(Table 3) Chemical composition of phosphatized rocks from the Kammu Seamount

Phosphatized biogenic limestones and phosphorites with initial Fe-Mn mineralization dredged from the summit surface of the Kammu Seamount (Milwaukee Seamounts, northwestern Pacific) are studied. The rocks are largely composed of nannofossils and planktonic foraminifers with an admixture of benthic foraminifers, bryozoans, and other organic remains, presumably including bacterial ones. The nannofosssil and foraminiferal assemblages indicate Quaternary age of sediments, and their phosphatization is consistent with the phosphatization age determined previously based on nonequilibrium uranium (within the limits of 1 My). The age of phosphatization and the Fe-Mn mineralization in the sediments from Pacific seamounts that young implies dependence of these ore-forming processes on oceanic environments favorable for ore accumulation rather than on their age.

Año Internacional de la Francofonía 2006 : Léopold-Sédar Senghor: un carrefour de culturas

2006 ha sido declarado el Año Internacional de la Francofonía, puesto que se cumplen veinte años desde su institucionalización. La puesta en marcha de la misma se realizó durante la gestión presidencial de François Mitterand. 2006 coincide igualmente con el centenario del natalicio del senegalés Léopold-Sédar Senghor (1906-2001), hombre visionario, pionero en la defensa de la diversidad cultural y del respeto de la alteridad. El nuevo milenio parece signado por una creciente intolerancia cultural a nivel planetario. Con este trabajo nos hemos propuesto dos objetivos medulares. En primer lugar, recordar y difundir la trayectoria del presidente-poeta, uno de los artífices mayores de un concepto reciente: la Francofonía. En segundo término, mostrar los nuevos desafíos de la Francofonía, entendida ésta como una alternativa válida para el diálogo de culturas y la tolerancia.

Geochemistry of oceanic arc basement rocks of Sumisu Rift and Ohmachi Seamount

Prehnite-pumpellyite facies metamorphism is described in the oceanic-arc basement rocks of Ocean Drilling Program Leg 126, Site 791 in the Sumisu Rift, western Pacific. Chemical variations of pumpellyite, epidote, chlorite, and prehnite are examined and paragenetic relations discussed. The metamorphism took place during the pre-rifting stage of an intraoceanic arc. During the backarc rifting stage, the geothermal gradient of the area was not as high as that of a spreading mid-oceanic ridge.