bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paragenese a faible variance dans les metapelites de la serie de Filali (Rif interne marocain); description, interpretation et consequence geodynamique
Authors: El Maz Abdelkader , Guiraud Michel 
Published: June 2005

Abstract
The metamorphic series of Filali and the Beni Bousera massif represent the most metamorphic unit in the inner part of the Moroccan Rif. The Filali series is composed of micaschists, gneisses, migmatites and granulites wrapped around the ultramafic body of the Beni Bousera. The foliation is broadly coherent all over the massif although differences in lineation and fold axis have been found between the granulites and the micaschists-gneisses. Metamorphic grade increases continuously towards the ultramafic body; however, seven metamorphic zones which account for this increase can be defined: - chlorite zone: muscovite and chlorite underline the S1 schistosity refolded by S2. Small garnet is wrapped by or cut across S2; - chloritoid zone: chloritoid displays the same textures as chlorite and muscovite, underlining S1 and S2 schistosity. Chlorite reacts out to biotite; - staurolite+andalusite zone: staurolite, andalusite, cordierite and garnet have pre-, syn- and post- kinematic features with respect to S2. Garnet reacts out to muscovite, biotite and plagioclase; - staurolite+andalusite+kyanite zone: same textural relationships as in the previous zone. Kyanite is an additional phase, often displaying epitaxial textures with staurolite and andalusite; - andalusite+kyanite+sillimanite zone: fibrolitic sillimanite generally associated with biotite crystallizes from staurolite. However, sillimanite is also directly formed from andalusite and kyanite. As in the previous zone garnet reacts out to biotite, muscovite and plagioclase; - sillimanite+k-feldspar zone: muscovite reacts out to k-feldspar. Modes of biotite and sillimanite increase; - migmatites zone are composed by biotite, sillimanite, garnet, cordierite quartz and feldspars. Garnets do not display the reaction textures seen in the previous zones; - granulites are composed of a primary paragenesis with kyanite+k-feldspar+garnet+ or -biotite+plagioclase+rutile, partially obliterated by a secondary paragenesis with cordierite, sillimanite and spinel.
Reaimantation regionale eocene, migration de fluides et mineralisations sur la bordure cevenole (France)
Authors: Rouvier Henri , Henry Bernard , Macquar Jean-Claude , Leach David L. , Le Goff Maxime , Thibieroz Jacques , Lewchuk Michael T. 
Published: June 2005

Abstract
Widespread remagnetization has been identified in fold belts and forelands inboard of mountain ranges and has usually been interpreted as resulting from fluid migration related to orogenesis in these mountain ranges. The geochemical properties of these fluids should be compatible with the formation or the transformation of ferrimagnetic minerals, thus allowing acquisition of remanent magnetization during fluid migration. Carbonate hosted lead-zinc (+ or -barite and fluorite) mineralization of the Mississippi Valley-type (MVT) are also generally considered to have formed during the migration of enormous volumes of fluids and are commonly located in foreland fold belts or their forelands. This suggests a similar origin for widespread carbonate remagnetization and MVT mineralization. The paleomagnetic dating of MVT deposits has been successfully applied in MVT districts, mainly of North America. Thus, it was used for the MVT deposits hosted by Mesozoic carbonate rocks of the Cevennes region of southern France. In view of the structurally complexity in the region, and because the results presented here are intended to provide an initial reference direction on which further results can be based, only sites belonging to the most stable parts of this border are considered here. Most samples were collected from three surface sites in the area of the Largentiee mine and from independently oriented cores of the two deep boreholes (Balazuc and Morte-Merie) from the Geologie Profonde de la France program. Several samples were also collected from three sites around the area of the Saint Felix-de-Pallieres mine. All these samples come from different stratigraphic levels: Carboniferous, Permian, Triassic, Liassic and Middle Jurassic.
A new Lepisosteidae (Actinopterygii, Ginglymodi) from the Cretaceous of the Kem Kem Beds, southern Morocco
Authors: Cavin Lionel , Brito Paulo M. 
Published: June 2005

