Slide 11: Proxy data sources: Oceanic sediments
Calcareous plankton such as foraminifera and coccolithophores express preferential uptake of O18 under cool conditions. Through isotopic analysis of sedimentary deposits of these plankton, the temperature of the water at the time of deposition can be assessed. (Urey, 1948).
Species assemblages show variation in the number of warm- and cold-water plankton species. (Williams & Johnson, 1975)
Morphological variations are expressed by a number of species in response to climatic variables. (Kennett,1976).
The content of terrigeneous material in sediments corresponds to continental weathering. Consequently, the purity of the calcareous ooze gives a strong indication of the extent of weathering to which the continents were subjected, and therefore the intensity of the climatic processes. (Hays & Perruzza,1972).
The physical and chemical processes affecting inorganic sediments before deposition correspond to particular climate regimes, and are evidenced by the form of the inorganic sediments. (Kolla et al., 1979).
Hays, J.D. & Perruzza, A., 1972. The significance of calcium carbonate oscillations in eastern equitorial Atlantic deep-sea sediments for the end of the Holocene warm interval. Quat. Res., 2, pp. 335-362.
Kennett, J.P., 1976. Phenotypic variation in some recent and late Cenozoic planktonic foraminifera. In: Foraminifera, Vol. 2, Hedley, R.H. & Adams, C.G. (eds.), Academic Press, New York, pp. 111-170.
Kolla, V., Biscaye, P.E. & Hanley, A.F., 1979. Distribution of quartz in late Quaternary Atlantic sediments in relation to climate. Quat. Res., 11, pp. 261-277.
Urey, H.C., 1948. Oxygen isotopes in nature and in the laboratory. Science, 108, pp. 489-496.
Williams, D.F. & Johnson, W.C., 1975. Diversity of recent planktonic foraminifera in the southern Indian Ocean and late Pleistocene temperatures. Quat. Res., 5, pp. 237-250.