Stratigraphic resolution and calcareous nannofossil age datums derived for the Leg 170 calcareous nannofossil record have been determined by applying the global calcareous nannofossil extinction event (last occurrence datum [LOD]), global appearance event (first occurrence datum [FOD]), and paleomagnetic datums as outlined in Berggren et al. (1995a, 1995b). In addition, the standard calcareous nannoplankton zones of Martini (1971), Bukry (1973b, 1975), and Okada and Bukry (1980) have been determined for the calcareous nannofossil distribution recorded from the Leg 170 cores (Tables T1, in PDF format; T2, in PDF format; T3, in PDF format; T4, in PDF format; T5, and T6, in PDF format;). The comprehensive correlation between the nannofossil zones of Martini (1971) and Bukry (1973b, 1975) used in this study and the astronomical/geomagnetically derived chronologic scale of Berggren et al. (1995a, 1995b) is shown in Figure F5 for the Pleistocene and Pliocene and Figure F6 for the Miocene.
In this study, the last observed occurrence of a particular species is called its top and the first observed occurrence of a particular species is called its bottom. Top and bottom are used because paleontologists generally work cores downsection, thus observing the top of a species range first and the bottom of the range farther down the core. In all of our cored intervals, it is unknown whether the actual first occurrence (new species introduction) or actual last occurrence (extinction) of an index fossil has been observed. Nevertheless, for the purposes of reporting an absolute date to a particular top or bottom, the LOD or FOD of the species will be reported. The ages of the bottom or top of the observed ranges of calcareous nannofossil species identified in this study are outlined in Table T7.