Abstract
Lepisosteids or gars constitute a very special neopterygian group, with seven living species in two genera: Lepisosteus and Atractosteus. They live in freshwaters from the eastern part of North America and Central America. A new lepisosteid, Oniichthys falipoui gen. nov., sp. nov., is described on the basis of two well preserved specimens. Although the type locality is unknown, information provided by the fossil collector, the type of preservation of the specimen, and the nature of the attached matrix indicate, with confidence, that it comes from the Kem Kem beds of southern Morocco (fig. 1). The Kem Kem beds are rich fossiliferous horizons, exposed along the face of an escarpment extending from the north of Erfoud town to the Kem Kem area. The age of these outcrops is still debatable being considered as ?Albian in age [Forey and Grande, 1998] or regarded as Cenomanian, due to their elasmobranch assemblage [Sereno et al., 1996]. Oniichthys falipoui shows several derived characters of gars such as an elongated ethmoid region, an upper jaw formed by a chain of tooth-bearing bones, a joint between the quadrate and the lower jaw lying far forward, in front of the orbit and a large splint-like quadratojugal overlying the horizontal branch of the preopercle. O. falipoui shares with the primitive gar, Obaichthys decoratus, from the ?Albian Santana Formation of Brazil, the presence of toothed maxillaries, although in the Moroccan taxon, the maxillaries are anteriorly fused with infraorbitals. This structure confirms that, at least, some of the "infraorbital chain" bones bear maxillary teeth, fused to them during ontogeny. Discussion of characters leads to regard O. falipoui as more derived than Obaichthys, and to place it as the sister-group of Lepisosteus-Atractosteus.
Nature and properties of suspended solids in the Amazon Basin
Authors: Allard Thierry , Ponthieu Marie , Weber Tiphaine , Filizola Naziano , Guyot Jean-Loup , Benedetti Marc 
Published: June 2005

Abstract
Suspended solids from several rivers of the Amazon Basin (Brazil) have been studied in both the particulate (&gt; 0,2 μm) and colloidal (0.2 μm-5kD) fractions through a combination of tools including Fourier transform infrared spectroscopy (FT-IR), electron paramagnetic resonance (EPR) and potentiometric measurements. Particulate and colloidal matter are organo-mineral and organic, respectively. Signatures of the particulate fractions distinguish Rio Amazonas/Rio Solimoes rivers and the northern basin rivers (Rio Negro, Rio Branco, Rio Trombetas). In the latter, kaolinites are the dominant clays and exhibit close crystal chemistry characters such as degree of disorder. FT-IR of colloids exhibits similar signatures of humic substances in all rivers. By contrast, EPR reveals various species which qualitatively and quantitatively differentiate the riverborne colloids: trivalent iron occurring as specific complexes with organic functional groups or as oxides sensu lato, divalent manganese, organic free radicals. The observed differences may be inherited from the weathering processes working in the main pedoclimatic regions drained by the studied rivers. Insights from potentiometric measurements of the recovered colloids also evidence a humic like reactivity consistent with carboxyl and phenol moieties, the relative contributions of which differentiate the Rio Negro and Rio Solimoes/Amazonas.
Trace elements and major species in precipitation at African stations: concentrations and sources
Authors: Freydier Rémi , Dupré Bernard , Dandurand Jean-Louis , Fortune Jean-Pol , Sigha-Nkamdjou Luc 
Published: June 2005

