Epithermal Gold-Silver Deposits in Western Java, Indonesia: Gold-Silver Selenide-Telluride Mineralization

Abstract

-The gold-silver ores of western Java reflect a major metallogenic event during the Miocene-Pliocene and Pliocene ages. Mineralogically, the deposits can be divided into two types i.e. Se-and Te-type deposits with some different characteristic features. The objective of the present research is to summarize the mineralogical and geochemical characteristics of Se-and Te-type epithermal mineralization in western Java. Ore and alteration mineral assemblage, fluid inclusions, and radiogenic isotope studies were undertaken in some deposits in western Java combined with literature studies from previous authors. Ore mineralogy of some deposits from western Java such as Pongkor, Cibaliung, Cikidang, Cisungsang, Cirotan, Arinem, and Cineam shows slightly different characteristics as those are divided into Se-and Te-types deposits. The ore mineralogy of the westernmost of west Java region such as Pongkor, Cibaliung, Cikidang, Cisungsang, and Cirotan is characterized by the dominance of silver-arsenic-antimony sulfosalt with silver selenides and rarely tellurides over the argentite, while to the eastern part of West Java such as Arinem and Cineam deposits are dominated by silver-gold tellurides. The average formation temperatures measured from fluid inclusions of quartz associated with ore are in the range of 170 -220°C with average salinity of less than 1 wt% NaCl equiv. for Se-type and 190 -270°C with average salinity of ~2 wt% NaCl equiv. for Te-type.

Formation conditions of high-grade gold–silver ore of epithermal Tikhoe deposit, Russian Northeast

“…Bortnikov et al (1987) showed that the development of Se-bearing minerals in ore is evidence for the high oxidation potential of the ore-formation medium, which may result from mixing of ore-bearing fluids with highly aerated meteoric water. The widespread selenium mineralization in ore testifies to near-surface ore deposition and insignificant erosion (Kovalenker, 2007;Yuningsih et al, 2014).…”

“…A selenium impurity (up to 1.86 wt %) has been detected in electrum (Table 2). It should be noted that enrichment of main ore minerals in selenium is a typomorphical feature of high-grade ore of epithermal low-sulfidation deposits Yuningsih et al, 2014).…”

Geology, Vein Textures, and Fluid Inclusions of the Cibeber Low-Intermediate Sulfidation Epithermal Au-Ag Orefield, Western Java

“…A previous study mentioned that the abundance of mineral deposit in this area is mostly controlled by advanced magma evolution that increases the alkali content of the magmatichydrothermal system (Setijadji et al, 2006). The mineralization is interpreted to have occurred during the Mio-Pliocene period based on K-Ar dating from surrounding areas (McInnes et al, 2004;Yuningsih et al, 2014). Syn-ore structures are likely the result of subduction activity in southern Java as indicated by the lineament pattern, while the pre-ore structures are associated with caldera formation in the Bayah Dome Volcanic Complex as suggested by the presence of a regional circular (caldera-like) structure.…”

Петрологические Аспекты Современного Островодужного Вулканизма На Примере Лав Вулкана Батур (О. Бали, Индонезия)

“…С другой стороны, островная дуга Сунда-Банда, как и другие вулканические провинции, связанные с зонами субдукции, является областью локализации экономически значимых медно-порфировых и эпитермальных Au-Ag месторождений [12][13][14][15][16]. Известно, что эволюция большинства мантийных и коровых силикатных магм неизбежно приводит к несмесимости силикатного и несиликатного расплавов [17].…”