Table T4.
Age assignments of biostratigraphic diatom zones used during Leg 181.
Zone
Reference
Top
(Ma)
Base
(Ma)
Datum used to
define base
Neogene
Thalassiosira
lentiginosa Subzone c
1
0
0.18
Thalassiosira
lentiginosa Subzone b
1
0.18
0.42
Thalassiosira
lentiginosa Subzone a
1
0.42
0.65
F. reinholdii LO
Actinocyclus ingens Subzone
c
1
0.65
1.07
Actinocyclus ingens Subzone
b
1
1.07
1.30
Actinocyclus ingens
Subzone a
1
1.30
1.80
P. barboi LO, ?T.
elliptipora
Proboscia barboi
1
1.77
2.00
T. kolbei LO
Thalassiosira kolbei/Fragilariopsis
matuyamae
1
2.00
2.50
T. vulnifica LO,
?F. matuyamae
Thalassiosira
vulnifica
1
2.50
2.63
F. interfrigidaria
LO, T. insigna LO
Thalassiosira insigna
2
2.63
3.26
T. vulnifica FO
Fragilariopsis
interfrigidaria
2
3.26
3.80
F. interfrigidaria FO
Fragilariopsis
barronii
2
3.80
4.44
F. barronii FO,
T. complicata FO
Thalassiosira inura
2
4.44
4.92
T. inura FO
Thalassiosira
oestrupii
2
4.92
5.56
T. oestrupii FO
Fragilariopsis
reinholdii
2
5.56
8.10
F. reinholdii FO
Actinocyclus ingens var.
ovalis
2
8.10
8.68
C. intersectus FO,
A. ingens var. ovalis FO
Thalassiosira torokina
2
8.68
9.01
T. torokina FO
Asteromphalus
kennettii
2
9.01
10.23
T. kennettii FO
Denticulopsis
hustedtii
2
10.23
10.63
D. dimorpha LO
Denticulopsis dimorpha
2
10.63
11.67
N. denticuloides
LO
Denticulopsis dimorpha/Nitzschia
denticuloides
2
11.67
12.20
D. dimorpha FO
Denticulopsis
praedimorpha
2
12.20
12.84
D. praedimorpha FO
Nitzschia
denticuloides
2
12.84
13.51
N. grossepunctata LO,
N. denticuloides FO
Denticulopsis
hustedtii/Nitzschia grossepunctata
2
13.51
14.17
D. hustedtii FO
Actinocyclus ingens
var. nodus
2
14.17
14.38
A. ingens var.
nodus FO
Nitzschia
grossepunctata
2
14.38
15.38
N. grossepunctata FO
A. ingens/D.
maccollumii
2
15.38
16.20
A. ingens FO
Denticulopsis
maccollumii
2
16.20
16.75
D. maccollumii FO
Crucidenticula kanayae
2
16.75
17.72
C. kanayae FO
Thalassiosira fraga
2
17.72
20.79
T. fraga FO
Thalassiosira
spumellaroides
2
20.79
22.58
T. spumellaroides FO
Oligocene
Rocella gelida
2
22.58
26.50
R. gelida FO
Lisitzinia ornata
2
26.50
27.95
L. ornata FO
Azpeitia gombosii
2
27.95
28.35
A. gombosii FO
Rocella vigilans
2
28.35
30.24
R. vigilans
(small) FO
Cavitatus jouseanus
2
30.24
30.62
C. jouseanus FO
Rhizosolenia gravida/oligocaenica
2
30.62
33.22
R. oligocaenica FO
Note: References: 1 = Gersonde and Barcena (in press), 2 = Gersonde et al. (1999). This table is also available in ASCII format.