Abstract
The chemical composition of rainwaters is important in obtaining information on the aerosols and gaseous species present in the atmosphere. Original data on the concentrations of trace elements and major species in the dissolved and particulate fractions of rainwater samples collected in intertropical Africa were used to determine the potential sources of chemical species. The photographic and mineralogical characterization of rainwater particles using scanning electron microscopy allow to identify the various origins of aerosols and the associated chemical elements: (i) the crustal source characterized by clay minerals, kaolinite (Al, Si), illite (Al, Si and K) and Fe, Ti, and Mn oxides, (ii) vegetation relicts: Mg, Si, Cl, Mn and Zn have been identified in these biogenic particles and (iii) carbonaceous particles (mainly Si) emitted during vegetation fires. Ionic charge balance calculation for the stations located in the rain forest and wet savanna zones (Cameroon, Centrafrican Republic and Ivory Coast) exhibit an anion deficit from 20 to 50 % (between 7 and 9 μeq.l−1). Measured total organic carbon concentrations (between 0.5 and 3.3 mg.l−1), are much higher than acetic and formic acid. The presence of mimic and/or fulvic substances emitted from the vegetation can explain this anion deficit. The results obtained in this study confirm the existence of three important sources of atmospheric compounds in intertropical Africa: (i) the silicate upper crust source: Sc, Ti, Fe, Y, Zr, Nb, Cs, La, Ce, Nd, Yb, Th and U exhibit enrichment factors very close to 1, (ii) the biogenic and biomass burning source characterized by the following elements: Mg, Cl, K, Ca, Mn, Zn, Rb, Sr, and (iii) two minor sources; marine (Mg, Na, Cl) and anthropogenic (Cr, Co, Zn, Ba and Pb). For the stations located in the rain forest zone, all these sources appear strongly linked. High correlations are observed between elements of various origins. This suggest a strong interaction between terrigenous, biogenic, marine and anthropogenic aerosols. The deposition of aerosols onto vegetation and the re-mobilization of the chemical species through natural emissions or biomass burning could explain these correlations and the observed chemical fractionation of marine origin elements such as Cl and Na.
New insights about the rare earth elements (REE) mobility in river waters
Authors: Deberdt Samuel , Viers Jérôme , Dupré Bernard 
Published: June 2005

Abstract
While the rare earth elements (REE) have largely contributed to the understanding of some internal geological processes, their use as tracers of superficial mechanisms (i.e., weathering and elements transport) remains tricky. This results from the poor knowledge we have of the REE distribution in the different fractions of solutions.
Up to recently, the studies carried out on the REE behavior in continental aquatic systems were mainly based on the “paniculate” and “solution” fractions separated by an arbitrary filtration through a 0.20 or 0.45 μm pore size membrane. Some recent work has shown, using ultrafiltration experiments, that REE are mainly contained in the colloidal fraction (i.e., 0.20 μm - 1 nm). However, studies devoted to the control of REE by the colloidal matter, have essentially focused on the organic pool (i.e., humic substances). By contrast, the mineral colloidal pool has received little attention.
In order to model these processes, we have developed a combined approach that consider (1) ultrafiltration experiments performed on a series of rivers located in Africa (Cameroon) and south America (Brazil, Venezuela) and (2) speciation calculations. This quantitative approach reveals, for the first time, that more than 60 % of the total REE in the solution of river waters is controlled by the mineral colloidal pool.
The Lozère sands and the Sologne sands : two detrital discharges in the Paris basin during the early Miocene. New interpretations
Authors: Larue Jean-Pierre , Etienne Robert 
Published: June 2005

Abstract
Following a review of the previous interpretations concerning the drainage pattern modifications of the Loire-Seine in the Paris basin, this work attempts to show the chronological and distributional relations between the Lozère sands and the Sologne sands.
Heavy mineral analyses of about 300 samples, extracted from sands of a series of outcrops and drill holes from the detrital deposits coming from the Massif Central and located between the Nivernais and the Pays de Caux, makes it possible to separate the Lozère sands and the Sologne sands (fig. 1 and tabl. I). The first deposits show analogies with the Albian sands, having poor mineralogical variety and containing only a few feldspars, whereas the second ones incorporate greater mineralogical variety and more feldspars (fig. 2).
The identification of Lozère sands outcrops in the Loire valley, south of the Sologne area (fig. 3) proves that a palaeo-Loire-Seine existed before the discharge named Sologne sands during the Lower Burdigalian. A tectonical evolution (fig. 4) is proposed to explain the changes in mineralogy and distribution of the deposits. The progressive uplift of the northern border of the Massif Central caused the erosion of the Albian sands which contributed to the fluvial discharge of the Lozère sands. But when the Ligerian depression extended to the Sologne area, the fluvial discharge diverted toward the Atlantic, the Albian sands being excluded from erosion, and the Sologne sands were mainly supplied by basement derived alterites showing a greater mineralogical variety.
Since the Burdigalian, the Loire and the Seine basins had a distinct evolution. While the Sologne sands were buried under the Bourbonnais sands, the augite river deposits and the Lozère sands were reworked on the polygenic erosional surface [Dewolf et Pomerol, 1997] which developed from late Burdigalian to early Pleistocene times, before the Quaternary incision of the rivers.
EXAFS evidence of sorbed arsenic(V) and pharmacosiderite in a soil overlying the Echassières geochemical anomaly, Allier, France
Authors: Morin Guillaume , Lecocq Delphine , Juillot Farid , Calas Georges , Ildefonse Philippe , Belin Stéphanie , Briois Valérie , Dillmann Philippe , Chevallier Pierre , Gauthier Christophe , Sole Armando , Petit Pierre-Emmanuel , Borensztajn Stephan 
Published: June 2005

