bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicifications (silcrètes) et évaporites dans la Zone-limite violette du Trias inférieur lorrain. Comparaison avec le Buntsandstein de Provence et le Permien des Vosges
Authors: Durand Marc , Meyer Robert
Published: June 2018

In the Lorraine Triassic, at the top of the Middle Buntsandstein red beds, the «Zone-limite violette » is a very varying rock unit, often showing dolomitic or silicified facies (fig. 2).

After a petrographical study, some processes become obvious :

— weathering, shown by the presence of greenish, cracked or partially dissolved quartzite pebbles,

— authigenesis of dolomite, gypsum, anhydrite, ferriillite, hematite and silica minerals : quartz, quartzine (length-slow chalcedony) and chalcedonite (lenght-fast chalcedony).

Structures and textures, many ghosts and boxworks, let us suppose that the siliceous facies replaced sediments rich in evaporites. This silicification tooks place in the deposit environment, far away from the sea. Silica could be liberated after the destruction of silicates in some soils, e.g. solonetz, or in brine lakes ; it would accumulate in favoured sites in the landscape : calcretes, duripan soils, swamps or ponds.

Permian silicifications seem to be bound to calcretes ; they do not show wide differentiation. In the Provence Triassic, as in the Lorraine one, silicified facies are rapidly changing and they probably appear in very alcaline, often sulphate-rich, environments.
Géochimie de la silice dans les milieux évaporitiques sulfato-chlorurés. Etude des saumures du Chott El Jerid en Tunisie
Authors: Gueddari Moncef , Fritz Bertrand , Tardy Yves
Published: June 2018

Waters and brines of the Chott El Jerid in Tunisia are of sulfate, chloride, sodium and magnesium type. The silica molality in solution decreases as a function of the brine concentration. A new calculation method of ion and water activities (Pitzer's model) and silica activity in brines (Marshall's equations) allows the discussion of the precipitation conditions of silica and silicates in evaporitic environments.
Ein Fund von Pithonella sp., einer kalkigen Dinoflagellaten-Zyste im Fischschiefer von Bremmelbach, Elsass
Authors: Weiler Helmut
Published: June 2018

Description of Pithonella sp., a calcareous dinoflagellate cyste, found in the Fischschiefer of Bremmelbach, which is identical with Pithonella of the Mainz-basin, indicating a wide distribution in the Rhinegraben. Two organic layers, endo-and periphragma within the calcite-layers could be isolated in diluted acide. These phragmas are not identical with «Thèques vides », described in 1976 (Doebl et al.) from the same layers of Bremmelbach.
Modifications géochimiques d'une granodiorite, près d'une veine minéralisée dans la région des mines d'Aghios Philippos, Kirki (Grèce du Nord)
Authors: Economou Constantin , Marcopoulos Théodore , Sideris Constantin
Published: June 2018

La kaolinite, l'illite, la montmorillonite et la pyrophyllite sont les produits d'une intense altération hydrothermale d'une granodiorite dans la région des mines d'Aghios Philippos (Kirki, Grèce du Nord). La granodiorite altérée se trouve au contact d'une veine minéralisée, qui se caractérise par un remplissage de blende, pyrite, galène et chalcopyrite. Comme elle résulte de l'altération hydrothermale, on observe une brusque diminution des éléments Ca, Mg, Na, Fe et Al et une augmentation relative de Si, en allant de la roche inaltérée à la veine minéralisée.
Hydrothermal alteration of submarine basalts : from zeolitic to spilitic facies in the upper Triassic pillow-lavas of Antalya, Turkey
Authors: Malley Patrick , Juteau Thierry , Blanco-Sanchez José-Antonio
Published: June 2018

The upper Triassic alkalic basalts of the Alakir Çay valley (Antalya nappes, Turkey) have been hydrothermally metamorphosed under the zeolite facies conditions. Two of these submarine volcanic massifs, mainly made of pillow-lavas flows, offer good field sections over more than 650 m thick. In the Çalbali Dag massif, the zeolite and associated minerals have been analyzed inside and outside the pillow-lavas (inter-pillow matrix), from bottom to top of the volcanic pile. Natrolite, gonnardite, thomsonite, analcite, gmelinite, stilbite, heulandite and laumontite have been determined, associated with calcite, K-feldspar, celadonite, smectites and chlorite. No evolution of the zeolite assemblages with depth has been detected : this fact implies a rather smooth thermal gradient in the volcanic pile during the hydrothermal circulation. In the Sayrun massif , the same widespread development of zeolites, calcite and smectite is observed, with the addition of true albite-chlorite spilitic paragenesis, well developed in some areas. The reality of a progressive transition from zeolitic assemblages to spilitic ones is an important conclusion of this study.
Modification of residual glass and precipitation of a neoformation layer : experimental evidence for a double origin of the «palagonite » derived from the alteration of basaltic glass by sea-water
Authors: Thomassin Jean-Hugues , Baillif Patrick , Touray Jean-Claude
Published: June 2018

To understand how palagonite forms during the basaltic glass — sea-water interactions, experimental investigations have been performed using the labelling of the initial interface with Ni, introduced at one ppm level in solution. This element is quickly concentrated in early hydrotalcite crystals grown on the initial interface. In Al-serpentine formed after epigenization of the hydrotalcite, Ni remains concentrated. On ultramicrotome thin sections, the onset of the Ni chemical profile labels the initial interface. Alteration products appear on both sides of this surface : on the inner part lies a Si-Fe bearing layer and a Si-Al-Mg one on the outer part. They respectively result from a in situ evolution of residual hydrated glass and a precipitation followed by an epigenization.

