DISCOVERY AND EXPLORATION OF THE GOSOWONG EPITHERMAL GOLD DEPOSIT, HALMAHERA, INDONESIA

Citation
Jc. Carlile et al., DISCOVERY AND EXPLORATION OF THE GOSOWONG EPITHERMAL GOLD DEPOSIT, HALMAHERA, INDONESIA, Journal of geochemical exploration, 60(3), 1998, pp. 207-227
Citations number
6
Categorie Soggetti
Geochemitry & Geophysics
ISSN journal
03756742
Volume
60
Issue
3
Year of publication
1998
Pages
207 - 227
Database
ISI
SICI code
0375-6742(1998)60:3<207:DAEOTG>2.0.ZU;2-V
Abstract
The Gosowong epithermal gold deposit, on the island of Halmahera in ea stern Indonesia, is located in an ar ea of primary tropical rain fores t with no previous history of gold mining or record of gold mineralisa tion. The deposit occurs in a newly recognised mineral district which contains a number of epithermal vein systems and at least two centres of low-grade porphyry style Cu-Au mineralisation. Several zones of arg illic and advanced argillic alteration have been noted which may be re lated to additional centres of mineralisation. Gosowong is classified as a low-sulphidation epithermal quartz vein. Bonanza-grade gold-silve r mineralisation is developed in shoots over a 400-m strike section of the vein system. Three types of veining are recognized; quartz-adular ia veins and breccias; quartz-chlorite-illite veins and breccias; and crystalline or chalcedonic quartz vein stockworks. The area was target ted using a simple geological concept and the deposit was discovered a nd tested using basic exploration techniques commonly applied in the r ugged tropical terrains of Indonesia. Sequential exploration methods c omprised reconnaissance drainage sampling of stream sediment, BLEG and float media, ridge and spur soil sampling, prospect scale grid soil s ampling, hand trenching and diamond drilling. Lapse time from identifi cation of the initial reconnaissance anomaly to an inferred resource e stimate of almost 1 million ounces of gold was less than 3.5 years. Th is case history illustrates that very detailed exploration is necessar y to locate high-grade vein-type gold deposits in a tropical environme nt, but demonstrates that such resources still remain to be discovered in the relatively under-explored Neogene magmatic arcs of Indonesia. (C) 1998 Elsevier Science B.V.