Arc exploration has started drilling on the Trenggalek Copper-Gold Project in East Java with its joint venture partner, Anglo American, which is fully funding the program. The program is under way at Jerambah prospect, one of several targets identified on the exploration IUP.
Arc officials say further interpretative and field work is also under way with the aim of firming up a pipeline of other targets for drill testing.
The 300sqkm Trenggalek project lies in the prospective Southern Mountains province of East Java, which contains the giant Tumpangpitu porphyry copper-gold deposit in the Tujuh Bukit district. The project has excellent infrastructure with a network of sealed to graded roads traversing almost all of the tenement area.
The current program is planned to test a number of geophysical targets associated with possible porphyry copper-gold systems located beneath large near-surface alteration features. The geophysical targets were generated from the earlier airborne magnetics/radiometrics survey and are ranked with the results of surface geochemical sampling, detailed mapping and alteration studies.
The recently identified Jerambah prospect is about 2 km southwest of the Buluroto epithermal gold-breccia prospect on the southern side of the Trenggalek tenement.
Previous drilling at Buluroto returned narrow epithermal gold intersections that included 2 metres @ 8.7 grams/tonne gold. Copper sulphide mineralisation in silicified breccia was intersected in another hole which returned a broad gold-copper-molybdenum intercept of 24.5 metres @ 0.51 grams/tonne gold, 0.21% copper and 16ppm molybdenum from 138.5 metres depth. This provided one of the first indications of the deeper porphyry potential at Trenggalek.
The subsequent discovery of a large high-sulphidation epithermal alteration system centred on quartz-feldspar porphyry intrusions at Sumber Bening prospect, on the western side of the Trenggalek tenement, provided further evidence for porphyry potential.
Arc's managing director Dr Jeffrey Malaihollo says, “We are very pleased to report that drilling has now started at Trenggalek. This is the first drilling program to test the porphyry copper-gold targets identified alongside our JV partner, Anglo American.
"Previous drilling at Trenggalek has identified several shallow epithermal gold-vein and breccia systems. This exciting new phase of exploration is testing for deeper porphyry copper-gold systems associated with geophysical anomalies detected beneath large near-surface alteration features. We look forward to reporting results as they become available.”
The company has two Indonesian projects - Trenggalek and a strategic alliance with the Anglo American group in Papua.