Lead-lead systematics,the “age of the Earth” and the chemical evolution of our planet in a new representation space     

Gérard Manhes  Claude J. Allègre  Bernard Dupré  Bruno Hamelin 《Earth and Planetary Science Letters》1979,44(1):91-104

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Reflectance spectrophotometry extended to u.v. for terrestrial,lunar and meteoritic samples     

Audouin Dollfus  André Cailleux  Bernard Cervelle  Chon Trung Hua  Jean-Claude Mandeville 《Geochimica et cosmochimica acta》1980,44(9):1293-1310

Extension of remote sensing of planetary bodies to the ultraviolet is now feasiable up to 2000 Å from earth-orbiting telescopes and spacecraft. The benefits of this extension is analysed on the basis of laboratory spectra taken on a large variety of terrestrial, lunar and meteoritic samples. Knowledge of the albedo for two wavelengths at 2300 and 6500 Å permits classification of a surface into one of the following types: lunar, carbonaceous chondrites, ordinary chondrites, achondrites or acidic rocks, basaltic rocks, irons. For lunar-type surfaces, a simple albedo measurement at 6500 Å can be converted into quantitative abundance determinations of silicate, aluminium oxide and iron; a large amount of telescopic lunar photometry data is available for mapping these abundances. Extension of the photometry to 2300 Å permits quantitative measurement of TiO₂ abundances. For asteroids and non-icy satellites, rock-type classification and constraints in chemical abundances of Si, Al, Fe and Ti can be derived from photometry at 2300 and 6500 Å. The IUE telescope already orbiting the earth, the Space Telescope to come, the lunar polar orbiter and other spacecraft under prospect are potentially available to provide the photometric observations at 6500 and 2300 Å required.  相似文献   

Low-degree partial melting trends recorded in upper mantle minerals     

Pierre Schiano  Bernard Bourdon  Robert Clocchiatti  Dominique Massare  Maria E. Varela  Yan Bottinga 《Earth and Planetary Science Letters》1998,160(3-4):537-550

The study of glass inclusions inside mantle minerals provides direct information about the chemistry of naturally occurring mantle-derived melts and the fine-scale complexity of the melting process responsible for their genesis. Minerals in a spinel lherzolite nodule from Grande Comore island contain glass inclusions which, after homogenization by heating, exhibit a continuous suite of chemical compositions clearly distinct from that of the host basanitic lava. The compositions range from silicic, with nepheline–olivine normative, 64 wt% SiO₂ and 11 wt% alkali oxides, to almost basaltic, with quartz normative, 50 wt% SiO₂ and 1–2 wt% alkali oxides. Within a single mineral phase, olivine, the inferred primary melt composition varies from 54 to 64 wt% SiO₂ for MgO content ranging from 8 to 0.8 wt%. An experimental study of the glass and fluid inclusions indicates that trapped melts represent liquids that are in equilibrium with their host phases at moderate temperature and pressure (T≈1230°C and P≈1.0 Gpa for melts trapped in olivine). Quantitative modelling of the compositional trends defined in the suite shows that all of the glasses are part of a cogenetic set of melts formed by fractional melting of spinel lherzolite, with F varying between 0.2 and 5%. The initial highly silicic, alkali-rich melts preserved in Mg-rich olivine become richer in FeO, MgO, CaO and Cr₂O₃ and poorer in SiO₂, K₂O, Na₂O, Al₂O₃ and Cl with increasing melt fractions, evolving toward the basaltic melts found in clinopyroxene. These results confirm the connection between glass inclusions inside mantle minerals and partial mantle melts, and indicate that primary melts with SiO₂ >60 wt%, alkali oxides >11%, FeO <1 wt% and MgO <1 wt% are generated during incipient melting of spinel peridotite. The composition of the primary melts is inferred to be dependent on pressure, and to reflect both the speciation of dissolved CO₂ and the effect of alkali oxides on the silica activity coefficient in the melt. At pressures around 1 GPa, low-degree melts are characterized by alkali and silica-rich compositions, with a limited effect of dissolved CO₂ and a decreased silica activity coefficient caused by the presence of alkali oxides, whereas at higher pressures alkali oxides form complexes with carbonates and, consequently, alkali-rich silica-poor melts will be generated.  相似文献   

Relations entre contraintes tectoniques et propriétés magnétiques des roches volcaniques permiennes de la vallée du Guil (briançonnais,Alpes Françaises)     

Bernard Henry 《Pure and Applied Geophysics》1976,114(4):685-700

Résumé Les roches volcaniques permiennes de la vallée du Guil présentent une ARN de direction voisine du plan de la schistosité alpine qui les affecte. Leur aimantation permienne a probablement été modifiée, lors de l'orogénèse alpine, par les efforts tectoniques (modification d'origine purement mécanique, ou acquisition d'une nouvelle aimantation par effet de pression). L'ARN des roches du Guil ne peut donc pas être prise en référence pour une étude géotectonique de l'arc alpin.

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Summary The Guil valley permian volcanic rocks have NRM whose direction is very near to the plane of alpine schistosity affecting these rocks. During the alpine orogeny, their permian magnetization was probably modified by tectonic stresses (mechanical modification, or new magnetization by piezo-magnetic effect). The NRM of the Guil valley rocks cannot be used as a reference for geotectonic study of the Alps.

