396
Walter et al.
margin
interior
O.02521--+--·I"h------l
production rate
(dpm'm-3-y-l )
particle flux
(g'm-2'y-l )
scavenging
residence
time
(t s ) in years
O.00233t::::::±=~P!::a ===:::l
200
:
~
100
o~~----------~
300
200
r----:Pal----I
100 -.ib.~
o
model A: closed ocean basin
; - - - T h - - - - I
a
b
c
model B: ventilated ocean basin
,
0.5
i - P a - - - - i d
-Pa"';
dissolved
concentration
(dpm'm- 3 )
0.5
~T' h----l
-T~
O~~------~
3 r-~------,
2 -Pa-:
e
tracer flux!
production
ratio
Pa
a - -- -i
Th' :
oL-~------------J
3r-~------,
2
,
~
1 P9---------r----------:...---p,a----i
O ~~------------J
0. 1 86 .--~------,
0 ~-2------~
0 . 186~---..---------,
0.093
f
231 Pa/230Th
ratio on sinking particles
0.093
9
h
Fig. 2. Model results of two hypothetical scenarios (closed and ventilated basin) in an idealized ocean to demonstrate the basin-wide fractionation of 2J IPa and 2JOTh and the resulting consequences for the sedimentary 231PaI
23°Th record. See text for explanation.