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Low Temperature Phase Relations in the SystemH2O-NaCl-FeCl2
Paige Marie Baldassaro
Thesis submitted to the Faculty of
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
MASTER of SCIENCE
in
GEOLOGICAL SCIENCES
Dr. Robert J. Bodnar, Chair
Dr. Robert J. Tracy
Dr. J. Donald Rimstidt
May 8, 1998
Blacksburg, Virginia
Key words: synthetic fluid inclusions, iron chloride, sodium chloride, low temperature aqueousgeochemistry
Low Temperature Phase Relations in the System H2O-NaCl-FeCl2
Paige Marie Baldassaro
(ABSTRACT)
The low temperature phase behavior of the system H2O-NaCl-FeCl2 was
examined using synthetic fluid inclusions. Experiments were conducted along the 5 wt%
NaCl (relative to the total solution) pseudobinary, with FeCl2 concentrations varying from
2 to 33 wt%, and along the pseudobinary defined by mixing known amounts of
FeCl2⋅4H2O with a 5 wt% NaCl solution, with final FeCl2 concentrations varying from 0 to
29 wt%. Synthetic fluid inclusions in quartz were prepared in cold-seal pressure vessels
at 500°C – 800°C and 2 or 3 kilobars. The fO2 conditions were controlled by the Ni-NiO
equilibrium curve. The liquid released from the capsule upon opening was initially
colorless, but turned yellow-orange after contact with atmospheric O2. The clear color is
characteristic of ferrous iron solutions, whereas the yellow-orange color is consistent
with the presence of Fe3+ in solution. This color change suggested that the unopened
capsules initially contained ferrous iron in solution, which oxidized to ferric iron when
exposed to the atmosphere.
Borisenko (1977) reported a eutectic temperature of -37°C for the system H2O-
NaCl-FeCl2. In this study, it was not possible to verify this temperature due to the
persistence of a metastable liquid down to liquid N2 temperatures (~-196°C).
Final ice melting temperatures were obtained for concentrations less than 24
wt% FeCl2 and show a decrease in temperature with increase in FeCl2 concentration.
For more concentrated solutions, final melting temperatures could not be obtained
because the samples could not be frozen.
iii
I dedicate this work to the true roses of my life,
my mother and father.
They always believed in me, even when I didn’t.By the way, take a sniff, I think it happened again…
iv
Acknowledgements
I would like to take this opportunity to acknowledge and thank those who made
this work possible. I would like to express my sincerest appreciation to my family, my
father and mother, Walter and Tanya Baldassaro, and to my brother and sister, Lance
and Jenny Baldassaro. They never failed to support me and were always patient and
loving. I will always be grateful that they never stood in my way, even when they didn’t
agree with my choices. I hope that I have made them proud. They deserve it.
To my boyfriend, John Deighan, I wish to offer my deepest thanks. He was and
is a solid anchor on which I rely again and again. Words can not express how grateful I
am to be in his life and how much this work was enhanced and made easier by him
being in mine. Because of him, my experience here at Virginia Tech, and my work, has
far exceeded even my own expectations.
My friends, Nancy Brauer, Theresa Denson, Luca Fedele and Amy Johnson, I
could never have done this without their validation and support. I will always remember
the many times I went to them, and they never failed to be there for me. Everyone
should have such a great group of friends.
To my committee members, I bid them a fond farewell and a hearty thanks! To
Dr. Robert J. Bodnar, I asked that he only teach me what he knew, and he did. I asked
that he only give me a chance, and he did. I thank him. To Dr. J. Donald Rimstidt, I
thank him for his patience and guidance. I thank him for our many conversations. This
work was greatly enhanced by his presence. To Dr. Robert J. Tracy, I thank him for his
enthusiasm and knowledge. He provided an atmosphere of ease from which I learned
most readily. I will always be grateful for that.
To Connie Lowe, I will be forever indebted. Her determination in helping me
achieve my goals was without end. Her loyalty to me and the other graduate students is
without question. She is an asset to the department and I will miss her tremendously.
There are many others I should mention here. People who helped me along the
way and provided me support when I didn’t even realize I needed it, or needed it now,
or needed it constantly. Listing all of them would fill a book itself, so I merely will have
to limit myself to a few words: I thank you ALL!
v
TABLE OF CONTENTS
Title Page i
Abstract ii
Dedication iii
Acknowledgements iv
Table of Contents v
List of Figures vi
List of Tables viii
List of Appendices ix
Chapter 1. Introduction 1
Chapter 2. Previous Studies 3
Chapter 3. Experimental Methodology 3
Chapter 4. Results 8
Chapter 5. Observations of Phase Behavior 14
Phase behavior during cooling from 25°°°°C 14
Behavior during heating from -196°°°°C 16Behavior during cooling with a single crystal present 18Behavior during heating with a single crystal present 19Additional unusual behavior 19
Chapter 6. Discussion 23
Chapter 7. Conclusion 28
Vita 36
vi
LIST OF FIGURES
1. Low temperature phase relations in the system H2O-NaCl 4
2. Low temperature phase relations in the system H2O-FeCl2 4
3. Low temperature phase relations in the system H2O-NaCl-FeCl2 5
4. Equilibrium curves for oxygen fugacity buffers 6
5. Schematic diagram showing the experimental design 6
6. Ternary diagram for the system H2O-NaCl-FeCl2 showing the twopseudobinaries used in this study 7
7A. Final ice melting temperatures for inclusions having compositions alongpseudobinary A 8
7B. Final ice melting temperatures for inclusions having compositions alongpseudobinary B 8
8. T-X diagram showing the relationship between temperature of formation ofsynthetic fluid inclusions and the measured final ice melting temperatures
9
9. Diagram illustrating the relationship between the range in measured final icemelting temperatures and salinity 10
10. T-X diagram showing the heating and cooling sequence of a synthetic fluidinclusion 15
11. Expected phase behavior in an inclusion representing the H2O-NaCl-KClsystem 17
12. Low temperature phase behavior indicating the presence of a metastableliquid 17
13. Inclusion containing 5 wt% FeCl2 showing freezing behavior 20
vii
14. Growth of ice at temperatures below the reported eutectic temperatureindicating the presence of a metastable liquid 20
15. Inclusion containing a solid at room temperature 20
16. Inclusion at room temperature showing small solids that were never affectedby heating or freezing 22
17. Unusual low temperature phase behavior that indicates the presence of ametastable liquid 22
18. Further evidence of a metastable liquid 22
19. Synthetic fluid inclusion in the system H2O-NaCl-MgCl2 showing similarunusual phase behavior documented in this study 24
20. Diagram illustrating calculations of total salinity for different systems basedon average final ice melting temperatures in this study 27
viii
LIST OF TABLES
1A. Summary of experimental conditions for each sample represented bypseudobinary A 11
1B. Results obtained in this study for pseudobinary A 12
2A. Summary of experimental conditions for each sample represented bypseudobinary B 13
2B. Results obtained in this study for pseudobinary B 13
3. Estimates of total salinity and their corresponding percent error usinggeologically relevant aqueous salt systems for which a wide range of T-Xdata is available 26
ix
LIST OF APPENDICES
A. Experimental values obtained in this study 32
1
Chapter 1. Introduction
One of the most commonly used techniques for determining the composition of
aqueous fluid inclusions is based on the phase behavior at low temperatures. The first
melting temperature, or eutectic temperature, is characteristic of the chemical system in
the inclusion and the final ice-melting temperature is related to the concentration, or
salinity, of the aqueous solution. Roedder (1962) was among the first to describe the
use of low-temperature microthermometric measurements to determine salinities of
fluids in inclusions. These early studies used the low temperature phase relations of the
system H2O-NaCl to interpret microthermometric data from all aqueous inclusions,
because it was the only geologically relevant aqueous-salt system for which phase
behavior was known over a wide range of T-X conditions.
