Evidence for vapor transport of the base and precious metals in the Panormos Bay Ag-Au-Te deposit, Tinos Island, Cyclades

Abstract

Tellurium-bearing, base and precious metal sulfides from the Au-Ag-Te mineralization at Panormos Bay, Tinos Island, Cyclades, preceded and followed the main telluride-forming event. Ore petrography and chemistry of the sulfides suggest that they have precipitated under supersaturation conditions, i.e., grown with hopper habit, enriched in Zn, Fe, Ag, Cd and Pb, and Te in stage II, III and VI sulfides and incorporate nanoparticles with variable Ag/(Pb + Ag + Cu + Fe + Zn)% values. The noble gas, i.e., He, Ar and Ne isotope compositions obtained from these sulfides form two distinct populations, the “Liquids” and “Vapors”. All these features constitute overwhelming evidence that favors vapor transport for the base and precious metals by the vapor-like Panormos ore fluid.The widespread occurrence of CO2-effervescence and boiling at the Panormos Bay Au-Ag-Te ores provoked degassing of the CO2, HCl(g), H2S(g), H2Te(g), Te2(g), light noble gas isotopes (3He, 36Ar, 20Ne, and 21Ne), base- and precious-bearing laden vapors from the mineralizing fluid and transported a fraction of the base and precious metals to vapor. Geochemical simulation suggests that supersaturation in the vapor phase, rapid up-vapor transport, and subsequent condensation in the Panormos Bay ore solution of H2Te(g), Te2(g), and base and precious-bearing vapors led to the precipitation of sulfide (stages II, III and VI) and telluride (stage V) mineral assemblages.