Isotopic stratigraphy

Isotopic stratigraphy is based on the study of isotopes, especially carbon and oxygen isotopes. This technique can be used to study variations in temperature, salinity and volume of masses of ice in time. Generally,  planktonic and benthonic foraminifera living in the surface layers of the sea or in sea sediments, are studied. After treating the organisms with the help of a specific instrument, the isotopic ratio of “heavy” oxygen-18 and normal oxygen-16, contained in the calcite shells of the foraminifera, is measured. If the calcite shows an isotopic equilibrium with the sea water, the ratio of the two oxygen isotopes varies with the precipitation temperature of the calcite. Therefore an increase in the isotopic equilibrium of the oxygen in a carbonate indicates a drop in the temperature, while a decrease in the same indicates a rise in temperature. Simplifying, it is therefore possible to trace the periodic fluctuations of the climate in time.

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    ecosystems

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    air

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    Icebergs, ice packs and glaciers

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    Mean sea level rise foreseen by IPCC

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