Accordingly, palagonitization is a two ways process carried out with a volume increase.
L'ichthyofaune des milieux confinés : intérêt pour l'étude paléolimnologique
Authors: Gaudant Jean
Published: June 2018

Die Ursachen rezenten Auftretens von Massensterben und die Bedingungen für die Erhaltung von Weichteilen von Tieren und Pflanzen werden untersucht. Dabei können die Umstände definiert werden, unter denen im lakustrinen Bereich fossile Ablagerungen mit artikulierten Fischskeletten entstanden. Wichtigste Bedingung scheint das Vorhandensein von Stillwasserkörpern gewesen zu sein. Es ist für die Entwicklung von Schichtung im Wasser notwendig und damit verantwortlich für die Bildung dauerhafter, stagnierender Tiefwasserschichten mit Sauerstoffentzug, in denen eine anaerobe Zersetzung organischen Materials stattfand. Drei Haupttypen lakustriner fossilführender Sedimente werden unterschieden und durch konkrete Beispiele veranschaulicht.
Nickel content of olivine as discriminatory factor between tectonite and cumulate peridotite in ophiolites
Authors: Leblanc Marc , Dupuy Claude , Merlet Claude
Published: June 2018

In ophiolite complexes, the Mohorovicic discontinuity is assumed to be located between cumulate and mantle peridotites. As pétrographie and structural criteria are often insufficient to discriminate between these two units, we suggest that the Ni content of olivine should be used instead. In the New Caledonia ophiolite, the olivine from the tectonite peridotites contains about 3, 150 ppm Ni as in most mantle rocks, whereas the Ni contents of olivine from the cumulate peridotites are lower than 2, 600 ppm. Thus the cumulates are clearly separated from the tectonite peridotites. Secondary diffusion processes between chromite and olivine resulted in strongly Ni-rich olivine inclusions in chromitite ores.
Sur la découverte de Poissons fossiles dans les marnes grises rayées de la Zone fossilifère (Oligocène basal) d'Altkirch (Haut-Rhin)
Authors: Gaudant Jean , Burkhardt Thierry
Published: June 2018

The find of fossil Fishes is reported from the basal Oligocene of Altkirch (Haut-Rhin, France). Three species have been identified : Enoplophtalmus alsaticus nov. sp., Notogoneus cf. cuvieri (Agassiz) and Dapaloides ( ?) sp. Among the genera recognized at Altkirch, only Notogoneus had been reported up to now from the Lower Oligocene of Alsace. The palaeoecological significance of this fish-fauna is examined : this community is indicative of feebly brackish water occurring in the sedimentary basin.
Modélisation du transfert d'éléments avec interactions géochimiques. Modelling of element transfer with geochemical interactions
Authors: Coudrain-Ribstein Anne
Published: June 2018

Le transfert d'éléments chimiques dans un milieu souterrain dépend d'une part de phénomènes de transport liés à la présence et au mouvement du fluide, et d'autre part de phénomènes d'échanges géochimiques entre phases de mobilité différente. Le besoin et les difficultés d'une modélisation générale sont décrits succinctement. L'exemple d'un modèle analytique est présenté. Il est basé sur une conceptualisation très simple des phénomènes et de la configuration étudiée. Il est illustré par l'étude d'un cas théorique. On a calculé l'épaisseur d'un dépôt de silice à partir d'une solution qui est saturée à l'origine et qui circule dans le sens des températures décroissantes.
Simulation de l'évaporation sur micro-ordinateur / Simulation of evaporation using micro-computers
Authors: Risacher François , Fritz Bertrand
Published: June 2018

Till now, programs simulating evaporation required powerful computers. Owing to several modifications, it is possible to implement such a program on a micro-computer, without sensible loss in accuracy. The principle remains the same : concentrations are calculated from a quadratic Taylor's expansion. The first and second order derivatives are obtained by solving two arrays of linear equations. The main modifications are : (1) A simplified treatment of the water budget : each elemental calculation step is monitored by a strictly fixed initial and final amount of water-solvent, and not by a little amount of evaporated water. This avoids making, among others, any corrections for the water used up by precipitating hydrated minerals. (2) Elemental mass-balance equations include complex species expressed only in terms of simple species. The total number of unknowns, and therefore the size of the linear equations set, are significantly reduced. (3) The introduction of a new unknown : the derivative of the ionic strength which makes the derivative of the activity coefficients much simpler. (4) The same matrix is used for both derivative calculations. Only the right-hand side vector is modified.
Interactions eau - argiles / Clay - water Interactions
Authors: Fripiat José Julien , Gatineau Lucien
Published: June 2018

This paper is a review of recent works concerning clay -water interactions from two different aspects ; namely the properties of the water layers directly in contact with the clay surfaces and the properties of water in clay suspensions and gels. In the first part, the significance of the exchangeable cation hydration number as well as that of the heat of hydration are discussed at large. Then the recent views on structural and dynamical properties of water molecules in the interlayer space are summarized. The chemical characteristics of that water and in particular, its acidity, are outlined. In the second part, the microdynamics properties of water molecules in clay gels and soils are described. It is shown that the surface forces have short range action and that they cannot explain the gel formation mechanism.
Etude du pollen de Lavandula viridis L'Her. (Lamiaceae) / Study of the pollen grains of Lavandula viridis L'Her. (Lamiaceae)
Authors: Suarez-Cervera Maria , Seoane-Camba Juan
Published: June 2018

