Spektroskopske analitičke metode Atomska apsorpcija spektroskopija AAS Atomska emisijska...

Spektroskopske analitičke metode

Atomska apsorpcija spektroskopija AAS

Atomska emisijska spektroskopija AES

Induktivno spregnuta plazma spektroskopija ICP

Mikrotermometrija fluidnih inkluzija

UvodKlasifikacija fluidnih inkluzija – morfologija, genetska klasifikacijaMehanizmi formiranja fluidnih inkluzija, zahvaćanje fluida Stupanj punjenja vs. gustoćaOdabir i priprema uzorakaOpremaEutektička svojstvaOsnovni principi mikrotermometrije (zamrzavanje/hlađenje)Definiranje izohoraJednokomponentni sustav H2ODvokomponentni sustav NaCl-H2OTrokomponentni sustavi NaCl-CaCl2-H2O, NaCl-KCl-H2O

VježbeI. Priprema uzoraka (Lab)Dvostruko polirane pločiceII. Dokumentacija (Mikroskopska vježba)

1. Petrografija i odabir fluidnih inkluzija2. Crtanje i fotografiranje3. Klasifikacija FI-s

a. Opis (jednofane, dvofazne, višefazne, minerali kćeri…)b. Relativni volumen faza (stupanj punjenja) c. Veličina inkluzija, morfologijad. Relativna starost (primarne, pseudosekundarne, sekundarne)

Prije početka mjerenja

Literatura

Bakker, R.J., 2003. Package FLUIDS 1. Computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties. Chemical Geology, 194, 3–23.

http://fluids.unileoben.ac.at/Home.html

Brown P.E., 1989. FLINCOR; a microcomputer program for the reduction and investigation of fluid-inclusion data. American Mineralogist, 74/11-12, 1390-1393.

Roedder, E., 1984. Fluid inclusions. Mineralogical Society America, Review in Mineralogy 12, Washington, 644 pp.

Shepherd, T.J., Rankin, A.H., Alderton, D.H.M., 1985. A practical guide to fluid inclusion studies. Blackie and Son Ltd, Glasgow, 239 pp.

Henry Clifton Sorby (1826-1908)English microscopist and geologist 1858 On the Microscopical Structure of Crystals (Quart. Journ. Geol. Soc.)

What is a Fluid Inclusion?

Cavity in a mineral that may contain 1 or more phasesvapor (V) - H2O, CO2, CH4, N2, H2Sliquid (L)- H2O, CO2, petroleumsolid (S) - NaCl, KCl, hematite, anhydrite, muscovite, magnetite, carbonates

L

V

S

The liquid of the inclusion is normally an aqueous solutions with dissolved ions of Na+, Cl-, Ca2+, Mg2+, SO4

2-, HCO32-, CO3

2-

The concentration of the salts ranges from <1 wt. % to >50 wt. %

Occurrence and distribution

Earth Crust – magmatic, metamorphic and sedimentary rocks,ore deposits, fault zones

Extraterrestrial - Mars

Volume and diameter of spherical inclusions assuming a fluid of density 1.0 g/cc

Top 10 minerals1. Quartz2. Fluorite3. Halite4. Calcite5. Apatite6. Dolomite7. Sphalerite8. Barite9. Topaz10. Cassiterite

Abundance of FI-s in single crystal if the total population occupy 0.1% volume

Average FI-s size

No of FI-s occupying 0.1% volume

1 mm 1

100 µm 103

10 µm 106

1 µm 109

> mm museum specimens

3-20 μm range for microthermometry

1.5 μm smallest workable size for H2O or CO2 inclusions

5 μm smallest workable size for H2O+CO2 inclusions

Size of fluid inclusions in minerals

Size and abundance

What can I study?

