF is datedfrom the Acanthodiscus radiatus chronozone, a time-interval of overall high sea level in Western Europe, but it yields arich shallow-water fossil fauna mostly represented by benthic invertebrates. Of the 54 echinoid species ever described inthe CSF, 26 species are recognized here. They are distributed into 16 different families, among which regular (13 species)and irregular (13 species) echinoids are represented in equal proportion. This work confirms the high level of echinoid diversity in the CSF for that time-period.

The specific name of the crab <em>Hebertides jurassica</em> Guinot, De Angeli &amp; Garassino, 2007, reflects the belief that the single known specimen is of Jurassic age and hence would represent a very early heterotreme eubrachyuran. The specimen was collected from a quarry at Ranville in Calvados, France, where Bathonian limestones of the Calcaire de Langrune Formation outcrop. However, bryozoans in the matrix of the specimen are of undoubted Cenozoic, probably Miocene, in age. Good preservation of both crab and bryozoans in the same matrix allows the assumption that they are contemporaneous, necessitating re-dating of <em>H. jurassica</em> as probably Miocene in age. It seems likely that the piece of matrix was discarded in the Ranville quarry by a fossil collector who had previously visited a Cenozoic locality elsewhere. Despite the revised dating, the genus <em>Hebertides</em> and species <em>H. jurassica</em> are distinct from related Corystidae and the names can be retained.

The new fossil decapod locality discovered recently in the NE extreme flank of the Chebka Timerchidou mountain, at the Moyenne Moulouya, NE of Morocco has yielded a rich decapod assemblage such as <em>Hasaracancer merijaensis</em> Ossó, Artal &amp; Vega, 2011, <em>Costacopluma maroccana</em> Ossó, Artal &amp; Vega, 2010, and <em>Ophthalmoplax minimus</em> Ossó, Artal &amp; Vega, 2010. We report <em>Pleuronassa timerchidouensis</em> n. gen., n. sp. (Callianassidae Dana, 1852) from the same locality. It represents the second species of thalassinid from the Upper Cretaceous of Morocco following the recent discovery of <em>Neocallichirus agadirensis</em> Garassino, De Angeli &amp; Pasini, 2011, from the Cenomanian of Agadir (W Morocco).

The geological sciences at the University of Liège: two centuries of evolution.Part 1: from the foundation to the First World War. By the time the University of Liège was founded in 1817, geology was a young science and the geological composition of the country was being unveiled. The works of precursors such as Robert de Limbourg were about to inspire the first generation of Belgian geologists, among which Jean-Baptiste Julien d’Omalius d’Halloy is the most renowned. Geology was not taught at the University of Liège before 1818, when Henri-Maurice Gaëde was appointed. He taught geology, mineralogy and crystallography as well as anatomy and botany. He was followed by Armand Lévy in 1828, then again by Gaëde in 1830, Philippe-Adolphe Lesoinne in 1831, Charles-Philippe Davreux 1834 and Michel Gloesener in 1834. Except the mineralogist Lévy, none of them conducted any geology-based research. Nevertheless, geological knowledge, especially palaeontology, progressed due to the work of scientists such as Philippe-Charles Schmerling who described the first fossil human in 1830. Geology became a true research area at the university with the arrival of André Dumont in 1835. Before his appointment as professor, Dumont had already proved his mastery of geology by publishing his Description géologique de la province de Liége which earned him the golden medal of the Academy of Sciences and Arts of Brussels and a great reputation. He was the first to demonstrate the stratigraphic succession of the strata (geognosy) and to trace those strata on a map to show how they correlate. A great field geologist, Dumont was appointed by the Belgian Government to map the geology of the country, providing the first geological map of Belgium and neighbouring areas as a whole in 1849. At the same period (1846), Laurent-Guillaume de Koninck was appointed to teach palaeontology. His expertise on all groups of fossil animals drove him to produce an impressive number of monographic publications, on Belgian material but also on collections sent to him from all over the world. His Faune du Calcaire carbonifère de la Belgique – of which only