Bulletin of the Geological Society of Malaysia, Volume 43, Dec. 1999, pp. 251 – 259
1P.T. Aneka Tambang Tbk, Indonesia
2Department of Geology-ITS, Indonesia
3Independent Consultant, Indonesia
Abstract: The Cikidang gold deposit in West Java is located within the Bayah Dome Complex, hosted in the Cimapag Miocene Volcanic Formation. It is typical of a low-sulphidation epithermal deposit, consisting of several veins up to 1 km across with 180°-210° trend, 0.7-2.7 m widths, and about 60°-80° dips to the west.
The veins are composed of disseminated and clusters of native gold, quartz-adularia-calcite assemblages, showing various textures such as colloform banding, vein breccia, comb texture, and rare massive texture. Gold and silver average grades are 11.80 g/t and 72.23 g/t respectively; the Ag/Au ratio is about 7. The proven ore reserve is 475,698.74 ton.
Hydrothermal alteration is widespread in the Cikidang veins; advanced argillic alteration extends from 1 m up to 10 m around the veins, and is gradually changed to argillic and propylitic alteration outward from the vein.
Fluid inclusion evidence indicates the mineralising fluids had temperature ranges from 175° to 210°C, salinities between 0.028 to 1.07 eq. wt% NaCl. Besides, the mineralization horizon of the Cikidang vein is located in the precious metal horizon.
The age of the mineralization is around 2.1-1.5 Ma (Plio-Pleistocene).