Oxygen Isotope Values of Planktic Foraminifera
175
g
- T emlX'ralur. rC)
o 6 12 1824
O ~-:-"l1'71
100
200
300
a .. 00
N~
-8
.!l
500
~ 600
700
600
900
1000
( PS2230-1)
size fraction
1 :
> 400 ,.m
~
2 : 315-4001"1'
3 : 2S~3'5 "m
4 : 200·250 I' m -2
5 : 125·200 I'm
~
~
432
- Sallnlty(psul
4321
........... 4321 321
-1 .............. .......
. ..... ..... ............ ... ... ... ........ ......... , . L...L..I...J L..LJ .. . .. . . .. ... ..... .. ... -1
21 ~
321 21
.... -1,1-'"
3 2 1- 54 3 -L..J
L...W _ L..J - 54 - - -J,-I.- - - - - - --f'-- 10 m
i! 0 L...W '-'-' , . ..J •
- r .Y.
21
~
../ ,;a-..
5432121
32 1 2 1 LJ
0- 50 m
a..
L-L-.L..L..J
w
L.....L...JI-I \
o
.................. ·.·.······· · 32 1 .. ~ .. \ ············· .. ··- .. ······ .. ·· .. ····· .... .... 2 ·~ ·· 1 ······
~
- -+ - -\- - 250 m
\ :
~
J
2 ........... .... ...... -.- . --- .......................................... ............................... .. ... ......... .. 2
c:
o
~
~
~
~
~
g'"
<:j
'" Q)
!1
g
::>
.0
<:j
'"
. '"
.~
t
.!!!
t::
~
=>
8
.~
-6 .c:
<:j
2:
<:j
.!!!
' "
.!!!
::>
~
~ g ~
.!!!
' "
=>
~=
g ~
:§!
~
u'"
.0
';:: "'~
.S;;
E 0 => Q.~
<:j
<:j n: 0 2:~
<3'
'" ' "
Q)
Q)
§'
' "
!1 !1
.!!!.
0
0
:E
':§ ~
~
Q)
~
. <:!
~
' "
'a
::> .!!! ~~ ~= !1
Q)
8 . ~
.0
u
C:.::: c:'" E
~
' "
u
.s' e 2~
2
'"
II)
-(I)
. <:j
<:j
<:j <:j <:jJ! <:j ~ <:j
Fig. 4. Site PS2230 (34.753°S, 17.357°E), west of the Cape of Good Hope (Subtropical Gyre): 6 1 '0 001 ,,10 composition
of examined foraminifera as a function of their shell-size. Profile of summer season temperature and salinity from
World Ocean Atlas (Levitus and Boyer 1994). The gray shaded lines indicate the isotope equilibrium to the seawater, respectively to the dissolved CO" at the water depths of 10,50 and 250 m.
Globigerinella aequilateralis calcifies in a
water depth between about 0 and 100 m (using the
reported range of "oxygen isotope disequilibrium",
Table 2) and occurs mainly north of the Subtropical Front (Figs. 3-5). This corresponds approximately to the observations of Berger (1969) and
Be (1977), who report a predominant depth habitat between 50 and 100 m. However, our results
are confirmed by plankton-tow and sediment-trap
studies of Deuser et al. (1981), Deuser (1987),
Deuser and Ross (1989) and Ottens (1992), who
place G. aequilateralis within the 0 to 75 m interval.
Globigerinoides ruber (white), thriving close
to the surface, has been widely used for
paleoceanographic reconstructions in subtropical
and tropical latitudes. This species occurs in the
Subtropical Gyre and in the Subtropical Front area
(Figs. 3-5). Compared with other planktic
foraminifera G. ruber (white) has a relatively wide
range of "oxygen isotope disequilibrium" between
0.0 %0 and -1.0 %0 (Table 2). Following most authors by using a mean "oxygen isotope disequilibrium" of -0.5 %0, G. ruber (white) calcifies in the
southern South Atlantic Ocean in a water depth between 0 and 50 m. These results are in agreement
175
g
- T emlX'ralur. rC)
o 6 12 1824
O ~-:-"l1'71
100
200
300
a .. 00
N~
-8
.!l
500
~ 600
700
600
900
1000
( PS2230-1)
size fraction
1 :
> 400 ,.m
~
2 : 315-4001"1'
3 : 2S~3'5 "m
4 : 200·250 I' m -2
5 : 125·200 I'm
~
~
432
- Sallnlty(psul
4321
........... 4321 321
-1 .............. .......
