Table T7. Comparison of average effective ages of biostratigraphic events for Congo, Walvis, and Cape Basin sites.
Age (Ma)
Congo sites
Walvis sites
Cape Basin sites
Biostratigraphic event
Shipboard age
Age range (weighted)
Age range (unweighted)
N
Age range (weighted)
Age range (unweighted)
N
Age range (weighted)
Age range (unweighted)
N
N FO Emiliania huxleyi acme
0.09 0.09 0.09 7
0.06 0.06 2
0.15 0.15 1
N FO Emiliania huxleyi
0.26 0.30 0.30 6
0.27 0.28 5
0.23 0.23 2
N Gephyrocapsa caribbeanica acme
0.26 0.30 0.30 6
0.27 0.28 5
0.23 0.23 2
R LO Axoprunum angelinum
0.46 0.38 0.38 3
0.39 0.38 3
0.48 0.48 1
N LO Pseudoemiliania lacunosa
0.46 0.41 0.43 4
0.44 0.45 4
0.42 0.42 2
N Small Gephyrocapsa acme
0.6 0.59 0.58 3
0.56 0.56 3
0.64 0.60 2
N LO Reticulofenestra asanoi
0.83 0.82 0.82 3
0.76 0.76 4
0.75 0.75 2
D LO Nitzschia fossilis
0.92 1.07 1.07 1
0.64 0.64 1



N Small Gephyrocapsa acme
0.96 0.91 0.93 3
0.97 0.96 3
0.93 0.93 1
N FO Reticulofenestra asanoi
1.06 1.07 1.07 1
1.09 1.09 1



R LO Lamprocyrtis neoheteroporos
1.07 1.43 1.37 2
0.97 0.92 3



N LO Helicosphaera sellii
1.25 1.29 1.30 4
1.23 1.23 4
1.08 1.06 2
N LO Calcidiscus macintyrei
1.67 1.52 1.56 2
1.63 1.63 4
1.35 1.52 3
N LO Discoaster brouweri
1.95



2.07 2.05 4
1.93 1.85 3
D LO Thalassiosira convexa
2.19



2.39 2.41 2
2.07 2.07 1
N LO Discoaster brouweri
2.55



2.70 2.67 2
2.45 2.46 3
R FO Cycladophora davisiana
2.70



2.61 2.56 3
2.47 2.47 1
N LO Reticulofenestra pseudoumbilicus
3.82



3.84 3.73 2
3.81 3.78 3
N LO Amaurolithus tricorniculatus
4.50



4.09 4.09 1
4.41 4.39 3

Notes: N = nannofossil, R = radiolarian, S = silicoflagellate, D = diatom. FO = first occurrence, LO = last occurrence. N = number of samples. Estimated age weighted according to narrowness of age range, and unweighted. Average effective ages of biostratigraphic events are as used in the age models. Weighted = estimated age weighted according to narrowness of age range, unweighted = not so weighted. (Differences between shipboard-assigned age and effectively used age arise from a number of sources such as sampling interval vs. sedimentation rate, intensity of search for presence and absence of a nannofossil, and problems of preservation. Thus, the data do not necessarily reflect real differences in assigned ages of events and their occurrence at the sites occupied. They do give an idea about the consistency of biostratigraphic shipboard assignments in the circumstances of Leg 175.)