Le sporoderme du grain de pollen de Lavandula viridis L'Hér. (Lamiaceae ) a été étudié par l'application de différentes techniques au MEB (grains de pollen frais, acétolysés et soumis à l'action du monoéthanolamine), et au MET (grains de pollen frais, fixés par glutaraldéhyde-tétroxyde d'osmium). En outre, les coupes semi-fines ont été diversment colorées pour mettre en évidence des protéines, des lipides et des polysaccharides totaux à l'exine et à l'intine. Nos observations permettent une meilleure connaissance sur le mécanisme apertural des grains de pollen de cette espèce surtout au niveau de la couche endexinique.
Age anté-Viséen de la phase varisque paroxysmale dans les nappes ghomarides du Rit interne (Maroc) / Pre-Visean age of the main Variscan folding in the Ghomarides nappes, Inner Rif, Morocco
Authors: Chaloüan Ahmed , Michard André
Published: June 2018

Des observations structurales et minéralogiques (cristallinité de l'illite) dans les nappes ghomarides du Rif permettent de mettre en évidence la discordance d'un conglomérat viséen V₃b sur une série plissée et métamorphisée ordovico-siluro-dévonienne. C'est la phase tectonique bretonne, démontrée pour la première fois dans le Rif, où elle apparaît comme la phase varisque paroxysmale.
The archeological sites of Lake Natron (Tanzania). Sites archéologiques du lac Natron (Tanzanie)
Authors: Mturi Amini A.
Published: June 2018

De récents travaux de terrain dans les dépôts pléistocènes du lac Natron ont mis en évidence deux sites acheuléens contenant une association d'outils à bifaces dominants. L'un d'entre eux, Kamare, une surface érodée dans des dépôts de chenaux post-Pléistocène inférieur, a été estimé à 125 000 ans. Le second site, Kipalagu, apparemment érodé dans des sédiments de la formation Humbu, contient des outils de l'Acheuléen inférieur, semblables à ceux des deux sites précédemment fouillés dans la formation Humbu. Il a été daté approximativement entre 1 et 1,5 millions d'années.
Les quartzites ferrugineux rubanés du Bassin de la Luzinzi (Zaïre) : un dépôt de placer à titane, fer et zirconium. The Precambrian banded iron-formations of the Luzinzi Basin (Zaire) : a deposit of black sand type with titanium, iron and zirconium
Authors: Chauvel Jean-Jacques , Villeneuve Michel
Published: June 2018

Les formations précambriennes du Bassin de la Luzinzi (Zaïre) peuvent être rapportées, sur la base des données géochronologiques disponibles, au Ruzizien, au Burundien et au Katangien. Dans les sédiments détritiques de la Formation de Mughera (Burundien) on a signalé la présence de quartzites ferrugineux rubanés qui ont fait l'objet d'une étude pétrographique et géochimique détaillée. Les résultats obtenus montrent que les sédiments rubanés doivent être considérés comme des dépôts de type «sables noirs » et que les lits de teinte sombre, riches en fer, sont constitués par une accumulation de grains détritiques de magnétite titanifère, d'ilménite, de rutile, de zircon et de tourmaline. La présence de ces placers à fer et titane et les caractères généraux de la Formation de Mughera montrent que la mise en place de cette formation correspond à l'installation de conditions de sédimentation de plus en plus littorales.
Composition modale des roches à l'aide de l'analyse d'images sur micro-ordinateur. Modal composition of rocks using image processing on a microcomputer
Authors: Allard Bruno , Sotin Christophe
Published: June 2018

COMODALE est un logiciel qui permet d'obtenir la composition modale de roches à partir des images vidéo de lames minces digitalisées sur 64 niveaux de gris. On distingue les phases minérales par leur luminance. Le logiciel se décompose en un programme MODALE (assembleur) qui calcule le spectre de luminance de la lame mince, et en un programme RESULT (basic) qui détermine la composition modale et édite les résultats. Ses avantages sur les méthodes classiques sont : la rapidité, la non-detruction de l'échantillon et un matériel micro-informatique et optique dont le coût n'excède pas 40 000 FF (en 1987). Ce logiciel a été utilisé de manière satisfaisante pour déterminer la composition modale de péridotites ou le pourcentage de feldspath dans une lherzolite.
Le traitement numérique d'images de roches à l'Institut Français du Pétrole. Digital processing of rock images in the Institut Français du Pétrole
Authors: Bieber Marie-Thérèse , Lallemand Claude , Rosenberg Elisabeth , Zinsner Bernard
Published: June 2018

This paper presents the rock image analysis equipment and methods available in the IFP. These images are either digital core sample images recorded at a macroscopic scale or images obtained with an electron microscope (STEM, SEM). We also show how one can study flow in porous media by the use of a medical scanner. In conclusion we expose the problems encountered and the developments that one can expect using these techniques.
Propriétés thermochimiques des composés du cuivre. Atlas de données thermodynamiques./ Thermochemical properties of the copper compounds. Thermodynamic data file
Authors: Vieillard Philippe
Published: June 2018

