[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54952

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, armée française] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54953

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, véhicules blindés] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54954

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, armée française] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54956

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, un maréchal à cheval et l'armée française] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54957

[Défilé du 14 juillet 1919, l'Arc de triomphe de l'Etoile et la foule] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54958

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, l'armée française] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54959

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, Joffre et Foch précédant la cavalerie] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54960

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, les blessés de guerre] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54961

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, cavaleries] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54963

[Défilé du 14 juillet 1919 passant sous l'Arc de triomphe de l'Etoile, la cavalerie française] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54977

[Dépôt de gerbes de fleurs en l'honneur des morts de la guerre 1914-1918, au pied du cénotaphe sous l'arc de triomphe de l'Etoile, 13 juillet 1919] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54889

High precision U/Pb zircon dating of the Chalten Plutonic Complex (Cerro Fitz Roy, Patagonia) and its relationship to arc migration in the southernmost Andes

We report new high-precision U/Pb ages and geochemical data from the Chalten Plutonic Complex to better understand the link between magmatism and tectonics in Southern Patagonia. This small intrusion located in the back-arc region east of the Patagonian Batholith provides important insights on the role of arc migration and subduction erosion. The Chalten Plutonic Complex consists of a suite of calc-alkaline gabbroic to granitic rocks, which were emplaced over 530 kyr between 16.90 +/- 0.05 Ma and 16.37 +/- 0.02 Ma. A synthesis of age and geochemical data from other intrusions in Patagonia reveals (a) striking similarities between the Chalten Plutonic Complex and the Neogene intrusions of the batholith and differences to other back-arc intrusions such as Torres del Paine (b) a distinct E-W trend of calc-alkaline magmatic activity between 20 and 17 Ma. We propose that this trend reflects the eastward migration of the magmatic arc, and the consistent age pattern between the subduction segments north and south of the Chile triple junction suggests a causal relation with a period of fast subduction of the Farallon-Nazca plate during the Early Miocene. Previously proposed flat slab models are not consistent with the present location and morphology of the Southern Patagonian Batholith. We advocate, alternatively, that migration of the magmatic arc is caused by subduction erosion due to the increasing subduction velocities during the Early Miocene.

Chemical and isotopic equilibrium between CO2 and CH4 in fumarolic gas discharges: Generation of CH4 in arc magmatic-hydrothermal systems

The chemical and isotopic composition of fumarolic gases emitted from Nisyros Volcano, Greece, and of a single gas sample from Vesuvio, Italy, was investigated in order to determine the origin of methane (CH,) within two subduction-related magmatic-hydrothermal environments. Apparent temperatures derived from carbon isotope partitioning between CH4 and CO2 of around 340degreesC for Nisyros and 470degreesC for Vesuvio correlate well with aquifer temperatures as measured directly and/or inferred from compositional data using the H2O-H-2-CO2-CO-CH4 geothermometer. Thermodynamic modeling reveals chemical equilibrium between CH4, CO2 and H2O implying that carbon isotope partitioning between CO2 and CH, in both systems is controlled by aquifer temperature. N-2/(3) He and CH4/(3) He ratios of Nisyros fumarolic gases are unusually low for subduction zone gases and correspond to those of midoceanic ridge environments. Accordingly, CH4 may have been primarily generated through the reduction of CO, by H, in the absence of any organic matter following a Fischer-Tropsch-type reaction. However, primary occurrence of minor amounts of thermogenic CH4 and subsequent re-equilibration with co-existing CO2 cannot be ruled out entirely- CO2/He-3 ratios and delta(13)C(CO2) values imply that the evolved CO2 either derives from a metasomatized mantle or is a mixture between two components, one outgassing from an unaltered mantle and the other released by thermal breakdown of marine carbonates. The latter may contain traces of organic matter possibly decomposing to CH4 during thermometamorphism. Copyright (C) 2004 Elsevier Ltd.