Pustaka Ilmiah Universitas Padjadjaran

Abstrak

Characteristics of Miocene and Pliocene Epithermal Gold-Silver Deposits in Western Java, Indonesia

Western Java has several gold-silver deposits and all of the mineralization follows the Sunda Banda magmatic are which is the longest magmatic are in Indonesia. The distribution of gold-silver ore deposits in western Java reflects major metellogenic event during the Miocene and Pliocene in age. The deposits can be divided into two types i.e., Se- and Te-types with some different miner¬alogical characteristic features, The Se-type mineralimtion of western Java are mostly lain within and on the flanks of the Bayah Dome and are represented by Pongkor, Cikidang, Cisungsang, Cirotan, and cibaliung deposits, while the Te-type are located eastern part and are represented by Arinem and Cineam deposits. The principal object of this research is to summarize the mineralogi¬cal and geochemical characteristics and to constrain the physico-chemical conditions of the epither¬mal mineralization in western Java. Geological studies indicate that volcanic rocks host the Te-type, while both volcanic and sedi¬mentary rocks host the Se-type. Dominant ore minerals from the Se-type deposits are Se-bearing Ag minerals (aguilarite, polybasite, naumannite, pyrargyrite, argentite) and electrum with various amounts Of sulfide minerals of sphalerite, galena, chalcopyrite, arsenopyrite end pyrite. Other ore minerals are also found in trace amount, Some rare Bi and Sn-bearing minerals such as lillinnite and canfieldite are reported from Se type deposit of Cirotan. On the other hand, the Te-type is char¬acterized by the occurrence of hessite, petzite, stritzite, tetradymite, altaite and with large amount of sulfide minerals such as sphalerite, galena, chalcopyrite. pyrite and arsenopyrite. Mineralogical dif¬ferences appear to reflect their intrinsic geochemical characteristics.