MAPPING and sampling work by Arc Exploration at Jerambah prospect of the Trenggalek project in East Java has identified two drill targets. The encouraging results have prompted the company to undertake scout drilling at the prospect.


Drilling at Arc Exploration’s Trenggalek project in East Java.

The Trenggalek Exploration IUP tenement is held by Arc’s Indonesian partner, PT Sumber Mineral Nusantara (SMN). The tenement, covering 29,969 hectares, is valid until November 2018. Arc is in the process of renewing a forestry permit affecting 3393 hectares within the tenement area.

PT Danusa Tambang Nusantara, a subsidiary of one of the largest contract miners in Indonesia, is managing and funding exploration work at Trenggalek.

Trenggalek lies in the prospective Southern Mountains Province of East Java, which contains the large Tumpangpitu porphyry copper-gold deposit in the Tujuh Bukit district.

Jerambah is about 5km west of the Singgahan prospect. It is an extensive 2km by 1.5km silica-clay-pyrite alteration zone centred on igneous intrusions mapped at surface.

Jerambah was tested by a single drill hole during the Anglo-American Joint Venture. The hole was drilled to a depth of 1022 metres and intersected an extensive hydrothermal alteration and pyrite mineralisation with traces of base metal mineralisation. Arc believes this hole was drilled on the margin of an anticipated copper-gold system.

Subsequent soil sampling and spectral analyses showed a new cluster of overlapping spotty copper-gold-molybdenum anomalies reporting up to 348 ppm copper, 0.095 ppm gold and 59 ppm molybdenum to the north of the drill hole.

In recent months this area was re-mapped and resampled on a more detailed basis with Induced Polarisation (IP) and ground magnetic surveys conducted. This work identified outcrops of diorite with quartz-sericite-(chlorite) alteration and quartz stockworks. Alteration zones were mapped with the aid of a Terraspec machine.

An IP survey was conducted in July and August 2017 along 10 lines using a 50 metre dipole spacing with two additional lines using a 200 metre dipole spacing to obtain a deeper profile. The ground magnetic survey confirmed the mapping results that the area is dominated by dioritic rocks with a strong NW-SE structural control.

The IP and magnetic results combined with re-interpretation of aeromagnetic data, spectral analyses, re-mapping and re-sampling of the area have identified two drill targets.

Resource Center Whitepapers, Videos, Case Studies