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We correlated Miocene δ 1 θ increases at Ocean Drilling Program Site 747 with δ 1 θ increases previously identified at North Atlantic Deep Sea Drilling Project Sites 563 and 608. The δ 1 θ increases have been directly tied to the Geomagnetic Polarity Time Scale (GPTS) at Site 563 and 608, and thus our correlations at Site 747 provide a second-order correlation to the GPTS. Comparison of the oxygen isotope record at Site 747 with records at Sites 563 and 608 indicates that three as-yet-undescribed global Miocene δ 1 θ increases may be recognized and used to define stable isotope zones. The δ 1 8 θ maxima associated with the bases of Zones Mila, Milb, and Mi7 have magnetochronologic age estimates of 21.8, 18.3, and 8.5 Ma, respectively. The correlation of a δ 1 8 θ maximum at 70 mbsf at Site 747 to the base of Miocene isotope Zone Mi3 (13.6 Ma) provides a revised interpretation of four middle Miocene normal polarity intervals observed between 77 and 63 mbsf at Hole 747A. Oxygen isotope stratigraphy indicates that the reversed polarity interval at 70 mbsf, initially interpreted as Chronozone C5AAr, should be C5ABr. Instead of a concatenated Chronozone C5AD-C5AC with distinct Chronozones C5AB, C5AA, and C5A (as in the preliminary interpretation), δ 1 8 θ stratigraphy suggests that these normal polarity intervals are Chronozones C5AD, C5AC, and C5AB, whereas Chronozones C5AA-C5A are concatenated. This interpretation is supported by the δC correlations. The upper Miocene magnetostratigraphic record at Hole 747A is ambiguous. Two upper Miocene δ 1 8 θ events at Site 747 can be correlated to the oxygen isotope records at Site 563 and 608 using the magnetostratigraphy derived at Hole 747B. Our chronostratigraphic revisions highlight the importance of stable isotope stratigraphy in attaining an integrated stratigraphic framework for the Miocene. PRINCIPLES OF STABLE ISOTOPE STRATIGRAPHY Variations in foraminifer δ 1 θ records are used widely for Pleistocene stratigraphic correlations and are potentially useful for pre-Pleistocene correlations (Shackleton and Opdyke, 1973; Imbrie et al., 1984; Ruddiman et al., 1986; Williams et al., 1988). Following the pioneering work of Emiliani (1955), Shackleton and Opdyke (1973) designated 22 late Pleistocene δ 1 8 θ cycles as "stages." (In view of changes in stratigraphic nomenclature [Hedberg, 1976; North American Commission on Stratigraphic Nomenclature, 1983], these cycles should now be termed chrons, not stages, when referencing time, or chronozones when referencing sections.) Hays et al. (1976) established that late Pleistocene (0-700 Ka) δ 1 θ fluctuations occurred with regular astronomical (Milankovitch) periodicities. Knowing the astronomical forcing allowed Imbrie et al. (1984) to correlate by "tuning" δ 1 8 θ records to Milankovitch periodicities. Imbrie et al. (1984) produced the SPECMAP δ 1 θ time scale, which is the standard for late Pleistocene marine correlations. This time scale provides correlations with relative accuracy of 5 k.y. (Imbrie et al., 1984). Ruddiman et al. (1986), Williams et al. (1988), and Joyce et al. (1990) extended the late Pleistocene "stages" into the early Pleistocene, but their numbering schemes are mutually exclusive (Williams et al., 1988, fig. 15). The possibility of using high-resolution (I0—10 yr) oxygen isotope stratigraphy for 1 Wise, S. W., Jr., Schlich, R., et al., 1992. Proc. ODP, Sci. Results, 120: College Station, TX (Ocean Drilling Program). 2 Lamont-Doherty Geological Observatory and Department of Geological Sciences, Columbia University, Palisades, NY 10964, U.S.A. 3 Department of Geological Sciences, Rutgers University, New Brunswick, NJ 08903, U.S.A., and Lamont-Doherty Geological Observatory, Columbia University, Palisades, NY 10964, U.S.A. pre-Pleistocene correlations was suggested by Ruddiman et al. (1986). Following this lead, Raymo et al. (1988) used highresolution δ θ stratigraphy to correlate upper Pliocene sections from Deep Sea Drilling Project (DSDP) Sites 552 and 607 in the North Atlantic with sections from Ocean Drilling Program (ODP) Site 677 in the eastern equatorial Pacific. Keigwin et al. (1987) similarly noted that high-frequency δ θ changes occurred at Site 552 in the late Miocene. Pisias et al. (1985) observed that high-frequency δ θ fluctuations occurred in the middle Miocene in the equatorial Pacific at DSDP Site 574. If these high-frequency δ 1 θ changes are global, then they have potential for high-resolution stratigraphic correlations. It has proven difficult to develop a high-resolution (104-105 yr) δ 1 θ stratigraphic scheme for the pre-Pliocene because of problems in sampling resolution and stratigraphic correlations. In fact, first-order (m.y. scale) structures are still being identified in the Cenozoic δ 1 θ record. Although the general nature of the Cenozoic δ 1 θ record was identified by Shackleton and Kennett (1975) and Savin et al. (1975), there are many stable isotope events on the m.y. scale that are only now being recognized. For example, Miller and Fairbanks (1985) and Miller et al. (1989) identified a distinct δ 1 θ increase near the Oligocene/Miocene boundary that was previously unknown because of poor sampling in this interval. Recent studies have shown that stable isotope records can be used to improve pre-Pliocene correlations on the m.y. or finer scale. The key to establishing a stable isotope stratigraphic framework is a firm chronology in the reference section. We have suggested that magnetostratigraphy provides the best chronology for Miocene reference sections, and that stable isotope records must be tied directly to the GPTS (Miller et al., 1985, 1989, 1991a, 1991b). Correlating δ θ records from different oceans to polarity patterns establishes synchrony, while it also allows absolute ages to be assigned to identified events.

Miocene Stable Isotope Stratigraphy, Site 747, Kerguelen Plateau