Un inventaire des données thermodynamiques des composés du cuivre est proposé. Les valeurs thermodynamiques des complexes aqueux et des minéraux de cuivre ont été calculées en utilisant les valeurs mesurées des constantes de dissociation et les valeurs thermodynamiques des ions de référence recommandées par CODATA. Les valeurs de certains composés du cuivre ont été recalculées et comparées avec les autres valeurs disponibles, d'où le problème de compatibilité pour les minéraux comme la ténorite, la malachite et l'azurite.
Bauxites and laterites of the Serra de Trucara (State of Para, Brazil). Geological survey and bauxitic evolution. / Bauxites et latérites de la Serra de Trucara (Etat du Para, Brésil). Etude géologique, évolution bauxitique
Authors: Hieronymus Bernard , Kotschoubey Basile , Truckenbrodt Werner , Boulègue Jacques
Published: June 2018

Bauxites et latérites de la Serra de Trucara (Etat du Para, Brésil). Etude géologique, évolution bauxitique

La Serra de Trucara, à l'Ouest de la ville de Tucurui, est constituée par des basaltes à intercalations de pélites (Formation Caraipé) et des grauwackes (Formation Morrote) datés du Protérozoïque moyen à supérieur. Seule la Formation Caraipé, qui forme l'ossature de la Serra de Trucara, porte un épais manteau d'altérites ferroalumineuses cuirassées à leur partie supérieure. Le profil latéritique type comprend, de bas en haut, une lithomarge qui peut atteindre 10 m d'épaisseur et passe à un niveau alumineux induré (2 à 4 m) surmonté par une cuirasse ferroalumineuse (2 à 5 m). Ces formations ont été affectées par des épisodes érosifs qui se sont traduits par la formation de produits colluviaux à leur tour affectés par de nouvelles transformations pédogénétiques. Les premières études concernant ces formations permettent d'envisager l'évolution polyphasée suivante : (1) formation d'une croûte latéritique par altération des basaltes et des pélites intercalées ; (2) accumulation de l'alumine vers la base de la ferralite ; (3) formation et mise en place des dépôts colluviaux ; (4) mise en place du niveau argileux supérieur ; (5) incision par le réseau hydrographique plus récent, associé à de nouvelles phases de colluvionnements et d'aluminisation.
Initial stages in spheroidal weathering. / Phases initiales de l'altération sphéroïdale
Authors: Prasad Gisela , Sarracino Robert
Published: June 2018

Phases initiales de l'altération sphéroïdale

Des structures géométriques d'altération sphéroïdale ont été analysées dans des basaltes tholéiitiques du Lesotho. Les travaux antérieurs ont abouti à un modèle mathématique décrivant une phase avancée de l'altération dans la zone centrale des structures sphéroïdales. Dans cet article, on étudie les phases initiales de l'altération à partir des angles aigus des polyèdres formés par les cassures originelles. On démontre que les courbes d'altération ainsi obtenues suivent deux fréquences consécutives, la première rapide, la seconde plus lente.
Modeling of mass transfer arising from buoyancy flow in sedimentary basins. Modélisation du transfert de masse lié à la convexion naturelle dans des bassins sédimentaires
Authors: Coudrain-Ribstein Anne , Marsily Ghislain de
Published: June 2018

Le transfert de masse lié à la convexion du fluide dans des bassins sédimentaires est étudié au moyen de l'expérimentation numérique. Le modèle mathématique permet de simuler le transfert d'éléments chimiques réactifs couplé à l'écoulement du fluide et au transfert de la chaleur. Le calcul des phénomènes de dissolution et de précipitation tient compte de la spéciation à l'équilibre thermodynamique de la solution et d'une loi de cinétique des réactions hétérogènes. Un exemple théorique sur une cellule thermoconvective illustre comment le transfert de calcédoine et de calcite dépend de la vitesse des réactions et de l'évolution du champ de température.
An analysis of gas-water-rock interactions during boiling in partially saturated tuff. Analyse des interactions vapeur-eau-roche durant l'ébullition dans un tuff partiellement saturé
Authors: Arthur Randolf C. , Murphy William.M.
Published: June 2018

Equilibrium geochemical speciation and mass transfer calculations show that porewaters analogous to those in the candidate high-level nuclear waste repository at Yucca Mountain, Nevada, can be strongly affected by open-system boiling. A modified Rayleigh distillation equation appropriate to reactive volatile species is derived and applied to calculate pH ranges during C02-H20 volatilization in a system of fixed alkalinity. Variations in pH by as much as + 2,3 units are caused by volatile weak electrolyte interactions as C02(g) exsolves from the aqueous phase. Protolysis reactions and precipitation of secondary minerals moderate the calculated increases in pH by less than 1 unit. The host rock mineralogy can be altered by boiling because differences in the chemical potentials of components in the aqueous phase and in minerals are created by pH changes. Experiments using pressurized carbonated solutions in closed systems may be inappropriate for simulating water-rock interactions in the proposed repository.
Thermodynamic properties of the aurochloride solute complex AuCI2- at temperatures of 350-500 °C and pressures of 500-1500 bars. Propriétés thermodynamiques du complexe aqueux auro-chloré AuCl2-de 350 à 500°C et de 500 à 1500 bars
Authors: Zotov Alexandr V. , Baranova Nina N.
Published: June 2018

