bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of mineralogy and moisture content on plasticity and induced anisotropic damage of a claystone; application to nuclear waste disposals
Authors: Chiarelli Anne-Sophie , Ledesert Beatrice , Sibai Malek , Karami Mohammed , Hoteit Nasser 
Published: June 2005

Abstract
The influence of mineralogy and moisture content on mechanical behaviour of a claystone rock is studied by the way of uniaxial and triaxial compression tests and microscopic observations. Some parameters characteristic of phenomena like plasticity and induced anisotropic damage are discussed as a function of these two factors. Rock behaviour becomes more brittle when calcite content grows or when clay or moisture content decreases. At the microlevel, plasticity is induced by slip of clay sheets and induced anisotropic damage appears by growth of oriented microcracks at the interface between grains and matrix.
Sedimentological and diagenetical conditions of the impact level of the Cretaceous/Tertiary boundary in Tunisia; no anoxia required
Authors: Tribovillard Nicolas , Dupuis Christian , Robin Eric 
Published: June 2005

Abstract
The Ain Settara section (Kalaat-Senan area, Tunisia) shows a well-exposed and expanded Cretaceous/Tertiary (K/T) boundary that can be divided into several units of contrasted lithologies. The bolide impact level is identified thanks to the occurrence of a peak of iridium and Ni-rich spinel abundance. The impact level is a jarosite nodule-rich horizon upon which the emphasis is placed: the jarosite nodules, initially present as pyrite nodules, may be interpreted as reflecting reducing depositional conditions at the K/T boundary. Trace metal geochemistry indicates that depositional conditions were not reducing and that the nodules must not have formed during earliest diagenesis. Consequently, water column-scaled anoxia cannot be put forward to account for the mass extinctions observed at the K/T boundary at Ain Settara.
Contribution de la photogrammetrie numerique a l'etude spatio-temporelle de versants instables; l'exemple du glissement de terrain de Super-Sauze (Alpes-de-Haute-Provence, France)
Authors: Weber Dominique , Herrmann Agnes 
Published: June 2005

Abstract
Recent developments in image processing and digital photogrammetry offer to the geomorphologists increasingly accessible and effective tools for the spatio-temporal knowledge of landslides. These techniques were used to reconstitute the historical evolution of a complex flow slide occurring in the "Terres Noires" of the Barcelonnette basin. The lithological and morphological environment of the studied site is characteristic of the whole southern French Prealps where are largely present Jurassic marly formations. Six digital elevation models (D.E.M.) generated from stereoscopic couples of aerial photography, but also various ortho-images and perspective views, allow to follow the morphological evolution of the unstable slope since the years 1950's -- before the releasing of the landslide -- until our days. Besides multitemporal descriptions of the landscape and of the morphological processes occurred on this site, the implemented method appears particularly useful for the quantitative analysis of the instabilities. It appears notably as a powerful tool for the 3-D reconstruction of the landslide geometry and by the same occasion for the calculation of its volume.
Structural evolution of the early Miocene in the eastern Betic internal-external zone boundary (SE Spain)
Authors: Tent-Manclu Jose Enrique , Martin-Martin Manuel , Martin-Perez Jose Antonio , Serrano Francisco 
Published: June 2005

Abstract
The Internal-External Zone boundary (IEZB) in the eastern Betic Cordillera partially coincides with the Cadiz-Alicante Accident, mainly a major transcurrent fault of N060E direction. The study of an area located along the IEZB at a point where it separates from the Cadiz-Alicante accident has provided details concerning the geodynamic evolution of the cordillera at the moment of its structuration. Here the Internal Zone, consists of rocks assigned to the Malaguide Complex, dating its last sedimentation to the Aquitanian, and deposits assigned to the Vinuela Group (early-middle Burdigalian). The nappes of the Internal Zone were emplaced during the latest Aquitanian and the Vinuela Group (here the El Nino Formation) sealed it but was afterwards affected by the collision with the External Zone. On the other side of the boundary, the External Zone comprises two tectonic units: the Penarrubia Unit (late Cretaceous-middle Burdigalian), which is made up mainly of limestones and marls, and the El Frances Chaotic Complex composed by a set of different lithologies, all from the External Zone in a marly matrix that could be interpreted as a collisional melange formed in the early-middle Burdigalian. The contact between the two domains corresponds to a backthrust of the External Zone over the Internal Zone which occurred in the middle Burdigalian. The deposits sealing the IEZB are dated by calcareous nannofossils and planktonic foraminifera as late Burdigalian, and comprise clasts from both domains.
La succession lithostratigraphique du bloc de Banda dans la region de Kolonodale (Sulawesi central, Indonesie)
Authors: Villeneuve Michel , Cornee Jean-Jacques , Gunawan Wahyu , Martini Rossana , Tronchetti Guy , Janin Marie-Christine , Saint-Marc Pierre , Zaninetti Louisette 
Published: June 2005

