Impact of amoco cadiz oil spill on the muddy fine sand Abra alba and Melinna palmata community from the Bay of Morlaix     

Jean-Claude Dauvin 《Estuarine, Coastal and Shelf Science》1982,14(5):517-531

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Magma evolution of Quaternary minor volcanic centres in southern Peru,Central Andes   总被引：1，自引：0，他引：1  

Adélie Delacour  Marie-Christine Gerbe  Jean-Claude Thouret  Gerhard Wörner  Perrine Paquereau-Lebti 《Bulletin of Volcanology》2007,69(6):581-608

Minor centres in the Central Volcanic Zone (CVZ) of the Andes occur in different places and are essential indicators of magmatic processes leading to formation of composite volcano. The Andahua–Orcopampa and Huambo monogenetic fields are located in a unique tectonic setting, in and along the margins of a deep valley. This valley, oblique to the NW–SE-trend of the CVZ, is located between two composite volcanoes (Nevado Coropuna to the east and Nevado Sabancaya to the west). Structural analysis of these volcanic fields, based on SPOT satellite images, indicates four main groups of faults. These faults may have controlled magma ascent and the distribution of most centres in this deep valley shaped by en-echelon faulting. Morphometric criteria and ¹⁴C age dating attest to four main periods of activity: Late Pleistocene, Early to Middle Holocene, Late Holocene and Historic. The two most interesting features of the cones are the wide compositional range of their lavas (52.1 to 68.1 wt.% SiO₂) and the unusual occurrence of mafic lavas (olivine-rich basaltic andesites and basaltic andesites). Occurrence of such minor volcanic centres and mafic magmas in the CVZ may provide clues about the magma source in southern Peru. Such information is otherwise difficult to obtain because lavas produced by composite volcanoes are affected by shallow processes that strongly mask source signatures. Major, trace, and rare earth elements, as well as Sr-, Nd-, Pb- and O-isotope data obtained on high-K calc-alkaline lavas of the Andahua–Orcopampa and Huambo volcanic province characterise their source and their evolution. These lavas display a range comparable to those of the CVZ composite volcanoes for radiogenic and stable isotopes (⁸⁷Sr/⁸⁶Sr: 0.70591–0.70694, ¹⁴³Nd/¹⁴⁴Nd: 0.512317–0.512509, ²⁰⁶Pb/²⁰⁴Pb: 18.30–18.63, ²⁰⁷Pb/²⁰⁴Pb: 15.57–15.60, ²⁰⁸Pb/²⁰⁴Pb: 38.49–38.64, and δ ¹⁸O: 7.1–10.0‰ SMOW), attesting to involvement of a crustal component. Sediment is absent from the Peru–Chile trench, and hence cannot be the source of such enrichment. Partial melts of the lowermost part of the thick Andean continental crust with a granulitic garnet-bearing residue added to mantle-derived arc magmas in a high-pressure MASH [melting, assimilation, storage and homogenisation] zone may play a major role in magma genesis. This may also explain the chemical characteristics of the Andahua–Orcopampa and Huambo magmas. Fractional crystallisation processes are the main governors of magma evolution for the Andahua–Orcopampa and Huambo volcanic province. An open-system evolution is, however, required to explain some O-isotopes and some major and trace elements values. Modelling of AFC processes suggests the Charcani gneisses and the local Andahua–Orcopampa and Huambo basement may be plausible contaminants.  相似文献   

Expertise in coastal zone environmental impact assessments     

Dauvin JC 《Marine pollution bulletin》2005,50(1):107-110

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Relief and Gravity Anomalies Over a Convecting Mantle     

Jean-Claude De Bremaecker 《Geophysical Journal International》1976,45(2):349-356

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Analysis of a UV Event in a Polar Coronal Hole     

