Title: MICRO-PIXE APPLICATION TO THE SPHALERITE-GALENA GEOTHERMOMETER
Abstract: We have applied the micro-PIXE technique to determining the cadmium content in sphalerite ( ZnS ) and galena ( PbS ) for use in geothermometry in the Bulawan gold-silver telluride deposit, Philippines. This geothermometry is based on the temperature control on the cadmium distribution between sphalerite and galena. For the analyses by the micro-PIXE, a beam of 3MeV protons was used at CSIRO, Sydney. The size of the beam was between 10-30μm such that during analysis, points within sphalerite-galena pairs which are located very close to the rims of the grains were analyzed and also pairs which are located farther away from each other. The X-rays obtained were deconvoluted for peak areas and converted to concentration using the Geo-PIXE software. The results for rim and non-rim pairs are indistinguishable. The micro-PIXE was capable of analyzing Cd to the level of about 100ppm in galena and 150ppm in sphalerite. Six pairs of galena-sphalerite at the earliest stage of mineralization were examined and only three pairs could be used for our purpose. The obtained temperatures, 402 to 527°C are about 90 to 210°C higher than estimates for the later stage of mineralization in the deposit. Thus, using micro-PIXE we concluded that deposition of early sphalerite and galena in the Bulawan deposit probably occurred at around 500°C before waning down to around 300°C.
Publication Year: 1997
Publication Date: 1997-01-01
Language: en
Type: article
Indexed In: ['crossref']
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