Statistical recognition of late Cretaceous cyclic sedimentation by means of calcareous nannofossil population studies

The relative abundance of calcareous nannofossil taxa in a sequence of samples collected from a continuous Upper Maastrichtian section in Alabama has been analyzed using statistical techniques. Results indicate that an increase of arbitrarily chosen long-ranging forms can be represented by a slowly fluctuating secular trend with a superimposed cyclical component. Provided that a number of reasonable assumptions are made, the dominant frequencies of the periodic component are within the order of magnitude of the accepted frequency of the Perihelion cycle or “Milenkovitch astronomical insolation curves” (Milenkovitch, 1938).