(e) sediment geochemistry€¦ · cao* na o 2 al o 23 ko 2 k von eynatten et al. 2002, math. geol....
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HvE - Sedimentpetrologie
Pettijohn et al. 1987 p.59
chemical composition of common arenites
(E) Sediment geochemistry
HvE - Sedimentpetrologie
Herron 1988
Pettijohn 1963, 1987
classification based on geochemistry
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HvE - Sedimentpetrologie
5%
25%
10%
NCI
CE
NCE
CIsandstone s.str.
NCI-bearingsandstone
NCI-richsandstone
hybrid areniteNCI-bearing
hybrid arenite
NCI-rich
hybrid
arenite
calcarenitecalclithite
quartzarenite, arkose, litharenite
glauconitic greensandoolithic ironstonereworked phosphoritegypsarenite
33%
90%
Q
F L incl. CE
arko
se
quartzarenite
lithic arkose feldspathiclitharenite
litharenitelithic subarkose
sublitharenitesubarkose
2.1.Example:
SwissMolasse Basin
classification based on petrography
-1
0
1
0 1 2
quar
tz a
reni
te
arkose
subarkose
sublitharenite
Fe-sandstoneFe-shale
shale
wack
e
litharenite
log(SiO /Al O )2 2 3
log(
FeO
)2
3/KO 2
classification based on geochemistry
HvE - SedimentpetrologiePettijohn et al. 1987 p.59
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HvE - Sedimentpetrologie
Rollinson 1993
HvE - Sedimentpetrologie
Tectonic Setting – Discrimination diagrams
Rollinson 1993 p.208
(1) Major elements:
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Rollinson 1993 p.207
HvE - Sedimentpetrologie
discrimination of tectonic settingby major elementsdoes it work properly ?
Armstron-Altrin & Verma 2005, Sed Geol 177
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Armstron-Altrin & Verma 2005
success rate
→ be very careful with such discrimination diagrams !!!
HvE - Sedimentpetrologie
the problem of grain-size
Bhatia 1983, Bhatia & Crook 1986, Roser & Korsch 1988
D
C
BA
A
B
C
D
increasing grain size
greywackes from type-locality “Oberharzer Grauwacke“
O-g
O-mO-f
G-g
G-m G-f
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HvE - Sedimentpetrologie
0
10
20
30
40
50
60
0 10 20 30 40
LOI
CaO
0
10
20
30
40
50
60
20 30 40 50 60 70 80
SiO2
CaO
0
4
8
12
16
20
0 10 20 30 40
LOI
MgO
0
4
8
12
16
20
0 10 20 30 40 50 60
CaO
MgO
Bivariate Ca / Mg / LOI-plots of Swiss Molasse sandstones (litharenites)
HvE - Sedimentpetrologie
3 2 146 578
31
29
27
25
23
21
19
17
15
13
Ma 60%
30 0S
3 2 146 578
31
29
27
25
23
21
19
17
15
13
Ma 60%
30 0SG
WSW ENE
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framework composition vs. wr-geochemistry
von Eynatten 2003
HvE - SedimentpetrologieRollinson 1993 p.208
(2) Trace elements:
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McLennan 1993,GSA Spec Pap 284
detection of various processessuch as recycling, sorting, etc.
Th/Sc monitors the compositional variation of the source area, and Zr/Sc monitors zircon enrichment due to sedimentary (sorting and) recycling
Active Margin Turbidites
Zr / Sc.1 1 10 100 1000
.1
1
10
.01
.001
Th /
Sc
Compo
sitio
nal v
ariat
ion
Trailing Edge Turbidites
Andean Foreland
Loess
SedimentRecycling
HvE - Sedimentpetrologie
% Lu(serpentinite clasts)
group III
group II
group I
recy
clin
g
Cr-spinel chemistry
0 0.05 0.10 0.15
2.0
1.5
1.0
0.5
0
TiO2 [Gew.-%]
IPB
IABMORB
FeIII/(Cr+Al+Fe)
0 0.05 0.10 0.15
FeIII/(Cr+Al+Fe)
2.0
1.5
1.0
0.5
0
IPB
IABMORB
TiO2 [Gew.-%]
von Eynatten 2003, Sedimentology 50
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HvE - Sedimentpetrologie
SW NEWSW ENE
3 2 146 578
31
29
27
25
23
21
19
17
15
13
MaSEDIMENTE
Granitoide
Granitoide
SEDIMENTE
SEDIMENTE
Sedimente
Sedimente
SedimenteGranitoide
Gra
nito
ide
(Ultra-)basite
Sedi
men
te
(Ultra-)basite
(Ultra-)
basite
(Ultra-)basiteFlysch M
etas
edim
ente
Meta-sedi-mente
> >>
?
~ 21 Ma~ 20 Ma
~ 25 Ma
? recycling ?
? recycling ?
> 75% 50 - 75% 25 - 50% 10 - 25%
WSW ENE
von Eynatten 2003
HvE - Sedimentpetrologie
Contribution of mafic to ultramafic (ophiolitic)
source rocks( Mixing! )
McLennan 1993
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Rare earth patterns of sedimentsfrom different sources
McLennan 1993
HvE - Sedimentpetrologie Nesbitt & Young 1989
Alteration(weathering, diagenesis, ...)
CIA = 100Al2O3 + CaO* + Na2O + K2O
Al2O3
Chemical Index of Alteration:
(with CaO* = CaO from silicate phases)
increasing alteration
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HvE - SedimentpetrologieLeeder 1999
HvE - Sedimentpetrologie Nesbitt & Young 1989
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chemical weathering of granitoid rocks
Toorongo granodiorite(Nesbitt et al. 1980, GCA 44)
Chemical Index of Alteration:
Al2O3+CaO*+Na2O+K2O
Al2O3
100
C I
A
A
CN K
50
100
+ KfPl
Ka
HvE - Sedimentpetrologie
p(A)
p(CN) p(K)
g
sk = (k ⊗ pw1) ⊕ g
pw1 = (0.49, 0.13, 0.38)99.5%
+
chemical weathering of granitoid rocks
Toorongogranodiorite
von Eynatten et al. 2003
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HvE - Sedimentpetrologie
Toorongogranodiorite
normalizedto Al2O3 = 1
0
0
1
1 2 3 4 5 6 7 8 9 10
0.2
0.4
0.6
0.8
CaO* Na O2
Al O2 3
K O2
kvon Eynatten et al. 2002, Math. Geol. 34
chemical weathering of granitoid rocks
HvE - Sedimentpetrologie
suspended sediment load of the world´s major rivers(McLennan 1993, J. Geol. 101)
s = cc ⊕ (k ⊗ pw2)
pw2 = (0.51, 0.13, 0.36)97.1%
pw1 = (0.49, 0.13, 0.38)99.5%
chemical weathering at global scales
g
p(A)
p(CN) p(K)
Mackenzie
cc
Orinoco
Indus
Ganges
Danube
St. Lawrence
Niger
Mekong
Congo
river k
St. Lawrence 0.13Danube 0.25
Ganges 0.75Indus 0.78Orinoco 1.01
Mekong 1.87Congo 2.15Niger 3.49
von Eynatten et al. 2003, Math. Geol. 35
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HvE - Sedimentpetrologie
Observed trends often due not correlate with predicted trends
She et al. 2006, Chem Geol.
X1
X2 X3
1
2 ?
a
superposition of processes
von Eynatten 2004, Sed Geol
HvE - Sedimentpetrologie
Trace elements such as Rb, Ba, Sr, U, Th, Zr, etc. may provide valuable additional information on weathering processes
McLennan 1993