Abstract
At Echassières (Allier, France), arsenic speciation was determined in a soil developed over a micaschist where Hercynian hydrothermal mineralization, including arsenopyrite FeAsS and löllingite FeAs2, has lead to a regional As anomaly. The overlying soils which have developed from long term weathering exhibit As levels as high as 900 ppm in the richest area, where the saprolite contains up to 5200 ppm As. Analysis by powder XRD, μ-X-ray diffraction on the 20μm scale, SEM-EDS and electron micro-probe analyses revealed that As, released from arsenopyrite and/or löllingite alteration, is concentrated in a secondary iron arsenate, pharmacosiderite, (Bax,K2-2x) (Fe,Al)4 (AsO4)3 (OH)5 • 6H2O. Quantitative mineralogical analysis by Rietveld refinement indicates that the proportion of As hosted by this mineral decreases systematically from the saprolite to the topsoil (from 70 % to 30 % of the total bulk As content, respectively). EXAFS spectroscopy indicates that the main form of the As occurring with pharmacosiderite, consists of As(V) ions sorbed on iron oxides. Sorption processes, which dominate As speciation in the topsoil horizons, appear as a key mechanism able to delay As dissemination from soils to plant and surface waters, provided that pH and Eh conditions remain sufficiently acidic and oxidizing, respectively.
Early diagenesis of marine organic-matter and magnetic properties of sedimentary rocks: the role of iron limitation and organic-matter source organisms
Authors: Tribovillard Nicolas , Averbuch Olivier , Bialkowski Anne , Deconinck Jean-François 
Published: June 2005

Abstract
The magnetic parameters of sedimentary rocks can record accurately tectonic and climatic influences upon sedimentary processes, when they are not altered during diagenesis. This paper is focused on the possible alteration of the primary magnetic-susceptibility signal during early diagenesis of marine organic matter (OM).
In the late Kimmeridgian-Tithonian Argiles de Châtillon Formation (Fm.) of the Boulonnais area (northern France – lateral time equivalent of the distal organic-rich sediments of the Kimmeridge Clay Fm. of Dorset), the organic content is dominated by amorphous OM (AOM), either brown or orange, originating from selective preservation or sulphurisation, respectively. Total sulphur content correlates well with orange + brown AOM abundance, and organic S content correlates well with orange AOM abundance. The magnetic signal of these claystones and paper shales is dominantly carried by clay minerals. The magnetic susceptibility vs. brown-AOM abundance relationship shows a clear correlation. Furthermore, if the part of the magnetic-susceptibility signal linked to the lithoclastic fraction of the sediments is removed from the total signal, a positive correlation is also drawn between the brown-AOM abundance and the ‘excess’ magnetic susceptibility. The cause for this resides in the iron-sulphide abundance. The presence of both types of AOM implies that intense sulphate reduction took place and that the HS−/H2S released reacted with either organic molecules (orange AOM dominating the palynofacies) or reactive iron (brown AOM dominating). When reactive iron was abundant enough and when sulphate reduction-induced sulphide ions could react with it, iron sulphides could form and this sediment component (present now as pyrite) influences the magnetic-susceptibility signal. The type of dominating source organisms (phytoplankton) may condition the reactivity of OM towards sulphide ions. This may influence iron-sulphide formation, and in turn the sediment magnetic signal.
Inversion tectonics of the northern margin of the Basque Cantabrian Basin
Authors: Gómez Manuel , Vergés Jaume , Riaza Carlos 
Published: June 2005

