Lithogeochemistry of the Collahuasi porphyry Cu–Mo and epithermal Cu–Ag (–Au) cluster, northern Chile: Pearce element ratio vectors to ore

Thallium isotope variations in an ore-bearing continental igneous setting: Collahuasi Formation, northern Chile

“…In some cases, an unambiguous identification of the original lithology is severely hindered by the chemical and mineralogical changes that occurred during hydrothermal overprinting. However, concentration data for elements that are generally thought to be relatively immobile during aqueous and hydrothermal alteration processes, such as Zr, Ti, Nb, and Y, generally support the mineralogical and field-based classification (Urqueta et al, 2009). For example, a plot of Zr vs. TiO 2 abundances reveals distinct trends and fields for the intrusive porphyry samples and the volcanic rhyolite, dacite and andesite suites, despite of clear differences in the observed alteration assemblages ( Fig.…”

“…The andesites display the largest scatter in this diagram. This appears to reflect both primary variability in the Ti/Zr ratios of the various andesite suites and a somewhat non-conservative behavior of TiO 2 in these rocks during metasomatism (Urqueta et al, 2009). …”

“…2) produced country rocks, which feature the typical alteration assemblages found in the vicinity of porphyry Cu systems (Sillitoe, 2010). This pattern of alteration was generated during three main stages of hydrothermal activity (Masterman et al, 2004(Masterman et al, , 2005Urqueta et al, 2009):…”

“…The Collahuasi rocks that were analyzed for Tl isotope compositions were chosen from a larger archive of previously studied samples (Table 1; Urqueta et al, 2009). The majority of the rocks were obtained from outcrops (n = 28) but a few are from drill-holes in and around the Rosario deposit (n = 8).…”

“…The major and trace elements concentrations of the samples had been determined previously (Urqueta et al, 2009) but the results were hitherto only published in figures and not provided in tabular format. Here, we provide key geochemical data for those samples that were analyzed for Tl isotope compositions ( Table 1).…”