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Astronomical calibration of the late Oligocene through early Miocene Geomagnetic Polarity Time Scale
No full textAt Ocean Drilling Program (ODP) Site 1090 (subantarctic South Atlantic), benthic foraminiferal stable isotope data (from Cibicidoides and Oridorsalis) span the late Oligocene through early Miocene (~24–16 Ma) at a temporal resolution of ~5 ky. Over the same interval, a magnetic polarity stratigraphy can be unequivocally correlated to the geomagnetic polarity time scale (GPTS), thereby providing direct correlation of the isotope record to the GPTS. In an initial age model, we use the newly derived age of the Oligocene/Miocene (O/M) boundary of 23.0 Ma of Shackleton et al. [Geology 28 (2000) 447], revised to the new astronomical calculation (La2003) of Laskar et al. [Icarus (in press)] to recalculate the spline ages of Cande and Kent [J. Geophys. Res. 100 (1995) 6093]. We then tune the Site 1090 18O record to obliquity using La2003. In this manner, we are able to refine the ages of polarity chrons C7n through C5Cn.1n. The new age model is consistent, within one obliquity cycle, with previously tuned ages for polarity chrons C7n through C6Bn from Shackleton et al. [Geology 28 447–450 (2000)] when rescaled to La2003. The results from Site 1090 provide independent evidence for the revised age of the Oligocene/Miocene boundary of 23.0 Ma. For early Miocene polarity chrons C6AAr through C5Cn, our obliquity-scale age model is the first to allow a direct calibration to the GPTS. The new ages are generally within one obliquity cycle of those obtained by rescaling the Cande and Kent [J. Geophys. Res. 100 (1995) 6093] interpolation using the new age of the O/M boundary (23.0 Ma) and the same middle Miocene control point (14.8 Ma) used by Cande and Kent [J. Geophys. Res. 100 (1995) 6093]
(Appendix B) Stable isotope ratios of Globigerinoides trilobus and Nuttallides umbonifer of ODP Site 154-925 from the Ceara Rise, western tropical Atlantic
No full textAge model from Shackleton and Crowhurst (1997)
(Appendix A, Table 1, 2) Stable isotope ratios of Menardella multicamerata and Menardella limbata of ODP Site 154-925 from the Ceara Rise, western tropical Atlantic
No full textAge model from Shackleton and Crowhurst (1997). Analysed size fraction 300-355 µm, 30 specimens per analysi
(Table 1) Oxygen and carbon isotopic composition of Globigerina altispira in DSDP Site 30-289, Western Equatorial Pacific
No full text(Table 1) Oxygen and carbon isotopic composition of Globigerina altispira in DSDP Site 30-289, Western Equatorial Pacifi
(Table 2) Oxygen and carbon isotopic composition of benthic and planktic foraminifera of samples from DSDP Site 30-289 in core 55, Western Equatorial Pacific
No full text(Table 2) Oxygen and carbon isotopic composition of benthic and planktic foraminifera of samples from DSDP Site 30-289 in core 55, Western Equatorial Pacifi
Stable isotope analysis on sediment core RC11-86
No full textOxygen isotope measurements have been made in foraminifera from over 60 deep-sea sediment cores. Taken together with the oxygen isotope measurements published by Emiliani from Caribbean and Equatorial Atlantic cores, this comprises a unique body of stratigraphic data covering most of the important areas of calcareous sediment over the whole world ocean. The oxygen isotopic composition of foraminifera from cores of Late Pleistocene sediment varies in a similar manner in nearly all areas; the variations reflect changes in the oxygen isotopic composition of the ocean. The oceans are mixed in about 1 ka so that ocean isotopic changes, resulting from fluctuations in the quantity of ice stored on the continents, must have occurred almost synchronously in all regions. Thus the oxygen isotope record provides an excellent means of stratigraphic correlation. Cores accumulated at rates of over about 5 cm/ka provide records of oxygen isotopic composition change that are almost unaffected by post-depositional mixing of the sediment. Thus they preserve a detailed record of the advance and retreat of the ice masses in the northern hemisphere, and provide a unique source of information for the study of ice-sheet dynamics
(Appendix D) Isotopic analyses of planktonic foraminifers at DSDP Leg 74 Holes
No full textSediment depth is given in mbsf. Ages are estimated as described in Shackleton et al. 1984 (doi:10.2973/dsdp.proc.74.117.1984)
(Appendix C) Adjusted isotopic analyses of benthic foraminifers at DSDP Leg 74 Holes
No full textSediment depth is given in mbsf. If more than one analysis was made, a mean was taken. Ages are estimated as described in Shackleton et al. 1984 (doi:10.2973/dsdp.proc.74.117.1984)
(Table 5) Depth and age series used for time-series analysis of ODP Site 138-846 in the eastern equatorial Pacific
No full textFor each sample in the sequence the adjusted delta18O and delta13C measurements are averaged. Depth mbsf and rmcd are given with age derived using the age model of Shackleton et al. (1995, data set doi:10.1594/PANGAEA.696452
(Table 6) Stable carbon and oxygen isotope ratios of Uvigerina peregrina from sediment core Y71-06-12 in the Atlantic Ocean
No full text(Table 6) Stable carbon and oxygen isotope ratios of Uvigerina peregrina from sediment core Y71-06-12 in the Atlantic Ocea
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