Cretaceous-Tertiary ichthyoliths of brown clay intervals

The pattern of ichthyolith distribution established in sequences with stratigraphies based on calcareous or siliceous microfossils is used to provide age correlations for three deep-sea pelagic clay intervals that lack the better known microfossils. At Site 637, approximately 25 m of brown clay in Cores 103-637A-21R through 103-637A-23R underlies upper Miocene sediments and is of Paleocene to early Eocene age. At Site 639, 1.7 m of brown clay in Core 103-639C-2R is Eocene to Oligocene. At Site 640, 3.5 m of clay in Cores 103-640A-1R and 103-640A-2R contains a Cretaceous to Paleocene sequence, with the Cretaceous/Tertiary boundary between 84 and 103 cm in Section 103-640A-2R-1.