the six first volumes were published before his death – is by itself the most exhaustive study of Carboniferous invertebrates ever published. De Koninck was in conflict with Dumont about the utility of fossils in geology, the latter being persuaded that they were too variable to have any significance. However, de Koninck’s palaeontological methods were indeed necessary and led to the development of biostratigraphy. Both Dumont and de Koninck received the Wollaston medal from the Geological Society of London for their work. Their successor Gustave Dewalque became – in 1857 – professor of geology and palaeontology and combined the scientific views of both his predecessors to produce very detailed and holistic research. His palaeontological work on the Jurassic fossils of S Belgium is most remarkable but his main achievement was his geological map of Belgium and surrounding areas, replacing Dumont’s with a much higher level of details. To make the reading of the map easier, Dewalque wrote his masterful Prodrome d’une description géologique de la Belgique (1868), which is no less than an encyclopaedia on geology of Belgium. His name is also inseparable from two major achievements in Belgium. Firstly the production of a detailed geological map at the 1/40,000 scale for which he achieved scientific posterity. Secondly he was the founding character of the Société géologique de Belgiquein 1874 and was also Secretary General of the society for 25 years. For his tremendous works, Dewalque received the prestigious Hayden medal from the Academy of Natural Sciences of Philadelphia in 1899. During his academic life, Dewalque progressively delegated his teaching to his young collaborators who eventually replaced him: Alfred Gilkinet for Palaeobotany, Julien Fraipont for Palaeontology, Adolphe Firket for Physical Geography, Guiseppe Cesàro for Mineralogy, and Max Lohest for General and Applied Geology. Alfred Gilkinet was one of the first palaeobotanists to embrace the theory of evolution and to recognise it among his fossils. He had a particular interest on Devonian fossil plants but also described material from the Paleogene. He was moreover a pharmacist and the institute of Pharmacy of the University bears his name. Julien Fraipont first entered the university at the laboratory of biology led by Edouard Van Beneden and published several papers on marine organisms for him. His work on Devonian crinoids was rewarded by the Société géologique de Belgiqueaward and de Koninck chose him to collaborate to his monography on Carboniferous bivalves. Fraipont published several papers on Palaeozoic fossils, the most remarkable being his work on the exquisitely-preserved echinoderms from the Marbre Noir de Denée. Furthermore, Fraipont was, with his colleague Lohest, a palaeoanthropologist and archaeologist and both were responsible for many discoveries in Quaternary cave deposits, including in Spy. Lohest was first a palaeontologist and published several contributions to the Palaeozoic fishes from Belgium, including a mandible identified by him as being from a fish but now interpreted as a rare Ichthyostega-like tetrapod. He then focused only on geology and applied geology after his major discoveries; such as the phosphate deposits in Hesbaye area, his prevision of the existence of coal measure in a deep basin in N Belgium, his interpretation of the metamorphism in Ardenne and description of the boudinage phenomenon. With Julien Fraipont and Marcel de Puydt, he discovered and described the human remains from the Spy cave – remains they interpreted as belonging to a species distinct from ours and that they attributed to the Neanderthal ‘race’. They demonstrated, for the first time in history, the co-occurrence of a fossil human species, Mousterian lithic industries and Pleistocene megafauna. Adolphe Firket mainly taught Physical Geography but was involved in the geological study of the Belgian coal measures and various mineral deposits. Guiseppe Cesàro was the true founder of mineralogy and crystallography in Belgium. His works on calcites and phosphates were very advanced despite that he was a self-taught man. They are still used as references today as are his works on crystallography. All those great names were part of the University and Belgian geology history, as men, scientists and professors. They left us a considerable heritage that needs to be rediscovered.

