Diagénesis temprana de metales pesados en sedimentos del Pacífico adyacente a Ia boca del Golfo de California, Mexico

Abstract

Core sediments from two sites in the Mexican Pacific near the mouth of the Gulf of California, were studied to determine the geochemical partition of heavy metals. Five operationally defmed fractions were separated and the concentrations of Cd, Cu, Co, Cr. Fe, Mn, Ni, Pb and Zn were determined in each sample by atomic absorption. The results indicate a contrasting behaviour of the phases and elements associated during early diagenesis. The carbonated fraction in the core collected from the Mazatlan basin suggests the ,formation of siderite(FeC03) with sedimentary depth; Pb is present as accessory. A simple model explain the transfer of Mn and Fe from oxidizable and reducible to lithogenic (silicatealuminates) forms. As the sedimentary material is buried an exponential concordant change of metal contents in all three phases occurs.