The Neogene astronomical tuned (polarity) timescale between 5 and 14 Ma revisited

The characteristic cyclic sedimentary sequence of ODP Leg 154 Sites 925-929 from the Ceara Rise in the western equatorial Atlantic allowed the construction of an astronomical-tuned geologic time scale for the entire Neogene (Shackleton et al. 1999). During the Leg it became already apparent that the splice of Site 926 contains some complications, which could affect the orbital tuning and hence the paleoclimatic interpretation of the record (Shackleton et al. 1997). This record is of major importance for biostratigraphic and paleoclimatologic investigations and, together with Mediterranean land-based sections, forms the backbone of the standard Neogene Geologic Time Scale (Lourens et al. 2004). We revisited the Ceara Rise physical property records and established a revised splice and orbital tuning, using the La2004 solution (Laskar et al. 2004). In addition, we evaluated the tuning by applying different values for the tidal dissipation parameter of the Earth-Moon system. According to our new tuning results, the eccentricity pattern of the physical property records resembles the orbital eccentricity very well; biostratigraphic datums differ from the initial tuning in the order of 100 kyr from ca. 10.5 to 11.2 and ca. 13.4 to 13.7 Ma. Finally, we compared our revised time scale with new data of the tuned Monte dei Corvi section in the Mediterranean, which contained a reliable magnetostratigraphy. This allowed us to improve the accuracy of magnetic reversals ages between 5 and 14 Ma