The state of gold in chloride solutions has been studied by the solubility method over a temperature range 350-500 °C and a pressure range 0.5-1.5 kbars as a function of acidity, ion CI' concentration and oxygen fugacity. The formation of the AuCl₂ complex have been calculated for the reaction :

Au(s)+ HCl⁰ + Cl⁻ + 0.25 O₂(g)= AuCl₂₋+ 0.5 H₂O Our experimental data (lg K°) appear in agreement with a number of experimental data sets from literature using the model of S hock and Helgeson (1988). Using this approach we approximated the AuCl₂₋ thermodynamic properties over a wide range of temperatures (25-750 °C) and pressures (1-1500 bars).
Le socle vosgien / The vosgian basement
Authors: Fluck Pierre , Piqué Alain , Schneider Jean-Luc , Whitechurch Hubert
Published: June 2018

The Vosges basement — This synthesis about the Vosges basement is based on the assessment of the geological results of the two last decades. The geologic units, their structures and their geodynamic evolution are described, first for the northern Vosges (Saxo-Thuringian Vosges), then for the middle and southern Vosges (Moldanubian Vosges). The history of these two areas which display a contrasted evolution during the Lower Palaeozoic can be studied as part of the geodynamics of the Variscan Central Europe. The metamorphism of the pre-Devonian basement shows a progressive retrograde evolution after an eclogitic episode at the base of the Palaeozoic. The magmatism is contemporaneous with the paroxysmal structuration of the variscan belt and displays a jerky evolution which leads to products resulting from an important crustal contamination. The Devono-Dinantian volcano-sedimentary cover gives evidence of marine sedimentary basins which evolve to emersion. Afterwards, this cover is affected by thrust tectonics which produces migmatization at the bottom of the crystalline nappes. The important Visean shortening generates the nappe structuration with vergences on both sides of the Lalaye-Lubine dislocation. At last, comparisons with other massives of the Variscan belt are outlined.
Manganese, methane and helium anomalies in sea water above the Mid-Atlantic Ridge : evidence of hydrothermal activity / Anomalies de manganèse, méthane et hélium dans la colonne d'eau de mer au droit de la ride médio-atlantique : des évidences d'activité hydrothermale
Authors: Grimaud Daniel , Blanc Gérard , Charlou Jean-Luc , Jean-Baptiste Philippe , Dmitriev Léonid
Published: June 2018

Manganese, helium and methane are highly enriched in hydrothermal effluents and their vertical distributions in sea water are commonly used as chemical tracers of hydrothermal activity. The cruise performed during may 1985 with the RV Akademik Boris Petrov (Vernatsky Institut of Geochemistry, Moscow) allowed us to present vertical total dissolved manganese and CH4 concentration profiles at seven stations : four along the south Middle Atlantic Ridge (13°20'S -14°64'W ; 14°12'S -13°58'W ; 21°28'S -11°37'W ; 19°56'S -11°52'W) and three along the north MAR (12°24'N -44°05'W ; 13°47'N -44°59'W ; 14°05'N -45°01'W). Some samples in each profile have been analysed for 3He/4He ratios and 4He amounts. The hydrographie stations have been set up over the axial ridge valley combined with bathymétrie and geochemical rock studies. The results show many hydrothermal tracer anomalies in the water column both in the northern and southern studied areas. Although the amplitude and shape of the anomalies are clearly smaller than those observed at the well documented hydrothermal sites (Galapagos Spreading Center, East Pacific Rise, Juan de Fuca Ridge, TAG), plumes originated by hydrothermal discharge are present in the two southern studied areas as well as in the northern one.
Fragmentation, amorphisation et propriétés superficielles de minéraux. Comminution, amorphization and surface properties of minerals
Authors: Papirer Eugène
Published: June 2018

Comminution, amorphization and surface properties of minerals

The comminution of minerals involves energetic, mechanical, structural and superficial phenomena. According to the principles of fracture mechanics, the propagation of cracks can be favoured by lowering the surface free energy of their walls (Rebinder's effect). It is also possible to promote breaking by modifying the electrical surrounding of discontinuities, for example by increasing the surface charge (Westwood's principle). However both these theories give only a partial explanation of experimental facts. Here it is proposed to consider that the elasticity of strongly structured layers of the medium to the solid-liquid interface protects the structure and spreads the stresses. Then, the mineral breaks according to its intrinsic weak strength directions. If the structured layers do not exist (apolar liquids) or are disordered (using hydrogen bond disruptors), the material amorphizes without breaking and the formation of amorphous substances can generate aggregation. The variation of surface properties of minerals resulting from grinding can be described by measuring the dispersive component of the surface free energy ; this measurement is achieved using inverse gas chromatography.
Caractérisation des minéraux finement divisés par physisorption. Théories les plus employées et instrumentation. / Characterization of finely grained minerals by physisorption. Most common theories and instrumentation
Authors: Grillet Yves , Rouquerol Jean
Published: June 2018

Characterization of finely grained minerals by physisorption. Most common theories and instrumentation

The morphometric and textural properties of any particulate or porous solid can be determined using physical adsorption experiments. The different shapes of adsorption isotherms are described with reference to their physical significance, methods are deduced to determine the specific surface, the mesopores distribution and an evaluation of the microporosity. Reciprocal thermal analysis is proposed as a method to produce an adsorbing surface in a reproducible state. Concerning measurement devices, several methods are proposed to determine the adsorption isotherms : the conventional adsorption volumetry, the chromatographic-like method, the quasi-equilibrium volumetry and the adsorption gravimetry. The adsorption enthalpies are directly measured by gas adsorption microcalorimetry, or indirectly, using the isosteric heat determination.
Séparation solide-solide. / Separation between solids
Authors: Houot Robert
Published: June 2018

