11.2 Denudation-Sediment Accumulation Systems
OPEN:
SRme = DRme Ad/Ab
a
SR bi + MIOS! = DRch Ad/Ab
Mme + M Ch
or DR me + DR ch
TOTAL
CLOSED: SRbi + SRev = DR ch Ad/A b DRANAGE AREA
TOTAL AREA ~ :
OF DEPOSITION
I
. _____
Ab
,.A
~ ACTUAL BASIN
\
SEDIMENTS
jkI
SPILL·OVER
OF SEDIMENT
Denudation rate DR
b
(mmlka)
Conversion
factor Fs
Rock
0.357
density r
(tim)
0,37
2,8
2.7
0,385
2.6
0.4
2.5
2.4
0.417
2,3
0.435
2,2
0.455
Example 1: DR= 2, p= 2.6, n= 0.4
SEDIMENT VOLUME
ISOCHRONE (STRATIGR.
TO BE DETERMINEO
(TERRIG.AND BIOGENIC)
BOUNDARY)
Sediment volume VS (m 3 /km 2 /a)
or sedimentation rate SR"" (mmika)
Conversion
Specific
Sediment
factor Fs
sediment
porosity
1.89
yield SY
n (-)
(tlkm 2 /a)
0.8
1.26
0.7
0.94
0.6
0.5
0.73
0.4
0,63
0.3
0.2
0.54
(mean grain
density 2.65 g/cm')
0.47
SY= ~~ = rit ~ 5.2 t/km
2
/a ; Vs= SY * Fs= 5,2 * 0,63= 3.3 m
3
/km
2
/a
Example 2: V s= 25, n= 0.6, p= 2.4
SY= ~ = 12- ~ 27 tJkm
2
/a ; DR= SY * F o = 27 * 4,17 * 10. 2 = 1.1 cmlka
Fs
0.94
483
Fig. 11.1. a Relationship between
mechanical and
chemical denudation, D~e and
DR~h' in the
dramage area,
Ad,> and sedimentatlOn rate, SR, in
the related basin
of the area Ab.
Trap efficiency
TE= 100 % signifies that an incoming sediment
is trapped by the
basin. M, mass;
SR me , SR bj ,
SRev, mechanical, biogenic and
evaporitic sedimentation rate.
See text for further explanation.
b Conversion of
mechanical denudation rates,
D~e' into speciflC sediment
yields, SY, as
wen as sediment
volumes or (linear) mechanical
sedimentation
rates, S~e' of
wet sediment of
different porosities