Oxygen Isotope Stratigraphy

Variations in the 18O/16O ratio of marine fossils and microfossils record changes in seawater 18O/16O and temperature and provide the basis for global correlation. Based on more than 64,000 measurements, this chapter presents oxygen isotope curves for Phanerozoic foraminifera, mollusks, brachiopods, and conodonts, as well as for Precambrian limestones, dolostones, and cherts. Periodic oxygen isotopic variations in deep-sea foraminifera define marine isotope stages that, when combined with biostratigraphy and astronomical tuning, provide a late Cenozoic chronostratigraphy with a resolution of several thousand years. Oxygen isotope events of late Cenozoic, Mesozoic, and Paleozoic age mark local and global climate change and serve as chemostratigraphic markers for regional and global correlation. Precambrian oxygen isotope stratigraphy is hampered by the lack of unaltered authigenic marine carbonate and phosphate.