Remote Sensing Observations of Effects of Mountain Blocking on Travelling Gravity-Shear Waves and Associated Clouds     

Roger F. Reinking  A. Shelby Frisch  Brad W. Orr  David L. Korn  Luc R. Bissonnette  Gilles Roy 《Boundary-Layer Meteorology》2003,109(3):255-284

Trapped Kelvin–Helmholtz (K–H) waves and vortices were monitored as they were generated immediately upwind of a mountain and driven into the barrier by a low-level jet. A stratus cloud visually revealed the embedded, propagating, gravity-shear waves. Interactions of the waves with the mountain were deciphered using remote sensing measurements of the structure, motions, and microphysics within the cloud and conceptual models based on existing theories. The observations show that the mountain acted as a dam to the flow that was primed for, but did not spontaneously induce, the waves. In response to the blocking, the waves spatially developed a pattern of formation, amplification, and breakdown between the upstream flow and the barrier, and altered the associated clouds in the process. Notably, radar signatures of velocity variance depicted organized, intertwined ribbons of relatively large vorticity within the wave layer. These provided measured evidence of the vortex sheet and streamwise vortex tubes predicted by advanced K–Hinstability theory, the three-dimensional version of Scorer's `stripe', the layer of rotational fluid between opposed flows that led to the wave generation. A theory of resonant interaction of wave trains, but with blocking imposed, appears to explain the internal structure of the pile-up of the flow and wave amplification approaching the barrier. Evolution of the supporting atmospheric thermal structure and introduction of a boundary-layer flow reversal follow a current model of blocking, although some features may have developed more directly from wave-driven mixing. The remote sensors also measured the influence of the waves on the cloud liquid water, including a cumulative enlargement of droplets as they were carried through a series of waves.  相似文献   

Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean)   总被引：1，自引：0，他引：1  

Claire Carvallo  Pierre Camps  Gilles Ruffet  Bernard Henry  T. Poidras 《Geophysical Journal International》2003,154(3):767-782

  相似文献   

Discovery of two ophiolite complexes of different ages in the Khoy area (NW Iran)     

Morteza Khalatbari-Jafari  Thierry Juteau  Hervé Bellon  Hashem Emami 《Comptes Rendus Geoscience》2003,335(12):917-929

New field and laboratory studies on the ophiolite of Khoy (northwestern corner of Iran) lead to the discovery that there are not one, but two ophiolitic complexes in the Khoy area: (1) an old, poly-metamorphic ophiolite, whose oldest metamorphic amphiboles yielded a Lower Jurassic apparent ⁴⁰K–⁴⁰Ar age, and whose primary magmatic age should logically be pre-Jurassic (Upper-Triassic?); (2) a younger non metamorphic ophiolite of well dated Upper Cretaceous age. To cite this article: M. Khalatbari-Jafari et al., C. R. Geoscience 335 (2003).  相似文献   

La stratigraphie oligo-miocène et la surface d'érosion messinienne en mer Noire,stratigraphie sismique haute résolution     

Hervé Gillet  Gilles Lericolais  Jean-Pierre Rehault  Corneliu Dinu 《Comptes Rendus Geoscience》2003,335(12):907-916

The stratigraphy of the Black Sea western margin is revisited through seismic data acquired during two French-Romanian surveys. These data are calibrated by industrial and DSDP drillings; they display several major discontinuities regarded as Tertiary erosional surfaces. The major seismic discontinuity underlines the base of Miocene formations and corresponds to a composite surface including at least three erosional phases ranging from Oligocene to Pontian times. Moreover, a Messinian erosional surface is clearly identified. This is in agreement with the Hsü's proposition [Palaeogeogr. Palaeoclimatol. Palaeoecol. 29 (1979) 75–93] suggesting a Messinian sea-level drop of Black Sea related to the Messinian Salinity Crisis described in the Mediterranean Sea. To cite this article: H. Gillet et al., C. R. Geoscience 335 (2003).  相似文献   

Nouvelles données structurales et datations 40K–40Ar sur les roches métamorphiques de la région de Neyriz (zone de Sanandaj–Sirjan,Iran méridional). Leur intérêt dans le cadre du domaine néo-téthysien du Moyen-Orient     

Reza Sheikholeslami  Hervé Bellon  Hachem Emami  Mossaı̈eb Sabzehei  Alain Piqué 《Comptes Rendus Geoscience》2003,335(13):981-991

The metamorphic rocks of the Neyriz area (Sanandaj–Sirjan zone) represent a Palaeozoic sequence, the upper part of which being palaeontologically dated from the Carboniferous and the Permian. Field structural analysis of the whole sequence, detailed in laboratory by microstructural one and ⁴⁰K–⁴⁰Ar dating carried on separated minerals, lead to establish that the whole sequence, from gneisses to Permian rocks, has suffered a unique synmetamorphic deformation, of variable intensity, marked by a foliation. Isotopic ages measured on extracted amphiboles and micas, clustered in four groups between 300 and 60 Ma, show the successive stages of their slow exhumation, which ended by the end of the Cretaceous. To cite this article: R. Sheikholeslami et al., C. R. Geoscience 335 (2003).  相似文献   

