- Ten reverse circulation ("RC") holes drilled for 2,943m advance
- Eight diamond ("DD") holes (five tails) drilled for 1,592m advance
- New significant intersections at Crown Prince (downhole widths):
o 3.5m at 7.6 gpt Au from 109m in TGGRC086
o 2.6m at 7.5 gpt Au from 130m in TGGDD090
o 4.0m at 16.5 gpt Au from 166m in TGGRC103
o 3.8m at 3.5 gpt Au from 220m in TGGRCDD108
- Previously announced intersections from TGGRCDD110:
o 2.40m at 66.5 gpt Au from 263.4m; within
o 5.65m at 29.2 gpt Au from 260.8m; within
o 8.00m at 22.3 gpt Au from 259.2m downhole
Visible free gold next to fresh sulphide (arsenopyrite) in quartz-carbonate veining from 263.80m down hole TGGRCDD110. Scale bar at top is in millimetres. ASX announcements dated 15 November and 12 December 2017 present full details.
Gold mineralisation was intersected in 11 of the 18 holes drilled: an excellent result for a first programme. Results proved at least 130m vertical down dip / plunge extension to the Crown Prince Main Lode, which remains open. Next programmes will work towards delivering maiden resources at both the Crown Prince and the Lydia prospects.
Results from over 26,000m drilled in 141 holes (23,556m RC; 2,523m DD) since mid-2016 continue to support the potential for a major new gold discovery at Garden Gully, located in one of Western Australia's most productive gold provinces.
Details of the holes drilled at Crown Prince in the latest programme (collar locations and drill traces for each hole) can be found in Table 1 and Figure 3 (see link below).
The inaugural exploration drilling programme at the Crown Prince prospect, part of Thundelarra's Garden Gully Project, comprised 4,534.7m total advance from 18 holes: 2,942.7m advance in 15 RC holes, of which five were pre-collars finished with diamond tails; and 1,592.0m advance in the eight DD holes. Six of the RC holes had to be abandoned before reaching the target zones due to difficult ground conditions (see Table 1, Figure 3 in link below).
Significant intersections are summarised in Table 2 and a cross-section (see A-A' on Figure 3 in link below) through the Main Lode is presented in Figure 4. Figure 15 shows a further cross-section (see B-B' on Figure 3 in link below) and Figure 14 (see link below) provides a conceptual model showing interpreted positions of inferred down dip/plunge extensions of the Main and Northern Lodes, based on 3-D modelling of drilling data to date. These Main and Northern Lodes are interpreted as potentially dismantled elements of the same folded lode that plunges steeply to the south-west.
Previous RAB drilling had identified a strong arsenic anomaly about 150m south-west of the main shaft, within an area now called Crown Prince South (see Figure 3 in link below). Four holes (TGGRC104, 106, 117 and TGGDD125) were drilled in different directions from the same pad to target the anomaly, with TGGDD125 also designed to intercept the east-west trending magnetic anomaly in the area. Minor gold mineralisation was encountered in two holes, warranting further investigation.
Holes TGGDD086 and TGGDD090 were planned to test the validity and reliability of historical intersections reported by previous explorers / miners and to gain structural information about the geometry of the Main Lode and the mineralisation system present at depth beneath the old workings of the historical Kyarra Gold Mine. Maximum recorded vertical depth of the underground development is about 120m from surface. It is not clear if ore was being mined from the bottom of these workings, or if development ceased due to water ingress exceeding pumping capacity, or if the miners lost the lode.
A main objective of this programme was to test the possibility that the Main Lode might continue plunging deeply to the south-west to significant depths beyond the extent of the old workings.
TGGDD086 was drilled north-easterly to test the Main Lode and its structural setting. The hole intersected the remaining unmined / hanging-wall portion of the lode and penetrated unmapped old workings between 112.5-119m. Recovered core included remnants of wood from old beams used as supports in the mine development (see Figure 5 in link below).
Assay results from the left selvage of the Main Lode above the stope returned 3.5m at 7.6 g/t Au from 109m-112.5m (see Table 2 in link below).
TGGDDC090 was drilled at a higher angle to test down-dip of the Main Lode and intersected it successfully just below the base of the historical workings. Samples from 129m -136.1m assayed 7.1m at 3.4 g/t Au. The gold is associated with high silver content (see Appendix 1 in link below) with silver appearing to be associated with late-stage galena veins cross-cutting the arsenopyrite (see Figure 6 in link below).
Gold inclusions within euhedral arsenopyrite crystals were observed at 135.02m (see Figure 7 in link below).
TGGRCDD099 targeted the mineralised structure down-dip and from a different angle and intersected two main mineralised zones (see Figure 2 in link below). The upper one was intersected within the weathering profile and returned low grade gold between 47m-52m (5.0m at 1.0 g/t Au) and between 55m-60.9m (5.9m at 1.4 g/t Au). The Main Lode was intersected from 151.1m-160.5m and assayed 9.4m at 2.8 g/t Au.
