980 resultados para 141-862
Resumo:
Fil: Zecchin de Fasano, Graciela Cristina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
Resumo:
Core recovered from Hess Rise contains concentrations of pyrite, marcasite, and barite in the lowermost meter of limestone (Unit II) and in the brecciated upper part of the underlying volcanic basement (Unit HI). Petrographic and chemical data indicate that the sulfide-barite assemblage in the limestone is mainly a product of low-temperature diagenetic processes. The iron-sulfide phases are biogenic and their concentrations mark the diffusion of sea water sulfate through sedimentary horizons containing abundant organic matter and mafic, glassy volcanogenic detritus. There is some evidence, however, that elevated temperatures augmented or intensified the synsedimentary diagenetic process.