Les microcodium sont des fossiles calcaires, arborescents, de dimension millimetrique, dont la nature n'est toujours pas etablie avec certitude. Ces fossiles correspondent aux restes d'etres vivants souterrains endolithes, qui apparaissent au campanien et semblent s'eteindre au pliocene. Recemment, plusieurs auteurs ont decrit dans des sols actuels des racines calcifiees de structure comparable a celle des microcodium. Ce travail a pour objectif de comparer l'architecture, la structure et la composition des microcodium et des racines calcifiees actuelles, afin de tester l'hypothese d'une origine racinaire des microcodium. Les principaux resultats acquis consistent en la mise en evidence chez les microcodium de ramifications de type lateral monopodial en la mise en evidence de la presence systematique de stries d'accroissement au sein des prismes constitutifs, et en l'analyse de la composition isotopique des carbonates constitutifs. La comparaison avec les racines calcifiees actuelles montre que les microcodium consistent tres probablement en des racines de vegetaux superieurs, mais appartenant a un groupe fossile disparu actuellement. Differents elements suggerent qu'il pourrait s'agir d'un groupe apparente aux premieres monocotyledones

Les foraminifères sont d'importants proxies des lentilles calcaires de la fin du Mississippien du Sud de la France. Les foraminifères mississippiens sont surtout des endobenthiques et de rares épiphytes. Huit nouvelles biozones régionales sont définies : SF1 (Asbien terminal), SF2 (limite Asbien/Brigantien), SF3 (Brigantien basal), SF4 (Brigantien inférieur), SF5 (Brigantien supérieur), SF6 (limite Brigantien/Serpukhovien), SF7 (Serpukhovien inférieur), SF 8 (Serpukhovien supérieur). Une paléobathymétrie comparative des édifices microbialithiques comporte : un étage à Saccamminopsis (zone dysphotique entre la limite inférieure de la zone photique et la ZAVT), un étage à Frustulata (entre les zones dysphotique et euphotique), la zone des foraminifères opportunistes (zone euphotique inférieure), la zone à Fasciella, Renalcis et foraminifères dans la zone euphotique supérieure. Au sommet des bioconstructions s'ajoutent des lagons à grande biodiversité de foraminifères et d'algues. Le peuplement uniforme des foraminifères téthysiens de l'époque s'observe de la Nouvelle Ecosse (Canada) au Japon; la dépendance ouralienne le conduit jusqu'au Nord de l'Alaska. Le peuplement algaire est plus endémique et permet de supposer que la Montagne Noire constitue au moins au Brigantien une microplaque isolée. Cette unité est nommée Province à Eovelebitella ou Eovelebitelland. Eovelebitelland se situe entre un supercontinent nord Euramerica (où les juxtapositions des différents Blocs : Avallonia, Armorica et Baltica se reconnaissent encore) et le supercontinent sud qui est un Gondwana classique. Une quarantaine de taxons d'algues et foraminifères sont introduits en tant que nomina nuda
The foraminifers, the important proxies in the Late Mississippian carbonate lenses of southem France, belong nearly exclusively to the Fusulinata class. The Mississippian foraminifers are especiaIly endobenthic forms and rare epiphytes. Height new regionaI bizones are defined: SFI (latest Asbian), SF2 (Asbian/Brigantian boundary), SF3 (earliest Brigantian), SF4 (early Brigantian), SF5 (late Brigantian), SF6 (Brigantian/Serpukhovian boundary), SF7 (early Serpukhovian), SF 8 (late Serpukhovian). A comparative paleobathymetry of the microbialitic buildups indicates: a Saccamminopsis stage (in the disphotic zone); a Frustulata stage (between the disphotic and euphotic zones); the opportunistic foraminifers (in the lower euphotic zone); the Fasciella, Renalcis and foraminifers zone in the upper euphotic zone. At the top ofbioconstructions, there are lagoons with a great biodiversity offoraminifers and algae. The homogenous populations of Tethyan foraminifers are found, during the Mississippian, from Nova Scotia (Canada) to Japan. Thanks to the Uralian seaway, these populations attain the North-Alaska. The algal population is more endemic and permits to suggest that Montagne Noire constitutes at least during Brigantien an isolated microplate. This unit is denominated Province with Eovelebitella or Eovelebitelland. It is located between the northem supercontinent North. Euramerica (where different Blocks: Avallonia, Armorica and Baltica are connected) and the southem supercontinent which is the traditionally reconstructed Gondwana. More than fourty foraminiferal and algal taxa are introduced as Domina nuda and will be officially re-described in further publications