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On some properties of Venedikov's method of tidal analysis     

Bernard Ducarme  Reviewer J. Pícha  Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1976,20(3):301-303

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Petrogenesis of garnet lherzolite, Cima di Gagnone, Lepontine Alps   总被引：10，自引：0，他引：10  

Bernard W. Evans  Volkmar Trommsdorff 《Earth and Planetary Science Letters》1978,40(3):333-348

Garnet lherzolite at Cima di Gagnone has chemical and mineralogical properties similar to those of other garnet lherzolites in the lower Pennine Adula/Cima Lunga Nappe (Alpe Arami, Monte Duria). The Cima di Gagnone occurrence encloses mafic boudins that belong to an eclogite-metarodingite suite common in the numerous neighboring ultramafic lenses. The ultramafic rocks at Cima di Gagnone, including the garnet lherzolite, are interpreted as tectonic fragments of an originally larger lherzolite body that underwent at least partial serpentinization prior to regional metamorphism. This lherzolite body cycled through at least three metamorphic facies: greenschist or blue-schist (as antigorite serpentinite) → eclogite (as garnet lherzolite), pre-Alpine or early Alpine → amphibolite facies (as chlorite-enstatite-tremolite peridotite), Lepontine metamorphism. Relics of titanoclinohumite in the garnet peridotite, as also recorded by Möckel near Alpe Arami, are consistent with this metamorphic history, since they indicate a possible connection with Pennine antigorite serpentinites, e.g., Liguria, Piedmont, Zermatt-Saas, Malenco, Pustertal, all of which have widespread titanoclinohumite belonging to the antigorite paragenesis. Estimated pressures in excess of 20 kbar and temperatures of 800°±50°C for the garnet lherzolite assemblage are not inconsistent with conditions inferred for Gagnone and Arami eclogites. These conditions could have been reached during deep subduction zone metamorphism. It is shown by calculation that the effects of Fe and Cr on the location of the garnet lherzolite/spinel lherzolite phase boundary largely counter-balance each other.  相似文献   

Essai de revue des concentrations métallifères dans le cycle sédimentaire     

Prof. A. J. Bernard 《International Journal of Earth Sciences》1974,63(1):41-51

The author summarizes the main arguments in the debate between syngenetic and epigenetic deposits and then underlines the importance of the arguments which prove that the formation of the sediments and of the metalliferous concentrations which they bear are contemporaneous. This is strongly suggested by very early syn-sedimentary reworking of the mineralization. This approach leads to a consideration of metallogenesis of syngenetic sedimentary concentrations both as a supply of metal and a sedimentary trap. The exploitability of mineralized rocks is presently such that only the coincidence of an outstanding supply of metal and a receptive sedimentary environment will yield a workable ore deposit. Reviewing all metalliferous sources which could be contemporaneous with sedimentation (terrigenous, exhalative, marine and possibly also fluidogenic) the author stresses the geological and geochemical characteristic of the surrounding sediments. At the same time, the examination of traps in sandy, shaly and carbonate environments permits to the identification of the main characteristics of the concentration on the scale of the deposit and of the ore itself. The search for an understanding of metalliferous concentrations in the sedimentary cycle becomes a question of defining criteria for the quality of supplies and traps. On the level of the trap these would be the duration and the regulation of parameters which govern the efficiency of the concentrating system: the sedimentary features which result from these concentrating processes must be recognized within the lithologic column during tactical exploration. On the level of the metallogenetic province it is the purpose of strategic exploration to search among the available geological and geochemical data for features which favor each type of supply. These are the basic principles of the indirect method of exploration for sedimentary ore deposits.  相似文献   

Coexisting alkali feldspars in felsic members of the Cauro-Bastelica ring complex,Corsica     

Bernard Bonin  Robert F Martin 《Lithos》1974,7(1):23-28

The granodioritic and gneissic Hercynian basement in Corsica was intruded, in the Triassic, by non-orogenic ring complexes in which the association early rhyolite-hypersolvus granite-granophyre-late subsolvus granite is clearly developed. The association of low albite and maximum microcline in mesoperthites cannot be attributed to Alpine low-grade metamorphism, restricted to fault zones. On a number of lines of evidence, the development of ordered, almost pure K-feldspar in this rapidly cooled complex appears related to an episode of mild reheating attending emplacement of late subsolvus granites, rocks formed from melts enriched, perhaps even saturated in aqueous fluids.  相似文献   

On the derivation of the energy flux of linear magnetohydrodynamic waves     

Bernard Leroy 《地球物理与天体物理流体动力学》2013,107(2):123-133

Abstract

New light is shed on the derivation of the energy flux of the linear MHD waves. It is shown that, according to a suggestion of Lighthill, the usual perturbation procedure, which starts from the general expression for the energy flux, need not be supplemented by an averaging procedure. As a result, it is shown that to second order in the wave amplitude, a quantity identifiable as the wave energy flux is conserved. Some of the subtleties inherent in the derivation of the pertubation energy equation are discussed.  相似文献   

Numerical local analysis of relevant internal variables for constitutive modelling of granular materials     

Yuhanis Yunus  Eric Vincens  Bernard Cambou 《国际地质力学数值与分析法杂志》2010,34(11):1101-1123

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