Ore deposits (hydrothermal, porphyry, skarn)

Large, well developed crystals in vughs and druses, all phases of vein developing, alterations

Igneous rocks Quartz (remnant of magmatic fluid or late stage hydrothermal circulation)

Apatite from carbonatite

Phenocrysts from volcanic

Pegmatites Quartz, beril, tourmaline

Metamorphic rocks Quartz from veins, pods, segregations

Sedimentary rocks Diagenetic fluids preserved within veins, pods, vughs, geodes, diagenetic cement or overgrowth

Which type of material do I use?

What can I get from this method?

1. Composition of fluid form which mineral precipitated

2. Changes of fluid composition during precipitation (mixing, dilution, boiling, cooling)

3. Minimum temperature and pressure at the time of precipitation

4. True temperature and pressure applying pressure correction (i.e. independent geothermometer or boiling fluid)

5. Depth of formation (i.e. overlying deposits)

What type of samples do I need?

Type Advantage Disadvantage

Thin sections Available, easy prepared, host rock petrography can be determined

Can not use for heating-freezing, large FI-s destroyed

Cleavage fragments No specific equipment needed, fast scanning of the samples, direct measurements

Relationships between individual FI-s and grains cannot be established

Cut, doubly polished wafers

0.2 – 0.5 mm thick

Direct use on heating-freezing stage, large FI-s preserved

Mineral identification by optical properties difficult - thick, highly colored or milky samples – thin (<100mm), difficult to prepare

How to prepare doubly polished wafers?

Stage 1 Sawing to surface 3-4 cm2

Grit Grit size (F)/m Lapping time (min)

SiC 320/29 5-10

SiC 400/17 5-10

SiC 800/6.5 5-10

Stage 3 Polishing

Soft polish cloth mounted on rotary lapping machine

ά-Al2O3 /0.3 ~20

Stage 2 Grinding

Fluid inclusions morphology

Negative crystal shape (halite cubes)

Irregular

Flattened

Faced along clevage

Spheroidal or oblate

Tubular in elongated crystals

Roedder, 1984,American Mineralogist

Primary (P) FI-s are formed during the mineral growth within the growth zones. These are overgrowths defined by seudo-secondary (PS) FI-s formed in healed fracture in mineral during original mineral growth. Secondary (S) FI-s developed after the crystallization of the host.

FI-s Major textural criteria

PS

P = Primary PS = PseudoSecondary S = Secondary inclusions

(a) Diagnostic criteria for classifying fluid inclusions as primary (after Roedder, 1979)(b) Different occurrences of primary fluid inclusions in relation to growth zoning (compilation)(from: Van den Kerkhof & Hein, 2001, Lithos 55, 27-47)

Primary FI-s classification

A dendritic growthB partial disolutionC between growth spiralsD sub-parallel block growthE fracture during growthF foreign object

Mechanisms of trapping of primary FI-s

Secondary inclusions

Look at essentially anysandstone/quartzitesamples in the lab

Trail terminology (Vollbrecht,1989) composed after Simmons and Richter (1976) and Kranz (1983).

a) main distinction ismade between transgranular,intergranular, and intragranularinclusions

(b) The intragranularfluid inclusions may decoratedifferent internal grain texturesand are accordingly subdivided

Secondary and pseudosecondary FI-s classification

The P and PS inclusions in the inner growth zone are older than the P and PS ones in the outer zone.Inclusions along the growth planes are denoted as primary. The S trail, extending tothe surface of the crystal, postdates all P and PS inclusions.

(Hansteen, 1988)g

row

th z

on

ing

gro

wth

zo

nin

gWorking example 1:Determine relative age

FI-s content - classification

Single-phase Two-phase

Multi-phase Immiscible-liquid

Liquid-rich

Vapor-rich

Liquid or Vapor H2O, CH4, CO2

Classification scheme for fluid and melt inclusions in minerals based upon phases observed at room temperature L=liquid, V= vapour, S=solid, GL=glass

(from: Sheperd, 1985)

Working example 2:Classify the inclusions

15 m 10 m

10 m

10 m

1. Trapped fluid was a single homogeneous phase2. The cavity has not changed in volume3. Nothing is added or lost after sealing4. Effects of pressure are insignificant or known5. The origin of the inclusion is known6. The determinations of Th are both precise and accurate

