Thundelarra Limited (ASX:THX) has delivered more high grade, broad widths of copper mineralisation from Red Bore.
The company owns 90% of Red Bore, which is located in Western Australia’s Doolgunna region, less than 1,500 metres from the processing plant at Sandfire Resources (ASX:SFR) operating DeGrussa copper-gold mine
Mineralisation is still open at depth below 94 metres vertical from surface.
Highlights include:
- 21 metres at 5.3% copper, 1.2g/t gold, 7.0g/t silver from 50 metres in hole TRBC077;
- 68 metres at 1.9% copper, 1.0g/t gold, 3.8g/t silver from 26 metres in hole TRBC080, including 7 metres at 5.0% copper, 0.5g/t gold and 10.8g/t silver from 87 metres; and
- 5 metres at 10.4% copper, 0.50g/t gold, 11.0g/t silver from 59 metres in hole TRBC081.
High gold and silver values, include: 14.2g/t, 11.4g/t, 9.8g/t and 7.8g/t of gold; as well as 46.2g/t, 23.3g/t, 18.7g/t and 17.6g/t of silver.
More magnetite and secondary copper mineralisation in hole TRBC087 at Impaler Prospect underpins conceptual model of further “pipes”.
The company said the main area of exploration successes to date, around the Red Bore Gossan, will now simply be called “Gossan” prospect.
The newly discovered area of secondary copper mineralisation associated with magnetite 900 metres west of Gossan will be called “Impaler” prospect.
The geological evidence remains consistent with the model of a deeper-seated source of the primary copper-gold-silver mineralisation.
Each successful deeper drill program adds to this pool of evidence and improves the company’s understanding and confidence in its interpretation.
Planned Future Work:
- Complete program of downhole geophysical surveys, with results of interpretation expected during February.
- Incorporate all data – geological logging and assay data; down-hole geophysical survey data (magnetics, resistivity); low-level airborne magnetic and radiometric survey data – into a revised interpretation of the conceptual mineralisation model.
- Undertake an audio magneto telluric (AMT) survey during February. AMT can deliver information on conductive/resistive contrasts in the underlying rock formations, thereby assisting in the interpretation of folding and structural controls.
This has the potential to contribute significantly to the planning of future drill programs and has the added benefit of better cost efficiencies than other alternatives.
- Prepare Programs of Work for both Red Bore and Curara Well based on analysis of geophysical survey data and, for Red Bore, new geological data from recent drilling.
Plan, commission and conduct relevant Heritage Surveys as required for submission of PoWs to DMP WA for approval.
Drilling Details
The December 2014 follow-up drill program comprised 11 reverse circulation holes for a total advance of 1,432 metres.
Five of the 11 holes were designed to provide further understanding of the geological setting and controls at the Gossan prospect.
This included deeper testing of the two inferred “pipes” already identified. This part of the program was successful in extending the known mineralisation deeper.
The downhole magnetic response combined with anomalous copper values, as noted in hole TRBC078, also supports the model of further “pipes” being present at Gossan and this will be followed up.
At Gossan, TRBC077 successfully intersected primary copper mineralisation well below the base of oxidation.
Designed to follow up the change in direction of the vent / ”pipe” (inferred after hole TRBC070 lost the “pipe” at 34m), this vertical hole intersected significant mineralisation over a 21 metre interval, confirming the interpretation that the “vent / “pipe” had steepened:
- 21m at 5.3% copper, 1.2g/t gold, 7g/t silver from 50 metres including 7 metres at 9.1% copper, 3.4g/t gold, 13.8g/t silver from 50 metres; and 6 metres at 7.2% copper, 0.1g/t gold, 7.2g/t silver from 62 metres.
Downhole survey of this hole should help resolve the continuity and direction of the mineralisation as it trends deeper. Based on all previous observations, the most likely interpretation is that the mineralisation will continue trending in a south-westerly direction.
TRBC081 was drilled south-westerly and has pierced the core of the vent / “pipe” between 59 metres and 64 metres, returning a 5 metre intercept of high grade copper mineralisation within an larger interval of lower, albeit still potentially commercial, average copper grade:
- 5 metres at 10.4% copper, 0.5g/t gold, 11g/t silver from 59 metres; within 24 metres at 2.9% copper, 0.3g/t gold and 3.9g/t silver from 59 metres.
Several narrow mineralised zones have been intersected downhole at 70 metres and 83 metres and these are probably associated with subsequent reverse faulting affecting the main magmatic vent. This new observation further supports the interpretation that the most likely trajectory of the “pipe” / vent is in a south-westerly direction.
TRBC080 targeted at depth the main mineralised zone intersected in TRBDD09.
The hole has successfully intersected primary copper mineralisation of potentially commercial grade for 68 metres between 26 metres and 94 metres, including zones of high grade mineralisation:
- 68 metres at 1.9% copper, 1g/t gold, 3.8g/t silver Ag, from 26 metres; including 3 metres at 12.4% copper, 1.5g/t gold, 14.9g/t silver from 26 metres.
Although the grade of the mineralisation varies along the intersection, the occurrence of several massive magnetite-bearing sections suggest the proximity of the main magmatic vent / “pipe”.
These observations are consistent with a straight drillhole passing close by, and through, an irregular-shaped, twisting “pipe”. Downhole survey should help resolve the position of the main mineralised vent / “pipe” relative to this hole, as well as down dip continuity below 94 metres.
Vertical hole TRBC087 collared north of TRBC064 has intersected strong copper anomalism (with anomalous gold and silver values) associated with magnetite between 35 metres - 58 metres:
- 23 metres at 0.5% copper, 0.1g/t gold, 1.1g/t silver, from 35 metres including 1 metres at 1.1% copper, 0.1g/t gold, 0.8g/t silver from 51 metres.
The weathering profile is much deeper in this area and consequently the geochemical dispersion is wider.
The geological and assay data at Impaler, together with the magnetic signatures, continue to support the theory that mineralised “pipe(s)” similar to Gossan exist here too. Further drilling is required to locate the primary copper source that we believe exists.
Analysis
The results from Red Bore demonstrate the progress Thundelarra has made in following the mineralisation “pipes”.
Today's results put Thundelarra back on track at Red Bore, with drilling bringing good widths and grades. Promisingly, the primary copper mineralisation at Gossan extends to at least 94 metres vertical depth and remains open.
It is also supports the model of a deeper-seated source of the primary copper-gold-silver mineralisation.
Thundelarra is fully funded for 2015 exploration program at Red Bore and Curara Well with $6.45 million in cash as at 31st December 2014 providing more catalysts ahead.
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