Heavy mineral analysis - uni-goettingen.de · ATiATi Apatite = Apatite – Tourmaline index = 100 *...

Heavy mineral analysisWhat are heavy minerals?

Heavy mineral analysisy

accessory minerals in clastic sediments with a proportion

minerals with a specific density > 2.85 g/cm3

are smaller than the average grain size of the sediment

accessory minerals in clastic sediments with a proportionof usually <1%

amphibole, pyroxene, zircon, tourmaline, rutile, apatite, ...

g g

Ho to anal se them?

fine to medium-grained sandstones, as fresh as possible (!)

How to analyse them?

crushing and desaggregation (e.g., 10% acetic acid, ultrasonic, H2O2, etc.sieve fraction 63 – 125 μm (may be coarser, if necessary)separation of HM by specific density fluids such as Na metatungstateseparation of HM by specific density fluids such as Na-metatungstatecounting of at least 200 grains under the microscope; embedded in specialresins or waxes with well defined optical properties (e.g., Meltmount 1.66)

HvE - Sedimentpetrologie

( g )for details see Mange & Maurer (1991, 1992)


HvE - SedimentpetrologieBoenigk 1983

Grain-size dependence of HM assemblages

63 – 125 μm

Boenigk 1983


Boenigk 1983

HydraulicXYi = mineral X – mineral Y index

= 100 * X / (X + Y)

ybehavior

100 X / (X + Y)

ATi = Apatite – Tourmaline indexATi Apatite Tourmaline index= 100 * apatite / (apatite + tourmaline)


Morton & Hallsworth 1994

Modification of HM assemblages

source areaweathering

abrasionmixing

sortingweathering sorting

authigenesis, 991

sedimentary basin

authigenesis,intrastratal solution

Mau

rer 1

9



Man

ge &

Occurrence and stability of HM (weathering profiles)

-deecreasinng stabillity -

HvE - SedimentpetrologieMorton & Hallsworth 1999

HvE - Sedimentpetrologie Mange & Maurer 1991

Modification of HM assemblages

instrastratalsolution



Tha-2

Sal-2

Huy-1

os: H

vE


Foto

Weathering on transitg(alluvial storage)

example by Morton & Johnsson 1993p y

SMA / NMA

CMM

SMA / NMA


Weathering

NMA

gon transit

SMA

NMA

CM/MA Llanosprox mid distCM/MA Llanosprox. mid. dist.

CMM

Morton & Johnsson 1993


Example:

L RhiLower RhineBay, Cologne


gk 1

983

HvE - Sedimentpetrologie Boe

nig

HvE - Sedimentpetrologie Berger et al. 2005

Schwerminerale

Minerale mit spezifischer Dichte > 2.89 (2,86) g/cm3

(engl.: heavy minerals oder dense minerals)

Charakteristische Merkmale:

Habitus (Form Spaltbarkeit Oberflächenstruktur )- Habitus (Form, Spaltbarkeit, Oberflächenstruktur, ...)- Farbe (Pleochroismus!)

Li htb h ( t hi dl Ei b tt itt l!)- Lichtbrechung (unterschiedl. Einbettungsmittel!)- Doppelbrechung (Mineraldicke und -orientierung beachten!)- Auslöschung, opt. Charakter/Interferenzbild, Einschlüsse, ...

für die spezifische Merkmale der einzelnen Minerale siehe v.a. Mange & Maurer 1991; im Skript sind nur einige Folien enthalten mit Bezug zur Schwermineralchemie


g

zircon

a: Eocene tuff horizonb: Carboniferous sediments

Meltmount 1,662100 μm

tetragonal, = 4.60 – 4.79

HvE - SedimentpetrologieMange & Maurer 1991

n = 1.92 – 2.02= 0.042 – 0.065

tourmaline trigonal, 1- , = 3.00 – 3.25, n = 1.61 – 1.66, = 0.017 – 0.036

Al(tot)Elbaiteelbaite

1

Meltmount 1,582100 μm Schorl Dravite2

4

57

draviteschorl

91

Uvite3 6 8 uvite

Mau

rer 1

99

Al50Fe(tot)50 Al50Mg50

Henry & Guidotti 1985,von Eynatten & Gaupp 1999

1,2: granitoid host (source) rocks4 5 6 t di t h t ( ) kM

ange

& M

EY 6-1 (LOS)H 1021-5 (BRA)

detritaltourmaline grains

von Eynatten & Gaupp 19994,5,6: metasedimentary host (source) rocksM

EY 9-34 (BRA)

EY 6-3/b (LOS)EY 6-3/c (LOS)

tourmaline grains

tourmaline frommetasandstoneclasts


EY 6-3/d (LOS)clasts

Henry & Guidotti 1985,von Eynatten & Gaupp 1999

rutile – properties and occurrence 991

beside sphene and ilmenite Mau

rer 1

9

beside sphene and ilmenitethe most important Ti - mineralin the earth‘s crust M

ange

&

chemistry:TiO2 ( >99 wt.-%)

main primary occurrence

but ... Nb 28000 ppmCr 4400 ppmFe >30000 ppm

tetragonal, 1 +n = 2.61 – 2.90

= 0.286 – 0.296in medium to high-grade metamorphic rocks

Fe >30000 ppmZr 8400 ppm V 7600 ppm

0.286 0.296

stable in sedimentaryenvironments

W 8100 ppmU 84 ppm

frequent occurrence as heavy mineral in (mature) clastic sediments


used for maturity (ZTR) and other indices reflecting source materials (RZi)

4000

5000

(rut

ile)

metacumulatesrutile

3000

Cr i

n pp

m

rutile frommafic rocks

1000

2000

C

0

1000

0 500 1000 1500 2000

rutile frommetapelitic rocks

2500 3000

28000

0 500 1000 1500 2000

Nb in ppm (rutile)

2500 3000

Zack et al. 2002, Chem Geol 184,

Zack et al 2004 CMP 184


Zack et al. 2004, CMP 184

Al)

Mg/(Mg+Fe )2+

01.01.0

01.0

t IIIchrome

Cr/(

Cr+

A

A chromitites

0.8

type-IIIophiolitesB

chromespinel

Kubischharz-

burgites0.6

Kubisch= 5.09

n = 2.00

TiO wt.-%2

cumulates(dunites)0.4

type-IIophiolites

Meltmount 1,662= ./.

2.0

IPBlherzolites

0.2type-Iophiolites

Diagramm nach Arai 1992,Daten aus v. Eynatten 1996

1.5

MORB

IPB

Dick & Bullen1984

Pober & Faupl1988

0.0

1.01984 1988

0.5 IAB

HvE - Sedimentpetrologie0 0.05 0.150

Fe3+/(Cr+Al+Fe )3+

amphibole - ??HvE - Sedimentpetrologie

blue sodic amphiboles1.0

Mn)

0.8

Fe2+

+

0.6(Mg+

F

0 4Fe2+

/(

0.4

Mg-

0.2

griebeckite

0.00.0 0.2 0.4 0.6 0.8 1.0

von Eynatten et al.1999, Sed. Geol.

HvE - SedimentpetrologieFe3+/(AlVI+Fe3++Ti)

(G) Case Studies( )

1. Oligo-/Miozänes Vorland der Betischen Kordillere

2. Schweizer Molassebecken (Zentralalpen-Vorland)

3 Subherzynes Kreidebecken (Harz-Vorland)3. Subherzynes Kreidebecken (Harz Vorland)

44. ... ... ...


Heavy mineral analysis - uni-goettingen.de · ATiATi Apatite = Apatite – Tourmaline index = 100 *...

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