More recently, improved optical equipment coupled with advances in our ability to
analyze individual inclusions has shown that natural fluid inclusions from many
environments are not adequately approximated by the H2O-NaCl system. This,
combined with the recently developed synthetic fluid inclusion technique, (Sterner and
Bodnar, 1984; Bodnar and Sterner, 1987) has led to a renewed interest in the low
temperature phase relations in aqueous-salt systems. Recent studies of low
temperature phase behavior in multi-component systems such as H2O-NaCl-KCl (Hall et
al., 1988; Davis et al., 1990), H2O-NaCl-CaCl2 (Oakes et al., 1990; Davis et al., 1990),
H2O-NaCl-MgCl2 (Dubois and Marignac, 1997) and H2O-NaCl-KCl-MgCl2 (Bodnar et al.,
1997) reflect this renewed interest.
The equilibrium phase behavior observed in an inclusion can be complex and
may be further complicated by various non-equilibrium or kinetically controlled factors.
Differentiating between all possible equilibrium and non-equilibrium phase behaviors is
vital to the correct interpretation of microthermometric data. The two most important
low-temperature equilibrium phase changes used in fluid inclusion research are eutectic
melting (Te) and final melting (Tm). During heating from low temperatures, Te is
indicated either by a sudden brightening of the inclusion or by the generation of a
2
significant amount of a separate liquid phase. When determining Te, non-equilibrium
behavior such as crystallization of an originally glassy phase during heating from low
temperature is often incorrectly interpreted to be eutectic melting, resulting in reported
values lower than the actual Te.
Metastable eutectic behavior occurs near the eutectic temperature and is a solid-
state rearrangement of the contents of the inclusion that is easily confused with eutectic
melting (Crawford, 1981). If the bulk fluid composition in the inclusion is not near the
eutectic, where a large percentage of liquid will be generated at first melting, or if the
inclusion is very small, distinguishing metastable behavior from equilibrium eutectic
melting is difficult. Metastable eutectic melting behavior has been observed in both
synthetic and natural fluid inclusions and has been discussed extensively in the
literature (Crawford, 1981; Roedder, 1984; Davis et al., 1990; Spencer and Lowenstein,
1992; Goldstein and Reynolds, 1994).
It is possible that the fluid in the inclusion will never nucleate a solid, remaining
metastable even after cooling to liquid nitrogen temperatures (~-196°C). The fluid
within the inclusion at these very low temperatures may be very viscous and could be
considered a glass or a super-cooled liquid (Rawson, 1967). As a glass, it might display
glass-transition behavior. Glass-transition behavior occurs when the glass transforms
(crystallizes or devitrifies) into the stable crystal structure upon heating from low
temperatures. Glass-transition behavior can occur well below the eutectic temperature
and is most common for compositions that are close to the eutectic composition
(Rawson, 1967). This behavior has been reported in both natural and synthetic
samples (Borisenko, 1977; Roedder, 1984). This process can also be incorrectly
interpreted as eutectic melting and is commonly seen in very small inclusions. The
glass-transition temperature has been shown to vary systematically with composition
and increases with increasing salt concentration (Vuillard and Kessis, 1960; Angell and
Sare, 1970; Kanno and Angell, 1977). If it were a super-cooled liquid, no phase
behavior would be observed in the liquid upon heating from low temperatures.
3
Chapter 2. Previous Studies
The purpose of this study was to examine the low temperature phase behavior
and provide new T-X data for the system H2O-NaCl-FeCl2. Low temperature phase
diagrams are available for the binary systems H2O-NaCl (Linke, 1958; Bodnar, 1993)
and H2O-FeCl2 (Linke, 1958; Borisenko, 1977) and are depicted in Figures 1 and 2,
respectively. The only experimental study for the system H2O-NaCl-FeCl2 is that of
Chou (1985), who studied compositions between 35 and 45 wt% FeCl2 (figure 3).
In most magmatic hydrothermal systems, the dominant iron species in solution is
ferrous chloride (Fein et al., 1992). The presence of ferrous iron chloride hydrates and
sodium chloride hydrates has been noted in inclusions from hydrothermal deposits from
around the world (Lyakhov, 1967; Naumov and Shapenko, 1980; Eadington, 1983;
Rankin et al., 1992), as well as significant concentrations of dissolved iron in under-
saturated inclusion fluids (Bodnar, 1995; Philippot et al., 1995; Vanko and Mavrogenes,
1998).
Chapter 3. Experimental Methodology
Synthetic fluid inclusions were generated using the technique outlined by Sterner
and Bodnar (1984) and Bodnar and Sterner (1987). The synthetic fluid inclusion
technique was chosen because it could provide both quantitative (T-X data) and
qualitative (descriptions of phase behavior) information about the H2O-NaCl-FeCl2system. Ferrous iron chloride was chosen for this study because it is the dominant iron
species in most magmatic hydrothermal systems (Fein et al., 1992). The choice of this
aqueous species necessitated the design of the experiments such that P-T-fO2
conditions were within the ferrous iron stability field. The oxidation state of the aqueous
iron species is controlled by the oxygen fugacity (fO2), and the fluid inclusion technique
provides several means to control the fO2 (intrinsic fO2 of the pressure vessel, added
chemical buffers, capsule materials and capsule designs).
4
Figure 1: Low temperature phase relations in thesystem H2O-NaCl. E represents the eutecticpoint and P is the peritectic (Linke, 1958;Bodnar, 1993). The numbers in parenthesesnext to the peritectic and eutectic pointsrepresent the temperature and salinity of thatpoint.
-60-40-20
020406080
100120
0 5 10 15 20 25 30 35 40 45 50
Salinity (wt% NaCl)
Fina
l Mel
ting
Tem
pera
ture
(o C)
Ice + Hydrohalite
Hydrohalite + Liquid
Halite + Liquid
PE
Ice + Liquid
Liquid
(-21.2 C, 23.2 %)
(-0.01 C, 26.1 %)
Figure 2: Low temperature phase relations forthe system H2O-FeCl2. E is the eutectic pointand P1 and P2 are peritectics (Linke, 1958;Borisenko, 1977). The numbers in parenthesesnext to the peritectic and eutectic pointsrepresent the temperature and salinity of thatpoint.
