On the Formation Temperatures of Minerals by Thermal Microscope (Heating Microscope Stage) and Decrepitation Method

Abstract

In the previous papers, the authors reported the formation temperatures of some deposits by decrepitation method.
In order to examine into the results, they designed the heating stage attached to a microscope and measured the vacuole filling temperatures by observing the disappearance of gas bubbles in liquid inclusions.
The filling temperatures of 50 vacuoles thin sections of a sample of quartz aggregate from the Hosokura mine (specimen no. Hosokura 395) range from 184°C to 217°C and average about 200°C. Most of the filling temperatures are concentrated between 197°C-208°C. Those of 20 vacuoles of the quartz aggregate from the Rendaiji mine (specimen no. Rendaiji A-1-3) range from 190°C to 225°C and average 208°C. Most of the filling temperatures are concentrated between 201°C-210°C. The cause of the discrepancy of filling temperature of ±15°C in a sample is unknown.
In the previous experiment, decrepitation temperature of the quartz (Hosokura 395) was determined to be 210°C, which almost coincides with the filling temperature by the heating stage method. Also, decrepitation temperature of the quartz (Rendaiji A-1-3) was determined to be 260°C which does not coincide with filling temperature by the heating stage method. The discrepancy in the specimen (Rendaiji A-1-3) would be due to the incompleteness of the counting apparatus and the misinterpretation of the decrepigraph shown in Fig.8. If one regards 210°C as the decrepitation temperature in this decrepigraph, it coincides with the temperature determined by the heating stage method.
Also, the authors are studying another method of determination of formation temperature of minerals, using a heating stage with "Ultropak" lens, whereby the temperature at which the immersed liquid begins to bubble will be determined.