Atomska apsorpcija spektroskopija AAS
Spektroskopske analitičke metode
Atomska emisijska spektroskopija AES
Induktivno spregnuta plazma spektroskopija ICP
Mikrotermometrija fluidnih inkluzija
Uvod
Klasifikacija fluidnih inkluzija – morfologija, genetska klasifikacija
Mehanizmi formiranja fluidnih inkluzija, zahvaćanje fluida
Stupanj punjenja vs. gustoća
Odabir i priprema uzoraka
Oprema
Eutektička svojstva
Osnovni principi mikrotermometrije (zamrzavanje/hlađenje)
Definiranje izohora
Jednokomponentni sustav H2O
Dvokomponentni sustav NaCl-H2O
Trokomponentni sustavi NaCl-CaCl2-H2O, NaCl-KCl-H2O
Prije početka mjerenja
Vježbe
I. Priprema uzoraka (Lab)
Dvostruko polirane pločice
II. Dokumentacija (Mikroskopska vježba)
1. Petrografija i odabir fluidnih inkluzija
2. Crtanje i fotografiranje
3. Klasifikacija FI-s
a. Opis (jednofane, dvofazne, višefazne, minerali kćeri…)
b. Relativni volumen faza (stupanj punjenja)
c. Veličina inkluzija, morfologija
d. Relativna starost (primarne, pseudosekundarne, sekundarne)
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.
What is a Fluid Inclusion?
Henry Clifton Sorby
(1826-1908)
English microscopist and
geologist
1858 On the Microscopical
Structure of Crystals
(Quart. Journ. Geol. Soc.)
Cavity in a mineral that may contain 1 or more phases
vapor (V) - H2O, CO2, CH4, N2, H2S
liquid (L)- H2O, CO2, petroleum
solid (S) - NaCl, KCl, hematite, anhydrite, muscovite,
magnetite, carbonates
V
L
S
The liquid of the inclusion is normally an aqueous solutions with dissolved ions of Na+, Cl-, Ca2+,
Mg2+, SO42-, HCO32-, CO32The 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
Top 10 minerals
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Quartz
Fluorite
Halite
Calcite
Apatite
Dolomite
Sphalerite
Barite
Topaz
Cassiterite
Abundance of FI-s in
single crystal if the total
population occupy 0.1%
volume
Size and abundance
Average
FI-s size
No of FI-s occupying
0.1% volume
1 mm
1
100 µm
103
10 µm
106
1 µm
109
Size of fluid
inclusions in minerals
> 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
Volume and diameter of spherical inclusions assuming a fluid of density 1.0 g/cc
What can I study?
Which type of material do I use?
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
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 heatingfreezing, large FI-s
destroyed
Cleavage fragments
No specific equipment
Relationships between
needed, fast scanning of the individual FI-s and grains
samples, direct
cannot be established
measurements
Cut, doubly polished wafers
0.2 – 0.5 mm thick
Direct use on heatingfreezing 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
Stage 2 Grinding
Grit
Grit size (F)/mm
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
Fluid inclusions
morphology
Negative crystal shape (halite cubes)
Irregular
Flattened
Faced along clevage
Spheroidal or oblate
Tubular in elongated crystals
Roedder, 1984,
American Mineralogist
FI-s Major textural criteria
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.
PS
P = Primary
PS = PseudoSecondary
S = Secondary
inclusions
Primary FI-s classification
(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)
Mechanisms of trapping of primary FI-s
A dendritic growth
B partial disolution
C between growth spirals
D sub-parallel block growth
E fracture during growth
F foreign object
Secondary inclusions
Look at essentially any
sandstone/quartzite
samples in the lab
Secondary and
pseudosecondary
FI-s classification
Trail terminology (Vollbrecht,
1989) composed after Simmons
and Richter (1976) and Kranz
(1983).
a) main distinction is
made between transgranular,
intergranular, and intragranular
inclusions
(b) The intragranular
fluid inclusions may decorate
different internal grain textures
and are accordingly subdivided
Working example 1:
Determine relative age
growth zoning
growth zoning
(Hansteen, 1988)
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.
FI-s content - classification
Single-phase
Liquid or
Vapor
H2O, CH4,
CO2
Multi-phase
(from: Sheperd, 1985)
Two-phase
Liquid-rich
Vapor-rich
Immiscible-liquid
Classification scheme for fluid and melt inclusions in
minerals based upon phases observed at room
temperature
L=liquid, V= vapour, S=solid, GL=glass
Working example 2:
Classify the inclusions
10 mm
15 mm
10 mm
10 mm
Basic Assumptions
1.
