APPENDIX C

The results of the present study and data from the most recent literature (Wei, 1993; Raffi et al., 1993; Rio, Raffi, et al., 1997) suggest the proposal of a new zonation for the Pleistocene and that the late Miocene zonation of Okada and Bukry (1980) needs to be adapted to be applied to the California Margin paleobiogeographic setting where many low-latitude marker species are missing or rare.

Pleistocene new zonal scheme

For the early and middle Pleistocene the following zones are proposed. Note that the alphanumerical code of Okada and Bukry (1980) has been maintained. The proposed biostratigraphic intervals have been ranked at zone level because they are virtually global. In addition, the nomenclature of the zones on the basis of the generally adopted taxonomy of Perch-Nielsen (1985) has been adjusted.

 

CN13a - Dictyococcites productus Zone

 

Definition: Interval between the LO of Discoaster brouweri and the FO of Gephyrocapsa oceanica s.l.

Occurrence: This zone has been recognized at most Leg 167 sites and can be recognized globally as demonstrated by the works of Gartner (1977); Rio (1982); Rio, Raffi, et al. (1990); Wei (1993); Raffi et al. (1993); and so on.

Remarks: The zone was introduced by Raffi and Rio (1979) and emended by Rio, Raffi, et al. (1990) for the Mediterranean area. It corresponds most probably to the Emiliania annula Subzone of Bukry (1973) and to the Coccolithus doronicoides Zone of Wise (1973).

 

CN13bA Gephyrocapsa caribbeanica Zone

 

Definition: Interval between the FO of G. oceanica s.l. and the FO of large Gephyrocapsa spp.

Occurrence: This zone has been recognized at Sites 1010, 1012, 1013, 1014, 1017 (pars), 1018, and 1020 and can be recognized globally as demonstrated by the works of Rio (1982); Rio, Raffi, et al. (1990); Wei (1993); Raffi et al. (1993); and so on.

Remarks: In the original definition of Bukry (1973), the bottom of the zone was defined by the FO of G. caribbeanica, and the top was defined by the FO of G. oceanica. Most probably, G. caribbeanica of Bukry (1973) corresponds to G. oceanica of Gartner (1977) and to G. oceanica s.l. of Rio (1982), and the G. oceanica of Bukry (1973) corresponds to Gephyrocapsa sp. 3, as intended here following Rio (1982). Hence, the proposed zone corresponds to the lower part of the original Subzone CN13b of Bukry (1973; see Fig. 2).

The LO of C. macintyrei occurs in the lowermost part of the zone.

 

CN13bB Large Gephyrocapsa Zone

 

Definition: Interval corresponding to the total range of large Gephyrocapsa spp.

Occurrence: This zone has been recognized in Sites 1010, 1012, 1014, 1017, 1018, and 1020 and can be recognized globally as demonstrated by the various studies of Rio (1982); Rio, Raffi, et al. (1990); Wei (1993); Raffi et al. (1993); and so on.

Remarks: The zone was first introduced by Rio, Raffi, et al. (1990) for the Mediterranean area. In many areas H. sellii becomes extinct at the top of the zone.

 

CN13bC small Gephyrocapsa Zone

 

Definition: Interval between the LO of large Gephyrocapsa spp. and the FO of Gephyrocapsa sp. 3

Occurrence: This zone has been recognized at Sites 1010, 1012, 1014, 1017, 1018, 1019 (pars), and 1020 and can be recognized globally as demonstrated by the works of Gartner (1977); Rio (1982); Rio, Raffi, et al. (1990); Wei (1993); Raffi et al. (1993); etc.

Remarks: The zone was first defined by Rio, Raffi, et al. (1990) in the Mediterranean area. It corresponds substantially to the small Gephyrocapsa spp. Zone of Gartner (1977), which was defined on the basis of the LO of H. sellii (bottom) and the acme end of small Gephyrocapsa spp. (top), two biohorizons of more limited applicability than those utilized here.