-60-40-20
020406080
100120
0 5 10 15 20 25 30 35 40 45 50
Salinity (wt % FeCl2)
Fina
l Mel
ting
Tem
pera
ture
(o C)
Ice + Liquid
Ice + Iron II Chloride Hydrate
FeCl2·6H2O + Liquid
FeCl2·4H2O + Liquid
FeCl2·2H2O + Liquid
E
P1
P2
(-36.5 C, 30.4 %)
(8.0 C, 36.7 %)
(76.5 C, 47.4 %)
5
The composition of the pressure vessels used in this study is Ni-NiO. The Ni-
NiO equilibrium boundary lies within the stability field of magnetite (figure 4). Wang et
al. (1984) showed that the stable aqueous iron species in equilibrium with magnetite at
the conditions of the experiments reported here is ferrous iron. Therefore, the intrinsic
fO2 of the pressure vessel generated by the Ni-NiO composition was enough to control
the fO2 in the experiments, and keep the iron in the ferrous state. In the experiments
defined by mixing a known amount of FeCl2⋅4H2O with a 5 wt% NaCl solution, this
control was enhanced by the use of Ni filler rods in the pressure vessels.
All experiments were conducted in gold capsules. Figure 5 is a schematic
diagram of the experimental design. At the end of the experiments, the capsules were
quenched and examined to verify that the iron inside the capsule remained in the
ferrous state. The solution released from the capsule indicated that the iron remained
reduced. The solution was initially colorless or pale green, then, upon contact with
atmospheric O2, turned yellow-orange. A solution containing 10 wt% ferric iron was
Figure 3: Low temperature phaserelations in the system H2O-NaCl-FeCl2for compositions defined by mixing knownamounts of FeCl2⋅4H2O with a 5 wt%NaCl solution (Chou, 1985). The lineconnecting the points represents the bestfit through the data.
0
20
40
60
80
35 40 45
Salinity (wt % FeCl2)
Fina
l Mel
ting
Tem
pera
ture
(o C
)
FeCl2·4H2O + Liquid
Liquid
6
H2O-NaCl-FeCl2
Figure 5: Schematic diagram showing theexperimental design.
Au Capsule
Fractured Quartz Core
Figure 4: Equilibrium curves for oxygen fugacitybuffers (Chou, 1987). HM = hematite-magnetite,NNO = nickel-nickel oxide, MI = magnetite-iron,MW = magnetite-wustite, IW = iron-wustite. Theshaded region represents the stability field formagnetite.
7
made to determine if color could be used to qualitatively indicate the presence of ferric
iron in solution. Indeed, the color of the ferric iron solution was also yellow-orange. This
indicated, after release from the capsule and contact with atmospheric O2, the ferrous
iron in solution oxidized to ferric iron.
The temperature of the experiments represented by pseudobinary A (figure 6)
ranged from 500°C to 800°C and the pressure ranged from 2 to 3 kilobars (tables 1A
and 2A). This P-T range was used in an attempt to generate larger inclusions and to
determine the cause of the unusual phase behavior. The experiments represented by
pseudobinary B (figure 6) were conducted at 600°C and 3 kilobars. The pseudobinaries
for this study are shown in figure 6 and can be divided into 2 groups. One group is
defined by solutions that were made ensuring that the overall composition remained
along the 5 wt% NaCl (relative to the total solution) pseudobinary (Line A, figure 6). The
second group is defined by solutions that were made by mixing known amounts of
FeCl2⋅4H2O with a 5 wt% NaCl solution (Line B, figure 6). The second group of
Figure 6: Ternary diagram for the system H2O-NaCl-FeCl2 showing the two pseudobinariesused in this study. Line A represents solutionswith constant 5 wt% NaCl and line Brepresents solutions defined by mixing solidFeCl2⋅4H2O with an aqueous 5 wt% NaClsolution (details in text).
50 % NaCl50 % FeCl2
H2O
A
B
8
experiments (pseudobinary B) were conducted as a comparison to the inclusions
containing compositions along pseudobinary A and as a way to generate data that is
comparable to the data from Chou (1985).
Chapter 4. Results
The experimental conditions are summarized in tables 1A (pseudobinary A) and
2A (pseudobinary B). The pseudobinaries corresponding to compositions used in this
study are shown in figure 6. The microthermometric data collected in this study are
listed in appendix A. Average final ice melting temperatures as a function of salinity
(wt% FeCl2) are plotted on figures 7A and 7B. There is a trend of decreasing Tm values
with increasing FeCl2 concentrations as expected. The equations that best describe the
relationship between average final melting temperature and salinity (wt% FeCl2) were
determined by fitting 2nd order polynomials to each of the data sets.
Pseudobinary A: Salinity = -4.03 – 0.0536 Tm –0.0573Tm2
Pseudobinary B: Salinity = -3.03 – 0.5345 Tm – 0.0288Tm2
Figure 7A: Final ice melting temperatures forinclusions having compositions alongpseudobinary A. For each data point, thecomplete range in measured final meltingtemperatures lies within the area of the point.
Figure 7B: Final ice melting temperatures forinclusions having compositions alongpseudobinary B. For each data point, thecomplete range in measured final meltingtemperatures lies within the area of the point.
-40
-30
-20
-10
0
0 5 10 15 20 25
Salinity (wt % FeCl2)
Fina
l Mel
ting
Tem
pera
ture
(o C)
(5 wt% NaCl)
-40.0
-30.0
-20.0
-10.0
0.0
0 5 10 15 20 25
Salinity (wt % FeCl2)
Fina
l Mel
ting
Tem
pera
ture
(o C)
(5 wt% NaCl)
9
The significance of the two outlying points in pseudobinary A is currently unknown. As
such, they were excluded from the data set when determining the polynomial equation
for pseudobinary A.
Samples with concentrations above 24 wt% FeCl2 could not be frozen.
Microthermometric data collected from the samples are summarized in tables 1B
(pseudobinary A) and 2B (pseudobinary B). Average final ice melting temperatures as
a function of salinity (wt% FeCl2) for different formation temperatures are shown in
figure 8 (pseudobinary A). No correlation was observed between the formation
temperature and the Tm values. The range in the Tm values as a function of
composition is shown in figure 9 for pseudobinaries A and B. Most of the samples
exhibited a range of ice melting temperatures less than 1°C. Similar ranges in final
melting temperatures were observed in the synthetic fluid inclusion study conducted by
Davis et al. (1990). The numbers in parentheses represent the actual number of data
points for each sample.
Figure 8: T-X diagram showing therelationship between temperature offormation of synthetic fluid inclusions and themeasured final ice melting temperatures.
-40.0
-30.0
-20.0
-10.0
0.0
0 5 10 15 20 25
Salinity (wt % FeCl2)
Fina
l Mel
ting
Tem
pera
ture
(o C)
600
700
800
500
(5 wt% NaCl)
10
Figure 9: Diagram illustrating the relationship between the range in measuredfinal ice melting temperatures and salinity. The number in parenthesesindicates the number of microthermometric measurements per sample.
0.0
0.5
1.0
1.5
2.0
0 5 10 15 20 25
Salinity (wt% FeCl2)
Ran
ge in
Tm v
alue
s(o C
)
(10)
(10) (10)
(10)
(11)(10)
(10)
(9)(10)
(10)
(10)
(10)
(10)
(20)
(14)(10)
(10)
(6)
(10)
(10)
(10)
(10)
(5 wt% NaCl)
(10)
(10) (10)
(10)
11
Table 1A: Summary of experimental conditions for each samplerepresented by pseudobinary A.