Abstract
Sulawesi island is the convergence area of the Eurasian, the Pacific and the Australian plates. Villeneuve et al. demonstrated, from both lithostratigraphic and tectonic studies, that east and southeast Sulawesi was composed of two major continental blocks. - The "Banda block", including also Buru, Seram and Sinta Ridge, collided with the Asian volcanic arc of west Sulawesi during Oligocene times, then was dismembered during the Late Neogene Banda sea opening. - The Banggai-Sula block which was drifted from Irian Jaya and collided with the Banda block during Mid-Late Pliocene times. One of the fragments of the Banda block is in East Sulawesi, corresponding to the ophiolitic zone. There, in the Kolonodale area, it is possible to reconstruct the sedimentary succession under the ophiolite, despite intensive deformations. Over several years the stratigraphic framework of this area was detailed, following general mapping, and it is now possible, by including unpublished data concerning Cainozoic rocks, to reconstruct the Mesozoic-Cainozoic succession. Reconstructing the succession was possible by joint structural, stratigraphic and palaeoenvironmental studies. An example of structural cross-sections around the Kolonodale gulf is given on figure 4, from which local successions were built. We can now propose the general succession.
Influence of paleoenvironment and radiolytic alteration on the geochemistry of organic matter from Autunian shales of the Lodeve uranium deposit, France
Authors: Schlepp Laurence , Landais Patrick , Elie Marcel , Faure Pierre 
Published: June 2005

Abstract
Thirty-three samples of shales from the Lodeve Permian uranium deposit were examined by different analytical techniques. Samples were analyzed by Rock-Eval pyrolysis and by gas chromatography-mass spectrometry after extraction and fractionation. The determination of uranium content was carried out by atomic emission spectrometry. The composition of the organic extracts allows two groups of shales to be distinguished: the first one is marked by a high proportion of aliphatic hydrocarbons and the second by the predominance of aromatic compounds. These two groups exhibit distinctive biomarker characteristics. One group is characterized by (1) pristane/phytane ratios higher than 1, (2) distributions of terpanes dominated by the tricyclic terpanes and (3) the predominance of C 29 and C 28 steranes. The second group is marked by (1) pristane/phytane ratios lower than 1, (2) the predominance of the pentacyclic terpanes over the tricyclic terpanes and (3) the predominance of C 27 and C 29 steranes. It is suggested that the differences observed are mainly related to different depositional environments, although the uranium content may also influence some parameters such as the hydrogen index and the extraction yield.
The evolution of the Massif Central Rift; spatio-temporal distribution of the volcanism
Authors: Michon Laurent , Merle Olivier 
Published: June 2005

Abstract
The Massif Central area is the largest magmatic province of the West-European Rift system. The spatial-temporal distribution of Tertiary-Quaternary volcanism in the Massif Central, France, shows that three magmatic phases can be defined, each of them characterized by different volumes and different locations. The first event, termed the pre-rift magmatic event, is very scarce and restricted to the north of the Massif Central. It is suggested that this could result from lithospheric bending of the European lithosphere ahead of the incipient Alpine chain during the Paleocene. The second event, termed the rift-related magmatic event, is located in the north of the Massif Central only and is spatially connected with zones of high crustal thinning (i.e. the Limagne graben). It immediately follows Oligocene graben formation and associated sedimentation, and is represented by more than 200 scattered monogenic edifices. This second event can be attributed to partial melting as a consequence of lithospheric thinning that affected the north of the Massif Central during the rifting event. The lack of volcanism in the south during the same period of time is probably related to the very slight lithospheric thinning during the Oligocene. The third event, termed the major magmatic event, started first in the south in the upper Miocene at about 15 Ma, well after the end of the sedimentation. It is unrelated to any extensional event. This major magmatic event reached the north of the Massif Central at about 3.5 Ma, following a pause in volcanism of about 6 Ma after the rift-related magmatic event. These two episodes of the major magmatic event are spatially and temporally associated with the two main periods of uplift, suggesting a common origin for volcanism and uplift processes. The major magmatic event can be attributed to late thermal erosion of the base of the lithosphere above a mantle diapir, as suggested by seismic tomography data. This general magmatic evolution drawn from data at the Massif Central scale may apply to the Eger graben as well, as the three magmatic events described in this study (pre-rift magmatic event, rifting event and post-Miocene volcanic event) are also reported in the literature. This suggests that a single cause should explain the formation of the entire western European rift surrounding the Alpine mountain belt.
Melting of lower continental crust in a young post-collision setting; a geochemical study of Plio-Quaternary acidic magmatism from central Sulawesi (Indonesia)
Authors: Polve Mireille , Maury Rene C. , Vidal Philippe , Priadi Bambang , Bellon Herve , Soeria-Atmadja Rubini , Joron Jean-Louis , Cotten Joseph 
Published: June 2005

