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Journals and Conferences
A study of the evolution of the oxygen-18/oxygen-16 ratio of the oceans suggests that this ratio is unlikely to have remained constant with time. Our models suiggest that early formation of the oceans is more likely than linear growth.
Oxygen-18-oxygen-16 fractionation of coexisting quartz and magnetite from the Biwabik iron formation varies as a function of distance of the sample from an intrusive contact. This isotope fractionation is related to observed mineralogic variations and compared with a theoretical heat-flow model.
A freshwater lens underlain by saltwater exists beneath the entire northern Yucatan karst plain, Mexico. Water levels recorded in this plain, during the period June 1987 April, 1989, were used to map the water table, identify inland hydrogeologic boundaries, and estimate the thickness of the freshwater lens using the Ghyben-Herzberg relation. The water… (More)
Strontium isotope chemistry, presented here, combined with previously obtained groundwater ion chemistry elucidates the stratigraphy of buried sedimentary rocks of the southern Yucatan Peninsula, Mexico. Whereas in groundwater of the northern Peninsula, ion chemistry is dominated by contact with a saline intrusion, the groundwater of southern Campeche and… (More)
Sedimentary barites from the Swaziland System of South Africa (more than 3000 million years old) have sulfur-34 ratios that are enriched by only 2.5 per mil with respect to contemporary sulfides. To explain this small fractionation, it is proposed that oxygen pressure in the earth's atmosphere was very low and that local oxidation occurred in a… (More)
Oxygen, carbon, and strontium isotope variations in vein-filling calcite and quartz cements and their host rocks are used to elucidate the origin, spatial and temporal evolution, and migration pathways of fluids in the detachment Nuncios fold complex, northeastern Mexico. The folded Mesozoic sedimentary sequence contains two regional paleohydrostratigraphic… (More)