The Fluids Research group of the Geosciences Department at Virginia Tech uses Linkam Scientific Instruments' 1,400C high-temperature stage to study silicate melt inclusions
Researchers in the Fluids Research group at Virginia Tech are concerned with the distribution, properties and role of fluids in and on the Earth, from its surface (shallow Earth's crust) to its deep interior (Earth's mantle).
One of the research goals is to understand how volcanoes erupt.
The volatile content of a magma chamber beneath a volcano is of paramount importance because it determines the energy of the volcanic eruption.
Magmas with high volatile contents tend to produce violent eruptions, such as the eruption of Vesuvius that destroyed Pompeii, whereas magmas with lower volatile contents tend to produce more quiescent lava flows, such as those in Hawaii.
If the volatile content of the magma beneath a volcano can be predicted, then it is possible to predict the style of future eruptions and use this information in risk assessments.
The only direct way to determine what the volatile content in the magma chamber was before an eruption is by measuring the volatile content in melt inclusions (MI).
MI are droplets of melt entrapped during the growth of a crystal in a magma chamber.
It is only possible to determine the volatile content of the MI if it remains as a homogeneous quenched melt (glass) as it cools following eruption from the magma chamber.
Unfortunately, MI are often found partially or totally recrystallised.
Thus, with some exceptions, one cannot analyse an MI to obtain a representative composition of the volatile content of the melt.
However, a crystallised melt inclusion can be heated in a controllable temperature stage to re-melt the contents and then rapidly quench the MI to a homogenous glassy state.
In this process, the volatiles are dissolved back into the melt and the quenched glass will have the same volatile abundance as it did at the moment of entrapment in the magma chamber.
Professor Bob Bodnar acquired the very first prototype Linkam high-temperature X-Y stage for the Fluids Research Laboratory at Virginia Tech about 15 years ago and has pioneered its use in many papers in the intervening years.
Used in conjunction with other techniques to homogenise samples, the current Linkam TS1400 X-Y stages provide a number of experimental advantages over other stages or test methods.
The group also uses the Linkam THMS600 stages, one in conjunction with a JY Horiba Raman spectrometer.
A benefit of the Linkam stage is that it has an automatic heating/cooling rate controller, whereas other temperature control systems have to be manually controlled.
The Linkam TS1400 X-Y stage is claimed to have excellent optics that make it easier to observe the various phase changes in the melt inclusions during heating.
It has a ceramic tube heater that completely encases the sample in a uniform, temperature-controlled environment that enables high accuracy control up to 1,400C within a gas-sealed chamber.
Samples are mounted on a sapphire sample slide that can be moved up to 6mm in X and Y directions to better explore the sample.
Fluid-inclusion geologists and material scientists interested in high-speed quench cooling can add a special manipulator that enables rapid transfer from the heater to a much colder platform, resulting in ultra-fast cooling rates of up to 240C per second.
