Plankton stratigraphy. Volume 1. Planktic foraminifera, calcareous nannofossils and calpionellids / Планктонная стратиграфия. Том 1. Планктонные фораминиферы, известковые наннофоссилии и кальпионеллиды

The last 15 years have been of vital importance in the history of the use of planktic microfossils for the dating of Cretaceous and Cenozoic deep sea sediments. During this time, the Glomar Chall eng er of the Deep Sea Drilling Project (DSDP) has drilled at a total of 624 sites in almost every ocean basin in the world and brought up Cenozoic and Mesozoic sediment cores from the great majority of them. As the oceans occupy 72% of the surface of the Globe, the results were bound to have a profound effect on geologic thinking. A review of some of the important findings of the first ten years of the project is given in Warme et a!. (1981).
Zonal schemes based on planktic foraminifera and calcareous nannofossils were well established and already proven in many land sections, both surface and subsurface, by the time the DSDP began in 1968. They provided the tool for the dating not only of the sedimentary sequences but also of the underlying oceanic crust that was reached at many of the sites. The latter dating has relied heavily on a knowledge of the age of the sediments immediately above the crust because direct dating of oceanic basalts has hardly ever proved possible. Magnetostratigraphy has lately developed into a most important tool but as a magnetic reversal has no unique signature, it has to be identified by other means - for example micropaleontologic - or be recognized in an established sequence that has previously been dated, perhaps by reference to a section on land that has radiometric tie-points.<...>