Separation between solids

The concept of separation between solids includes two different notions : separation aims at producing several sets based either upon the "size" criterion, or the mineralogical species criterion. A classification according to particle sizes will be carried on in the first case and a concentration in the second one. In both the lines, various possible technologies are quickly described : * screening, hydraulic or pneumatic classification, special devices for submicronic particles ; * magnetic separation (low and high intensity, high field-high gradient possibilities), present trends in froth flotation (new cells, classical or column), gravimetry.
Polysporia doubingeri n.sp., un nouvel organe reproducteur de lycophyte du Stéphanien (Carbonifère supérieur) de Blanzy-Montceau (Massif Central, France) / Polysporia doubingeri n.sp., a new lycopod reproductive organ from the Stephanian (Upper Carboniferous) of Blanzy-Montceau (Massif Central, France)
Authors: Grauvogel-Stamm Léa , Langiaux Jean
Published: June 2018

Dans l'abondante macroflore du Stéphanien du bassin houiller de Blanzy-Montceau (Massif Central, France) ont été trouvés plusieurs très grands cônes hétérosporés de lycophyte dont les microspores et les mégaspores correspondent, respectivement, aux genres Endosporites Wilson & Сое et Valvisisporites (Ibrahim) Potonié & Kremp. La structure de ces cônes et la nature de leurs spores nous ont conduit à les attribuer au genre Polysporia newberry et à créer la nouvelle espèce, P. doubingeri. L'association Endosporites-Valvisisporites existe aussi chez d'autres lycophytes, parmi lesquelles le genre Chaloneria Pigg & Rothwell du Pennsylvanien d'Amérique du Nord qui a été classé dans la famille des Chaloneriaceae (Isoétales). P. doubingeri n.sp. semble cependant très différent des fructifications de C. cormosa et C. periodica qui sont connues uniquement en structure. Aussi peut-on se demander si la seule similarité des microspores et des mégaspores produites par ces trois espèces peut suffire à justifier l'attribution de P. doubingeri n.sp. à la famille des Chaloneriaceae. Une grande variété d'aspect semblait caractériser les genres de plantes inclus dans cette famille.
Palynologie des couches de passage du Trias supérieur au Lias dans l'Est du Bassin Parisien. Problèmes de datation du «Rhétien» de Lorraine / Palynology of the Upper Triassic to Lias transition beds in the eastern part of the Paris Basin. Dating problems of the «Rhaetian» in Lorraine
Authors: Rauscher Raymond , Hilly Jean , Hanzo Micheline , Marchal Claude
Published: June 2018

In the eastern part of the Paris Basin, the «Rhaetian » is usually defined and subdivided by means of purely lithostratigraphical criteria whose chronostratigraphical value has still to be demonstrated. Therefore, several new sections in Lorraine have been palynologically analysed. From the top of the «Marnes irisées supérieures » (Upper Keuper) to the Lower Hettangian, five successive palynological episodes are distinguished. This microfloristic evolution is firstly compared to the palaeoenvironment evolution. Moreover, the chronostratigraphical interpretations of these palynological data are discussed and compared to those proposed for other fossils (Rhaetavicula contorta, Vertebrates), in order to clear up the dating problems of the transition beds from the Upper Triassic to the Lias in Lorraine.
Specimens, Databases, and Accession Books: Using TaxonWorks to Integrate Multiple Sources of Modern and Historical Data in the INHS Insect Collection
Authors: McElrath Thomas , Dmitriev Dmitry , Yoder Matthew , DeWalt R. Edward , Dietrich Christopher
Published: June 2018

Grant-supported digitization projects over the past 20 years at the Illinois Natural History Survey (INHS) have yielded over 1,000,000 occurrence records (representing over 2.7 million specimens), one of the most successful digitization efforts within the United States. However, receiving multiple grants at the cutting edge has led to numerous projects left at various stages of completeness, several relational databases, orphaned data, and specimens at various stages of curation. TaxonWorks (taxonworks.org), an integrated web-based workbench developed by the Species File Group and supported by the INHS and the National Science Foundation, has provided the digital infrastructure to unify multiple workflows, projects, databases, and even historical accession books into one easy to access, open-source platform. We demonstrate the practical utility of this platform and summarize past, present, and future efforts at the INHS towards integrating all our data within TaxonWorks.
Producing High-Quality 3-D Models for Specimen Research with the Creaform 3-D Scanner at the Sternberg Museum of Natural History
Authors: Shelburne Edward
Published: June 2018

Digitization of natural history collections for specimen accessibility, research, and posterity has been a major push in museums over the past decade. One increasingly common form of specimen digitization is three-dimensional (3-D) surface scanning. There are numerous 3-D scanners on the market, including visible light and laser surface scanners. However, mobility of the scanning device, mesh resolution, and texture fidelity are among the most prominent issues facing regular implementation of 3-D scanning procedures for research purposes. Morphometrics research involving the digitization of Xiphactinus at the Sternberg Museum of Natural History (FHSM) using a Creaform Go!SCAN 50 visible light 3-D surface scanner has necessitated the development of a workflow using this 3-D scanner and the associated VXelements software. This workflow maximizes model quality with minimal loss of speed or efficiency when scanning numerous specimens. Major components of this workflow include proper use of positioning targets, appropriate merging of multiple specimen scans, and how to perform post-processing on models without sacrificing model resolution or texture.

