aeolian or hemipelagic sources) and material affected
by chemical alteration through diagenetic processes
has to be avoided. The isotopes of Sr are usually
measured on carbonates or barite, while those of Be,
Nd, or Hf are extracted from chemical sediments,
such as ferromanganese (Fe-Mn) crusts, manganese
nodules, the authigenic phase of deep-sea sediments,
or marine phosphorites, argillites, and glauconites.
Results
Sr
Sr isotopes represent the best-studied long-term tracer,
as well-dated carbonate sequences are readily available, the extraction and analysis is simple, and the
long residence time ensures worldwide homogenization. Therefore, a single isotope evolution curve has
Nd
Station 315
61°S/62°W
Station 271
49°S/33°W
Station 302
33°S/42°W
_ 14 _ 10 _ 6
_ 12
_ 6
_ 15
_ 11 _ 16
_ 12
_ 8 _ 20
Station 63
7°N/40°W
Station 30
36°N/62°W
Station 11
52°N/47°W
0
Depth (m)
1000
2000
3000
4000
5000
60°S
4 0 °S
6 0 °N
40°N
20°S
2 0 °N
0°
Latitude
_ 12
_ 6
(A)
3 4 .2 5
3 4 .6
5
34 .6 0
3 4 .5 5
34 .7 0
3
4
.7
5
34 .8 0
3 4 .8 5
34. 35
34. 30
34.85
34.85
34.45
34.50
34.5 5
34. 95
34.9 5
3 5 .0 0
34. 60
10 Be/
9 Be (x10
_ 7
)
Station 114
24°S/38°W
Station 22XC
34°N/63°W
Station 8
41°N/63°W
Station 64
45°N/41°W
0.4 0.8
0.4
0.0
0.8 1.6
0.0
0
Depth (m)
1000
2000
3000
4000
5000
60°S
4 0 °S
6 0 °N
40°N
20°S
2 0 °N
0°
Latitude
(B)
0.4 0.8
3
4
.6
5
3 4 .6 0
34 .7 0
3 4 .5 5
3
4
.7
5
34. 30
3 4 .2 5
34. 35
34 .8 0
34 .8 5
34.85
34.85
34.45
34.50
34. 55 34 .6 0
34.9 5
34 .90
3 5 .0 0
34.9 5
Figure 1 (A) Salinity contours of Atlantic sea water with superimposed dissolved Nd isotope compositions. Stippled line gives the
typical composition of NADW (e Nd ¼ À13). Note the pronounced tongue of NADW with intermediate salinities and e Nd of À 13
spreading south, and the tongues of AABW and AAIW with lower salinities and e Nd of À 9 spreading north. (Reprinted with permission
from von Blanckenburg F (1999) Tracing past ocean circulation? Science 286: 1862–1863. Copyright 1999 American Association for
the Advancement of Science.) (B) Salinity contours of Atlantic sea water with superimposed dissolved Be isotope compositions.
Stippled line gives the typical composition of NADW (
10 Be/
9 Be ¼ 0.6 Â 10
À7
). Note the pronounced tongue of AAIW with lower
salinities and
10
Be/
9 Be of 1 Â 10
À7 spreading north. (Data reproduced with permission from Ku et al., 1990; Xu, 1994; Measures et al.,
1996).
126 LONG-TERM TRACER CHANGES
by chemical alteration through diagenetic processes
has to be avoided. The isotopes of Sr are usually
measured on carbonates or barite, while those of Be,
Nd, or Hf are extracted from chemical sediments,
such as ferromanganese (Fe-Mn) crusts, manganese
nodules, the authigenic phase of deep-sea sediments,
or marine phosphorites, argillites, and glauconites.
Results
Sr
Sr isotopes represent the best-studied long-term tracer,
as well-dated carbonate sequences are readily available, the extraction and analysis is simple, and the
long residence time ensures worldwide homogenization. Therefore, a single isotope evolution curve has
Nd
Station 315
61°S/62°W
Station 271
49°S/33°W
Station 302
33°S/42°W
_ 14 _ 10 _ 6
_ 12
_ 6
_ 15
_ 11 _ 16
_ 12
_ 8 _ 20
Station 63
7°N/40°W
Station 30
36°N/62°W
Station 11
52°N/47°W
0
Depth (m)
1000
2000
3000
4000
5000
60°S
4 0 °S
6 0 °N
40°N
20°S
2 0 °N
0°
Latitude
_ 12
_ 6
(A)
3 4 .2 5
3 4 .6
5
34 .6 0
3 4 .5 5
34 .7 0
3
4
.7
5
34 .8 0
3 4 .8 5
34. 35
34. 30
34.85
34.85
34.45
34.50
34.5 5
34. 95
34.9 5
3 5 .0 0
34. 60
10 Be/
9 Be (x10
_ 7
)
Station 114
24°S/38°W
Station 22XC
34°N/63°W
Station 8
41°N/63°W
Station 64
45°N/41°W
0.4 0.8
0.4
0.0
0.8 1.6
0.0
0
Depth (m)
1000
2000
3000
4000
5000
60°S
4 0 °S
6 0 °N
40°N
20°S
2 0 °N
0°
Latitude
(B)
0.4 0.8
3
4
.6
5
3 4 .6 0
34 .7 0
3 4 .5 5
3
4
.7
5
34. 30
3 4 .2 5
34. 35
34 .8 0
34 .8 5
34.85
34.85
34.45
34.50
34. 55 34 .6 0
34.9 5
34 .90
3 5 .0 0
34.9 5
Figure 1 (A) Salinity contours of Atlantic sea water with superimposed dissolved Nd isotope compositions. Stippled line gives the
typical composition of NADW (e Nd ¼ À13). Note the pronounced tongue of NADW with intermediate salinities and e Nd of À 13
spreading south, and the tongues of AABW and AAIW with lower salinities and e Nd of À 9 spreading north. (Reprinted with permission
from von Blanckenburg F (1999) Tracing past ocean circulation? Science 286: 1862–1863. Copyright 1999 American Association for
the Advancement of Science.) (B) Salinity contours of Atlantic sea water with superimposed dissolved Be isotope compositions.
Stippled line gives the typical composition of NADW (
10 Be/
9 Be ¼ 0.6 Â 10
À7
). Note the pronounced tongue of AAIW with lower
salinities and
10
Be/
9 Be of 1 Â 10
À7 spreading north. (Data reproduced with permission from Ku et al., 1990; Xu, 1994; Measures et al.,
1996).
126 LONG-TERM TRACER CHANGES