- Sixteen reverse circulation holes drilled for 2,924.3m advance
- Two diamond tails drilled for 168.3m advance
- Gold mineralisation encountered in all new holes
- Significant new intersections at Lydia from this programme:
o 8m at 2.6 gpt Au from 81m in TGGRC087
o 10m at 1.9 gpt Au from 127m in TGGRC087
o 11m at 2.9 gpt Au from 120m in TGGRC096
o 9m at 4.8 gpt Au from 213m in TGGRC097
o 10m at 2.6 gpt Au from 115m in TGGRCDD098
o 4m at 2.9 gpt Au from 131m in TGGRCDD098
o 5m at 3.1 gpt Au from 137m in TGGRC114
- Previously announced significant intersections at Lydia:
o 6m at 2.8 gpt Au from 49m in TGGRC015
o 7m at 24.5 gpt Au from 11m in TGGRC018
o 37m at 1.8 gpt Au from 71m in TGGRC026
o 4m at 3.8 gpt Au from 97m in TGGRC032
o 14m at 2.2 gpt Au from 216m in TGGRC033
o 80m at 1.9 gpt Au from 79m in TGGRC034
o 5m at 3.8 gpt Au from 97m in TGGRC073
o 30m at 3.0 gpt Au from 105m in TGGRC073
o 8m at 2.9 gpt Au from 104m in TGGRC077
All holes intercepted gold mineralisation in both the weathering profile and the underlying primary zone, confirming the presence of an extensive mineralisation system which extends for over 500m strike identified so far and remains open to the north and south and at depth.
Thundelarra began exploring Garden Gully in mid-2016. To date almost 26,000m of drilling has been completed in 141 holes, comprising 23,432m of RC and 2,522.6m of diamond as we aggressively explore the unquestioned potential of the exciting Garden Gully project, located in one of Western Australia's most productive gold provinces. Results continue to support the potential for a major new discovery at Garden Gully.
Details of the holes drilled at Lydia in the latest programme are given in Table 1 (see link below). Drill collar locations and drill traces for each hole are shown in Figure 3 (see link below). Two cross-sections through the median section of the Lydia NW shear zone display the steep, south-westerly plunging mineralised shoots within the main mineralised structure (see Figures 4, 5 in link below).
The infill drilling on this campaign was within the north-western part of the main Lydia shear zone where a dilational jog is present, hosting multiple deep plunging mineralised shoots. Mineralisation is hosted by mafic rocks and is completely concealed by a thin transported overburden. The dominant plunge of the mineralised sulphidic shoots is south/south-westerly and consequently the azimuth of the holes drilled was towards the north-east to maximise the chance of intersections.
The Programme of Work ("POW") submitted and approved was designed to test a possible extension of the mineralisation towards the north-west. The structural data from TGGRCDD098 indicates a plunge and down-dip extension of the mineralisation towards the south-west. Because the approved POW did not contemplate this revised geological understanding, no deep drilling could be undertaken on this campaign and a new POW must be submitted and approved before these newly interpreted extensions can be tested.
Two of the RC holes were completed with diamond tails, designed to determine the structural setting controlling the mineralisation. TGGRCDD098 was sited behind TGGRC073 and was cored from 80.0m to 147.8m (total: 67.8m). TGGRCDD116 was sited behind TGGRC115 and was cored from 113.3m to 213.8m (total: 100.5m).
Both TGGRC087 and 088 have intersected two mineralised shoots consisting of silica-arsenopyrite alteration (see Figure 4 in link below). TGGRC089 also intersected two deep shoots within the main shear zone and indicates a clear south-westerly plunge of these mineralised shoots. These deep primary shoots occur below 182m in this hole, while in hole TGGRC091 (collared about 100m to the north) the mineralisation was intercepted at a much shallower depth; from 124m (see Table 2 in link below).
TGGRC092 was drilled over the inferred shear and only narrow gold intersections were recorded between 118-122m, including 1m at 2.42 gpt Au from 118m. TGGRC093 intersected narrow mineralised veins within the weathering profile of the shear zone and has just touched a mineralised shoot at 124m. TGGRC094 hit a deep mineralised shoot below 228m.
TGGRC097 intersected a higher grade interval within the mineralised shoot which was encountered below 213m (9m at 4.8 gpt Au, including 3m at 11.6 gpt Au from 214m (see Figure 5 in link below).
Based on the results of this and previous drilling campaigns, the geology at Lydia essentially consists of a massive dolerite with localised sheared / foliated zones. In these shear zones, strongly foliated dolerite is better described as mafic schists. The transition from the massive undeformed dolerite to the mafic schist is gradual. An intrusive unit with porphyritic textures has also been intersected in the shear and is foliated. Its origin is uncertain but initial interpretation is that it could be of lamprophyric or syenitic origin.
Structural interpretation, particularly from the core from TGGRCDD001 and TGGRCDD098, has identified three main deformation events. D1 is interpreted as responsible for the main schistosity S1 of the mafic schists. D2 (E-W compression) has folded and rotated S1 along a moderate to steep south-west fold axis. S2 schistosity is locally observed crenulating S1 near the gold mineralisation. Generally the strike of S2 ranges from 3500 N to 0400 N and dips moderately to steeply to the west. It is the mains shear zone orientation. D3 (NE/SW compression) is responsible for the rotation of the F2 folds.
The mineralisation controls appear structural rather than rheological, with gold mineralisation associated with arsenopyrite in quartz-sericite-sulphide vein systems. The zones of highly mineralised veining are constrained within S2 shear zones, striking to the NNE and steeply dipping to the WNW. The mineralised shoots follow the S1/S2 lineation, typically plunging at about 700 to the SSW. At vein scale, two main mineralisation styles are observed:
- Laminated orogenic-type stringers with fine grain gold-bearing arsenopyrite associated with the S1 schistosity;
- Gold-bearing arsenopyrite and pyrrhotite in silicified and sericitised quartz vein selvages. Sulphides are following S2 foliation and are more concentrated (and thus higher grade) in the multiple fold hinges.
The vein systems hosting the gold mineralisation are still open at depth and along strike.
The next phase of work will involve stepping collars back to the south-west along the extent of the shear zone to drill deeper towards the north-east to test for extensions and continuity beneath the mineralisation discovered to date, and also to test for further repetitions of the stacked shoots. Infill holes will also be drilled, potentially at 25m spacing, as a basis for an initial resource calculation.
About Garden Gully.
Thundelarra's wholly-owned Garden Gully project comprises 15 granted Prospecting Licences and 2 granted Exploration Licences covering about 78 square kilometres, located in Western Australia's Murchison region about 20 kilometres north-west of the town of Meekatharra.
Thundelarra began exploration at Garden Gully in mid-2016 and continues to explore the project aggressively. To date almost 26,000m of drilling has been completed in 141 holes, comprising 23,432m of RC and 2,522.6m of diamond as we test the unquestioned potential of the exciting Garden Gully project, located in one of Western Australia's most productive gold provinces.
To view tables and figures, please visit:
About Thundelarra Ltd
Thundelarra Ltd (ASX:THX) is primarily an Australian gold exploration company. Gold, either in stand-alone geological settings or in association with copper, is our principal target. Copper remains an important focus too. Our portfolio also boasts prospects with discovery potential for base metal (nickel, zinc, silver, lead), uranium and graphite mineralisation. We are active in Western Australia (WA) and the Northern Territory (NT).
ContactMr Tony Lofthouse
Chief Executive Officer