The primary benefit of the Creaform 3-D scanner is hardware mobility, allowing for use on large exhibited specimens or digitizing specimens during research trips. Shortcomings include relatively low mesh resolution, (bottoming out at 0.5 mm), difficulty scanning highly complex structures, and low texture fidelity of scanned models. However, texture fidelity can be improved through use of the free software, Meshlab, by overlaying high-quality stacked photographs onto the 3-D mesh. Incorporating Meshlab texture overlays into the workflow allows for the production of digital models with improved color and textural data – ideal for accurate visualization of specimens in 3-D viewers for educational outreach and online databases. While not perfect for all applications, the Creaform 3-D scanner allows for rapid digitization of specimens in an increasingly digital collections environment, and is sufficient for some research applications. The workflow established at the FHSM can serve as a framework for other institutions to use the Creaform 3-D scanner to best suit their digitization needs.
A Workflow for Adding Specimen Metadata to Images Captured in the Field
Authors: Levy Richard
Published: June 2018

Museum collections and their use is bolstered by supplying robust and comprehensive metadata and supplementary assets, such as genetic samples, methodology metadata, and images. In speaking with and working alongside scientists interested in using museum specimen data for addressing ecological questions, it has often been brought up that understanding the context in which a specimen was collected can lend helpful insight. One such way of adding contextual information to our collections is the capture of in situ and habitat images in the field during collection. Managing and linking such images with specimen data poses a logistical challenge.

Collections managers and field researchers at the Denver Botanic Gardens have created a workflow that allows for the recording of image metadata in the field and the eventual addition of Darwin Core occurrence metadata to in situ and habitat field image files. Designated field photographers, a role that can be filled by volunteers or paid field assistants, record information pertaining to each image they capture. Upon returning from the field, the data is uploaded to a MySQL database, alongside associated specimen and site data. The data is then queried in the form of a script and utilizing the ExifTool application, the information is then added to the XMP metadata of the image. Having this data embedded within the image not only aids in linking the corresponding field images with their specimen records, but also in the downstream management and access to images from the field. Here I present the current workflow we have developed and how its use has aided our effort to curate data rich specimens and images.
Improving Security for Natural Science Collections at the Michigan State University Museum
Authors: Abraczinskas Laura , Lundrigan Barbara
Published: June 2018

Established in 1857, the Michigan State University (MSU) Museum houses natural science collections that include 117,000 research and teaching specimens of mammals, birds, reptiles, amphibians, fishes, and vertebrate fossils. These collections are worldwide in scope and provide a record of biodiversity that ranges from 1844 to the present day. The collections contain specimens of rare, endangered, threatened, and extinct species. Within each vertebrate discipline, specimens are cataloged into designated research or teaching collections; these are housed within multiple research and preservation spaces, occupying 678 square meters. Currently, 394 natural science specimens are on exhibit in the Museum's gallery spaces, which include an additional 1,830 square meters. Over the past three decades, the Museum has experienced a number of thefts from both collections and exhibit areas, with the most recent specimen theft occurring in 2011: a silky anteater (Cyclopes didactylus) stolen from the Museum's rainforest habitat diorama. That theft, along with the history of the others, initiated a series of improvements to the Museum's security. These included changes in personnel access to the Museum building and to collections areas; replacement and installation of new technological equipment, including key-card access and camera systems Museum-wide; and revisions of associated policies and procedures. These effectively closed "loopholes" that formerly compromised security best practice. Targeted improvements have been made at the building, gallery, elevator, room, and cabinet levels, and included specialized accommodation for specimens that are particularly sensitive, such as rhino horn (in keeping with Natural Sciences Collections Association guidance). In addition, the Museum modified operating procedures for behind-the-scenes tours of the research and collections spaces (for example, staff-to-visitor ratio and policy for use of imaging and recording equipment).
Using Data From Index Herbariorum to Assess Threats to the World’s Herbaria
Authors: Thiers Barbara , Rivas Roslyn , Kiernan Elizabeth
Published: June 2018

During the past few years, natural disasters, political or social unrest and institutional actions have imperiled herbaria. The question has been raised multiple times whether or not the data gathered about herbaria in Index Herbariorum could be used to predict which herbaria are at the greatest risk. Armed with such knowledge curators and the greater collections community might be in a better position to safeguard those herbaria. To explore the feasibility of using Index Herbariorum data in this way, we have identified a set of specific threats and then scored herbaria according to their susceptibility to those threats. These threats fall into two categories: Physical and Administrative. Physical threats are those that could lead to loss of collections through outright destruction due to catastrophic events (e.g., earthquake, flood) or loss of the protective controls (e.g., air conditioning, building security) that ensure a safe collections environment. Determination of these threats is based on location.

