The latest assays and geophysics at Pinjin have heavily bolstered the project’s multi-million ounce potential, as Kalgoorlie Gold Mining (ASX: KAL) gears up for its most extensive drilling campaign to date, which will test a litany of high priority targets in a regionally well understood mineralisation structure. A total of 50 RC holes for 6,200m and 4 diamond drill holes for 1,070m are set to commence imminently, in a high-yielding exploration program that has the potential to lay a solid foundation for adding serious size to Pinjin’s resource. Our initial take on KAL can be read here.
Inside of a 6km long mineralised corridor, KAL now has 1,450m of strike at Lighthorse, with gold mineralisation and anomalism that is too extensive to be the result of a single small deposit. This is especially interesting when compared to the 1.8km strike of the same structure that holds the 960koz main zone of Ramelius Resources’ (ASX: RMS) Rebecca Project, just 22km away.
KAL deployed a Sub-Audio Magnetics (SAM) geophysical survey across 9.5km2 of Pinjin, which excitingly showed extensive elevated conductivity at both known gold distribution zones – such as the 76.4koz at Kirgella Gift and Providence, as well as Lighthorse – but also at other areas of gold anomalism such as Kirgella West, T12 and T15. This not only allows precise refinement of drill targets, but importantly – significantly increases the chances of KAL continuing to hit primary orogenic gold mineralisation. There’s still more value to be extracted from the dataset, including geophysical inversion modelling to define drill targets in 3D space, which KAL will commence shortly.
The 99 hole, 4,710m aircore drilling results released in July proved that the program achieved exactly what it was designed for – detect widespread, anomalous gold mineralisation, increase the strike length at Lighthorse, and confirm the same structure seen during earlier drilling at the prospect.
Using a 0.1 g/t Au cut-off grade is typical for reconnaissance exploration programmes of this kind, and is what has been used across many great Australian gold discoveries. This is true all the way from the 1.4Moz Rebecca deposit, to the 10Moz Gruyere gold mine, and the 13.6Moz Hemi deposit.
Before the previous Rebecca owner Apollo Consolidated (ASX: AOP) was acquired by RMS for a $146 million enterprise value, they recorded outstanding assays of 42m at 7.75g/t Au from 61m and 17.84m at 15.95g/t Au from 142m – literally right below historical aircore intercepts of 4m at 0.56g/t Au from 20m, 3m at 0.34g/t Au from 20m and 1m at 0.30g/t Au from 20m.
While KAL stunned the market earlier in the year upon the discovery of supergene-enhanced gold mineralisation at Lighthorse, recording 17m at 4.81 g/t Au from 48 m, including 8m at 9.21 g/t Au from 52m, the latest aircore results of 15m at 0.41g/t Au from 36m and 25m at 0.21g/t Au from 28m are crucial indicators of widespread mineralisation that significantly increases the potential scale of the mineralisation system at Lighthorse – which is now similar in size to Rebecca.
The 6km long mineralised corridor that KAL has defined at Pinjin also bears extensive pathfinder elements such as arsenic and antimony enrichment, which in addition to gold anomalism – strongly indicates the potential for numerous significant gold deposits. Overall, these results firmly support KAL’s exploration model of a multi-deposit gold camp at Pinjin, further validating the strategy of wide-spaced drilling under cover.
With $3.8 million in cash, gold trading at US$3,410/oz, and being just 37km from Northern Star’s Carosue Dam mine that is operating at 73.5% capacity, it is the perfect time for KAL to be putting RC holes underneath every single aircore intercept that has recorded significant gold – especially the ones that have ended mineralisation. Part of the planned 40 hole, 4,750m RC program at Lighthorse can be seen below, which will follow the regionally proven strategy of targeting higher grades at depth, below lower-grade anomalous aircore assays near surface:
Source: KAL
Tracing Anomalous Aircore Mineralisation is the Key to Finding High-Grade Gold
When AOP was exploring the Rebecca project back in 2012, they quickly realised that there was almost always no significant mineralisation in the weathered profile – but there was strong potential for high grades below. The anomalous gold containing oxide zones were found by Aberfoyle Resources in the 1990’s, during a period of broad-based exploration for a variety of commodities across a whole litany of projects throughout WA, NT, SA, NSW, Tasmania and Indonesia.
Aberfoyle used aircore and RAB to punch through the transported cover at surface, which was up to 30m, and the oxide layer beneath, up to another 30m for a total of 60m, and were able to trace relatively consistent anomalous gold above 0.1g/t over the full strike length.
When the company didn’t hit exciting grades or sulphides, they moved on – leaving behind precious data for future explorers such as AOP and KAL. An AFR article from 1996 titled “Aberfoyle Has Cash But Not Much Time” characterises this intense period of resources M&A where the ASX was crawling with predators, and companies were desperate for significant discoveries and major acquisitions.
AOP came in and formed a solid understanding of how to trace the shallow aircore hits, as well as the RC drill holes below that contained anomalous gold because they had clipped the outskirts of primary mineralisation. A cross section of one part of Rebecca’s Jennifer Lode, which shows region-typical transported cover on top of an oxide layer, and anomalous gold as low as 0.20g/t right outside an intercept of 50m at 4.05g/t Au, can be seen below:
Source: AOP
The widely spaced aircore intercepts from KAL’s recent campaign can be seen below, combined with previously released intercepts and overlaid with gold-intensity contours that have been derived from geophysics:
Source: KAL
A Geophysical Pattern Excitingly Reminiscent of Mineralisation
SAM geophysics has a solid history of being successfully used by major gold miners and explorers to discover gold mineralisation beneath cover, and is often very accurate down to depths of 100m. The high resolution Total Magnetic Intensity (TMI) and Magnetometric Conductivity (MMC) datasets bode well for KAL’s exploration model.
Further North-East past Pinjin, SAM has been applied to much of the gigantic 9.5Mtpa, 10Moz Tropicana Gold Mine – significantly enhancing the discovery and aggressive exploration of the project.
MMC is extremely sensitive to conductive structures and alteration halos, with high readings typically correlating with sulphide accumulations related to gold. While conductivity highs can be intrinsically related to host rock type, such as sheared ultramafic rocks, they can also be attributed to structural features like shear zones, and hydrothermal alteration zones, such as sericite alteration associated with gold mineralisation.
SAM has specific utility for mapping shear zones and sulphides tied to orogenic gold under cover, which is exactly what Pinjin hosts. Work continues processing and interpreting the datasets generated by KAL, aiming to define new high-quality targets – and the initial results from the survey can be seen below on the left, compared to previously published gold distributions on the right:
Source: KAL
As KAL gets ready to launch a widespread RC drilling campaign that will examine the areas of highest prospectivity at Pinjin, they also have the WA Government putting in $130k for four diamond drill holes that will test a conceptual high grade structural intersection exploration target at depth between the Kirgella Gift and Providence – which makes for an exciting few months of newsflow ahead.
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Disclaimer: This article is for informational and marketing purposes only, and does not constitute financial advice or a recommendation to invest. All opinions expressed are our own. We may receive fees or other forms of compensation in connection with the publication of this content, and may own shares in any of the mentioned companies. Please do your own research and seek professional advice before making any investment decisions.