This zone is corresponds to the upper part of Subzone CN13b of Okada and Bukry (1980).

 

CN14a Pseudoemiliania lacunosa Zone

 

Definition: Interval between the FO of Gephyrocapsa sp. 3 and the LO of Pseudoemiliania lacunosa

Occurrence: This zone has been recognized at all Leg 167 sites and can be recognized globally as demonstrated by the works of Gartner (1977); Rio (1982); Rio, Raffi, et al. (1990); Wei (1993); Raffi et al. (1993); and so on.

Remarks: The zone as defined here was introduced by Raffi and Rio (1979) and emended by Rio, Raffi, et al. (1990) for the Mediterranean area. It corresponds substantially to the P. lacunosa Zone of Gartner (1977), which was defined on the basis of the acme end of small Gephyrocapsa spp. (bottom) and the LO of P. lacunosa (top), and to the Emiliania ovata Subzone (CN14a) of Okada and Bukry (1980), which was defined on the basis of the FO of G. oceanica at the bottom and the LO of E. ovata (P. lacunosa of this work) at the top.

Adopted California Margin Miocene Zones

The original late Miocene zones of Okada and Bukry (1980) have been emended (emendation is denoted by the asterisk [*]) as follows:

 

*CN6-CN7 Catinaster coalitus-Discoaster hamatus combined Zones

 

Definition: Interval between the FO of Catinaster spp. and the FO Minylitha convallis.

Occurrence: This zone has been recognized at Sites 1010 and 1021.

Remarks: The CN6 and CN7 zones of Okada and Bukry (1980) are combined and their definitions emended because the FO of C. coalitus (base of Zone CN6), the FO of D. hamatus (base of Zone CN7), and the LO of D. hamatus (base of Zone CN8) are unreliable datums in the California Margin.

 

*CN8a Discoaster bellus Zone

 

Definition: Interval of common occurrence of Minylitha convallis below the PB of R. pseudoumbilicus

Occurrence: This zone has been recognized at Sites, 1010, 1011 (pars), and 1021.

Remarks: The original definition of Subzone CN8a of Okada and Bukry (1980) is emended because the LO of D. hamatus (base of Zone CN8a) and the FOs of D. loeblichii and D. neorectus (base of Zone CN8b) are not reliable in the California Margin.

 

*CN8b Discoaster neorectus Zone

 

Definition: Interval between the PB of R. pseudoumbilicus and the LO of Minylitha convallis

Occurrence: This zone has been recognized at Site 1011

Remarks: The original definition of Subzone CN8b of Okada and Bukry (1980) is emended because the FOs of D. loeblichii and D. neorectus (base of Zone CN8b) and the FO of D. berggrenii (base of Zone CN9) are not reliable in the California Margin. Note that the nominal species of the zone is missing in the area and that the FO of M. convallis seems to approximate the FO of D. berggrenii in the area.

 

*CN9a Discoaster berggrenii Subzone

 

Definition: Interval between the LO of Minylitha convallis and the FO of Amaurolithus primus.

Occurrence: This subzone has been recognized at Site 1010, 1011 and 1021 (pars).

Remarks: See Zone CN8b.

 

CN9bA Amaurolithus primus Subzone

 

Definition: Interval between the FO of A. primus and the PE of R. pseudoumbilicus.

Occurrence: This subzone has been recognized at Sites 1010, 1011, and 1021.

Remarks: This new biostratigraphic interval is introduced for improving the biostratigraphic resolution in the California Margin. The biohorizons defining the biostratigraphic intervals (FO of A. primus and the PE of R. pseudoumbilicus) are recognized also outside the California Margin and probably the proposed subzone is widely recognizable.

 

CN9bB Calcidiscus leptoporus Subzone

 

Definition: Interval between the PE of R. pseudoumbilicus and the LO of D. quinqueramus.

Occurrence: This subzone has been recognized at Sites 1010, 1011 and 1021.

Remarks: See Subzone CN9bA.