BIOSTRATIGRAPHIC ZONATION

We followed the planktonic foraminiferal zonal scheme of Blow (1969) as amended by Kennett and Srinivasan (1983). In addition, we adopted the coiling change of all species of Pulleniatina to define the top of Zone N19 (Chaisson and Leckie, 1993). Figure F2 depicts this zonal scheme and the primary biostratigraphic datums used for this report. Where possible, we used the astrochronologically tuned planktonic foraminiferal ages of Chaisson and Pearson (1997) for datums between 4.08 and 13.42 Ma. For species not listed by these authors or for samples older than 13.42 Ma, the untuned ages of Berggren et al. (1995) and Curry, Shackleton, Richter, et al. (1995) were used (see Tables T3 [Site 1143], T4 [Site 1146]).

Definition: Interval between the first occurrence (FO) of Sphaeroidinella dehiscens s.l. (interval base) and the coiling change of Pulleniatina, sinistral to dextral (interval top).

Age: 5.54-4.08 Ma; latest Miocene-early Pliocene.

Occurrence:

Site 1143: The base of this zone is at an average depth of 218.1 mcd (between Samples 184-1143A-24X-3, 115-117 cm [216.6 mcd], and 24X-5, 115-117 cm [219.6 mcd]).

Site 1146: The base of this zone is at an average depth of 319.88 mcd (between Samples 184-1146A-33X-1, 9-12 cm [318.36 mcd], and 33X-3, 14-17 cm [321.41 mcd]).

Definition: Interval between the FO of Globorotalia tumida (interval base) and the FO of Sphaeroidinella dehiscens s.l. (interval top).

Age: 5.82-5.54 Ma; latest Miocene.

Occurrence:

Site 1143: The zone is between the average depths of 218.1 mcd (between Samples 184-1143A-24X-3, 115-117 cm [216.6 mcd], and 24X-5, 115-117 cm [219.6 mcd]) and 228.30 mcd (between Samples 25X-CC, 26-33 cm [224.07 mcd], and 26X-1, 115-117 cm [232.52 mcd]).

Site 1146: The zone is between the average depths of 319.88 mcd (between Samples 184-1146A-33X-1, 9-12 cm [318.36 mcd], and 33X-3, 14-17 cm [321.41 mcd]) and 322.88 mcd (between Samples 33X-3, 14-17 cm [321.41 mcd], and 33X-5, 9-12 cm [324.36 mcd]).

Definition: Interval between the FO of Pulleniatina primalis (interval base) to the FO of Globorotalia tumida (interval top).

Age: 6.4-5.82 Ma; late Miocene.

Occurrence:

Site 1143: The zone is between the average depths of 228.30 mcd (between Samples 184-1143A-25X-CC, 26-33 cm [224.07 mcd], and 26X-1, 115-117 cm [232.52 mcd]) and 239.79 mcd (between Samples 26X-5, 115-117 cm [238.52 mcd], and 26X-CC, 41-48 cm [241.05 mcd]).

Site 1146: The zone is between the average depths of 322.88 mcd (between Samples 184-1146A-33X-3, 14-17 cm [321.41 mcd], and 33X-5, 9-12 cm [324.36 mcd]) and 338.04 mcd (between Samples 34X-CC, 5-9 cm [337.56 mcd], and 35X-1, 10-14 cm [338.52 mcd]).

Definition: Interval between the FO of Globorotalia plesiotumida (interval base) to the FO of Pulleniatina primalis (interval top).

Age: 8.58-6.4 Ma; late Miocene.

Occurrence:

Site 1143: The zone is between the average depths of 239.79 mcd (between Samples 184-1143A-26X-5, 115-117 cm [238.52 mcd], and 26X-CC, 41-48 cm [241.05 mcd]) and 454.56 mcd (between Samples 184-1143C-48X-1, 115-117 cm [453.06 mcd], and 48X-3, 115-117 cm [456.06 mcd]).

Site 1146: The zone is between the average depths of 338.04 mcd (between samples 184-1146A-34X-CC, 5-9 cm [337.56 mcd], and 35X-1, 10-14 cm [338.52 mcd]) and 408.13 mcd (between Samples 184-1146A-41X-4, 0-2 cm [406.63 mcd], and 41X-6, 0-2 cm [409.63 mcd]).

Definition: Interval between the FO of Neogloboquadrina acostaensis (interval base) and the FO of Globorotalia plesiotumida (interval top).

Age: 9.82-8.58 Ma; late Miocene.

Occurrence:

Site 1143: The zone is between the average depths of 454.56 mcd (between Samples 184-1143C-48X-1, 115-117 cm [453.06 mcd], and 48X-3, 115-117 cm [456.06 mcd]) and 467.26 mcd (between Samples 49X-3, 115-117 cm [465.76 mcd], and 49X-5, 115-117 cm [468.76 mcd]).

Site 1146: The zone is between the average depths of 408.13 mcd (between Samples 184-1146A-41-4, 0-2 cm [406.63 mcd], and 41X-6, 0-2 cm [409.63 mcd]) and 433.13 mcd (between Samples 44X-3, 0-2 cm [432.38 mcd], and 44X-4, 0-2 cm [433.88 mcd]).

Definition: Interval between the last occurrence (LO) of Paragloborotalia mayeri (interval base) and the FO of Neogloboquadrina acostaensis (interval top).

Age: 10.49-9.82 Ma; late Miocene.

Occurrence:

Site 1143: The zone is between the average depths of 467.26 mcd (between Samples 184-1143C-49X-3, 115-117 cm [465.76 mcd], and 49X-5, 115-117 cm [468.76 mcd]) and 470.6 mcd (between Samples 49X-5, 115-117 cm [468.76 mcd], and 50X-1, 113-115 cm [472.44 mcd]).