Basic Assumptions

HOWEVER

1. Bulk leakage

2. Leakage through diffusion

3. Stretching

4. Re-equilibration

5. Necking-down

6. Migration

1. Bulk leakage – soft, easy cleaved material – visual estimation on constancy of L to V ratio, reproducibility of thermometric results

2. Leakage through diffusion – proved as extremely low (H+ found by Raman)

3. Stretching – change of volume without changing of composition

4. Re-equilibration – irregularly shaped FI-s tend to change shape and morphology during time into negative crystal of spherical – insoluble minerals as quartz -isochemical at constant volume

5. Necking-down – if original FI is large, flat and irregular will split into many small but more regular FI-s. If the process occur during homogenous stage – good, preserved L to V ratio, if not L to V ratio disturbed – erroneous values

6. Migration – in a thermal gradient – important for water soluble materials

Recognition

Necking-down

Streaching and leackage

time

Working example 3:What happened?Why?How do you know?

Estimation of volume fractions relative to FI-s size – cylindrical FI-s

Estimation of volume fractions of vapor-rich inclusions – here comes the problem

Estimation of volume fractions of spherical inclusions

Cylindrical

Spherical

Trapping mode

Accidental trapping of solids

Naziv faze Sastav Stupanj refleksije

Kristalni sustav

Habitus

Tekući ugljik-dioksid

CO2 (l) 1,195

Led H2O 1,31 Heksagonski Zaobljen,anizotropan, izgleda izotropno

Hidrohalit NaCl×2H2O 1,41 Monoklinski Sitna zrnca svjetlucavog izgleda

Silvin KCl 1,49 Kubični Kockice

Gips CaSO4×2H2O 1,52 Monoklinski Tabularni, prizmatski

Halit NaCl 1,54 Kubični Kockice

Ahidrit CaSO4 1,57 Rompski Prizmatski

Ca,Mg karbonati

(Ca,Mg)CO3 1,49 – 1,66 Trigonski Romboedrijski

Phase proportion of individual inclusion

Degree of fill (F) of two phase L+V FI-s

F = VL/VL + VV where VL + VV = VTOT

F is related to total density (TOT) of the fluid by following expression

TOT = LF + V(1-F) where L = density of the liquid phaseV = density of the vapor phase

In most cases we can assue that density of the vapor phase is zero, thus:

TOT = LF

Deg

ree

of f

ill (

F)

0

0.5

1

Total density (TOT) of the fluid in g/cm3

0 0.5 1 1.1 1.2

0 15 25 wt % NaCl equ.

Analytical equipment – Linkam stage

Cross-section of the Linkam stage (Sheperd, 1981) Pt= platinum resistance temperature sensor

Technical specifications

-180º to +600ºC (gaseous N2)

Fully automatic

0.1º - 0.9ºC/min; 1º - 9ºC/min; 10º - 90ºC/min

Max. sample size 20 mm, 1.5 mm thick

Viewing area – 2.2 mm

x-y micromanipulators

Eutectic properties of SALT SOLUTIONS

What types of FI-s can we found?

Diagnostic features

(Hein, 1990)

Phase transitions during microthermometry runs

Phase transitions in aqueous inclusions2D phase diagram pt diagram for water

Lines of equilibrium or phase boundaries

Tripple point

Critical point

H2O system

Density (g/cm3) or degree of fill

Supercritical fluid

vapor

liquid

Trapping temperature

A B C D

coo

ling

Two phase L+ V

Principle of fluid inclusion geothermometry PT diagram

for pure water P

ress

ure

KB

ar

Temp oC

1.0

0.5

0

50 150 350

Isochore (g/cc)

Boiling

L=V curve

Critical point

Liquid water

0.95 0.80

0.60

Dry steam -Vapour

H2O system

Consider an inclusion trapped at a given temperature and pressure (Tt, Pt)P

ress

ure

KB

ar

Temp oC

1.0

0.5

0

50 150 350Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

On cooling, the inclusion follows an isochoric PT path until it meets the L=V curve

