Arc: First scout drilling confirms porphyry potential at Trenggalek project
Monday, July 21 2014 - 04:11 AM WIB
ASX-listed Arc Exploration Limited announced Monday the completion of the first phase of scout drilling with its joint venture partner, Anglo American, on the Trenggalek Project located in East Java.
?The results from this first phase of drilling with our joint venture partner, Anglo American, have confirmed the presence of a porphyry system at Singgahan, albeit so far at low-grade. These porphyry-type systems normally have multiple intrusions and there are indications that stronger mineralization may be present in Singgahan area,? said Arc Exploration Managing Director Jeffrey Malaihalo in a statement.
?Singgahan is only one of several targets identified under the joint venture. Large parts of the project area where there are several other prospects are underexplored for porphyry deposits. We will do a detailed review of the results and undertake more surface work before further drilling,? he added. ?These results highlight the porphyry potential of the Trenggalek project area, which lies in the same segment of volcanic arc that hosts the Tumpangpitu porphyry copper-gold deposit further to the east.?
The first phase of scout diamond drilling has been completed on the Singgahan Prospect located in the southeast corner of the Trenggalek Exploration IUP tenement. A total 1,541 meters was drilled in four inclined diamond holes (TRDD055-58). These holes have tested only part of an extensive copper-goldmolybdenum soil anomaly that is underlain by a discrete magnetic anomaly centred on an altered diorite intrusion.
TRDD057 was collared on the same drill pad as TRDD055 but drilled in the opposite direction to test the eastern edge of the soil anomaly and a magnetic low zone. The hole intersected a fault zone at the top of the hole and then a weakly mineralized, silica-clay-pyrite altered polymictic breccia and containing scattered quartz-pyrite veined intraclasts and a deeper quartz diorite/tonalite intrusion cut by minor quartz-pyrite veining with traces of disseminated chalcopyrite and molybdenite mineralization.
A stronger developed zone of quartz-pyrite veining was intersected over the final 12 meters of this hole within silica-clay-pyrite altered volcaniclastic rocks and returned an intercept of 12 m at 670 ppm copper (or 0.067% Cu) and 0.1 g/t gold from 371.4 m. The peak result within this interval was 810 ppm Cu (or 0.081% Cu), 0.14 g/t Au & 7 ppm Mo. The hole was terminated in mineralization.
TRDD058 was collared as a scissor hole to TRDD055. TRDD058 was testing for a possible increase in grade on the down-dip projection of the low-grade intercepts obtained in TRDD055.
The upper part of TRDD058 intersected low-grade copper-gold-molybdenum mineralization in a quartz-anhydritemagnetite-sulphide veined diorite intrusion and intrusion breccia. Multiple low-grade intercepts were returned including a best intercept of 70 m at 373 ppm copper (or 0.037% Cu), 0.05 g/t gold & 4 ppm molybdenum from 142 m down-hole. Similar intercepts were previously reported from TRDD055, which is collared about 200 m to the east of TRDD058.
A gold intercept of 14 m at 0.24 g/t gold from 128 m down-hole with elevated associated arsenic-antimonymolybdenum was returned in silicified calcareous volcaniclastic rocks near the upper contact with the mineralized diorite. The peak result within this interval was 0.36 g/t Au with 1.68% As, 197 ppm Sb & 9 ppm Mo. This intercept correlates with a similar gold intercept returned in TRDD055 about 150 m to the east.
Silicified and locally skarnified calcareous volcaniclastic rocks were intersected in the lower part of the hole beneath the mineralised diorite. These rocks returned patchy elevated arsenic and molybdenum results of up to 1230 ppm As & 46 ppm Mo.
Editing by Reiner Simanjuntak