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
1 5.01 23.00 500 22 5.01 23.00 600 23 5.02 23.09 600 24 5.02 23.09 600 25 5.01 11.08 600 26 5.01 20.61 600 37 5.00 18.32 600 38 5.01 15.97 600 39 5.01 6.61 600 310 5.00 2.02 600 311 5.02 18.01 700 212 5.00 13.37 700 213 5.02 10.21 700 214 5.01 4.62 700 215 4.82 33.14 700 216 5.04 22.45 800 217 4.65 20.55 800 218 4.99 18.40 800 219 5.00 9.47 800 220 4.25 6.60 800 2
12
Sample Ave Tm°C
Min Tm°C
Max Tm°C
Range°C
1 -33.5 -33.7 -33.4 0.32 -33.8 -33.9 -33.6 0.33 -33.0 -33.5 -32.2 1.34 -32.2 -32.7 -31.8 0.95 -11.1 -11.3 -11.0 0.36 -28.2 -28.6 -27.8 0.87 -21.3 -21.8 -20.1 1.78 -18.6 -19.2 -18.0 1.29 -7.5 -7.5 -7.4 0.110 -3.9 -4.0 -3.9 0.111 -20.0 -20.7 -19.8 0.912 -14.0 -14.2 -13.8 0.413 -10.3 -10.5 -10.1 0.414 -5.7 -5.8 -5.7 0.115 DNF - - -16 -34.7 -35.9 -34.0 1.917 -14.5 -14.8 -14.3 0.518 -12.9 -13.3 -11.6 1.719 -9.0 -9.5 -8.5 1.020 -5.3 -5.6 -4.8 0.8
Table 1B: Results obtained in this study forpseudobinary A. DNF = Did not freeze.
Table 2A: Summary of experimental conditions for each sample represented by pseudobinary B.
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
21 2.69 29.35 600 322 3.13 23.68 600 323 3.54 18.48 600 324 3.85 14.60 600 325 4.24 9.61 600 326 4.61 4.80 600 327 4.75 3.09 600 328 4.99 0.00 600 3
Table 2B: Results obtained in this study forpseudobinary B. DNF = Did not freeze.
13
Sample Ave Tm°C
Min Tm°C
Max Tm°C
Range°C
21 DNF - - -22 -32.3 -32.6 -31.2 1.423 -22.5 -22.9 -22 0.924 -15.7 -15.9 -15.3 0.625 -11.6 -11.7 -11.4 0.326 -6.8 -7.2 -6.1 1.127 -5.6 -5.7 -5 0.728 -3.0 -3.3 -2.8 0.5
14
Chapter 5. Observations of Phase Behavior
During the process of obtaining the microthermometric data, unusual phase
behavior was observed. Others have reported similar behavior in both synthetic and
natural fluid inclusions. Davis et al. (1990) reported similar unusual behavior for multi-
component systems such as H2O-NaCl-MgCl2 in synthetic fluid inclusions in halite.
They suggested that the behavior represented metastable hydrate melting. Also,
Roedder (1984, p. 297) described relatively large natural inclusions that did not freeze.
The phase behavior observed in this study will be discussed in the following
manner: Behavior during cooling from 25°C, behavior during heating from -196°C,
behavior during cooling with a single crystal present, behavior during heating with a
single crystal present and additional unusual behavior. Descriptions of expected phase
behavior shall be discussed first.
Phase behavior during cooling from 25°CThe expected phase behaviors in an aqueous brine fluid inclusion with salinity
less than the eutectic composition is shown diagrammatically in figure 10. An example
of a synthetic fluid inclusion that shows expected phase behavior is shown in figure 11.
At room temperature (point A, figure 10) the inclusion contains liquid and vapor. When
cooled, the inclusion enters the ice + liquid field. Under equilibrium conditions, the
inclusion should nucleate a small crystal of ice upon entering the ice + liquid field. Once
the inclusion reaches the eutectic temperature, complete crystallization should occur
and only ice + hydrohalite + vapor should be present. However, due to various kinetic
barriers to nucleation, the solution usually does not freeze until the inclusion is
supercooled well below the eutectic temperature, indicated by point B in figure 10.
Once nucleation does occur, the inclusion suddenly becomes dark owing to the
formation of a large number of tiny crystals of ice and hydrohalite phases and the vapor
bubble may deform. An example of this behavior is shown in figure 11A. The inclusions
in this study were initially cooled from room temperature to -196°C. Figure 12 highlights
15
the phase changes during initial cooling for a sample containing 18.32 wt% FeCl2. This
sample was chosen to illustrate the unusual phase behavior because its salinity was
high enough to generate a significant amount of liquid at the eutectic temperature and
the inclusions were large. Both of these characteristics made phase changes easier to
recognize. For this sample, crystallization was indicated by a faint meniscus beginning
on one side of the inclusion (usually the side farthest away from the vapor bubble) and
sweeping through the entire inclusion, deforming the vapor bubble. The contents of the
inclusion remained transparent (figure 12A). No additional phase changes were
observed during further cooling from the point at which a solid nucleated to -196°C. For
inclusions with FeCl2 concentrations lower than ~15 wt% FeCl2, crystallization was
indicated when the vapor bubble deformed and the inclusion took on a granular
appearance (figure 13) similar to the expected phase behavior. For inclusions with
FeCl2 concentrations higher than ~20 wt%, no phase change was observed during
cooling from 25°C to -196°C.
Figure 10: T-X diagram showing the heating and cooling sequence discussedin the text. The inclusions along the right side schematically show the phasebehavior at each point (A through G).
16
Behavior during heating from -196°CWhile heating fluid inclusions that display the expected phase behavior, usually
no changes are observed within the inclusion until the eutectic temperature (point C,
figure 10) is reached. Then, the inclusion becomes lighter in appearance as some of
the microcrystals of ice and hydrohalite melt to produce a liquid with the eutectic
composition. Upon further heating, ice continues to melt. At point D, only a single ice
crystal is present (open circle in inclusion D, figure 10).
The sample containing 18.32 wt% FeCl2 was cooled to -196°C and then heated.
At -80°C, the inclusion contained solid and a deformed vapor bubble (figure 12A).
Between -70°C and -75°C, the inclusion became darker and coarser grained. At -65°C,
the temperature was held constant for three minutes, during which time the contents
within the inclusion became coarse enough such that separate phases could be seen
(Figure 12B). The coarsening that began between -70°C and -75°C occurred slowly,
therefore, holding the temperature constant for a minimum of 3 minutes was required for
the phase behavior to properly manifest itself.
At -65°C, it was not possible to determine whether the phase behavior observed
was metastable or equilibrium eutectic melting. However, metastable eutectic melting is
instantaneous as metastable solids rearrange into the stable solid for that composition.
This type of behavior was observed by Bodnar et al. (1985) in a study of synthetic
inclusions in the H2O-NaCl system. Conversely, in this study, the changes were gradual
and continued until one solid remained in the inclusion. This behavior is similar to the
process known as Ostwald ripening that was first described by Ostwald (1901) and later
explained by Gibbs (1961).
