The use of mercury vs. cerium in recognising seismically induced fluid overprints on weathered profiles

Abstract Reconnaissance whole-rock analyses for Hg and Ce in weathered Mn-oxide-rich rocks from the Quadrilatero Ferrifero, Minas Gerais, Brazil, show a positive linear correlation. In contrast, manganiferous duricrusts from lateritic profiles in south-western Amazonia, Brazil, have no Hg–Ce correlation. Considering the presence fault-related rock fabrics in the former, such as slickenside striae, breccias and veinlets, and the Hg sensitivity to seismic activity, as well as the adsorption of aqueous Ce onto Mn-oxide precipitates, it is proposed that the positive Hg–Ce correlation can be used as an indicator of seismically induced, low-temperature hydrothermal fluid flow in the weathering zone.