L'hétérogénéité du manteau supérieur à l'aplomb du volcan de Nyos (Cameroun) révélée par les enclaves ultrabasiques     

Robert Temdjim  Pierre Boivin  Gilles Chazot  Claude Robin  Émilie Rouleau 《Comptes Rendus Geoscience》2004,336(14):1239-1244

Volcanic deposits from the lake Nyos (Cameroon) contain ultrabasic xenoliths: lherzolites, harzburgites and websterites, sometimes containing amphibole. Major and trace element compositions of clinopyroxene and amphibole allow the recognition of an old depletion event followed by two episodes of incompatible-element enrichment. One is high in light rare-earth elements, while the other one is low in these elements, but high in U and Th. Their relative chronology is not yet established. To cite this article: R. Temdjim et al., C. R. Geoscience 336 (2004).  相似文献   

Water solubility in a calcium aluminosilicate melt     

Paul McMillan  Gilles Peraudeau  John Holloway  Jean -Pierre Coutures 《Contributions to Mineralogy and Petrology》1986,94(2):178-182

We have measured the water solubility between 1 atmosphere and 5 kilobars for a calcium aluminosilicate melt of molar composition CaO 0.28, Al₂O₃ 0.06, SiO₂ 0.66 (An₉Wo₃₈Qz₅₃). The water contents were measured via thermogravimetric analysis of isobarically quenched glasses, and range from 0.121 wt% H₂O near 1 aim to 9.25 wt% H₂O at 5 kilobars. The molar water solubility lies between those of SiO₂ and albite melts below around three kilobars, and crosses the albite solubility curve above this pressure. The present results are compared with data in the literature on related calcium aluminosilicate melts. There seems to be little variation of water solubility with composition for calcium aluminosilicate melts, unlike analogous alkali aluminosilicate compositions. Examination of the data suggests that there may be a maximum in molar water solubility along the albite-anorthite join.  相似文献   

An XPS and SEM study of gold deposition at low temperatures on sulphide mineral surfaces: Concentration of gold by adsorption/reduction   总被引：1，自引：0，他引：1  

Gilles E. Jean 《Geochimica et cosmochimica acta》1985,49(4):979-987

Using X-ray photoelectron spectroscopy (XPS or ESCA) and scanning electron microscopy (SEM), we have examined the mechanism of adsorption and reduction of gold solutions on sulphides. KAu^IIICl₄ solutions are quickly adsorbed on the sulphide surfaces, and the Au(III) is quickly reduced to Au(0). Monolayer Au coverage is attained within one minute. The reduction is auto-catalyzed and Au metal grows on the surface. SEM photographs clearly show agglomerates of gold unevenly distributed on the surface. Specific sites of abnormally high Au concentration are found. We propose possible mechanisms for the adsorption and reduction. Our results suggest that adsorption of Au(III) and Au(I) by sulphide minerals, followed by reduction, could play an important role in the deposition of gold in natural systems especially at low temperature and low gold solution concentrations.  相似文献   

Separation of phytoplanktonic pigments by HPLC for the study of phyto-zooplankton trophic relationships     

Catherine Quiblier  Gilles Bourdier  Christian Amblard  Denise Pepin 《Aquatic Sciences - Research Across Boundaries》1994,56(1):29-39

Phyto-zooplankton trophic relationships were studied using phytoplanktonic pigments (chlorophylls and carotenoids) as organic natural markers. Pigments were separated by high-pressure liquid chromatography (HPLC).Comparison of pigment profiles from monospecific cultures of various taxonomic groups (Chlorophyceae, Bacillariophyceae and Cyanobacteria) and from Cladocera crustaceans (Daphnia magna) fed with these cultures, showed that the characteristic pigment associations of the different taxa are conserved during their transfer from primary producers to secondary consumers.Chromatographic profiles of the Bacillariophyceae and Chlorophyceae type were obtained fromDaphnia respectively fed with mixtures of a Chlorophyceae and a diatom species and mixture of a Chlorophyceae and a Cyanobacterium. This showed the importance of this method in demonstrating a possible selective feeding by the herbivorous zooplankton.The observation of pigment profiles of the Dinophyceae type following feeding of a zooplankton assemblage from Lake Pavin within this natural medium (phytoplankton dominated by a Dinophyceae) and of a Chlorophyceae type profile as the same assemblage was fed in the laboratory on phytoplankton from Lake Villerest (composed of about 80% Cyanobacteria and 20% Chlorophyceae), suggested that this method could be applied to the natural environment.  相似文献   

Reflection seismic imaging and physical properties of base-metal and associated iron deposits in the Bathurst Mining Camp, New Brunswick, Canada   总被引：1，自引：0，他引：1  

Alireza Malehmir  Gilles Bellefleur 《Ore Geology Reviews》2010,38(4):319-333

  相似文献