sedimentpetrologie skript 10 4
TRANSCRIPT
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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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5%
25%
10%
NCI
CE
NCE
CIsandstones.str.
NCI-bearingsandstone
NCI-richsandstone
hybrida
renite
NCI-be
aring
hybrid
arenite
NCI-rich
hybrid
arenite
calcarenitecalclithite
quartzarenite, arkose, litharenite
glauconitic greensandoolithic ironstonereworked phosphoritegypsarenite
33%
90%
Q
F L incl. CE
ark
ose
quartzarenite
lithic arkose feldspathic
litharenite
litharenitelithic subarkose
sublitharenitesubarkose
2.1.Example:
Swiss
Molasse Basin
classification based
on petrography
-1
0
1
0 1 2
quar
tz
arenit
e
arkose
subarkose
sublitharenite
Fe-sandstoneFe-shale
shale
w
acke
litharenite
log(SiO /Al O )2 2 3
lo
g(F
eO
)
2
3/K
O2
classification based
on geochemistry
HvE - SedimentpetrologiePettijohn et al. 1987 p.59
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Rollinson 1993
HvE - Sedimentpetrologie
Tectonic Setting Discrimination diagrams
Rollinson 1993 p.208
(1) Major elements:
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Rollinson 1993 p.207
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discrimination of tectonic setting
by 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
B
A
A
B
C
D
increasing grain size
greywackes from type-locality Oberharzer Grauwacke
O-g
O-m
O-f
G-g
G-m G-f
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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
32 146 578
31
29
27
25
23
21
19
17
15
13
Ma 60%30 0S
32 146 578
31
29
27
25
23
21
19
17
15
13
Ma 60%30 0S
G
WSW ENE
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framework composition vs. wr-geochemistry
von Eynatten 2003
HvE - Sedimentpetrologie
Rollinson 1993 p.208
(2) Trace elements:
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McLennan 1993,
GSA Spec Pap 284
detection of various processes
such as recycling, sorting, etc.
Th/Sc monitors the compositional
variation of the source area, andZr/Sc monitors zircon enrichment
due to sedimentary (sorting and)recycling
Acti ve Margi n Turb idi tes
Zr / Sc.1 1 10 100 1000
.1
1
10
.01
.001
Th/Sc
Compositional
varia
tion
Trailing Edge Turbidites
Andean Fo reland
Loess
Sediment
Recycling
HvE - Sedimentpetrologie
% Lu(serpentinite clasts)
group III
group II
group I
recycling
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
IAB
MORB
TiO2 [Gew.-%]
von Eynatten 2003, Sedimentology 50
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SW NEWSW ENE
32 146 578
31
29
27
25
23
21
19
17
15
13
Ma SEDIMENTE
Granitoide
Granitoide
SEDIMENTE
SEDIMENTE
Sedimente
Sedimente
SedimenteGranitoide
Gran
ito
ide
(Ultra-)basite
Se
dim
en
te
(Ultra-)basite
(Ultra-)
basite
(Ultra-)basiteFlysch
Me
tase
dim
en
te
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 sediments
from different sources
McLennan 1993
HvE - Sedimentpetrologie Nesbitt & Young 1989
Alteration(weathering, diagenesis, ...)
CIA = 100Al2O3 + CaO* + Na2O + K2O
Al2O3
Chemical Index ofAlteration:
(with CaO* = CaO from silicate phases)
increasing alteration
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Toorongogranodiorite
normalized
to 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
k
von Eynatten et al. 2002, Math. Geol. 34
chemical weathering of granitoid rocks
HvE - Sedimentpetrologie
suspended sediment load of
the worlds 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 0.13
Danube 0.25
Ganges 0.75
Indus 0.78
Orinoco 1.01
Mekong 1.87
Congo 2.15
Niger 3.49
von Eynatten et al. 2003, Math. Geol. 35
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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 valuableadditional information on weathering processes
McLennan 1993