Abstract
Acidic potassic calc-alkaline (CAK) magmas have been emplaced in the central part of the western arm of Sulawesi from 6.5 to 0.6 Ma, mostly as peraluminous dacites, rhyolites and granites. They overlay or crosscut a high-grade metamorphic basement including lower crustal garnet peridotites and granulites, the latter showing evidences for incipient melting during rapid uplift. Major and trace element data coupled with a Sr, Nd and Pb isotopic study of the CAK magmas and their lower crustal basement rocks demonstrate that they share a number of common features, including radiogenic Sr and Pb and unradiogenic Nd signatures, consistent with those of Australian granulites and Indian Ocean sediments. We propose that the CAK magmas derived from the anatexis of lower crustal rocks of Australian origin (the Banggai-Sula microcontinent) during the phase of uplift which followed their collision with the Sundaland margin (the western arm of Sulawesi) during the Middle Miocene, and possibly the breakoff of the subducted Molucca Sea slab.
The Lias/Dogger boundary in Iberia; Betic and Iberian cordilleras and Lusitanian Basin
Authors: Sandoval Jose , Henriques Maria Helena , Ureta Soledad , Goy Antonio , Rivas Pascual 
Published: June 2005

Abstract
In this paper we present a synthesis on the Toarcian/Aalenian (Lias/Dogger) boundary in the Iberian Peninsula. We have selected in each domain the most representative areas and sections in which this boundary is represented: Fuentelsaz and Moyuela sections in the Iberian Cordillera, Sierra de Ricote and Cerro Mendez in the Betic Cordillera, and Sao Giao in the Lusitanian Basin. In these areas the succession across the Toarcian/Aalenian boundary is represented mainly by pelagic grey marl-marly limestone rhythmites, which contain abundant and characteristic ammonites. The standard ammonite zones of Aalensis (Mactra, Aalensis and Buckmani Subzones) for the uppermost Upper Toarcian, and Opalinum (Opalinum and Comptum Subzones) in the Lower Aalenian are recognised and characterised. Although the ammonite assemblages of the Betic Cordillera are typical of the Mediterranean province, and the Iberian and Lusitanian basins constitute a Sub-Mediterranean one, the ammonite assemblages are similar in the three basins, with the only significant difference being that phylloceratids and lytoceratids are abundant in the Betic domain and are scarcer in the other basins.
Nature des sources des composants andesitiques des Gres du Champsaur et des Gres de Taveyannaz; implications dans l'evolution des Alpes occidentales au Paleogene
Authors: Boyet Maud , Lapierre Henriette , Tardy Marc , Bosch Delphine , Maury Rene 
Published: June 2005

Abstract
Paleogene magmatism is widespread in the western Alps and its origin is still a matter of debate. It consists of calc-alkaline and shoshonitic suites with mainly granodioritic intrusions in the Internal Zone (northern Italy), andesitic volcanism in the Delphino-Helvetic Zone (French-Swiss domain) and the Esterellite intrusions in Provence. In the External Alpine Zone, the Taveyannaz Sandstones and the Champsaur Sandstones preserve andesitic pebbles and mineral fragments dated at 32 Ma. On the basis of trace-element and isotopic geochemistry (Sr, Nd, Pb and O) of mineral separates (amphibole, pyroxene and plagioclase) and andesitic clasts, we characterise the nature of magmatic source(s) and compare the isotopic compositions of the andesites with those of well known Paleogene igneous suites.
Interet de l'etude du cycle biogeochimique du silicium pour interpreter la dynamique des sols tropicaux
Authors: Meunier Jean-Dominique , Alexandre Anne , Colin Fabrice , Braun Jean-Jacques 
Published: June 2005