. ..... ..... ............ ... ... ... ........ ......... , . L...L..I...J L..LJ .. . .. . . .. ... ..... .. ... -1
21 ~
321 21
.... -1,1-'"
3 2 1- 54 3 -L..J
L...W _ L..J - 54 - - -J,-I.- - - - - - --f'-- 10 m
i! 0 L...W '-'-' , . ..J •
- r .Y.
21
~
../ ,;a-..
5432121
32 1 2 1 LJ
0- 50 m
a..
L-L-.L..L..J
w
L.....L...JI-I \
o
.................. ·.·.······· · 32 1 .. ~ .. \ ············· .. ··- .. ······ .. ·· .. ····· .... .... 2 ·~ ·· 1 ······
~
- -+ - -\- - 250 m
\ :
~
J
2 ........... .... ...... -.- . --- .......................................... ............................... .. ... ......... .. 2
c:
o
~
~
~
~
~
g'"
<:j
'" Q)
!1
g
::>
.0
<:j
'"
. '"
.~
t
.!!!
t::
~
=>
8
.~
-6 .c:
<:j
2:
<:j
.!!!
' "
.!!!
::>
~
~ g ~
.!!!
' "
=>
~=
g ~
:§!
~
u'"
.0
';:: "'~
.S;;
E 0 => Q.~
<:j
<:j n: 0 2:~
<3'
'" ' "
Q)
Q)
§'
' "
!1 !1
.!!!.
0
0
:E
':§ ~
~
Q)
~
. <:!
~
' "
'a
::> .!!! ~~ ~= !1
Q)
8 . ~
.0
u
C:.::: c:'" E
~
' "
u
.s' e 2~
2
'"
II)
-(I)
. <:j
<:j
<:j <:j <:jJ! <:j ~ <:j
Fig. 4. Site PS2230 (34.753°S, 17.357°E), west of the Cape of Good Hope (Subtropical Gyre): 6 1 '0 001 ,,10 composition
of examined foraminifera as a function of their shell-size. Profile of summer season temperature and salinity from
World Ocean Atlas (Levitus and Boyer 1994). The gray shaded lines indicate the isotope equilibrium to the seawater, respectively to the dissolved CO" at the water depths of 10,50 and 250 m.
Globigerinella aequilateralis calcifies in a
water depth between about 0 and 100 m (using the
reported range of "oxygen isotope disequilibrium",
Table 2) and occurs mainly north of the Subtropical Front (Figs. 3-5). This corresponds approximately to the observations of Berger (1969) and
Be (1977), who report a predominant depth habitat between 50 and 100 m. However, our results
are confirmed by plankton-tow and sediment-trap
studies of Deuser et al. (1981), Deuser (1987),
Deuser and Ross (1989) and Ottens (1992), who
place G. aequilateralis within the 0 to 75 m interval.
Globigerinoides ruber (white), thriving close
to the surface, has been widely used for
paleoceanographic reconstructions in subtropical
and tropical latitudes. This species occurs in the
Subtropical Gyre and in the Subtropical Front area
(Figs. 3-5). Compared with other planktic
foraminifera G. ruber (white) has a relatively wide
range of "oxygen isotope disequilibrium" between
0.0 %0 and -1.0 %0 (Table 2). Following most authors by using a mean "oxygen isotope disequilibrium" of -0.5 %0, G. ruber (white) calcifies in the
southern South Atlantic Ocean in a water depth between 0 and 50 m. These results are in agreement