U.S.-France Cooperative Research: Oxygen and Hydrogen Isotope Geochemistry of Laterites

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This two-year award supports U.S.-France cooperative research involving Samuel Savin and Jean-Pierre Girard of Case Western Reserve and Daniel Nahon of the University of Aix-Marseille III. The investigators propose to apply isotopic techniques to the study of laterites, which are tropical soils that cover a substantial portion of the earth. The objectives of their cooperation involve analyzing oxygen and hydrogen ratios of minerals in well-characterized, active laterites found in Brazil. Drs. Savin and Girard bring to the collaboration their extensive experience in stable isotope studies of clays and related minerals in geologic materials of low temperature origin. This is complemented by the French investigator's expertise in problems of soil genesis and geochemistry of laterite weathering. They will jointly collect laterite samples found in the Amazon Basin in Brazil and conduct laboratory analysis. Laterites offer one of the best prospects to obtain information about ancient climates. Using stable isotopes studies, the investigators propose to determine both paleotemperatures and isotopic values of ancient rainfall as recorded in the mineral content of the laterites. The results will be important to research into the use of stable isotopes for paleoclimatic reconstructions. Knowledge about these ancient climatic factors particularly rainfall in tropical regions will advance our understanding of the link between change in equatorial rainfall patterns and global climate change.