pektroskopske analitičke metode Atomska apsorpcija spektroskopija AAS Atomska emisijska spektroskopija AES Induktivno spregnuta plazma spektroskopija rotermometrija fluidnih inkluzija
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