The sample containing 18.32 wt% FeCl2 was heated to -50°C where it appeared
to contain a solid coexisting with a vapor and liquid (figure 12C). It is important to note
that this temperature (-50°C) is below the reported eutectic temperature (-37°C) and
below the highest reported freezing temperature (-44°C) observed in this study. The
17
Figure 11: Expected phase behavior in asynthetic fluid inclusion representing theH2O-NaCl-KCl system. A) Below theeutectic temperature, solids + vapor arethe only phases present. B) A singlecrystal has been isolated and grownthrough cooling. C) At -50°C, theremaining metastable fluid has frozen. D)At the eutectic temperature (-22.9°C) thefirst solid to melt is the rim of liquid thatfroze in (C).
A B
C D
Figure 12: Low temperature phase behavior indicating the presence of ametastable liquid. A) Inclusion at -80°C containing solid + vapor. B)Inclusion at -65°C, the solids are beginning to coarsen, but separate phasesare not yet distinguishable. C) Inclusion at -50°C where separate phases(solid, metastable liquid and vapor) can be seen. D) Inclusion at -190°Ccontaining a single large crystal, vapor bubble and metastable liquid.
18
crystals were most often rectangular with rounded edges. No other phase transition
occurred from -50°C to the measured Tm, which was -21.2°C for this inclusion, although
the volume percentage of solid decreased during heating over this interval as expected.
Once the appropriate Tm was reached for the inclusion, the solids completely melted
and only vapor and liquid remained.
In order to confirm the presence of a metastable liquid phase, the inclusion
shown in figure 12 was frozen again (after the solids completely melted) and heated to
-47°C (Figure 14A). Once again, the inclusion contained 3 different phases, including a
metastable liquid. However, because the temperature never reached the eutectic
temperature, no liquid should exist. From this temperature, the inclusion was rapidly
cooled (50°C per minute) to determine if the solid would grow, which would confirm the
presence of a liquid phase. Figure 14B shows the inclusion at -72°C after being rapidly
cooled from -47°C. By comparing the two photomicrographs, it is clear that the solid
phase has indeed grown larger. Upon further cooling, the solid phase does not grow to
completely fill the inclusion and the remaining liquid never freezes. It is because of the
presence of this metastable liquid that point C in figure 10 (which represents equilibrium
eutectic melting) could not be observed in inclusions from this study.
For samples 15 and 21, no phase change was observed in spite of repeated
attempts to freeze the sample. These samples contained 33.14 and 29.35 wt% FeCl2,
respectively. These samples had ferrous iron chloride concentrations in excess of 24
wt% where it is believed that ferrous iron chloride hydrates would be the stable solid
phase in the solid + liquid region.
Behavior during cooling with a single crystal presentWith expected phase behavior, upon cooling with a single ice crystal present, the
crystal grows, possibly deforming the vapor bubble (figure 11B). Supercooling is
necessary in order to nucleate any phases other than ice out of the remaining liquid,
which occurs at some point E in figure 10. Freezing the remaining liquid (nucleating
19
remaining solid phases) in the presence of a single crystal occurs well below the
eutectic temperature as shown in figure 11C.
The final portion of Figure 12 (12D) illustrates what happens when an inclusion
with a single crystal is cooled to -196°C in this study. Figure 12D shows the inclusion at
-190°C. Even at -196°C, the single crystal never grew to completely fill the inclusion, no
phase change was ever observed in the remaining liquid and deformation of the vapor
bubble was not observed unless the solid impinged upon the vapor bubble directly.
Behavior during heating with a single crystal presentWith expected behavior, first melting occurs at point F in figure 10. Further
heating from point F causes the ice crystals to melt until one crystal remains. The
single crystal decreases in volume until the temperature reaches the ice-liquid/liquid
boundary where it disappears (point G, figure 10). At this point, only liquid + vapor
remain in the inclusion.
In this study, the solid would begin to decrease in volume during heating, but at a
temperature well below the eutectic temperature reported for this system. No changes
were observed in the liquid. The ice would continue to decrease in volume until it
disappeared when the temperature reached the ice-liquid field boundary (point G, figure
10).
Additional unusual behaviorOne sample with an FeCl2 concentration of 33 wt% contained a solid at room
temperature. The solids observed were very "ratty" looking elongated crystals (figure
15). When the crystals were partially melted and allowed to grow during slow cooling
from high temperatures (5°C per minute), they appeared cubic or rod-shaped and the
larger crystals had a greenish tint. Other solids were also seen in the inclusions and are
shown in figure 16. These solids appeared in most of the samples regardless of
concentration, but did seem to be more common in inclusions with dilute solutions. The
20
Figure 13: Fluid inclusion containing 5wt% FeCl2. This inclusion has thehighest recorded freezing temperaturefor this study (-44°C). A suddendarkening of the inclusion anddeformation of the vapor bubbleindicated freezing.
Solid
Vapor
16 um
Figure 14: Growth of ice attemperatures below the reportedeutectic temperature indicating thepresence of a metastable liquid. A)Inclusion below the eutectictemperature has vapor + solid +metastable liquid. The temperatureis lowered and the solid grows (B).This would not occur if themetastable liquid was, in fact, a solid.
B
Figure 15: Fluid inclusion containing a solidat room temperature.
21
tiny solids represented in figure 16 did not change size or shape during cooling and
heating. The composition and significance of these solids is unknown.
Additional unusual behavior was noted for certain inclusions in the sample
containing 18.32 wt% FeCl2 which further confirms the presence of a metastable liquid
phase. The unique behavior of one very large flat inclusion is shown in figure 17.
Figure 17A shows the inclusion after it has frozen, the small vapor bubble at the top of
the inclusion is deformed. During heating at a moderately rapid rate (55°C per minute),
the vapor bubble became significantly deformed. This second deformation began at
-71°C and the maximum deformation was achieved by -65°C and is shown in Figure
17B. Upon further heating, the bubble increased in size until it refilled the space it
formerly occupied. The space that was once occupied by the retreating vapor bubble
maintained the exact shape of the bubble. The “vacancy” appeared to be filled with a
solid with a higher relief than the surrounding solids.
In the sample used to illustrate the unusual phase behavior seen in this study
(18.32 wt% FeCl2), a crystal nucleated from the metastable liquid in one inclusion at
-72.5°C. This occurred during heating from -80°C at a rate of 20°C per minute. This
smaller crystal grew slowly, never displaying any euhedral form. At the lowest
temperature (-190°C), a significant volume of liquid remained (Figure 18A). Upon
heating, the larger crystal and the smaller crystal both began to melt at the same
temperature (but still at a lower temperature than the reported eutectic temperature for
this system, -37°C) as seen by comparing figures 18A and 18B. As expected, the
smaller crystal completely disappeared before the larger crystal, which melted at the
expected Tm value for that composition. This phase behavior could not be duplicated.
Normally, behavior that is not representative or reproducible, like the previously
described behavior, is not reported in fluid inclusion studies. However, the importance
of the previously discussed behaviors is that they occurred at approximately the same
temperature, which also coincides with the temperature range (-75°C to -70°C) in which
the sample with 18.32 wt% FeCl2 begins to darken and become coarse grained. It is
22
Figure 16: Fluid inclusion at roomtemperature showing small solidsthat were never affected by heatingor freezing.
