Jan 21 2011
Robert Friedland, Chairman, and Peter Reeve, Chief Executive Officer of Ivanhoe Australia Limited (TSX:IVA)(ASX:IVA) announced today that new drill intersections have identified a zone of strong copper-gold mineralisation on the Houdini prospect in northwestern Queensland.
The new intersections indicate that this zone extends at least 200 metres down-dip of the initial Houdini intercept from drilling conducted in 2008 by Barrick, the former holder of the tenements that were acquired by Ivanhoe Australia as part of the Osborne transaction in 2010. Houdini is located 20 kilometres northwest of the Osborne mine complex.
"Houdini was an important part of the Osborne acquisition and these drill results confirm Ivanhoe Australia's continuing belief that the relatively underexplored Osborne tenements hold strong potential for discoveries that will extend the company's known resources," Mr. Reeve said.
Intercepts from the diamond drilling include:
- HOD0036 – 6 metres @ 5.07% copper and 0.23 g/t gold from 144 metres;
- HOD0037A – 23 metres @ 1.51% copper and 0.25 g/t gold from 239 metres;
- HOD0038A – 12.5 metres @ 1.95% copper and 0.31 g/t gold from 353.5 metres.
"Part of the significance of these initial Houdini results for Ivanhoe Australia is that they are only the first fence of step-out drilling on the system, which is shallow, open at depth and open along strike," Mr. Reeve said.
"We will be drilling additional fences north and south of these latest intercepts, where the system remains untested. Houdini is located adjacent to the Osborne-Mount Dore Access Road, providing convenient access to the Osborne mine complex where material could be processed following definition of a resource."
The best intercept previously reported under Barrick ownership was 16 metres @ 3.0% copper and 0.58 grams of gold per tonne from 70 metres. Ivanhoe Australia began follow-up drilling immediately following its acquisition of the Osborne assets to explore the 500-metre conductivity anomaly at depth.
The Houdini prospect was first explored during the early 1990s when exploration initially focused on Starra and Osborne-style targets. Several prominent linear magnetic anomalies were drilled with no significant results; during the next 20 years, exploration focused on drilling broad-spaced air-core holes to define geochemical patterns beneath the Mesozoic Cover.
Several basement copper anomalies were identified; some associated with minor magnetic highs were drilled, with no significant copper results. A major linear anomaly of 200 to 1000 parts per million (ppm) copper was identified 200 metres east of these magnetic anomalies but was never drilled.
A sub-audio magnetics survey was completed to identify conductivity anomalies associated with the magnetic anomalies. This survey showed a linear conductivity anomaly associated with the linear copper anomaly which was named the Houdini anomaly. At 1000 ppm copper, the anomaly is 500 metres long; however, it extends to 1,000 metres at lower-grade anomalous thresholds.
Drilling on this anomaly by Barrick in 2009 included the following significant results:
- HORC00039 - 41 metres @ 1.4% copper from 120 metres
Incl - 16 metres @ 3.0% copper
- HORC00038 - 63 metres @ 0.75% copper from 94 metres
Incl - 8 metres @ 1.58% copper
- HORC00040 - 25 metres @ 0.25% copper from 60 metres
Following the settlement of the Osborne purchase, Ivanhoe Australia completed three pre-collared diamond-drill holes on one section in late October 2010. Pre-collars for an additional six diamond drill holes were drilled 100 metres north and south of the completed drill section. Heavy rains at the start of the wet season has presently halted further drilling.
This drilling returned the following significant widths and grades of copper and gold:
- HOD0036 - 6 metres @ 5.07% Cu and 0.23g/t Au from 144 metres
- HOD0037A - 14 metres @ 0.68% Cu and 0.10g/t Au from 123 metres
Incl - 4 metres @ 1.55% Cu and 0.28g/t Au from 133 metres
and - 23 metres @ 1.51% Cu and 0.25g/t Au from 239 metres
- HOD0038A - 26 metres @ 1.15% Cu and 0.17g/t Au from 340 metres
Incl - 12.5 metres @ 1.95% Cu and 0.31g/t Au from 353.5 metres
Incl - 2.2 metres @ 3.47% Cu and 0.47g/t Au from 353.8 metres
The copper and gold mineralisation occurs as chalcopyrite within a carbonate breccia, dominantly on the footwall of the fault. Within the fault, the main copper-bearing mineral is chalcocite, with minor bornite and chalcopyrite.
The grade across the mineralised zone appears to be uniform, with a true width between 10 and 15 metres. Below the supergene enrichment zone mineralisation also appears to be consistent between holes (HOD0037A and HOD0038A. The fault zone is hosted within a package of amphibolite between biotite and muscovite schist.
A significant feature of the Houdini mineralisation is its association with a north-south striking fault zone that is interpreted to be a splay off the southern extension of the Mount Dore fault zone. A recent large scale SAM survey mapped this structure over a 15-kilometre strike length providing the potential for extensions or repeats of the Houdini mineralisation.
Three drilling rigs will continue drilling 100-metre-spaced sections north and south of the current section as soon as the current wet season ends. Infill drilling will be initiated when a 500-metre strike length of mineralisation is drilled and further drilling will continue along both the 15-kilometre strike of the main fault and also down dip these new intercepts. Down-hole EM is planned for the deeper holes to help target down-dip extensions. A significant top-of-basement air-core program is planned north and south of the previous air-core patterns on targets selected with results of the recent extensive SAM survey. The survey highlighted the position of the Mount Dore fault zone and numerous splays.
Source: Ivanhoe Australia Limited