240 Deep-Sea Sediments - Patterns, Processes, and Stratigraphic Methods
Why do strontium isotopes change in the fashion observed? Presumably, the trend
stems from a decrease of basaltic sources of strontium (ratios near 0.702 to 0.703)
relative to continental sources (ratios from 0.705 to> 0.712). The reason, it may be
assumed, is an overall emergence of continents due to mountain-building since the
late Eocene, as well as a decrease in oceanic volcanism.
8.7.5 Cyclostratigraphy. The discovery that pelagic sediment properties show regular fluctuations with periods close to astronomical ones (as shown by spectral analysis: J. Hays, J. Imbrie, N. Shackleton, 1976; N. Pisias, 1976) opened the way for a
new dating method: counting of astronomical cycles within a record, extracted by
Fourier analysis. The method yields floating chronologies (unless tied into other
fixpoints). It has yielded valuable results, especially in Quaternary sediments. We
shall encounter the various cycles in Chapter 9, when discussing Quaternary sediments.
Further Reading
Hill MN (ed) (1963) The sea, Ideas and obseIVations on progress in the study of the seas, vol 3.
Interscience, New York
Lisitzin AP (1972) Sedimentation in the world ocean. SEPM Spec Publ 17, Soc Econ Paleontol
Mineral Tulsa, Okla
Hsii KJ, Jenkyns H (eds) (1974) Pelagic sediments on land and under the sea. Spec Publ Int Assoc
Sedimentol 1
Bolli HM, Saunders JB, Perch-Nielsen K (eds) (1985) Plankton stratigraphy. Cambridge Univ Press,
New York
Chester R (1990) Marine geochemistry. Unwin Hyman, London
Why do strontium isotopes change in the fashion observed? Presumably, the trend
stems from a decrease of basaltic sources of strontium (ratios near 0.702 to 0.703)
relative to continental sources (ratios from 0.705 to> 0.712). The reason, it may be
assumed, is an overall emergence of continents due to mountain-building since the
late Eocene, as well as a decrease in oceanic volcanism.
8.7.5 Cyclostratigraphy. The discovery that pelagic sediment properties show regular fluctuations with periods close to astronomical ones (as shown by spectral analysis: J. Hays, J. Imbrie, N. Shackleton, 1976; N. Pisias, 1976) opened the way for a
new dating method: counting of astronomical cycles within a record, extracted by
Fourier analysis. The method yields floating chronologies (unless tied into other
fixpoints). It has yielded valuable results, especially in Quaternary sediments. We
shall encounter the various cycles in Chapter 9, when discussing Quaternary sediments.
Further Reading
Hill MN (ed) (1963) The sea, Ideas and obseIVations on progress in the study of the seas, vol 3.
Interscience, New York
Lisitzin AP (1972) Sedimentation in the world ocean. SEPM Spec Publ 17, Soc Econ Paleontol
Mineral Tulsa, Okla
Hsii KJ, Jenkyns H (eds) (1974) Pelagic sediments on land and under the sea. Spec Publ Int Assoc
Sedimentol 1
Bolli HM, Saunders JB, Perch-Nielsen K (eds) (1985) Plankton stratigraphy. Cambridge Univ Press,
New York
Chester R (1990) Marine geochemistry. Unwin Hyman, London