Geochemical characteristics of pyrite in Duolanasayi gold deposit, Xinjiang

The Duolanasayi gold deposit, 60 km NW of Habahe County, Xinjiang Uygur Autonomous Region, is a mid-large-scale gold deposit controlled by brittle-ductile shearing, and superimposed by albitite veins and late-stage magma hydrothermal solutions. There are four types of pyrite, which are contained in the light metamorphosed rocks (limestone, siltstone), altered-mineralized rocks (chlorite-schist, altered albite-granite, mineralized phyllite), quartz veins and carbonatite veinlets. The pyrite is the most common ore mineral. The Au-barren pyrite is present mainly in a simple form and gold-bearing pyrite is present mainly in a composite form. From the top downwards, the pyrite varies in crystal form from {100} and {210}+{100} to {210}+{100}+{111} to {100}+{111}. Geochemical studies indicate that the molecular contents of pyrite range from Fe-{1.057}S-2 to Fe-{0.941}S-2. Gold positively correlates with Mn, Sr, Zn, Te, Pb, Ba and Ag. There are four groups of trace elements: Fe-Cu-Sr-Ag, Au-Te-Co, As-Pb-Zn and Mn-V-Ti-Ba-Ni-Cr in pyrite. The REE characteristics show that the total amount of REE (ΣREE) ranges from {32.35}×10{-6} to {132.18}×10{-6}; LREE/HREE, {4.466}-{9.142}; (La/Yb)-N, {3.719}-{11.133}; (Eu/Sm)-N, {0.553}-{1.656}; (Sm/Nd)-N, {0.602}-{0.717}; La/Yb, {6.26}-{18.75}; δEu, {0.628}-{2.309}; δCe, {0.308}-{0.816}. Sulfur isotopic compositions ({δ{}{34}S}={-2.46‰}-{-7.02‰}) suggest that the sulfur associated with gold mineralization was derived from the upper mantle or lower crust.