The fluid inclusion laboratory is supervised
by Dr. Virginia
Sisson, Assistant Professor
A heating-cooling
stage is used to bring the sample through a range of temperatures. Liquid
nitrogen is pumped through, allowing a minimum temperature between -180
and -190 degrees Celsius. A variable voltage source connected to a thermal
coil is the heat source, and a thermocouple is used to monitor temperature
to 0.1 degrees Celsius. As the sample is brought through temperature ranges,
groups of fluid inclusions are observed for phase changes. The type of phase
change is dependent on the fluid system and conditions of entrapment. Water
and NaCl systems trapped at low pressures will show melting of ice below
0° Celsius and a homogenization of the liquid and vapor phases to the
liquid phase above 70° Celsius. A H2O-CO2 system may show the formation
and disappearance of clathrate (a cage of CO2 around H2O) and separate melting
of CO2 and H2O. There are many other systems that are possible, including
hydrocarbons. Careful observation and documentation of the type and temperature
of such changes is necessary. Photomicrographs taken by a 35mm camera system
mounted to the microscope are useful for observation of complicated systems.
Current
research in the fluid inclusion lab includes