The decision was made to step back and drill some deep RC holes to speed up the process. TGGRC103 was drilled behind the first three holes and the interpreted position of the Main Lode mineralisation was successfully intersected down-dip to the west. Two significant zones were intersected: a healthy high-grade one of 6m at 11.2 g/t Au from 166m-172m downhole; and a wide zone of lower overall grade but with a higher grade core: 10m at 2.6 g/t Au from 185m-195m within the broader zone of 28m at 1.4 g/t Au from 181m-209m.
TGGRCDD110 was designed to intersect the interpreted position of the Main Lode still further down dip/plunge and successfully delivered on that objective. Six occurrences of visible free gold were observed on the drill core surface at 259.30m; 261.45m; 263.80m; 264.10m; 264.70m; and 264.80m downhole (see Figures 8-13 in link below). Assays confirmed the high tenor of the mineralisation:
o 2.40m at 66.5 gpt Au from 263.40m; within
o 5.65m at 29.2 gpt Au from 260.80m; within
o 8.00m at 22.3 gpt Au from 259.20m downhole.
Full details of these results were announced to the ASX on 12 December 2017.
The presence of the Main Lode at 260m downhole (about 245m vertical depth) represents a down dip / plunge extension of about 130m below the recorded base of the historical workings and the system remains open at depth, with several splays and multiple alteration zones present, which indicate different phases of mineralisation and reactivation zones.
It is significant that the high-grade interval is hosted within vuggy quartz-carbonate veins with low arsenic content which suggests a late phase of mineralisation along the same structural pathways.
Disseminated arsenopyrite with pyrite, pyrrhotite and chalcopyrite are present at depth and breccia zones with narrow high-strain structures occur. Alteration increases with depth and there are indications of the presence of a stockwork system, which is indicative of real potential for a larger system to exist beneath the old mine. Such features are present in TGGRCDD118 where remnants of tourmaline were identified. This hole, designed to test the south-western down-dip extension of the Main Lode, deviated significantly up and to the right and consequently failed to reach the intended target zone. The hole ended up following the hanging wall of the Main Lode and intersected wide-spread low-grade gold mineralisation. Petrology indicates the presence of potassic-boron metasomatism at depth which is associated with silica-carbonate-sericite-arsenopyrite-pyrite-pyrrhotite-chalcopyrite-sphalerite and magnetite alteration. Deep diamond drilling is required to test at depth the south-western plunge of the inferred mineralised body and the development of the mineralised system (see Figure 14 in link below).
TGGRCDD108 was drilled northerly under the main shaft and intersected wide spread gold mineralisation below 211m (including 3.8m at 3.5 g/t Au from 219.8m-223.6m) above the strongly deformed ultramafic unit which appears to be the only marker horizon in the whole lithological sequence and also the footwall of the main mineralised ore body. This is consistent with the chemical characteristics of ultramafics which act as a good reductant to drop gold out of any mineralising fluids. Consequently any mapped ultramafics in the project area will be a significant target for future follow-up exploration.
TGGRC111 was designed to test the down dip extension of the Northern Lode (see Figures 14, 15 in link below). It intersected mineralisation below 210m (9m at 1.2 g/t Au from 210m-219m) but failed to reach the footwall ultramafic due high water flow adversely affecting sample recovery and consequently was abandoned. It is worth noting that the high-grade gold intersected in the historical holes within the weathering profile is the surface expression of the Main Lode dipping south to south-westerly and intersected approximately 40m south by the holes drilled within the A-A' cross section (see Figure 4 in link below).
TGGRCDD129 was drilled northerly aiming to test for the western extension of the Main Lode, but no mineralisation was encountered and the ultramafic unit was intercepted at around 270m depth. It appears that the ultramafic footwall sill turns north-westerly close to the Garden Gully drainage and forms a sharp bend, creating the locus for the main mineralised body with a steep south-westerly plunge. Re-assessment of the geometry based on this interpretation warrants follow-up drilling to test the possibility of extensions in a different position to that originally tested.
This first drilling programme at Crown Prince has delivered outstanding results, especially given that Thundelarra's exploration of the prospect only began about four months ago. Demonstration of the down dip/plunge extension of the Main Lode at least 130m vertically below the lowest level of previous workings, plus the presence of free gold within high grade sections at depth, augurs well for future programmes and for the potential that commercial mineralisation exists. Furthermore, the discovery of geological indications that a stockwork system may be present at depth significantly enhances the potential of the prospect.
The results of our first programme at Crown Prince are very exciting: they wholly validate our aggressive exploration approach, fully justifying our pursuit of the Crown Prince tenement. The next phases of work will have two-fold objectives:
1) to continue to test for down-dip / plunge extensions, and possible repetitions, to both the Main and the Northern Lodes; and
2) to compile sufficient drilling data to allow the calculation of a maiden resource.
Thundelarra began exploration at Garden Gully in mid-2016 and continues to explore the project aggressively. To date over 26,000m of drilling has been completed in 141 holes, comprising 23,556m 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.
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.
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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