Figure 18: Further evidenceof a metastable liquidindicated by a small solidnucleating at -72.5°C out ofthe metastable liquid. Itnever filled the inclusion, andno other solids nucleated(A). Both solids began tomelt simultaneously attemperatures far below theeutectic temperature for thissystem (B).
Figure 17: Unusual lowtemperature phase behavior thatindicates the presence of ametastable liquid. A) Small vaporbubble is shown deformed whenthe inclusion freezes. Uponheating from low temperatures, thevapor bubble contracts (indicate bythe word "vacancy" in B). It isreplaced by what appears to be asolid with a relatively high relief.
-65C
B
23
also important to note that they behaved in the same manner as the sample with 18.32
wt% FeCl2 (during heating from low temperatures). Finally and most importantly, they
also provide further evidence that a metastable liquid persists at low temperatures.
The unusual phase behaviors documented in this study were reproduced in other
systems with multiple hydrate phases such as H2O-NaCl-MgCl2 and H2O-NaCl-CaCl2.
A synthetic fluid inclusion in the H2O-NaCl-MgCl2 system is shown in figure 19 as a
comparison to the microthermometric behavior seen in the H2O-NaCl-FeCl2 system. No
changes were observed in the inclusion during cooling to -196°C (figure 19B). During
heating from -196°C, the inclusion became coarse grained at -40°C (figure 19C) and
displayed the same behavior reported in figure 12B. The eutectic temperature for this
system is -35°C; therefore, no liquid should exist at -40°C. From this point, the inclusion
was heated until one crystal remained. During subsequent cooling, the crystal
increased in size (figure 19D). However, even when cooled to -196°C, the solid never
completely filled the inclusion and the remaining liquid never froze. Upon heating, the
crystal began to melt and became smaller at a temperature lower than the eutectic
temperature (figure 19E).
Chapter 6. Discussion
Microthermometric data collected from natural fluid inclusions are usually
interpreted in terms of the H2O-NaCl system for Te values greater than -21.2°C, and in
terms of the H2O-NaCl-CaCl2 system for Te values less than -21.2°C, because these are
the only geologically relevant aqueous salt systems for which phase behavior is known
over a wide range of T-X conditions. However, interpreting microthermometric data in
terms of these systems can generate significant errors. To illustrate this, total salinity
values were estimated using the H2O-NaCl system for Tm values of -5°C, -10°C, -15°C
and -20°C and the H2O-NaCl-CaCl2 system for Tm values of -25°C and -30°C. These
estimates were then compared to total salinity values obtained if the composition of the
inclusion fluid was better estimated by aqueous salt systems other
24
Figure 19: Syntheticfluid inclusion in thesystem H2O-NaCl-MgCl2 showing similarunusual phasebehavior documentedin this study, and inother systems withmultiple hydratephases. A) At roomtemperature, theinclusion containsvapor + liquid. B)Down to -196°C, theinclusion neverfreezes. C) Uponheating, the inclusionfreezes and it appearsas if only solids +vapor are present. D)Eutectic temperaturescould not be verifieddue to the presence ofa metastable liquid.Once a solid has beenisolated, it nevergrows to completely fillthe inclusion uponcooling. E) The solidsbegin to melt attemperatures wellbelow the eutectictemperature for thissystem (-35°C)
25
than H2O-NaCl or H2O-NaCl-CaCl2. The corresponding percent error suggests that
total salinity values can be incorrectly estimated by almost 30% (table 3). A positive
percent error indicates that the total salinity is overestimated when using the H2O-NaCl
or H2O-NaCl-CaCl2 system and a negative percent error indicates that the total salinity
is underestimated. For ternary systems, median values of total salinity were used
because the total salinity will vary as a function of the ratio of the two salts. For
example, a Tm value of -5°C in the H2O-NaCl-KCl system will generate a total salinity
ranging from 7.8 wt% for a NaCl/(NaCl+KCl) ratio of 1.0 to 10.3 wt% for a
NaCl/(NaCl+KCl) ratio of 0.0. Therefore, the total salinity value that would be used in
this discussion would be the median value of 9.1 wt%.
Additionally, a test was conducted to determine the effect of interpreting
microthermometric data from inclusions containing dissolved iron using aqueous salt
systems other than the one in this study. To this end, estimates of total salinity for
various geologically relevant aqueous salt systems were calculated using the average
Tm values obtained in this study and are shown in figure 20. The equations used to
calculate the total salinity were obtained by fitting a 2nd order polynomial curve to each
of the data sets. The equation that best fits the data obtained in this study is
Total Salinity = -1.7031Tm – 0.0265 Tm2
For each system, the maximum final melting temperature used to calculate a
total salinity was equal to or less than its eutectic temperature. Once again, median
values for total salinity were used for ternary systems. As expected, the values for total
salinity converge at higher final melting temperatures, and lower total salinities, and
diverge as the final melting temperature decreases and the total salinity increases.
Though, in general, using other systems to interpret microthermometric data from
inclusions containing dissolved iron would underestimate the total salinity.
26
Table 3: Estimates of total salinity using the H2O-NaCl system (Bodnar, 1993) for final melting temperatures greater than -21.2°C and the H2O-NaCl-CaCl2 system (Oakes et al., 1990) for final melting temperatures less than -21.2°C. The percent error corresponds to how much the system over or underestimates the actual salinity. A positive percent error indicates the system would overestimate the actual salinity, and a negative percent error indicates the system used to interpret the Tm value would underestimate the actual salinity.
Chemical System Total Salinity(Tm = -5 C)
% Error Total Salinity(Tm = -10 C)
% Error Total Salinity(Tm = -15 C)
% Error Total Salinity(Tm = -20 C)
% Error Total Salinity(Tm = -25 C)
% Error Total Salinity(Tm = -30 C)
% Error
H2O-NaCl-FeCl2 7.9 -2.0 14.4 -3.5 19.6 -4.2 23.5 -5.2 26.0 6.6 27.2 7.7H2O-NaCl 7.7 0.0 13.9 0.0 18.8 0.0 22.3 0.0 - - - -H2O-FeCl2 7.5 2.6 13.9 0.0 19.2 -2.1 23.4 4.9 26.5 8.6 28.4 12.3H2O-CaCl2 8.9 -15.6 14.2 -2.2 17.8 5.3 20.5 -8.1 22.9 -6.1 24.8 -2.0H2O-MgCl2 5.5 28.6 10.1 27.3 13.9 26.1 16.8 -24.7 18.8 -23.0 20.0 -20.9
H2O-NaCl-KCl 9.1 -18.2 15.9 -14.4 21.0 -11.6 24.2 8.5 - - - -H2O-NaCl-CaCl2 7.5 2.6 13.7 1.4 18.6 1.1 22.1 -0.9 24.4 0.0 25.3 0.0H2O-MgCl2-CaCl2 5.8 24.7 10.9 21.6 15.4 18.1 19.1 -14.3 22.1 -9.4 24.4 -3.6
27
Figure 20: Diagram illustrating calculations of total salinity based on averagefinal ice melting temperatures (Tm) in this study using models for geologicallyrelevant fluids for which data are available (dashed lines) and comparing themto a smooth curve drawn through total salinities of the actual fluid (H2O-NaCl-FeCl2, solid red line). Lines representing ternary systems are median values.