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

Beyond this point the inclusion cools along the L=V curve and a vapour bubble nucleates

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

Continued cooling results in further shrinkage of liquid and growth of the vapour bubble

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

On heating along the V/L curve, the liquid expands and the bubble shrinks

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

Until the bubble disappears at the homogenisation

temperature (Th) P

ress

ure

KB

ar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

The point Th uniquely defines the isochore along which the inclusions originally cooled

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

Isoc

hore

H2O system

With continued heating the inclusion follows the original isochore

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

If Pt is known, or estimated, the trapping temperature (Tt) can be determined

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

The difference between Th and Tt is known as the Pressure Correction

Pre

ssu

re K

Bar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

Principle of fluid inclusion geothermometry based on

PVT diagram for pure water P

ress

ure

KB

ar

Temp oC

1.0

0.5

0

50 150 350Th Tt

PtIsochore (g/cc)

L=V curve

Critical point

Liquid

Vapour

0.95 0.80

0.60

H2O system

H2O isochores modified from Fischer (1976). Enlargement of the low pressure region, in the box, appears to the right.

H2O system

3D phase diagram – two component system

A

B

composition

vapor

Sol A + L

Sol B + L

Sol A + sol B

Liquid

VaporSol B + V

Sol B + V

Sol A + V

SCF

Phase transitions during microthermometry runs

Phase transitions in two-phase NaCl-H2O aqueous inclusions

The next slides show the freezing and subsequent melting of a two phase aqueous inclusion. Note the first and last melting temperatures which tell us about composition

Heating

Cooling

350oC

25oC

-100oC

0oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

Temperature of Homogenisation Th

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

The next slides show the freezing and subsequent melting of a two phase aqueous inclusion. Note the first and last melting temperatures which tell us about composition

Heating

Cooling

350oC

25oC

-100oC

0oC

350oC

25oC

0oC

-100oCFreezing after Supercooling

350oC

25oC

0oC

-100oC

First melting temperature - Tfm

Eutectic - telling us about composition

Eutectic properties of SALT SOLUTIONS

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oC

350oC

25oC

0oC

-100oCLast ice melting temperature Tm(ice)

Telling us about salinity

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ V

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

30 20 10 0

Phase diagram for NaCl-H2O showing stability fields for halite, hydrohalite, liquid and vapour

NaCl-H2O system

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ V

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

30 20 10 0

An inclusion with 10 wt.% solution cooled below 0oC does not form ice because of metastability

NaCl-H2O system

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ V

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

30 20 10 0

Rapid cooling below the eutectic temperature (Te) is usually needed before the inclusion freezes

NaCl-H2O system

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ VTfm

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

30 20 10 0

On heating first melting (Tfm) occurs at -20.8 (Te), evident by “unlocking” of the vapour bubble

NaCl-H2O system

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ VTfm

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

Tm(ice)

30 20 10 0

Continued heating results in the melting of the last ice crystal (Tm_ice) at -6oC

NaCl-H2O system

0.1oC

-20.8oC

Ice + NaCl.2H2O + V

Ice + L+ V

L + V NaCl +L+V

NaCl.2H2O+L+ VTfm

Weight % NaCl

Tem

pera

ture

o C

-50

25

-25

0

Tm(ice)

30 20 10 0

Continued heating results in the melting of the last ice crystal (Tm_ice) at -6oC

NaCl-H2O system

Temperature of ice melting directly determine the salinity

For diferent composition of inclusions (Te) we apply different phase diagrame to calculate salinities

Sample calculations from fluid inclusion observations

300 bars fluid pressure (hydrostatic)Fluid T = Rock TAverage fluid density = 1.0 g/cc=> Depth = 3 km

Temperature = 300°C=> Thermal gradient = 100°C /km

Age: rock passed through 300°C1 million years ago=> Uplift rate = 3 mm/year

CaCl2-H2O system

Ternary water salt systems

Ternary water salt systems