1962 Volume 12 Issue 55 Pages 282-293
The results of the heating-stage method, of the decrepitation method and of the decrepitoscope method of the liquid inclusion geothermometry are discussed in this paper. From the comparison of the results obtained by the heating-stage method and the decrepitation method about quartz and sphalerite, it is recognized that the overshoot of the decrepitation temperature of quartz varies with the size of sample. The values of the overshoot are 50-60°C for 35-150 mesh and 70-80°C for 65-150 mesh, when the heating rate is 14-16°C/min. while, the overshoot of the decrepitation temperature of sphalerite is about 20-40°C. The filling temperatures of the liquid inclusions of quartz sampled from the Oppu mine are 200-270°C and those from the Yaso mine are 180-270°C.
Opaque minerals, such as chalcopyrite sampled from the Yaso mine and marmatite from the Taishu mine, were measured by the decrepitation method. The decrepitation temperatures of chalcopyrite range from. 200°to 260°C and those of marmatite are about 200°C. As the decrepitation temperatures of chalcopyrite nearly coincide with the lower parts of the filling temperature ranges of the primary inclusions in quartz that coexists with chalcopyrite, the overshoot of the decrepitation temperatures of chalcopyrite seems to be not so large as that of quartz. The decrepitation temperatures of marmatite of the Taishu mine are considerably lower than those expected from the paragenesis of the ore minerals and the geological setting of the ore deposit. It is inferred from the study of the inclusions in quartz from the Taishu mine that the decrepitation temperatures of the marmatite from this mine are related to the secondary inclusions of the marmatite.
It is concluded that the results of the decrepitation method are not so accurate and, if possible, they must be checked by the heating-stage method.
