Arc Exploration: First hole completed on porphyry target at Trenggalek project

By Ruli Setiawan

ASX-listed Arc Exploration Limited announced Thursday that it has completed the first drill hole with its joint venture partner, Anglo American, on the Trenggalek gold and copper project located in East Java, Indonesia.

Managing Director, Jeffrey Malaihollo, commented: ?This is the first drill hole in a program to test the Jerambah porphyry target identified at Trenggalek with our joint venture partner, Anglo American. Jerambah is one of several new targets on the exploration tenement.?

The results from the hole confirm the presence of a large alteration system with traces of base metal mineralization in a rock package that we believe is similar to that hosting the Tumpangpitu (Tujuh Bukit) porphyry copper-gold deposit further to the east.

?The Jerambah prospect is large and needs more work to confirm the presence of a porphyry system. We are in the process of completing soil sampling and spectral analyses to help plan the forward program and will report on the progress of this work in the coming weeks,? Malaihollo said in a statement.

The statement provides the following further details about the drill hole program.

The hole tested a combined geological and geophysics target identified at Jerambah Prospect on the southern side of the Exploration IUP tenement. The target is an extensive 2km by 1.5km silica-clay-pyrite alteration zone centred on igneous intrusions mapped at surface. This coincides with discrete magnetic anomalies extending from a deeper seated stock-like body that were modelled from a 3D magnetics-inversion analysis of the airborne magnetics data.

TRDD054 was an inclined diamond hole completed at a final depth of 1022.3 metres. It intersected a +800-m thick package of propylitic, argillic/intermediate argillic, and advanced argillic-altered diatreme breccias, diorite, quartz diorite, andesite porphyry and quartz-feldspar porphyry, bedded volcaniclastic and calcareous sedimentary rocks (see Table 1). These rock types and multiple overlapping alteration assemblages identified within them may be indicative of a porphyry-related system.

Disseminated pyrite mineralisation (<1-5%) occurs throughout the hole with locally traces of base metal sulphides. This is reflected by the final assay results, which returned a few narrow (<2m wide) intercepts of up to 0.1% copper, 0.1 g/t gold, 12 g/t silver and 88 ppm molybdenum. Some broader intervals of low-level molybdenum anomalism were returned, including 36-m at 6 ppm molybdenum.

The hole is interpreted to have intersected the weaker mineralized margins of a potential copper-gold system. Soil sampling and spectral analyses over a large area that includes the Jerambah target are in progress and the results of these are awaited to help plan the forward drilling program.

Editing by Reiner Simanjuntak