Notícies
27.05.2014
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El Dr. Javier García Veigas, responsable de la Tecnologia de Microscòpia Electrònica de Rastreig dels CCiTUB, ha publicat “Analyses of fluid inclusions in Neoproterozoic marine halite provide oldest measurement of seawater chemistry” a la revista Geology. L’estudi ha estat realitzat amb la tècnica Cryo-SEM-EDS. Els CCiTUB són un referent mundial en l’ús d’aquesta tècnica per l’estudi de la composició de l’aigua de mar en el passat geologic a partir de l’anàlisi d’inclusions fluids en formacions salines. El resum de l'article és el següent: “We analyzed primary fluid inclusions in halite from marine evaporites in the ca. 830 Ma Browne Formation of the Officer Basin in Western Australia using the cryogenic scanning electron microscopy–energy dispersive X-ray spectrometry analysis technique. The concentrations of the major ions, except K+ and possibly SO42−, fall within the range of Phanerozoic seawater. This is the first direct measurement of the composition of mid-Neoproterozoic seawater, and extends present-day knowledge of seawater chemistry by ∼300 m.y. Our estimates suggest that mid-Neoproterozoic marine sulfate concentrations were lower (∼90%) than modern values. By the terminal Neoproterozoic, fluid inclusions in halite and evaporite mineralogy indicate seawater sulfate levels rose significantly, to 50%–80% of modern concentrations, which parallels increases in atmospheric and oceanic oxygen.” | |