Administrative threats involve decisions made by the governing body to remove staff support, appropriate space or climate control measures for the collection. Physical threats were determined using GIS to plot the location of all herbaria, and then overlaying these with map layers indicating current earthquakes, floods, cyclones and landslides and potential future threats (sea level rise and civil unrest). We deduced Administrative threats from Index Herbariorum data elements. These include the status of the herbarium (active or inactive), whether or not the Index Herbariorum entry for an institution has been updated in the past 10 years, whether or not the herbarium has a designated curator, the ratio of staff to specimens, and whether or not the collection has been digitized. Each threat was assessed as absent or present, and assigned a value of 0 or 1 accordingly. Using this method, less than 4% face no identified threats; 65% face one to three threats and 35% face five or more threats. The criteria used in this study cannot alone predict the future security of a collection, or the lack thereof. The reasons for the loss of a collection are usually more complicated than Index Herbariorum data can convey. However, the large proportion of herbaria that face multiple threats suggests that all herbaria should be aware of the risk factors for their collection, perhaps conducting a self-evaluation using the criteria presented here or others, and where possible should incorporate responses to those threats into their strategic and disaster preparedness plans.
Panel Discussion: Institutional Earthquakes and Recovery Experiences: Continuing to be Collections Stewards in an Uncertain World
Authors: Butler Carol , Quaisser Christiane
Published: June 2018

Animals, plants, minerals, fossils etc. in our collections are part of our cultural and natural heritage. Their sustainable preservation and care is part of our mission as natural history collections and our main task. This demand for long-term stability is in contrast to an increasingly dynamic environment.

New technologies and methods enable different management and use of the collections. Research is moving from areas such as evolution and biodiversity discovery to applied sciences and public engagement with science. Institutional visions are changing over time with new leadership. Institutions are separating from or merging with other organizations. New laws and regulations are determining the way we collect and collaborate. Last but not least, we are facing a world of quickly changing financial resources, political and societal priorities, and values.

All these aspects have an impact on the way we manage and maintain our collections. Like earthquakes with possible impact in both directions, in positive, catalysing as well as negative, disruptive ways. Museum professionals have to deal with these challenges, react to them, anticipate them, and sometimes proactively integrate them into their plans and work.

What kind of questions are we facing as museum professionals? Is there always a correct decision? What is worth fighting for and what do we have to accept? How can museum professionals balance contradicting positions? How can we find alternatives?

Butler and Quaisser will draw upon their experiences in dealing with institutional earthquakes to lead a panel discussion with representatives from different management levels and institutional environments. We will focus on recovery experiences and strategies. We encourage the audience to bring their examples and experiences to the discussion engagement and hope for a lively and fruitful discussion that leads to greater capacity to recover quickly from these challenges.
Constantino de la Fuente (1502-1560), de predicador aclamado a hereje olvidado
Authors: Luttikhuizen Frances
Published: June 2018

Se hace un repaso de la vida del célebre predicador: su etapa en la Universidad de Alcalá; su amistad con el dr. Egidio; su etapa como magistral de la catedral de Sevilla; su viaje por Europa como predicador en el séquito del príncipe Felipe; sus publicaciones; su biblioteca; su detención por la Inquisición; su ingreso en la cárcel de Triana; su muerte; y la anulación de su memoria. El artículo concluye con una valoración de la relevancia de la obra.
La «Biblia filosófica» y la Reforma: el caso de John Locke
Authors: Herrero Montserrat
Published: June 2018

La transición de la Escritura como una obra sobrenatural a un mero texto es algo que tiene que ver con el movimiento reformado, sin embargo, no se puede atribuir como tal a la Reforma, sino sobre todo a la corriente filosófica ilustrada, nutrida de las convicciones que movilizó la Reforma. El artículo analiza esta corriente en uno de sus predecesores: John Locke. Su obra contribuyó a generar la «Biblia académica», como contrapuesta a la «Biblia escriturística». En la obra de Locke se pone de manifiesto una dialéctica entre el carácter sobrenatural de la Escritura y la consideración de la razón como revelación natural, que la conduce a numerosas aporías. De ahí que la bibliografía haya considerado a John Locke alternativamente calvinista, latitudinario, arminiano, sociniano o unitariano. El artículo presenta estas aporías y procura una evaluación de su aportación a la cuestión de la interpretación bíblica, que es indisociable de su fe, de su epistemología y de su teoría del lenguaje.
Christian Thomasius, el Estado de derecho y la separación entre Iglesia y Estado
Authors: Laursen John Christian
Published: June 2018

Christian Thomasius fue, ante todo, un profesor de Derecho que utilizó su formación jurídica para resolver todo tipo de problemas legales, políticos y morales. En este artículo veremos que dos de sus escritos plasmaron parte de su contribución a la articulación de las relaciones apropiadas entre religión y política en la modernidad. Asimismo, utilizó el incipiente concepto de Estado de derecho (rule of law) para defender a Denis Veiras, autor de la Histoire des Sevarambes, de la acusación de ateísmo. Del mismo modo, defendió la jurisprudencia escéptica de Georg Heber como el mejor instrumento para separar la Iglesia del Estado, y se valió de la teología escéptica para justificar la exclusión de los teólogos de la política y contener la intervención de los príncipes en asuntos religiosos, salvo en los casos en que estuviese en juego la paz política.
La profesión de fe de Rousseau
Authors: Villaverde Rico María José
Published: June 2018

Rousseau ha sido considerado un protestante cercano a los sectores calvinistas más liberales y próximo al socinianismo, así como uno de los grandes defensores de la tolerancia y de la libertad de conciencia. Sin embargo, si analizamos más en profundidad sus obras, encontraremos inquietantes notas de intolerancia con respecto a los ateos, a los católicos y a las mujeres en general, que dificultan encuadrarle entre los autores más tolerantes de su época.