(E) Sediment geochemistry€¦ · CaO* Na O 2 Al O 23 KO 2 k von Eynatten et al. 2002, Math. Geol. 34 chemical weathering of granitoid rocks HvE - Sedimentpetrologie suspended sediment

1

HvE - Sedimentpetrologie

Pettijohn et al. 1987 p.59

chemical composition of common arenites

(E) Sediment geochemistry


Herron 1988

Pettijohn 1963, 1987

classification based on geochemistry

2


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

3


Rollinson 1993


Tectonic Setting – Discrimination diagrams

Rollinson 1993 p.208

(1) Major elements:

4


Rollinson 1993 p.207


discrimination of tectonic settingby major elementsdoes it work properly ?

Armstron-Altrin & Verma 2005, Sed Geol 177

5


Armstron-Altrin & Verma 2005

success rate

→ be very careful with such discrimination diagrams !!!


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

6


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)


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

7


framework composition vs. wr-geochemistry

von Eynatten 2003

HvE - SedimentpetrologieRollinson 1993 p.208

(2) Trace elements:

8


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


% 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

9


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


Contribution of mafic to ultramafic (ophiolitic)

source rocks( Mixing! )

McLennan 1993

10


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

11

HvE - SedimentpetrologieLeeder 1999

HvE - Sedimentpetrologie Nesbitt & Young 1989

12


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


p(A)

p(CN) p(K)

g

sk = (k ⊗ pw1) ⊕ g

pw1 = (0.49, 0.13, 0.38)99.5%

+


Toorongogranodiorite

von Eynatten et al. 2003

13


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



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

14


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


Trace elements such as Rb, Ba, Sr, U, Th, Zr, etc. may provide valuable additional information on weathering processes

McLennan 1993

Documents

(E) Sediment geochemistry€¦ · CaO* Na O 2 Al O 23 KO 2 k von Eynatten et al. 2002, Math. Geol. 34 chemical weathering of granitoid rocks HvE - Sedimentpetrologie suspended sediment