The key to reinvigorating the Tennant Creek Mineral Field (TCMF) is the application of new concepts and importantly new technologies.
It can be seen in the following chart that discovery (and subsequent production) of new deposits is strongly tied to the application of new concepts and technology. Historically this was magnetic geophysics – bonanza discovery and production rates followed the BMR aeromagnetic survey in 1955, then reactivation of the near mine (brownfield exploration) combined with the more detailed AGSO survey in 1987 delivered another generation of gold and copper mines.
Historical Production of Tennant Creek Mineral Field
(New Technology Drives Discovery)
Emmerson’s strong belief is that the decline in discovery rates (and corresponding production) does not reflect metal depletion across the TCMF; rather it is a direct consequence of the lack and application of fresh concepts and technologies. Therefore Emmerson’s exploration approach is to maximize the probability of success through the application of those concepts and corresponding prediction and detection technologies most appropriate to the deposit types.
Emmerson is one of the first companies to apply new proprietary exploration techniques within the highly prospective Tennant Creek Mineral Field (TCMF) following the consolidation of a dominant tenement position covering approximately 2,200km2.
The application of ERM’s exploration approach continues to be underpinned by an ongoing investment in new geophysical data and state-of–the-art processing technology, coupled with new geological concepts which are applicable to exploring beneath the cover and unlocking the next generation of gold-copper deposits.
Mineralisation in the Tennant Creek Mineral Field
The gold-copper-bismuth mineralisation of the TCMF is predominantly hosted in magnetite-chlorite-hematite ironstones or sheared variants. The ironstones and mineralisation are localised in EW to WNW trending structures that have historically been referred to as “lines of lode”. These ironstones and mineralisation are discordant to the folded Warramunga Formation rocks and tend to be located in structural flexures, near the hinge zones of the fold axes.
Mineralisation occurs in small-to-medium sized lenses within sheared ironstone. Based on historical data, some of the historic deposits averaged life of mine grades of 15-20g/t gold and 2-4% copper. Examples include the classic Juno and Nobles Knob deposits with grades in excess of 50-60g/t gold.
These deposits are considered to be highly valuable exploration targets and now utilising modern exploration techniques, Emmerson has been successful in discovering copper and gold mineralisation at Goanna and Monitor in late 2011, the first discoveries in the TCMF for over a decade.
To date, Emmerson has only covered 5.5% of the total tenement package (in area) with these innovative exploration techniques and is confident that, with further exploration, more such discoveries will be made.
The TCMF is no different to other IOCG provinces, in that the metal assemblages and concentrations vary from deposit to deposit. Some deposits, such as Nobles Nob, Juno and White Devil are predominantly gold systems; Warrego is a gold-copper-bismuth deposit; while Peko and Gecko are copper-gold deposits.
Some primary deposits in the TCMF are hosted predominantly in magnetite ironstones (e.g. White Devil); others are mixed hematite-magnetite (Chariot) or hematite-dominant (Edna Beryl, Malbec West and Eldorado). Shear zone-hosted gold-copper mineralisation outside of the ironstones, further indicates the diversity of mineralisation styles present in the district. The recently discovered Goanna mineralisation within the Gecko shear zone is a recent example of this mineralisation style.
The sulphide content of these primary deposits rarely exceeds 10% and common ore minerals include chalcopyrite, native gold, cobaltite and bismuthinite. The gold-dominant oxide and primary ores are generally free-milling, which can result in high recoveries (up to 98%) being achieved.
Oxidation extends up to 120 metres below the surface and, within the ironstones, results in a hematite-goethite-quartz-clay assemblage. The copper mineralisation is typically leached and depleted while the gold mineralisation can be spectacularly upgraded.
As outlined in the strategy, our exploration approach is multi faceted and aims to integrate some new concepts (as applied to the TCMF deposits) with technology most appropriate to IOCG deposit types. At the highest level this includes establishing better prediction methodologies, such as vectors to the mineralisation through enhancing our understanding of the structural and alteration systems and vein paragenesis of the known mineralisation.
These prediction methodologies are coupled with the appropriate detection tools and applied in a systematic manner across the entire Emmerson tenement package.
Emmerson’s twofold strategy is being pursued in parallel and consists of:
- Building quality gold and copper resources through near mine and brownfield exploration, ahead of commencing production from the Company’s 100% owned CIP mill (the Warrego Mill); and
- Discovering new deposits utilising the Company’s proprietary exploration approach. There remains excellent potential to continue and accelerate Emmerson’s discovery track record as only 8% of historic drilling has penetrated below 150m, with only a small portion of the Company’s tenements systematically explored.
Strategy 1 has so far delivered the recently announced (28 November 2013) resource of 900,000 JORC compliant gold equivalent ozs. In addition, Emmerson is confident that further near mine and brownfields exploration will continue to add to this already substantial JORC resource.
Application of New Technologies to the TCMF
Initial work undertaken by ERM in 2010 suggested that there is a large contrast between the barren host rocks and those associated with mineralisation – in the case of the copper rich (and sulphide rich) deposits such as Gecko, this can be up to 80 times the background.
Fortunately this work coincided with the commercialisation of the world’s most powerful airborne time-domain electromagnetic system – HeliTEM.
This technique has the potential to screen large areas quickly and effectively and under ideal conditions is likely see down 500 metres below the ground surface.
In 2011 Emmerson trialled this technology in four small tenement areas designed to directly focus Emmerson on mineralised Tier 1 targets, particularly the sulphide rich targets such as Gecko and Peko styles. The possibility of discovering a new style of sulphide rich, copper-gold deposits not directly associated with ironstones (which have responsible for all historical production in the TCMF) but have been missed by previous exploration techniques was also a key consideration and was validated late in 2011 with the discovery of the Monitor and Goanna mineralisation (below) within a well explored brownfield camp.
Less than 6% of ERM’s tenement package has been explored using HeliTEM technology.
Emmerson Resources Tenement Package
The Tennant Creek Mineral Field is situated approximately 500km North of Alice Springs on the Stuart Highway, the main road link between Adelaide and Darwin. The town of Tennant Creek is approximately 1,000 km south of Darwin and 24 km south of the intersection of the Stuart and Barkly highways, the latter being the main road link with Mt Isa.
Important infrastructure running through Tennant Creek includes the Adelaide-Darwin railway and gas pipeline. Tennant Creek has a population of approximately 3,500 and is the main service centre of the Barkly Tablelands region.
The tenement package is geographically divided into four quadrants, each containing numerous exploration targets. Tenure is made up of Exploration Licences, Applications and Mining Leases and Claims governed by the Northern Territory Government.
Emmerson Resources Tenement Position
Emmerson Resources Business Model
In order to maximise shareholder value, Emmerson Resources have implemented a “business framework” that aims to optimise and actively manage our project pipeline where the exploration funds are always directed toward the best opportunities and that the funding is commensurate with the quality of the opportunity.