PB-ISOTOPE AND TRACE ELEMENTS ANALYSIS BY LA-Q-ICPMS OF GALENA FROM ARGENTINIAN EPITHERMAL DEPOSITS: A PRELIMINARY ANALYSIS

MAYDAGÁN, LAURA; MCFARLANE, CHRISTOPHER; LENTZ, DAVID; BOUHIER, VERÓNICA; CAFFE, PABLO J.; RAINOLDI ANA LAURA; PONS, JOSEFINA; FERNANDEZ, MARÍA LIS; FRANCHINI, MARTA; LUNA, GERALDINE

Ciudad de Salta

Simposio; 15th Quadrennial International Association on the Genesis of Ore Deposits Symposium; 2018

IAGOD

In situ laser ablation quadrupole inductively coupled plasma-mass spectrometry (LA-Q- ICPMS) allows us to obtain rapid, accurate, and precise Pb isotope measurements together with trace elements in galena (McFarlane etal., 2016). Recent investigations have shown that galena can host a broader range of elements than previously recognized, many of them (e.g., Ag, Bi, Se, Te) can be extracted as by-products of an ore containing galena andothers (Sb, Cd, Tl) existas impurities (George et al., 2015).Pb isotopic studies have been applied as a tool in exploration of metallogenic terrains based on comparing the isotopic compositions of existing deposits within a district to prospective showings. Bouhier et al. (2017) presentedPb isotopic data of the Navidad Ag world class epithermal deposit. These authors indicated that the Pb isotopic ratios of Jurassic volcanic rocks and ore minerals from epithermal deposits of Patagonia have distinctive signatures in the North Patagonian Massif, the Deseado Massif, and the Andean region that vary with time in the volcanic events of the Chon Aike Volcanic Province.The objective of this contribution is to present new Pb isotopic data and trace elements obtained with the method LA-Q-ICPMS in galena from epithermal deposits in Argentina in order to identify patterns at regional and local scales that may be useful in exploration or exploitation.We present new Pb isotopic data and trace elements in galena from Argentinian epithermal deposits. The Pb isotopic data obtained allow correlate galena to geological provinces and ages. Within the Patagonia it is possible todifferentiate galena from the Deseado Massif and the North Patagonian Massif according to their isotopic signatures, especially their 206Pb/204Pb and 208Pb/204Pb ratios. We suggest that these analyses could be useful to identifymetallogenetic events in Patagonia and could be applied in regional mining exploration complemented with conventional exploration techniques.Pb isotopes in galena from Chinchillas have the same signatures as the Eastern Cordillera basement domain defined by Aitcheson et al. (1995) and the Antofalla domain of Mamani et al. (2010). The similarity in isotope ratios with host volcanic rocks and regional volcanism (e.g., Caffe et al. 2002) suggests that Pb isotope compositions of Chinchillas ores were inherited from magmas in which the basement participates through different mechanisms (mixing of crustal and arc melts or as contaminants in AFC processes) that affect Puna backarc magma evolution (Caffe et al., 2002; Kay et al., 2010).Regarding trace elements, large standard deviations recognized in Ag and Sb contents in Navidad, Virginia and La Paloma samples, are interpreted as the result of nano-inclusions of Ag mineral phases and Sb-sulfosalts ingalena. The relative low standard deviations recognized in Andacollo and Chinchillas samples suggest that Ag and Sb in these crystals could be present as solid solution.Similarly, low standard deviations in Se from La Paloma galena crystals suggests its presence in solid solution. Bismuth values show high standard deviations in all the samples consistent with the presence of sub-micron-size Bibearing phases. The wide range of values of Te in Andacollo deposit suggests microinclusions of telluride minerals.