326
3
5
·2
:2:
· 1
f? 0
";.,
2
1.0
0.8
iu 0.6
1: 0.4
.2! 0.2
0 .0
15
iu
10
1:
.2!
100
Riihlemann et al.
10
11
a
b
,'\
c
200
Age Ika]
(\ West(1523-1) ! \
I
;
\ .. / .... \
i\.. "'/ \
/'",'
~t,l
. \_./ . . . . . oP\J" \,/\ ..... ..'
300
r
mer
Climate
cooler
400
Fig. 7. (a) Normalized standard isotope curve (Imbrie et al. 1984) indicating global climate variations. Comparison
of organic carbon (b) and carbonate accumulation (c) rates for the last 300,000 years between the high productivity
eastern Atlantic core GeoB 1016-3 (solid line; data from Schneider 1991) and the low productivity western Atlantic
core GeoB 1523-\ (dashed line, data from Riihlemarm et al. \996).
!?
o
o
6
5
4
3
2
GeeB 1523-1
~
40·W
Surficial sediment Corg contents in the tropical Atlantic
30·
•
African continental margin
•
pelagic sediments
<> South American continental margin
20·
Longitude
10·
O·
GeeB 1016-3 •
~
••
• #
• ••
10·E
Fig. 8. E-W profile of organic carbon contents in surface sediments in the tropical Atlantic between 6°N and 12°S
(positions of surface samples are shown in Fig. 2). Very high organic carbon contents in the eastern Atlantic coastal
upwelling region (I O-14°E) stand in contrast with the low contents in the pelag ic ocean and at the South American
continental margin.