Les calcaires carboniferes des pyrenees renferment des microorganismes: conodontes et foraminiferes dont l'analyse descriptive et comparative a permis de definir un reperage biostratigraphique et paleogeographique concernant les regions pyreneennes (zonation, essai de stratigraphie formelle). Cette etude micropaleontologique a egalement permis d'aborder divers problemes tels que ceux: de la limite entre devonien et carbonifere, de l'existence d'un hsitus regional entre le devonien et le tournaisien terminal. De l'age du debut des epandages synorogeniques varisques, de la definition d'une limite entre mississippien et pennsylvanien, de la signification paleogeographique et chronologique (dans l'optique de la dynamique varisque) des microfaunes benthiques (foraminiferes) resedimentes dans le culm, essai de stratigraphie formelle des series etudiees

Dans la zone prerifaine interne des regions de msila et de mouylay bou chta, l'etude de nombreuses coupes a permis d'etablir une stratigraphie detaillee des calcaires du jurassique superieur. Les importantes variations de facies tant verticales qu'horizontales ont conduit a definir 7 membres au sein de la formation des calcaires de msila. Les faunes d'ammonites et de tintinoidiens (chitinoidella et calpionelles) fournissent des datations nombreuses qui permettent des correlations precises. La barre des calcaires de msila est isochrone, le passage aux marnes sus-jacentes heterochrone. Les nombreux niveaux de slumps, de breches, d'ammonitoco-rosso et les variations brutales de facies dans le sens vertical sont le reflet de phases tectono-sedimentaires. Dans cette region, la polarite du bassin a ete conservee

L'eocene continental recemment mis en evidence dans les hautes plaines oranaises (djebel mekaidou) grace a une importante faune de bulimes decouverte dans de puissants depots continentaux rapportes neguere au mio-pliocene a ete etendu au sud oranais (atlas saharien) et aux regions orientales (sud du tell algerois, constantinois). Cette etude montre que: l'avant pays tellien a ete le siege d'une sedimentation typiquement continentale fluviatile (episodes palustres, lacustres ou evaporitiques); des sediemnts detritiques originels sont transformes par epigenie carbonatee, phenomene responsable de la mise en place de calcretes et de dolocretes dans un contexte climatique a saisons contrastees (seche et humide); les phases tectono-sedimentaires a travers le maghreb correspondent generalement aux mouvements de compression de la phase laramienne, puis de la phase intralutetienne du tell; la regression senonienne du maghreb s'est poursuivie jusqu'au lutetien-bartonien; des comparaisons perimediterraneennes avec des localites ou ont ete decrites les memes faunes expliquent les possibilites de communication entre le maghreb et l'europe meridionale a l'eocene

L'apparition d'efflorescences cristallines sur des objets calcaires stockés dans des environnements pollués, communément appelée "dégradation de Byne", résulte de l'émission de composés organiques volatils (COV) acides par les matériaux de stockage. Ces acides réagissent avec le carbonate de calcium en formant des sels organiques de calcium, dont des acétates et des sels mixtes acétate-formiate, qui provoquent une détérioration irréversible du substrat. Jusqu'à présent, seuls des objets macroscopiques subissant la dégradation de Byne avaient été décrits dans la littérature.Ce travail vise à comprendre comment la dégradation de Byne peut aussi affecter des spécimens calcaires microscopiques présents dans les collections de micropaléontologie. Il a été initié par la numérisation de la collection de foraminifères d'Alcide d'Orbigny (1802-1857), conservée au Muséum national d'Histoire naturelle (MNHN), qui a révélé des dommages importants liés à la présence d'efflorescences salines.Un constat d'état a été mené sur l'ensemble de la collection d'Orbigny (plus de 3600 spécimens), mettant en évidence que les altérations, à la fois anciennes et évolutives, sont influencées par la cristallinité des tests et l'origine des lieux de prélèvement des foraminifères. Des collections