Site 1146: The zone is between the average depths of 433.13 mcd (between Samples 184-1146A-44X-3, 0-2 cm [432.38 mcd], and 44X-4, 0-2 cm [433.88 mcd]) and 444.58 mcd (between Samples 45X-4, 0-2 cm [443.83 mcd], and 45X-5, 0-2 cm [445.33 mcd]).

Definition: Interval between the FO of Globoturborotalita nepenthes (interval base) and the LO of Paragloborotalia mayeri (interval top).

Age: 11.19-10.49 Ma; middle-late Miocene.

Occurrence:

Site 1143: The top of this zone is at the average depth of 470.6 mcd (between Samples 184-1143C-49X-5, 115-117 cm [468.76 mcd], and 50X-1, 113-115 cm [472.44 mcd]), whereas its base is below the drilled interval for this site (Sample 54X-CC, 43-48 cm [512.91 mcd]).

Site 1146: Zones N14 and N13 could not be distinguished at Site 1146 because of the stratigraphic overlap of Globoturborotalita nepenthes (FO) and Globorotalia fohsi s.l. (LO). Therefore, a combined Zone N13-N14 ranges between 444.58 mcd (between Samples 184-1146A-45X-4, 0-2 cm [443.83 mcd], and 45X-5, 0-2 cm [445.33 mcd]) and 470.28 mcd (between Samples 47X-6, 0-2 cm [469.53 mcd], and 47X-7, 0-2 cm [471.03 mcd]).

Definition: Interval between the LO of Globorotalia fohsi s.l. (interval base) and the FO of Globoturborotalita nepenthes (interval top).

Age: 11.68-11.19 Ma; middle Miocene.

Occurrence:

Site 1143: The base of this site is in Zone N14.

Site 1146: See above comments for Zone N14.

Definition: Total range of Globorotalia fohsi s.l. (interval base and top).

Age: 13.42-11.68 Ma; middle Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 470.28 mcd (between Samples 184-1146A-47X-6, 0-2 cm [469.53 mcd], and 47X-7, 0-2 cm [471.03 mcd]) and 504.85 mcd (between Samples 51X-4, 0-2 cm [504.1 mcd], and 51X-5, 0-2 cm [505.6 mcd]).

Definition: Interval from the FO of Globorotalia praefohsi (interval base) to the FO of Globorotalia fohsi s.l. (interval top).

Age: 14.0-13.42 Ma; middle Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 504.85 mcd (between Samples 184-1146A-51X-4, 0-2 cm [504.1 mcd], and 51X-5, 0-2 cm [505.6 mcd]) and 521.43 mcd (between Samples 52X-CC, 0-2 cm [519.85 mcd], and 53X-2, 0-2 cm [523 mcd]).

Definition: Interval between the FO of Globorotalia peripheroacuta (interval base) and the FO of Globorotalia praefohsi (interval top).

Age: 14.8-14.0 Ma, middle Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 521.43 mcd (between Samples 184-1146A-52X-CC, 0-2 cm [519.85 mcd], and 53X-2, 0-2 cm [523 mcd]) and 533.45 mcd (between Samples 54X-1, 0-2 cm [531.95 mcd], and 54X-3, 0-2 cm [534.95 mcd]).

Definition: Interval between the FO of Orbulina spp. (interval base) and the FO of Globorotalia peripheroacuta (interval top).

Age: 15.1-14.8 Ma; middle Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 533.45 mcd (between Samples 184-1146A-54X-1, 0-2 cm [531.95 mcd], and 54X-3, 0-2 cm [534.95 mcd]) and 541.38 (between Samples 54X-CC, 0-2 cm [539.81 mcd], and 55X-2, 0-2 cm [542.95 mcd]).

Definition: Interval between the FO of Praeorbulina sicana (interval base) and the FO of Orbulina spp. (interval top).

Age: 16.4-15.1 Ma; middle Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 541.38 mcd (between Samples 184-1146A-54X-CC, 0-2 cm [539.81 mcd], and 55X-2, 0-2 cm [542.95 mcd]) and 617.16 mcd (between Samples 62X-2, 10-14 cm [616.41 mcd], and 62X-3, 10-14 cm [617.91 mcd]).

Definition: Interval between the LO of Catapsydrax dissimilis (interval base) and the FO of Praeorbulina sicana (interval top).

Age: 17.3-16.4 Ma; early Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 617.16 mcd (between Samples 184-1146A-62X-2, 10-14 cm [616.41 mcd], and 62X-3, 10-14 cm [617.91 mcd]) and 622.3 mcd (between Samples 62X-5, 7-11 cm [620.88 mcd], and 62X-7, 10-14 cm [623.71 mcd]).

Definition: Interval between the FO of Globigerinatella insueta (interval base) and the LO of Catapsydrax dissimilis (interval top).

Age: 18.8-17.3 Ma; early Miocene.

Occurrence:

Site 1146: The zone is between the average depths of 622.3 mcd (between Samples 184-1146A-62X-5, 7-11 cm [620.88 mcd], and 62X-7, 10-14 cm [623.71 mcd]) and 636.31 mcd (between Samples 64X-2, 10-14 cm [634.81 mcd], and 64X-4, 9-13 cm [637.8 mcd]).

Definition: Interval between the LO of Paragloborotalia kugleri (interval base) and the FO of Globigerinatella insueta (interval top).

Age: 21.5-18.8 Ma; early Miocene.

Occurrence:

Site 1146: The top of the zone is at 636.31 mcd (between Samples 184-1146A-64X-2, 10-14 cm [634.81 mcd], and 64X-4, 9-13 cm [637.8 mcd]), whereas the base of this zone is below the drilled interval for this site (Sample 184-1146A-64X-CC, 10-14 cm [643.11 mcd]).