Plissements Quaternaires Dans la Région de Gafsa et le Sud Tunisien     

Gilbert Castany 《International Journal of Earth Sciences》1955,43(1):196-203

Résumé L'Atlas tunisien est affecté, dans la zone de Gafsa, de plissements quaternaires post-acheuléens et anté-moustériens. La succession stratigraphique se termine par des dépÔts continentaux qui, débutant avec le sommet du Miocène, sont surmontés en continuité de sédimentation par une série congloméatique renfermant des silex taillés de l'Acheuléen. Cet ensemble a été plissé en pli faillé avec flanc sud accentué et affaissé (pendages de 70 à 80 degrés). Au complexe plissé se superposent des alluvions horizontales dont la haute terrasse est datée par des industries à silex du Moustérien. Cette orogénèse s'intègre dans la géologie régionale du Sud tunisien où des faits analogues sont connus en plusieures localités.  相似文献   

Geologische Vereinigung     

Georges Millot  Gilbert Dunoyer de Segonzac 《International Journal of Earth Sciences》1964,53(2):904-904

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Cosmology and geophysics: Paul S. Wesson. Monographs on Astronomical Subjects: 3, Adam Hilger,London, 1978, 240 pp., £17.50, ISBN 0-85274-315-7     

C. Gilbert 《Physics of the Earth and Planetary Interiors》1980,22(2):162-164

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Brines and evaporites of the Lake Chad basin,Africa     

Hans P. Eugster  Gilbert Maglione 《Geochimica et cosmochimica acta》1979,43(7):973-981

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Unites structurales de la marge continentale sous-marine de Cannes a Menton d'apres la sismique refraction     

Maurice Recq  Jean-Pierre Rehault  Gilbert Bellaiche  Maurice Gennesseaux  Jean-Pierre Esteve 《Earth and Planetary Science Letters》1976,28(3):323-330

Offshore seismic refraction profiles permitted us to characterize the extent of the geological formations which prolong the principal units of the Provence and Alpes Maritimes southwards and to establish their respective relationships. The concept of a “Var graben” is confirmed and defined. A magma chamber, probably in relation with the volcanic deposits of the Cap d'Ail, has been disclosed and coincides with the positive magnetic anomaly observed in this area.  相似文献   

Geochemistry and origin of the early Precambrian crust of northeastern Minnesota   总被引：2，自引：0，他引：2  

Joseph G Arth  Gilbert N Hanson 《Geochimica et cosmochimica acta》1975,39(3):325-362

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La pêche dans les eaux vaudoises du lac Léman     

Gilbert Matthey lic. nat. 《Aquatic Sciences - Research Across Boundaries》1975,37(2):200-212

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Four Major Strike-slip Faults on the Moon     

Gilbert Fielder 《Geophysical Journal International》1963,8(2):187-195

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Sediment community metabolism associated with continental shelf hypoxia, Northern Gulf of Mexico   总被引：1，自引：0，他引：1  

Gilbert T. Rowe  Marta Elizabeth Cruz Kaegi  John W. Morse  Gregory S. Boland  Elva G. Escobar Briones 《Estuaries and Coasts》2002,25(6):1097-1106

Net fluxes of respiratory metabolites (O₂, dissolved inorganic carbon (DIC), NH₄ ⁺, NO₃ ^?, and NO₂ ^?) across the sediment-water interface were measured using in-situ benthic incubation chambers in the area of intermittent seasonal hypoxia associated with the Mississippi River plume. Sulfate reduction was measured in sediments incubated with trace levels of³⁵S-labeled sulfate. Heterotrophic remineralization, measured as nutrient regeneration, sediment community oxygen consumption (SOC), sulfate reduction, or DIC production, varied positively as a function of temperature. SOC was inversely related to oxygen concentration of the bottom water. The DIC fluxes were more than 2 times higher than SOC alone, under hypoxic conditions, suggesting that oxygen uptake alone cannot be used to estimate total community remineralization under conditions of low oxygen concentration in the water column. A carbon budget is constructed that compares sources, stocks, transformations, and sinks of carbon in the top meter of sediment. A comparison of remineralization processes within the sediments implicates sulfate reduction as most important, followed by aerobic respiration and denitrification. Bacteria accounted for more than 90% of the total community biomass, compared to the metazoan invertebrates, due presumably to hypoxic stress.  相似文献   

Petrographic and trace element analysis of uranium-rich tufa calcite, middle Miocene Barstow Formation, California, USA     

Jennifer M. Cole  E. Troy Rasbury†  Isabel P. Montañez‡  Vicki A. Pedone§  Antonio Lanzirotti¶  Gilbert N. Hanson† 《Sedimentology》2004,51(3):433-453

An integrated petrographic and spectroscopic (X‐ray diffraction, phosphor imaging and synchrotron X‐ray absorption spectroscopy) study of tufas from the Miocene Barstow Formation, California, relates sample morphology, mineralogy and geochemical composition. The tufas, composed mainly of calcite that formed at the interface between an ancient alkaline lake and ground or spring waters, have textures similar to those of microbially mediated terrestrial stromatolites and travertines. The tufas have elevated concentrations of a number of trace elements including Mn, Fe, Sr and U. Synchrotron X‐ray fluorescence analyses show that U concentrations can exceed 500 p.p.m. X‐ray absorption spectroscopy indicates that the U in these samples is incorporated as U(IV). It is suggested here that alkaline lake waters had a high U/Ca ratio and tufa calcite formed where groundwater or (possibly epithermal) springs brought in Ca and trace elements such as Sr. The rapid, and possibly microbially mediated, precipitation of calcite allowed for incorporation of high concentrations of trace metals as either structural substitutes or extremely fine‐scale inclusions.  相似文献