voisines ont été examinées à titre comparatif et des recherches en archives ont permis de retracer l'histoire de la collection depuis son entrée au MNHN. Elles mettent en évidence de nombreux déménagements et des accidents tels que la crue de la Seine de 1910, qui expliquerait l'humidité particulièrement élevée à l'intérieur des tubes où sont conservés les foraminifères. Des variations importantes de température, combinées à la présence de matériaux émetteurs de COV introduits à la fin du XIXe siècle dans le montage des spécimens, sont ainsi à l'origine de la pollution acide et de la prolifération des sels.Parallèlement à cela, une procédure de vieillissement artificiel a été élaborée pour reproduire la dégradation de Byne sur des foraminifères sains. Les produits de dégradation formés sur les spécimens vieillis, ainsi que sur une sélection représentative de spécimens historiques, ont été analysés de manière non invasive et sans contact par spectroscopie micro-Raman et par diffraction des rayons X sur rayonnement synchrotron. Ces analyses ont mis en évidence des phases minéralogiques différentes de celles observées dans la littérature sur les collections macroscopiques. Ce sont ainsi des formiates de calcium qui prédominent, et tout particulièrement le polymorphe tétragonal [β-Ca(HCOO)2] connu pour être instable lorsqu'il est synthétisé en laboratoire. Aucun acétate ou sel mixte de calcium n'a pu être identifié sur les foraminifères de la collection d'Orbigny. Les vieillissements montrent que l'humidité relative et la taille des spécimens jouent un rôle primordial dans la formation des sels : des conditions humides favorisent la cristallisation du formiate de calcium sur le spécimen, tandis que l'acétate, très hygroscopique, est sujet aux cycles de déliquescence-cristallisation qui le conduisent à se disperser autour de l'échantillon lorsque celui-ci est de très petite taille.Enfin, pour mieux comprendre la prédominance du formiate de calcium [β-Ca(HCOO)2], différentes solutions de formiate de calcium ont été laissées à évaporer et placées dans des environnements à humidité variée afin d'étudier la transformation vers la phase stable [α-Ca(HCOO)2]. L'analyse semi-quantitative des produits montre que la présence d'ions tels que ceux trouvés dans les coquilles de foraminifères (Mg2+, Sr2+...) favorise la formation de la phase métastable, et ralentit la transition β-->α.Ce travail montre que la nature des sels formés par la dégradation de Byne n'est pas seulement tributaire des COV présents mais dépend aussi de la taille des spécimens, leur composition, la cristallisation de leur test et des cycles d'humidité et de température auxquels ils ont été soumis
The appearance of crystalline efflorescence on calcareous objects stored in polluted environments is commonly referred to as "Byne's decay". It results from the emission of acidic volatile organic compounds (VOCs) from storage materials, which react with calcium carbonate to form organic calcium salts. This includes acetates and mixed acetate-formate salts that cause irreversible deterioration of the substrate. Until now, only macroscopic objects undergoing Byne's decay had been reported in the literature.This work focuses on how Byne's decay can also affect microscopic calcareous specimens from micropaleontology collections. It was initiated by the digitization of the foraminifera collection of Alcide d'Orbigny (1802-1857), housed at the Muséum national d'Histoire naturelle (MNHN), which revealed significant damage due to the presence of saline efflorescences.A condition report was carried out on the whole of the d'Orbigny collection (more than 3600 specimens), highlighting that the alterations, both ancient and evolutionary, are influenced by the crystallinity of the tests and the origin of the places where the foraminifera were collected. Similar collections closely located were examined for comparison and archival research was conducted to trace the material history of the collection since its entry into the MNHN. They highlight several moves and accidents such as the flooding of the Seine in 1910, which would explain the particularly high levels of humidity inside the tubes where the foraminifera are kept. Significant variations in temperature, combined with the presence of VOC-emitting materials introduced at the end of the 19th century in the assembly of