2.
3.
4.
5.
6.
Trapped fluid was a single homogeneous phase
The cavity has not changed in volume
Nothing is added or lost after sealing
Effects of pressure are insignificant or known
The origin of the inclusion is known
The determinations of Th are both precise and accurate
HOWEVER
1. Bulk leakage
2. Leakage through diffusion
3. Stretching
4. Re-equilibration
5. Necking-down
6. Migration
Recognition
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
Necking-down
time
Streaching and leackage
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 ugljikdioksid
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 (rTOT) of the fluid by following expression
rTOT = rLF + rV(1-F)
where
rL = density of the liquid phase
rV = density of the vapor phase
In most cases we can assue that density of the vapor phase is zero, thus:
1
0 15 25 wt % NaCl equ.
Degree of fill (F)
rTOT = rLF
0.5
Total density (rTOT) of the fluid in g/cm3
0
0
0.5
1 1.1 1.2
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 inclusions
2D phase diagram
pt diagram for water
Lines of equilibrium or
phase boundaries
Tripple point
Critical point
A
B
C
D
Trapping temperature
Supercritical fluid
H2O system
cooling
liquid
Two phase L+ V
Density (g/cm3) or degree of fill
H2O system
Principle of fluid inclusion geothermometry PT diagram
for pure water
1.0
Liquid
water
Isochore
(g/cc)
Critical
point
0.5
Dry steam
-Vapour
0
50
150
350
H2O system
Consider an inclusion trapped at a given
temperature and pressure (Tt, Pt)
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Tt
350
H2O system
On cooling, the inclusion follows an isochoric PT path
until it meets the L=V curve
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Tt
350
H2O system
Beyond this point the inclusion cools along the L=V
curve and a vapour bubble nucleates
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Tt
350
H2O system
Continued cooling results in further shrinkage of liquid
and growth of the vapour bubble
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Tt
350
H2O system
On heating along the V/L curve, the liquid expands and
the bubble shrinks
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Tt
350
H2O system
Until the bubble disappears at the homogenisation
temperature (Th)
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
The point Th uniquely defines the isochore along which
the inclusions originally cooled
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
With continued heating the inclusion follows the original
isochore
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
If Pt is known, or estimated, the trapping temperature
(Tt) can be determined
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
The difference between Th and Tt is known as the
Pressure Correction
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
Principle of fluid inclusion geothermometry based on
PVT diagram for pure water
1.0
Liquid
Isochore
(g/cc)
Pt
Critical
point
0.5
Vapour
0
50
150
Th
Tt
350
H2O system
H2O isochores modified from Fischer (1976).
Enlargement of the low pressure region, in the box, appears to the right.
3D phase diagram –
two component system
Liquid
Sol B + L
Sol A + sol B
A
B
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
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
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
0oC
-100oC
350oC
25oC
0oC
Freezing after Supercooling
-100oC
350oC
25oC
0oC
First melting temperature - Tfm
-100oC
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
Last ice melting temperature Tm(ice)
Telling us about salinity
-100oC
NaCl-H2O system
Phase diagram for NaCl-H2O showing stability fields
for halite, hydrohalite, liquid and vapour
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
NaCl-H2O system
An inclusion with 10 wt.% solution cooled below
0oC does not form ice because of metastability
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
NaCl-H2O system
Rapid cooling below the eutectic temperature (Te)
is usually needed before the inclusion freezes
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
NaCl-H2O system
On heating first melting (Tfm) occurs at -20.8
(Te), evident by “unlocking” of the vapour bubble
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
Tfm
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
NaCl-H2O system
Continued heating results in the melting of the last
ice crystal (Tm_ice) at -6oC
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
Tm(ice)
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
Tfm
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
NaCl-H2O system
Continued heating results in the melting of the last
ice crystal (Tm_ice) at -6oC
25
NaCl
+L+V
Temperature oC
L+V
0.1oC
0
Tm(ice)
NaCl.2H2O
+L+ V
-20.8oC
Ice + L+ V
Tfm
-25
Ice + NaCl.2H2O + V
-50
0
10
20
Weight % NaCl
30
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 T
Average fluid density = 1.0 g/cc
=> Depth = 3 km
Temperature = 300°C
=> Thermal gradient = 100°C /km
Age: rock passed through 300°C
1 million years ago
=> Uplift rate = 3 mm/year
CaCl2-H2O system
Ternary water salt systems
Ternary water salt systems