Patsourakos  Spiros  Vial  Jean-Claude 《Solar physics》2001,203(1):39-51

We present observations of a UV event which occurred in a polar coronal hole. They were obtained by SUMER on SOHO in several chromospheric and transition region spectral lines. Its birth site was about 50 arc sec inside the limb and in a network lane showing a net outflow before its initiation. The event had an extension of about 5 arc sec along the slit, a duration of about 3 min and was characterized by a large increase of intensity together with a significant line broadening with, however, downflows of about 50 km s^–1 being dominant. Proper motions with a velocity of about 10 km s^–1 were also observed. The event appeared at middle transition (Ovi) temperatures and it simultaneously showed up in chromospheric (Oi, Ly ) and low transition region (Cii) temperatures. We discuss this event in view of different scenarios to account for it. Our event could be a part of the large family of quiet-Sun explosive events observed by Ryutova and Tarbell (2000) taking place in polar coronal holes that are triggered by magnetic reconnection in the low solar atmosphere.  相似文献   

Geological and geotechnical characteristics of recent lahar deposits from El Misti volcano in the city area of Arequipa,South Peru     

Carlos Pallares  Denis Fabre  Jean-Claude Thouret  Claude Bacconnet  Juan Antonio Charca-Chura  Kim Martelli  Aurélie Talon  Calixtro Yanqui-Murillo 《Geotechnical and Geological Engineering》2015,33(3):641-660

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Victor Ambartsumian and the IAU     

Jean-Claude Pecker 《Astrophysics》1988,29(1):409-412

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A transmission electron microscope investigation of shock metamorphism in olivine of the Ilafegh 013 chondrite     

Pascal JOREAU  Hugues LEROUX  Jean-Claude DOUKHAN 《Meteoritics & planetary science》1997,32(2):309-316

Abstract— Ilafegh 013 is a slightly weathered, type-3 ordinary chondrite that is unusual in that it is highly shocked. Olivine grains in chondrules were studied in detail by transmission electron microscopy (TEM) to characterize the dislocations, fractures and recrystallization textures. Only c dislocations, in the (010) glide plane, seem to be activated by the shock wave. Fractures are more numerous in the TEM than at the scale of the optical microscope. They can be divided into two groups: (a) Open fractures with injections of molten metal, sulphide, and in some cases, phases containing Ca, Al, Na and K. (b) Very straight and narrow cracks parallel to {130} planes without injected material and consisting of imperfectly relaxed subgrain boundaries composed of two families of dislocations (Burgers vectors a and c ). Both types of dislocations are roughly in screw orientation (i.e., the subgrain boundaries have a pronounced twist character). It is suggested that they formed during the shock in order to relax stresses around shear fractures (fractures with displacements of their walls parallel to the fracture plane). Recrystallization occurs in areas where the dislocation density is high. Since diaplectic glass was not detected, it is suggested that recrystallization resulted from the large elastic energy of the lattice defects stored in the deformed crystals.  相似文献   

Neutral Hydrogen and Its Emission Lines in the Solar Corona     

Jean-Claude Vial  Martine Chane-Yook 《Solar physics》2016,291(12):3549-3566

Since the Lyman-\(\alpha\) rocket observations of Gabriel (Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic-equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisional and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations (e.g. L\(\alpha\) from Ultraviolet Coronal Spectrometer) and find a rough (model-dependent) agreement. Since the H\(\alpha\) line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 Å wide) bandpass filter.  相似文献   

Lizards and snakes from the late Miocene hominoid locality of Ravin de la Pluie (Axios Valley,Greece)     

Georgios L. Georgalis  Jean-Claude Rage  Louis de Bonis  George D. Koufos 《Swiss Journal of Geoscience》2018,111(1-2):169-181

We here describe lizards and snakes from the late Miocene (MN 10) of Ravin de la Pluie, near Thessaloniki, Greece, a locality widely known for its hominoid primate Ouranopithecus macedoniensis. The new finds comprise two large-sized lizards (a probable anguine and a varanid) and two snakes (an elapid and a small-sized “colubrine”). Even if the material is represented by few specimens, this is the first record of squamates from the late Miocene MN 10 biozone of southeastern Europe and the third only for the whole continent. The importance of the varanid vertebrae for systematic attributions is discussed. The new varanid limb elements described herein rank among the few such specimens in the fossil record of monitor lizards. Judging from the new and previously published varanid appendicular material, we suggest that Neogene monitor lizards from Europe possessed comparatively short and robustly built limbs. Distinctive scars on one of the limb elements are interpreted as bite marks of a predator or scavenger, offering insights on the palaeoecology of the herpetofauna of the locality.  相似文献