the specimens, are thus at the origin of the acid pollution and the proliferation of salts.At the same time, an artificial aging procedure was developed to reproduce Byne's decay on unaltered specimens. The degradation products formed on the aged specimens, as well as on a representative selection of historical ones, were analysed non-invasively and without contact by using micro-Raman spectroscopy and synchrotron X-ray diffraction. These analyses revealed mineralogical phases different from those observed in the literature on macroscopic collections. Thus, calcium formates and especially the tetragonal polymorphic phase [β-Ca(HCOO)2] known to be unstable when synthesized in laboratory conditions, predominate. No calcium acetate or mixed salt could be identified on d'Orbigny's foraminifera. Aging shows that the relative humidity and the size of the specimens play a primordial role in the formation of the salts: humid conditions favour the crystallization of calcium formate directly on the specimen, while acetate, very hygroscopic, is subject to deliquescence-crystallization cycles that lead to its redispersion around micrometer-scale specimens.Finally, to better understand the predominance of calcium formate [β-Ca(HCOO)2], different calcium formate solutions were left to evaporate and placed in environments with different humidity to study the transformation towards the stable phase [α-Ca(HCOO)2]. Semi-quantitative analysis of the products shows that the presence of ions such as those found in foraminiferal shells (Mg2+, Sr2+…) favours the formation of the metastable phase and slows down the transition β-->α.This work shows that the nature of the salts formed by Byne's decay is not only dependent on the VOCs present, but also on the size of the specimens, their composition, their test crystallization, and the moisture and temperature cycles to which they were exposed

Les stromatopores dévoniens connaissent leur apogée, en Ardenne, au Givétien. Ils sont également bien représentés au Frasnien. L'objectif de ce travail est d'analyser de la biodiversité des stromatopores en Ardenne méridionale pour ces deux étages et de la comparer à ce qui est connu dans le Boulonnais. Le calcul de la biodiversité, pour des faunes contraintes par le milieu (i.e. carbonaté), ne peut se faire sans une étude préalable des environnements dans lesquels se sont développés ces organismes. Les terrains givétiens appartenant au bord sud du syncIinorium de Dinant caractérisent globalement des milieux de plates-fonnes carbonatées peu profondes. Diverses unités récif ales (i. e. biostrome et bioherme) ont alors pu se développer à différents niveaux stratigraphiques et à différentes échelles. Les diversités semblent cependant rester homogènes sur l'ensemble du Givétien et pour l'ensemble des unités récifales. Cependant, de légères variations sont constatées avec les unités récif ales frasniennes. De plus, certaines espèces, adaptées à des milieux sédimentaires particuliers, semblent parfois dominer au sein des unités récifules. Enfin, les faunes de l'Ardenne méridionale montrent, au Givétien, des affinités avec des régions situées le long du même bloc (i. e. Laurentia) mais également avec une région (Afghanistan) proche du Gondwana
The Devonian stromatoporoids are developped in Ardenne mainly during the Givetian. They are also weil represented during the Frasnian. The aim of this work is to analyse the biodiversity of stromatoporoids in southem Ardenne during these two periods and to compare the result with what we know in Boulonnais. Stromatoporoids are constrained to the nature of sediments (i. e. carbonated facies). Preliminary studies of sedimentologic environments are necessary to realised an approach of biodiversity. During the Givetian, the southern Ardenne is mainly characterised by shallow water and carbonated shelves. Abundant reefs have found the best conditions for their developpment. They are distributed at different scale and at different time. Some differences are constated between Givetian and Frasnian reefs. Thus, some species seems to be more developped in restricted facies, and are predominant inside the builders. Finally, stromatoporoids of the southern Ardenne seems to have affinities with faunas distributed along the same continent (i. e. Laurentia) and also with other geographic area (Afghanistan) along the Gondwana