Alkali metals control the release of gold from volatile-rich magmas

作者：Zajacz Zoltan^*; Seo Jung Hun; Candela Philip A; Piccoli Philip M; Heinrich Christoph A; Guillong Marcel

来源：Earth and Planetary Science Letters, 2010, 297(1-2): 50-56.

DOI：10.1016/j.epsl.2010.06.002

• gold
• solubility
• ore deposit
• magma
• sulfur
• hydrothermal

Magmatic-hydrothermal ore deposits are a major resource of gold. Volatiles exsolving from magmas rising through the Earth's crust are the key agent for enrichment of gold in these deposits. We report the first experimental determination of gold solubilities in the magmatic volatile phases at conditions typical of most magmas associated with gold deposits (T = 1000 degrees C, P = 150 MPa). We show that gold hydrosulfide complexes supersede gold chloride complexes, and more importantly, that the stability of gold hydrosulfide complexes is greatly increased by the presence of minute concentrations of KC or NaCl (0.1-0.5 mol/kg H(2)O). The amplifying effect of alkali chlorides on the solubility of gold in H(2)S bearing volatiles may explain the preferential association of many giant hydrothermal gold deposits with high-potassium alkaline mafic to intermediate igneous rocks, which exsolve volatiles that simultaneously contain both H(2)S and alkali chlorides in significant concentrations.

• 出版日期2010-8-15