0
5
10
15
20
25
30
-35-30-25-20-15-10-50
Final Melting Temperature, Celsius
Tota
l Sal
inity
,w
t% H2O-NaCl-FeCl2
H2O-NaCl-KCl; Hall et al., 1988
H2O-NaCl-CaCl2; Oakes et al., 1990
H2O-MgCl2-CaCl2; Linke, 1958
H2O-MgCl2; Stephen et al., 1963
H2O-CaCl2; Oakes et al., 1990
H2O-FeCl2; Linke, 1958
H2O-NaCl; Bodnar, 1993
H2O-NaCl-FeCl2; this study
28
Chapter 7. Conclusion
The low temperature phase behavior of the H2O-NaCl-FeCl2 system was
investigated using the synthetic fluid inclusion technique. Unusual phase behavior
precluded the validation of Te as reported by Borisenko (1977). Values for Tm were
determined for concentrations between 0 and 24 wt% and show a systematic decrease
with increasing FeCl2 concentration. Above this concentration, Tm values could not be
determined because of the inability to nucleate a solid phase. The unusual phase
behavior was observed only in systems in which multiple hydrate phases are possible.
However, determining the exact cause of these unusual phase behaviors is beyond the
scope of this study. Even though the determination of the presence of either ferrous or
ferric iron still can not be accomplished through heating/freezing alone, this system can
be used to interpret microthermometric data for which independent analyses have
indicated the presence of dissolved iron in inclusion fluids.
29
Bibliography
Angell, C. and Sare, E. (1970) Glass-forming composition regions and glass transitiontemperatures for aqueous electrolyte solutions. Journal of Chemical Physics, v. 52, n.3, pp 1058-1068.
Bodnar, R. (1993) Revised equation and table for determining the freezing pointdepression of H2O-NaCl solutions. Geochimica et Cosmochimica Acta, v. 57, n. 3, pp683-684.
Bodnar, R. (1995) Fluid inclusion evidence for a magmatic source for metals in porphyrycopper deposits. In: Magmas, Fluids and Ore Deposits, Thompson, J. (ed.).Mineralogical Association of Canada Short Course Series, v. 23, pp 139-152.
Bodnar, R., Burnham, C. and Sterner, S. (1985) Synthetic fluid inclusions in naturalquartz; III Determination of phase equilibrium properties in the system H2O-NaCl to1,000 degrees C and 1,500 bars. Geochimica et Cosmochimica Acta, v. 49, n. 9, pp1861-1873.
Bodnar, R. and Sterner, S. (1987) Synthetic fluid inclusions. In: HydrothermalExperimental Techniques, Ulmer, G. and Barnes, H. (eds.). John Wiley & Sons, NewYork, pp 423-457.
Bodnar, R., Vityk, M., Hryn, J. and Mavrogenes, J. (1997) Phase equilibria in the systemH2O-NaCl-KCl-MgCl2 relevant to salt cake processing. In: Light Metals 1997,Proceedings of the 126th TMS Annual Meeting, Huglen, R. (ed.). The Minerals, Metals& Materials Society, Warrendale, PA, v. 1, pp 145-151.
Borisenko, A. (1977) Study of the salt composition of solutions of gas-liquid inclusions inminerals by the cryometric method. Geologiya i Geofizika, v. 18, n. 8, pp 16-27.
Chou, I. (1985) Solubility relations in the system sodium chloride-ferrous chloride-waterbetween 25 and 70 degrees C at 1 atm. Journal of Chemical Engineering Data, v. 30,n. 2, pp 216-218.
Chou, I. (1987) Oxygen buffer and hydrogen sensor techniques at elevated pressuresand temperatures. In: Hydrothermal Experimental Techniques, Ulmer, G. and Barnes,H. (eds.). John Wiley & Sons, New York, pp 61-99.
Crawford, M. (1981) Phase equilibria in aqueous fluid inclusions. In: Fluid Inclusions:Applications to Petrology, Hollister, L. and Crawford, M. (eds.). MineralogicalAssociation of Canada Short Course Handbook, v. 6, pp 75-100.
Davis, D., Lowenstein, T. and Spencer, R. (1990) Melting behavior of fluid inclusions inlaboratory-grown halite crystals in the systems NaCl-H2O, NaCl-KCl-H2O, NaCl-MgCl2-H2O and NaCl-CaCl2-H2O. Geochimica et Cosmochimica Acta, v. 54, pp 591-601.
30
Dubois, M. and Marignac, C. (1997) The H2O-NaCl-MgCl2 ternary phase diagram withspecial application to fluid inclusion studies. Economic Geology and the Bulletin of theSociety of Economic Geologists, v. 92, n. 1, pp 114-119.
Eadington, P. (1983 ) A fluid inclusion investigation of ore formation in a Tin-mineralizedgranite, New England, New South Wales. Economic Geology, v. 78, pp 1204-1221.
Fein, J., Hemley, W., D'Angelo, W., Komninou, A. and Sverjensky, D. (1992)Experimental study of iron-chloride complexing in hydrothermal fluids. Geochimica etCosmochimica Acta, v. 56, pp 3179-3190.
Gibbs, J. W. (1961) The Scientific Papers of J. Willard Gibbs. Oxbow Press,Woodbridge, Connecticut, v. I.
Goldstein, R. and Reynolds, T.J. (1994) Systematics of fluid inclusions in diageneticminerals. SEPM Shortcourse, v. 31.
Hall, D., Sterner, S. and Bodnar, R. (1988) Freezing point depression of NaCl-KCl-H2Osolutions. Economic Geology, v. 83, pp 197-202.
Kanno, H. and Angell, C. (1977) Homogenous nucleation and glass formation inaqueous alkali halide solutions at high pressures. Journal of Physical Chemistry, v. 81,pp 2639-2643.
Linke, W. (1958) Solubilities, Inorganic and Metal Organic Compounds. D. VanNostrand Company, Inc., Princeton, New Jersey.
Lyakhov, Y. (1967) Mineral composition of multiphase inclusions in morions fromVolynian pegmatites. Geochemical International, v. 4, n. 3, pp 618-625.
Naumov, V. and Shapenko, V. (1980) Evidence from fluid inclusions on the ironconcentrations in high-temperature chloride solutions. Geokhimiya, v. 2, pp 231-238.
Oakes, C., Bodnar, R. and Simonson, J. (1990) The system NaCl-CaCl2-H2O; I The iceliquidus at 1 atm total pressure. Geochimica et Cosmochimica Acta, v. 54, pp 603-610.
Ostwald, W. (1901) Analytische Chemie. 3rd ed., Englemann.
Philippot, P., Chevallier, P., Chopin, C. and Dubessy, J. (1995) Fluid composition andevolution in coesite-bearing rocks (Dora-Maria massif, Western Alps): Implications forelement recycling during subduction. Contributions to mineralogy and Petrology, v. 121,pp 29-44.
