Ramit Prospect

Updated: 300511

Exploration, geological and other work activities by Southern Arc on the Ramit Prospect of the Taliwang property on west Sumbawa Island originally started in March 2006, when IP resistivity surveys revealed an inferred porphyry-style prospect, several kilometres north of Newmont’s Batu Hijau gold-copper mine. The Ramit Prospect, a porphyry/structurally-controlled vein/stockwork target, is situated between, and possibly genetically-related to the Semoan-Raboya vein prospects couple.

Recent Activities

Detailed infill mapping continued over this area during April, giving further definition to geological contacts and alteration zoning. Collection of clay alterations samples also continued for PIMA analyses to be carried out at a later date. This will assist in defining the location of a possible, inferred blind porphyry target.

Previous and Scout Drilling Work

Phase 1 (scout) drilling and limited geology grid mapping/sampling over the Ramit Prospect were completed in May 2006.  By the end of that month all four holes (RMG-01, RMG-02, RMG-03 and RMG-04) had been completed with an average drill core recovery rate of 97.9 percent.

Four holes, totaling a length of 1,218.75m, were drilled to explore the conceptual porphyry and porphyry shoulder target beneath a 750 m east-west IP chargeability zone.

Drill hole descriptions are summarized below:

RMD-01

Below 2.5m of hematitic soil and rubble, a surficial breccia (either mass-flow or diatreme apron?) extends to 23.7m. The breccia is a chaotic mix of variably altered and oxidized dacite and andesite clasts of various sizes and roundness supported in pyritic illite clay. An old land surface, characterized by a large wood fragment in sand, was intersected between 23.7m and 25.35m. Porphyritic andesite was intersected from 25.35m to 333m (EOH).

The andesite generally exhibits a crowded assemblage of medium even-grained equant plagioclase feldspar and rarer hornblende phenocrysts in a fine grained mat of the above minerals. Alteration varies considerably downhole between zones of illite-pyrite, silica-pyrite, sericite-silica-pyrite (particularly below 115m), and chlorite±carbonate±epidote. Quartz±pyrite vein/veinlet density rarely reaches 10/m, but is usually 1-3/m, and most often between 0.5 and 1cm thick, once up to 40cm thick. Rare weak stockworks were noted.

Fine to medium grained euhedral pyrite crystals, usually as clumps, are disseminated throughout, and generally range between 1 to 2 percent of the rock volume. Some of the pyrite exhibits a bright iridescent, multi-coloured tarnish. A fine grained, metallic black mineral is also found weakly disseminated throughout, sometimes associated with the pyrite clumps, but often isolated. Occasional small zones of massive secondary magnetite occur sporadically down-hole from 123.5m, achieving greatest density between 317.7 to 333m.

RMD-02

Andesite also remains the dominant rock type in this drill hole down to 300.15m. It is often cut by dacite dykes ranging from 0.3m to 3m thick, with maximum frequency ranging between 30m to 65m and 125m to 165m. The andesite/dacite contacts are usually strongly brecciated and contain andesite, dacite, and silica clasts in a silicified matrix varying from 0.5 t0 1m thick.

Alteration generally varies from argillic to intermediate argillic, and possibly phyllic, with mineral assemblages exhibiting variable volumes and intensity of illite-kaolinite(possibly sec?)-sericite±qtz-py. Minor propylitic alteration is noted between 155.75m and 168.85m. Weak to moderate vuggy quartz alteration accompanied by kaolinite-illite-pyrite is noted between 31.15m and 55.2m. Quartz-pyrite veinlets are weakly developed, and reach a maximum frequency between 8m and 15m down-hole. Structural zones, some containing slickensides, are frequent throughout.

RMD-03

Drill hole RMD-03 was drilled westward towards hole RMD-02 in order to explore the  full width and mineral tenor of the Samporea structural zone. After a thin veneer (<10m thickness) of surficial breccia was intersected, the hole continued in variably altered (mainly intermediate argillic to phyllic) porphyritic andesite (similar to that encountered in hole RMD-02), displaying up to 4 percent disseminated fine euhedral pyrite, and sporadic zones of enhanced quartz-pyrite veinlet development and minor fluidized monomictic breccia zones.

RMD-04

Hole RMD-04 was drilled east towards RMD-01 to explore the western side of the high chargeability anomaly. After drilling through the surficial breccia to about 16m, the hole continued in altered and mineralized porphyritic andesite (similar to hole RMD-03) until about 210m, where alteration changes to an interpreted inner propylitic assemblage possibly overprinting an earlier, more sporadic, potassic phase. This required confirmation, and relevant core samples were shipped for petrological studies in June 2006.

Geochemical Results

Results from the majority of drilling (up to 193m of RMD-04) at Ramit had been received by the end of May 2006. They are only incomplete at this stage, with As, Sb, and Mo still pending. Molybdenum distribution is of interest.

Although alteration styles and intensity, sulfide (pyrite>>sphalerite>chalcopyrite, chalcocite, covellite) distribution and intensity, textures, and localized veinlet and breccia development are encouraging signs of a mineralized porphyry environment, assay results thus far have been uniformly disappointing with only a sporadic high of 0.26 ppm Au and low tenor Cu values (<550 ppm).

See geophysical line D drill hole lithology & alteration cross-section.

Subsequently, Southern Arc retained an international consulting geologist to review the Ramit drill core (RMD-01 to RMD-04), geophysical and surface data. In preliminary findings he believes that the 'inferred intrusive' is not related to a porphyry copper system. The alteration seems more related to near in-situ alteration above a cupola. But given that heat/solution passed up from a cupola, the silica capped ridges (Semoan & Raboya), including the silica cross-structures, might indicate sites where alteration is concentrated, and therefore a concentrating mechanism for gold may have operated. As such, they continue to be good, valid future exploration targets for Southern Arc.

Geological Grid Mapping & Sampling

Geological grid mapping and sampling alonf a survey grid was carried out in April 2006, realizing a total of nine selective channel samples. The area is underlain by porphyritic andesite (sub-volcanic or lava?) intruded by diorite, and possibly later stage quartz-feldspar porphyry (QFP). A young surficial breccia and a locally thin veneer of recent alluvium cover the central part of the area. The dominant lithology, andesite, was mapped in the north, central and southwest of the area. The QFP, in the NW, is whitish in color with prominent medium grained quartz (15 to 20 percent)-feldspar phenocrysts. This rock has a similar texture to the quarry rock near the main road.

Advanced argillic alteration is distributed in the NW and south, affecting both andesite and QFP lithologies, while argillic alteration appears distributed in a central N-S belt affecting mainly andesites.