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Glossary 1) δ18O (Oxygen isotope ratio) Oxygen has three stable isotopes, 16O, 17O, and 18O. Because these isotopes have different density, isotopic fractionation can occur such as when seawater evaporates or during precipitation. Because precipitation and isotopic fractionation are temperature dependent, the δ18O variations can be linked to temperature and climatic change. By using this characteristic, paleotemperatures have been deduced from analysis of deep-sea sediments and ice sheets in Antarctica and Greenland. 2) Pollen analysis, Modern Analogue Technique (MAT) Pollen analysis is a method used to estimate paleo-environments (vegetation) by statistical analysis of the pollen composition in sedimentary deposits. Pollen is very useful for this purpose because it has strong resistance to weathering, and is well preserved even in old deposits. The Modern Analogue Technique method of statistical analysis is based on the relationship between modern vegetation and climate. By using this technique, the past temperature and the past precipitation can be estimated quantitatively. - BACK - |