31
Rankin, A., Ramsey, M., Coles, B., Van Langevelde, F. and Thomas, C. (1992) Thecomposition of hypersaline, iron-rich granitic fluids based on laser-ICP and Synchrotron-XRF microprobe analysis of individual fluid inclusions in topaz, Mole Granite, easternAustralia. Geochimica et Cosmochimica Acta, v. 56, pp 67-79.
Rawson, H. (1967) Inorganic Glass Forming Systems. Academic Press, Inc., NewYork.
Roedder, E. (1962) Studies of fluid inclusions I: Low temperature application of a dualpurpose freezing and heating stage. Economic Geology, v. 57, pp 1045-1061.
Roedder, E. (1984) Fluid Inclusions. Reviews in Mineralogy, Mineralogical Society ofAmerica, v. 12.
Spencer, R. and Lowenstein, T. (1992) Phase equilibria in the system MgCl2-H2O.PACROFI IV, pp 138-141.
Stephen, H. and Stephen T. (1963) Solubilities of inorganic and organic compounds.[Oxford] Pergamon Press; New York, Macmillan, 1963.
Sterner, S. and Bodnar, R. (1984) Synthetic fluid inclusions in natural quartz; IIApplication to PVT studies. Geochimica et Cosmochimica Acta, v. 49, pp 1855-1859.
Vanko, D. and Mavrogenes, J. (1998) Synchrotron-source X-ray fluorescencemicroprobe: Analysis of fluid inclusions. In: Applications of Microanalytical Techniquesto Understanding mineralizing Processes, McKibben, M. Shanks, W. and Ridley, I.(eds.). Reviews in Economic Geology, v. 7, pp 251-263.
Vuillard, G. and Kessis, J. (1960) Equilibres solide-liquide et transformation vitreusedans le systhme eau-chlorure de lithium. Bulletin Society De Chimique, France, pp2063-2067.
Wang, S., Eugster, H. and Wilson, G. (1984) Solubility of magnetite in supercritical HCland NaCl solutions. Abstracts with Programs - Geological Society of America, v. 16, n.6, p 686.
32
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
Tm°C
1 5.01 23.00 500 2 -33.3, -33.4,-33.3, -33.1,-33.1, -33.1,-33.1, -33.1,-33.1, -33.1
2 5.01 23.00 600 2 -33.5, -33.6,-33.6, -33.5,-33.5, -33.5,-33.3, -33.3,-33.4, -33.6
3 5.02 23.09 600 2 -32.3, -32.6,-33.2, -33.1,-32.8, -32.6,-32.3, -32.3,-32.6, -32.7,-32.4, -32.4,-32.9, -32.8,-32.8, -31.9,-32.9, -33.0,-33.1, -33.0
4 5.02 23.09 600 2 -32.4, -32.4,-32.2, -31.5,-32.2, -32.1,-31.7, -31.6,-31.5, -31.5
5 5.01 11.08 600 2 -10.8, -10.7,-10.8, -10.8,-10.7, -10.7,-10.7, -10.7,-10.8, -11.0,-11.0, -10.9,-11.0, -10.9
6 5.01 20.61 600 3 -27.5, -27.6,-27.6, -28.2,-28.1, -28.0,-27.9, -28.3,-28.0, -28.2
7 5.00 18.32 600 3 -20.9, -19.8,-21.0, -20.6,-21.0, -21.2,-21.3, -21.4,-21.2, -21.5
Appendix A: Experimental values obtained in this study. DNF = Did not freeze.
33
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
Tm°C
8 5.01 15.97 600 3 -17.8, -17.9,-18.6, -17.7,-17.8, -18.3,-18.6, -18.9,-18.6, -18.6
9 5.01 6.61 600 3 -7.1, -7.1,-7.1, -7.2,-7.2, -7.2,-7.2, -7.2,-7.1, -7.2
10 5.00 2.02 600 3 -3.6, -3.6,-3.6, -3.7,-3.6, -3.7,-3.7, -3.6,-3.6, -3.6
11 5.02 18.01 700 2 -20.4, -20.1,-20.2, -20.2,-19.5, -19.6,-19.6, -19.5,-19.7, -19.5
12 5.00 13.37 700 2 -13.5, -13.6,-13.6, -13.5,-13.6, -13.8,-13.9, -13.9,-13.7, -13.9
13 5.02 10.21 700 2 -10.2, -10.2,-10.2, -9.9,
-10.0, -10.0,-10.0, -10.1,-10.0, -9.8
14 5.01 4.62 700 2 -5.5, -5.4,-5.5, -5.5,-5.4, -5.4,-5.5, -5.4,-5.4, -5.4
15 4.82 33.14 700 2 DNF
16 5.04 22.45 800 2 -33.7, -35.5,-35.6, -34.1,-34.3, -33.8,-34.3, -34.4,-33.8, -34.3,
-34.3
34
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
Tm°C
17 4.65 20.55 800 2 -14.3, -14.5,-14.1, -14.0,-14.1, -14.3,-14.4, -14.0,-14.1, -14.4
18 4.99 18.40 800 2 -13.0, -12.9,-13.0, -13.0,-13.0, -12.7,-12.8, -12.8,-11.4, -11.3
19 5.00 9.47 800 2 -9.1, -8.9,-8.7, -8.3,-8.5, -9.2,-9.1, -8.4,
-8.2
20 4.25 6.60 800 2 -4.9, -5.0,-4.9, -5.0,-5.0, -5.2,-5.2, -5.2,-5.3, -4.5
21 2.69 29.35 600 3 DNF
22 3.13 23.68 600 3 -31.8, -31.2,-32.4, -32.3,-32.5, -32.6,-32.6, -32.5,-32.6, -32.6
23 3.54 18.48 600 3 -22.9, -22.8,-22.6, -22.2,-22.9, -22.0,-22.5, -22.0,-22.6, -22.6
24 3.85 14.60 600 3 -15.9, -15.9-15.8, -15.9-15.8, -15.8-15.8, -15.3-15.4, -15.4
25 4.24 9.61 600 3 -11.5, -11.5,-11.4, -11.4,-11.6, -11.5,-11.7, -11.7,-11.7, -11.7
35
Sample SalinityWt% NaCl
SalinityWt% FeCl2
Temperature°C
PressureKbars
Tm°C
26 4.61 4.80 600 3 -7.1, -7.2,-7.2, -7.2,-7.2, -7.2,-6.1, -6.4,-6.5, -6.3
27 4.75 3.09 600 3 -5.5, -5.0,-5.6, -5.7,-5.7, -5.7,-5.6, -5.6,-5.6, -5.6,
28 4.99 0.00 600 3 -3.1, -3.0,-3.0, -3.0,-2.8, -3.0
36
VITA
Paige Marie Baldassaro was born on November 12, 1971 in New Orleans, LA. In1989, she began attending Louisiana State University where she obtained a B. S. inGeology in 1994. She pursed a Master’s degree at Virginia Polytechnic Institute andState University from 1994 – 2000. During that time, she worked in the summer of 1997at Exxon Production Research Company analyzing petroleum biomarkers in fluidinclusions. Currently, she is pursuing a Master’s degree in Geographical InformationSystems at Virginia Polytechnic Institute and State University.