δ18O
Sign in to saveIn geochemistry, paleoclimatology and paleoceanography '''δ18O or delta-O-18''' is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O). It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis. In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy for temperature.
Article
8 sectionsContents
- Mechanism
- Extrapolation of temperature
- Paleoclimatology
- Deep-sea Sediments
- Ice cores
- Biomineralized tissues
- See also
- References
In geochemistry, paleoclimatology and paleoceanography '''δ18O or delta-O-18''' is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O). It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis. In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy for temperature.
It is defined as the deviation in "per mil" (‰, parts per thousand) between a sample and a standard: \delta \ce{^{18}O} = \left( \frac{\left( \frac\ce{^{18}O}\ce{^{16}O} \right)_\mathrm{sample}}{\left( \frac\ce{^{18}O}\ce{^{16}O} \right)_\mathrm{standard}} - 1 \right) \times 1000 ‰ where the standard has a known isotopic composition, such as Vienna Standard Mean Ocean Water (VSMOW). The fractionation can arise from kinetic, equilibrium, or mass-independent fractionation.