Genesis and origin of Te–bearing gold–silver–base metal mineralization of the Arinem deposit in western Java, Indonesia

Abstract

The Arinem deposit is an epithermal-type, gold-silver-base metal mineralization, hosted by the Arinem vein system which cross-cut volcanic rocks of Oligocene to Miocene age. There are three main stages (I to III) of ore mineralization in quartz-illite-calcite veining. The physico-chemical conditions and the origin of the hydrothermal fluids in the Arinem deposit are examined. We find the f S2 to have decreased from~10 −8 to 10 −16 atm and the f Te2 to have increased from~10 −15 to 10 −8 atm with decreasing temperature of ore fluids during mineralization. Oxygen (δ 18 O), hydrogen (δD), and sulfur (δ 34 S) isotopic values as derived from quartz, fluid inclusions, and sulfides in the mineralized veins range −6.0 to −1.7‰, −66 to −34‰, and −3.6 to −1.8‰, respectively. The sulfur isotope values indicate that sulfur was mostly derived from a magmatic source, whereas the oxygen and hydrogen isotope values suggest an influx of meteoric water into the hydrothermal system. As a consequence of the mixing of magmatic and meteoric waters and changes in the physico-chemical conditions of the ore fluids (i.e., ore fluid temperature and chemistry), higher temperature mineralization was triggered during stage I, followed by lower temperature mineralization during stage II. Continued influx of meteoric water may have caused the ore fluids to become oversaturated, resulting in the precipitation of unmineralized stage III veins.

Ore–microscopy and Geochemistry of Gold–Silver Telluride Mineralization in Southwestern Hokkaido, Japan

“…According to Lindgren (1933) and Heald et al (1987), gold correlates strongly with Te but these relationships are not clear since there is insufficient thermodynamic information on Te aqueous species and their complexes under hydrothermal conditions. While sulfide sulfur, a close chemical analogue of Te and Se, known to a greater extent, controls on Au and Ag solubility and transport in hydrothermal fluids and fairly stable hydrosulfide complexes of Au and Ag metals formation (Barnes, 1979;Gammons and Barnes, 1989;Benning and Seward, 1996;Yuningsih and Matsueda, 2014). Comprehensive experimental studies for telluride systems were performed by Cabri (1965), Afifi et al (1988) etc.…”