Applied Mineral Exploration
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Rapid fluid inclusion data
for exploration (decrepitation) |
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Monomineralic samples of 0.5g of crushed, sieved grains are analysed and extensive studies have been done using magnetite, pyrite, galena, carbonates and quartz. Quartz vein samples often show three or more distinct decrepitation peaks. A peak at 570oC is related to the weakening of quartz during the alpha to beta phase transition, which facilitates the decrepitation of inclusions. A low temperature peak (below 300oC) is due to the presence of gas-rich fluid inclusions (the most common gas being CO2), while the intermediate temperature peak is due to primary inclusions. Pyrite and quartz of hydrothermal origin usually give strong decrepitation responses whereas sedimentary pyrite or low temperature cherts give negligible decrepitation. Carbonate samples give very intense decrepitation up to their thermal decomposition temperatures, at which point the decrepitation suddenly ceases.
Because of the speed and low cost of the
analyses,
the
technique is useful for exploration projects and for scanning
and
selecting
samples prior to conventional microthermometric studies.
Full paper as pdf. 3.5 Mbyte