PT Indika Energy fully owns Nusantara Resources Limited, which in turn owns 100% of PT Masmindo Dwi Area, the sole rights holder for the Awak Mas Gold Project.
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Summary:
The Awak Mas Gold Project includes the three main deposit areas of Awak Mas, Salu Bulo and Tarra.
The Awak Mas, Salu Bulo and Tarra deposits are mineralised systems comprised of a sequence of intercalated meta-sediments and intrusive rocks. A high level, low sulphidation hydrothermal system has developed, which is overprinted by a strong sub-vertical fracture control which has channeled mineralising fluids.
Awak Mas Deposit
The Awak Mas deposit is defined by a total of 786 diamond drill holes (~96,270m) and 158 reverse circulation (~16,290m) holes, of which Nusantara has completed 54 (pre-Close Spaced drilling program) diamond drill holes (~9,356m) with a further 132 diamond drill holes for 6,562m of CS drilling.
Host lithologies for mineralisation are the cover sequence of meta-sedimentary rocks and to a lesser degree the underlying basement sequence of diorites and biotite dominant schists. The Cover and Basement sequences are separated by an unconformable and sheared thrust contact.
A high level, low sulphidation hydrothermal system has developed at the Awak Mas deposit which is overprinted by a strong sub-vertical fracture control which has channelled the mineralising fluids. The mineralising fluids have exploited these pathways and migrated laterally along foliation parallel shallowly dipping favorable strata. In addition to the conformable style of mineralisation there is a late-stage hydrothermal overprint that has also deposited gold in some of the major sub vertical structures. The multiphase gold mineralisation is characterised by milled and crackle breccia, vuggy quartz infill, and stockwork quartz veining with distinct sub-vertical feeder structures.
The Awak Mas deposit consists of five broad geologically based mineralised areas (domains), which from west to east are Mapacing, Ongan, Lematik, Tanjung and Rante. These predominantly north-south to north-east striking zones lie adjacent to each other, cover an extent of 1,450m east-west by 1,050m north-south and extend to a maximum tested vertical depth of 400 m:
• Mapacing – Single shallowly NE dipping domain with a strike length 810m, plan width 230m width and average thickness ranging from 5-30m.
• Ongan – Shallowly dipping and sub-vertical domains with strike extent of 730m, plan width of 150m. Shallow domains vary in average thickness from 5-30m and sub-vertical domains have an average thickness of 5-10m.
• Lematik – Mainly sub-vertical domains with strike extent of 740m, plan width of 220m and average thickness of 5-60m. A central north plunging (at 60º) pipe has dimensions of 80m x 80m along a strike of 280m.
• Tanjung - Shallowly dipping and sub-vertical domains with strike extent of 910m, plan width of 340m. Shallow domains vary in average thickness from 5-40m and sub-vertical domains have an average thickness of 5-10m.
• Rante - Shallowly dipping and sub-vertical domains with strike extent of 700m, plan width of 320m. Shallow domains vary in average thickness from 20-70m and sub-vertical domains have an average thickness of 5-10m.
The complex interaction of multi-phased stockwork and breccia mineralisation associated with at least two dominant structural orientations (shallow thrusts and sub-vertical feeders) results in local changes in the grade tenor and orientation. This apparent structural control has been better-constrained by close-spaced drilling (12.5m) in areas defined for the initial mining area (IMA).
Salu Bulo Deposit
The satellite Salu Bulo deposit is located 2.5 km to the southeast of the main Awak Mas deposit and hosts a number of mineralised quartz vein breccia structures referred to as the Biwa, Bandoli and Lelating trends.
The Salu Bulo deposit consists of three main north-south trending mineralised corridors, which from west to east are Lelating, Biwa North and Biwa South. The mineralisation is hosted within a sequence of chloritic and intercalating hematitic meta-sedimentary rocks, with the two primary structural orientations being dominant sub-vertical north-south anastomosing structures, and foliation parallel low angle thrusts.
The ladder stockwork vein system developed at Salu Bulo deposit is analogous to that at Awak Mas deposit where there is inherent complexity of two mineralisation orientations, and short scale grade continuity at generally less than the drill hole spacing. (25m to 50m drill collar centres).
The multi-phase gold mineralisation is characterised by milled and crackle breccias, vuggy quartz infill, and stockwork quartz veining with distinct sub-vertical feeder structures. Gold mineralization typically occurs with minor disseminated pyrite (< 3%) within sub-vertical quartz veins, breccias, and stockwork zones.
The mineralised domains at Salu Bulo deposit are orientated north-south, and have an overall combined strike length of approximately 800m.
Tarra Deposit
The Tarra deposit lies approximately 4.5 km north of the main Awak Mas deposit. The mineralisation style at Tarra is considered to be analogous to Awak Mas, but with a more dominant sub-vertical structural control.
The Tarra deposit consists of a single 10 m to 50 m wide, northwest-trending, sub-vertical structurally controlled mineralized zone in the hanging wall of the Tarra Basal Fault. The mineralised zone is tabular and has an overall strike length of approximately 480 m, dips 70° to the northeast and extends to 300 m below the surface with the top of the mineralisation capped by a cover of colluvium.
Gold mineralisation occurs in a 30m silicified zone at the footwall of the fault and along quartz-pyrite filled fractures in the sandstone. Silica-albite-calcite-pyrite alteration is associated with veins, stockworks and zones of the silicified breccias. The Tarra deposits represents a relatively untested opportunity for Mineral Resource growth for the Project.