BADANIA IZOTOPÓW SIARKI W MINERAŁACH SIARCZKOWYCH ZE ZŁÓŻ RUD POLIMETALICZNYCH W SUDETACH ZA POMOCĄ MIKROSONDY JONOWEJ SHRIMP IIE/MC

Abstract

SULPHUR ISOTOPE MEASUREMENTS OF SULPHIDE MINERALS FROM THE POLYMETALLIC ORE DEPOSITS IN THE SUDETES, usin g THE SHRIMP IIE/MC ION MICROPROBEAbstract. Results of sulphur isotope analyses in sulphides by use of modern ion microprobe equipment – SHRIMP IIe/MC – are described in the paper. Measurements with an application of the SIMS method indicate high precision, fast procedure as well as high repeatability of results. Considering the sulphur isotopic ratio measured by the IRMS (the conventional method of gas spectrometry), advantage of the SIMS method is clearly visible. It allows for observation of the analysed surface at the micron-scale and for very precise selection of the area of analysis (about 20 μm in diameter), including the avoiding of other mineral microinclusions or microfractures in sulphide crystals, which are common features. In the case of the IRMS sulphur isotope analyses sample homogenization strongly influenced obtained results. The SIMS ion microprobe technique provides high spatial resolution which enables more reliable results. In the case of pyrites analysed from the abandoned Au–Cu–As Radzimowice deposit results of isotopic sulphur are close to δ34S = 0‰ (weighted average of δ34S for sample 10B is +0.84 ±0.24‰, n = 60, for sample M20 +0.37 ±0.13‰, n = 35, and for sample M21 –0.03 ±0.32‰, n = 26), which indicates the source of sulphur from processes related to magmas probably of mantle or lower crust origins. On the other hand pyrites from the old mining prospect in Leszczyniec have negative δ34S values below –1‰ (ranging from –3.24 ±0.08‰ to –1.19 ±0.09‰), which suggest a contamination process and possible minor input of sedimentary protolith during the magma generation.