Abstract
Recent studies on the biogeochemical cycle of silica put new constraints into models of genesis and evolution of silica in tropical environments. The role of plants in weathering mass balances are illustrated by phytolith studies. In Dimonika (Congo) latosols, dissolved silica originates mainly from the dissolution of phytoliths rather than from the dissolution of non-biogenic silicates. In andosols from La Reunion island (Indian Ocean), a 15 cm thick, biogenic silica accumulation formed within 4000 years from bamboo forests fires. The turn-over of silica by plants must therefore be taken into account in studies of weathering rates. Weathering rates of trachytic ash layers in La Reunion island show that all the primary minerals are destroyed and that 50% of amorphous secondary Al/Si products are transformed into halloysite. Theses rates, which are faster than the ones obtained in the Hawaii islands, may strongly influence the turn-over of carbon in soils. Besides, phytoliths preserved from dissolution may help to decipher the records of environmental changes in soils. In Salitre (Brazil), the phytolith distribution has been calibrated with charcoal and pollens. The age of phytoliths, which increases with depth, allow to trace the savanna/forest changes.
Tectonic evolution of the Cevennes para-autochthonous domain of the Hercynian French Massif Central and its bearing on ore deposits formation
Authors: Faure Michel , Charonnat Xavier , Chauvet Alain , Chen Yan , Talbot Jean-Yves , Martelet Guillaume , Courrioux Gabriel , Monie Patrick , Milesi Jean-Pierre 
Published: June 2005

Abstract
The Cevennes area belongs to the para-autochthonous domain of the Hercynian Belt of the French Massif Central. Three lithological series, namely: sandstone-pelite, black micaschist and gneiss-micaschist, are identified. They form an imbrication of five tectonic units which overthrust the unmetamorphosed Viganais Paleozoic units to the south and the gneissic Mamejean Unit to the north. The structural, metamorphic and magmatic evolution of the Cevennes area is characterized by three events, namely: (1) southward shearing coeval to a MP/MT metamorphism dated around 340 Ma; (2) post nappe anatexis (T&lt;750 degrees C, P&gt;5 kb); (3) Namurian (ca 315 Ma) E-W extensional tectonics and plutonism. The structure of the Mt-Lozere-Borne granitic complex is constrained by new AMS and gravimetric data. The plutons are the driving power of the hydrothermal convective circulations responsible for an early deposition of diffuse arsenopyrite in the thermal aureole. Gold bearing sulfides are afterwards concentrated in quartz veins along brittle normal and wrench faults around the granite. Lastly, ore bearing quartz pebbles are sedimented in the Stephanian Ales coal basin.
Les vallees fossiles de la baie de la Vilaine; nature et evolution du prisme sedimentaire cotier du Pleistocene armoricain
Authors: Proust Jean-Noel , Menier David , Guillocheau Francois , Guennoc Pol , Bonnet Stephane , Rouby Delphine , Le Corre C. 
Published: June 2005

Abstract
The study of a dense network of high resolution seismic profiles in the bay of Vilaine, INSU-CNRS cruise Geovill, have led to the characterization of the architecture of the sediment wedge preserved between the coast and the 50 m isobath. This wedge lies on a substratum composed of three seismic units, U1, U2 and U3 respectively attributed to metamorphic and magmatic rocks, Lutetian and Ypresian sandy carbonates and post-Eocene sediments. The coastal sediment wedge comprises three major units. A basal unit (U4), dated around 600 to 300 ky BP, interpreted as braided river sandy conglomerates. A median unit (U5) corresponding to estuarine and fluvial sandstones and clays that give way to the west to mouth bar sandstones. A sommital unit (U6) attributed to marine argillites and barrier island sandstones dated from 8110+ or -200 years at the base. These three units are bounded by two major surfaces: an unconformity between U4 and U5 and a marine (wave and tidal) ravinement surface between U5 and U6. The unconformity is interpreted as a sequence boundary between two depositional sequences: a lower one with U4 seismic unit and a topmost one with U5 and U6 seismic units. Based on the available datations, the lower sequence is attributed to the Saalian and/or Elsterian glacial cycles and, the upper sequence to the Weichselian (lowstand systems tract) and to the Holocene marine transgression (transgressive systems tract). The passage from one sequence to the other corresponds however to a drastic shift in the paleoflow directions (60 degrees ) in the Bay of Vilaine closely related to the main faults orientations. The tectonic activity in Brittany during the Pleistocene, linked to intraplate stress, seems to exert a control on sediment architecture in the coastal wedge. Indeed, the tilt of the Armorican Massif during that period has caused a complete rejuvenation of the fluvial profiles in land and the separation of the paleo-Vilaine from the Paleo-Loire river courses.
The Pre-Pan-African rifting of Saghro (Anti-Atlas, Morocco): example of the middle Neoproterozoic Basin of Boumalne
Authors: Fekkak Abdelilah , Pouclet André , Badra Lakhlifi 
Published: June 2005

