Rapid fluid inclusion data
for exploration (decrepitation)
The new model 216 decrepitometer is physically similar to the model 205 decrepitometer and uses the same furnace and operational computer and software but has updated and improved electronics which gives higher sensitivity and more convenient cable connections. As with the model 205, model 216 uses a standard single-board Linux computer running the Debian Ubuntu operating system. The decrepitometer operation software has a full graphical interface and operates in the X-windows environment. The temperature and counts are monitored and shown on screen during the analysis, and simultaneously plotted on screen in a separate window as the temperature rises. The data is saved to a file upon completion, and the graphical plot can also be saved as an image file or printed if required and easily regenerated from the saved data file for additional review.
This is the screen for data entry and sample analysis.
Operation is the same as for the model 205 decrepitometer. The
weighed sample is added to the sample tube, the sensor is added,
it is inserted into the furnace, the plugs are connected and the
door of the enclosure is closed. The sample information and
control settings are entered into the control window and the "GO"
button is clicked. The analysis then commences and a plot window
shows a graph of the data as it is collected. The entire analysis
is completed automatically without further user intervention. At
the end temperature, the furnace is turned off and the control
window re-appears to allow analysis of additional samples. The
plot remains in view, with additional plot windows being created
for additional samples. It is necessary to allow the furnace to
cool before analysing subsequent samples. The saved data files
include the operation parameters and sample details as well as the
decrepitation count values. These files are plain text and can be
viewed or edited in any text editor software as well as used by
Gnuplot or other graph plotting software.
Samples of 0.5gm are normally used while samples as small as 0.2 gm or up to 2 gm can be analysed according to the fluid inclusion abundance in the sample. The heating rate used is almost always 20ºC per minute, but the instrument can also be operated at 10ºC or 40ºC per minute. Analyses are usually performed on quartz samples, but other minerals containing fluid inclusions can also be used, such as carbonates, feldspars and opaque minerals such as haematite and magnetite. Sulphides can also be analysed, but they can be corrosive and this reduces the life of the temperature sensor. Quartz samples are usually analysed up to 620ºC because there is no significant activity above the alpha to beta phase transition at 573ºC, however the instrument can be used for analyses up to 800ºC.
The system can be installed in a normal quiet laboratory location as ambient sounds are suppressed. However loud sounds or vibration can interfere and should be avoided. It can be operated remotely across a network and the room can be unoccupied during the analysis.
Auxiliary software is provided to simplify plotting of the
previously saved data files. These saved data files can still be
plotted using Gnuplot which is very comprehensive but driven from
the command line. The plotting utility software still uses Gnuplot
but is specifically designed to plot decrepigram files and has a
fully graphical interface. It facilitates superimposing multiple
results on a single plot to allow inter-sample comparison. The
plots are viewed on screen and can also be saved as .png image
This is a screenshot of the plotting software (V3.0) for decrepigram files in operation.