Abstract
The northern margin of the Basque-Cantabrian Basin was analysed combining stratigraphic and structural data from both surface and subsurface together with reflectance of vitrinite data from oil wells. The use of cross-section balancing techniques in addition to thermal modelling enabled us to reconstruct the tectonic, burial and thermal evolutions of the basin margin as well as those of the Landes High to the N in two different periods. The section restoration at the end of the Cretaceous shows a northern basin margin structure influenced by evaporites related to south-dipping normal faults. The reconstruction in middle Eocene times yielded up to 1 800 m of Paleocene-middle Eocene deposits on top of the basin margin. Subsequent tectonic inversion related to the Pyrenean compression led to the north-directed thrusting of basement units and to the formation of thrust slices or inverted folds in the cover along the northern margin of the basin. Tectonic subsidence analysis together with maturity data provided evidence that oil was generated in the basin during the late syn-rift and post-rift stages in the Late Cretaceous and became overmature during the period of incipient inversion after 55 Ma. In the autochthonous Landes High, the oil was generated after the tectonic inversion period 37 Ma.
Facies and depositional setting of the Lower Cambrian archeocyath–bearing limestones of southern Montagne Noire (Massif Central, France)
Authors: Debrenne Françoise , Gandin Anna , Courjault-Radé Pierre 
Published: June 2005

Abstract
Archaeocyath-bearing limestones of the Lower Cambrian Pardailhan Formation of southern Montagne Noire are restricted to few intervals (H1, H2, H3) of the mixed carbonate-detrital succession exposed in several superposed tectonic units affected by severe deformation.
The comparative analysis of the archaeocyath assemblages together with a detailed sedimentological investigation leads to the understanding of the depositional settings and of the building style of the calcimicrobial-archaeocyath groups and to a better definition of the paleogeographic relationships of the different tectonic units.
Interval H1: small, low-relief ‘pioneer reefs’ built by Epiphyton bushes and Girvanella crusts, associated with clusters of small stick-shaped archaeocyaths, colonized the detrital sand of the bottom. They are frequent in southern Minervois and more randomly distributed in northern Minervois and northern and southern Pardailhan and represent short-lived attempts of carbonate colonization on the sandy, mobile substrate of a wide continental shelf.
Interval H2: Platy and bioclastic grainstones form the substrate and apron of small crust/cement reefs and associated clusters of ribbon-like and conical archaeocyaths in southern Minervois, or of mud-rich calcimicrobial mounds in southern Pardailhan. Displaced cups of stick-shaped archaeocyaths similar to those of Interval H1, occur in the granular facies, while in place saucer-like cups of Anthomorpha margarita are associated to the mud-rich mounds. This facies association records the repeated attempt at instauration and discrete development of a carbonate platform made of low-relief banks, the margins of which were colonized by Girvanella crust-buildups whereas in the more protected deeper zones Epiphyton/Renalcis mud-mounds dominated.
Interval H3: Epiphyton/Renalcis, mud-rich mounds with solitary, large saucer-like cups of Anthomorpha margarita, represented by long, ribbon-like fragments, are dominant in the upper part of the platform. They rest on reduced lenses of grainstone and Girvanella crust boundstone and in southern Pardailhan are interbedded with nodular, marly mudstones containing bioclastic debris partly derived from the buildups. In this area they mark the transition from platform to shallow basin.
Encrusting strategies in a Cambrian nonreefal epibenthic community
Authors: Clausen Sebastien , Álvaro J. Javier 
Published: June 2005

Abstract
Microfossils released by the action of acids from the Cambrian Valdemiedes Formation (Iberian Chains, NE Spain) contain evidence that encrusting microepifauna (foraminifers and serpulid tube worms) infested shelled hard substrates in nonreefal environments. They appear to have exploited parasitic and/or commensal ecological niches under medium- to low-energy bottom conditions. Despite the gregariousness character of the epifauna, skeletal overgrowths are rare, reflecting low-patterns on competitive interactions for space. Cambrian psammosphaerids (agglutinated foraminifers) were able to dissolve partly calcareous shells: although no evidence of pitting is observed, distinct depressed scars occur on the internal sides of host shells. The serpulids experienced a population bloom during the ecosystem recovery interval after the community turnover represented by the Valdemiedes event, and sharply disappeared during the ensuing return to background conditions. By contrast, the psammosphaerids are relatively abundant across the event, increasing in abundance during the same bloom of opportunistic taxa.