Abstract
In the Anti-Atlas, the Boumalne basin includes 3,000 m of Middle Neoproterozoic sediments. It consists of turbiditic deposits folded during the major Pan-African event ca 685 Ma. A syn-sedimentary basaltic pile of lava flows is interbedded in the upper part of the lower formation. These lavas show an initial rift tholeiite (IRT) chemical signature. Petrographical analysis of sediments and typology of detrital zircons indicate a continental margin sedimentation, without any volcano-sedimentary supply from a close volcanic arc. It is concluded that the Boumalne Basin formed in a continental passive margin evolving from an intracontinental rift. This interpretation differs clearly from that of a back-arc basin which is commonly accepted. Hence, the opening of this basin is related to the pre-Pan-African Saghro rift synchronous to the Central Anti-Atlas oceanization, and not to the demise of this oceanic domain along an active margin.
How does the Alpine belt end between Spain and Morocco ?
Authors: Michard André , Chalouan Ahmed , Feinberg Hugues , Goffé Bruno , Montigny Raymond 
Published: June 2005

Abstract
The Betic-Rif arcuate mountain belt (southern Spain, northern Morocco) has been interpreted as a symmetrical collisional orogen, partly collapsed through convective removal of its lithospheric mantle root, or else as resulting of the African plate subduction beneath Iberia, with further extension due either to slab break-off or to slab retreat. In both cases, the Betic-Rif orogen would show little continuity with the western Alps. However, it can be recognized in this belt a composite orocline which includes a deformed, exotic terrane, i.e. the Alboran Terrane, thrust through oceanic/transitional crust-floored units onto two distinct plates, i.e. the Iberian and African plates. During the Jurassic-Early Cretaceous, the yet undeformed Alboran Terrane was part of a larger, Alkapeca microcontinent bounded by two arms of the Tethyan-African oceanic domain, alike the Sesia-Margna Austroalpine block further to the northeast. Blueschist- and eclogite-facies metamorphism affected the Alkapeka northern margin and adjacent oceanic crust during the Late Cretaceous-Eocene interval. This testifies the occurrence of a SE-dipping subduction zone which is regarded as the SW projection of the western Alps subduction zone. During the late Eocene-Oligocene, the Alkapeca-Iberia collision triggered back-thrust tectonics, then NW-dipping subduction of the African margin beneath the Alboran Terrane. This Maghrebian-Apenninic subduction resulted in the Mediterranean basin opening, and drifting of the deformed Alkapeca fragments through slab roll back process and back-arc extension, as reported in several publications. In the Gibraltar area, the western tip of the Apenninic-Maghrebian subduction merges with that of the Alpine-Betic subduction zone, and their Neogene roll back resulted in the Alboran Terrane collage astride the Azores-Gibraltar transpressive plate boundary. Therefore, the Betic-Rif belt appears as an asymmetrical, subduction/collision orogen formed through a protracted evolution straightfully related to the Alpine-Apenninic mountain building.
The island of Maupiti : the oldest emergent volcano in the Society hot spot chain (French Polynesia)
Authors: Blais Sylvain , Guille Gérard , Guillou Hervé , Chauvel Catherine , Maury Rene C. , Pernet Gilles , Cotten Joseph 
Published: June 2005

Abstract
The island of Maupiti is the top of an eroded volcanic shield surrounded by a large lagoon and coral reef. The most important part of this shield is made up of alkali basaltic lavas grading upward into hawaiitic flows. The shield-building event is dated at ca. 4.51 ± 0.04 Ma. A few mugearitic and benmoreitic late dykes were emplaced at 4.21 ± 0.04 Ma. These chronological data are consistent with a Pacific plate motion of 11 cm/year with respect to a fixed Society plume. The Maupiti lava series results from the effects of fractional crystallisation of a parental alkali basalt magma displaying a prominent EM II isotopic and trace element signature, in many ways similar to that of the youngest Society hot spot lavas. This feature suggests that the geochemical signature of the Society plume did not change through time.