Type of Document Master's Thesis Author Baldassaro, Paige Marie Author's Email Address email@example.com URN etd-02072000-12380020 Title Low Temperature Phase Relations in the System H2O-NaCl-FeCl2 Degree Master of Science Department Geological Sciences Advisory Committee
Advisor Name Title Bodnar, Robert J. Committee Chair Rimstidt, james Donald Committee Member Tracy, Robert J. Committee Member Keywords
- sodium chloride
- low temperature aqueous geochemistry
- synthetic fluid inclusions
- iron chloride
Date of Defense 1998-05-08 Availability unrestricted AbstractABSTRACT
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 degrees C - 800 degrees 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 degrees 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 degrees 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.
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