This little geological body is a forgotten land. Actually, not forgotten but just not talked about so much. A few decades ago this was a much talked about piece of real estate for the mineral exploration industry. In the early 1990s, there were lots of conversation about diamonds. In reality, this is a good place to go hunting for minerals, after all, it is a subduction complex with the suite of forearc basinal, magmatic arc and backarc extensional elements [9].
Where and What is the New England Fold Belt?
The New England Fold Belt (NEFB) sits within the New England Orogen (NEO) which is the youngest and most eastern of the Australian craton. It has a west-dipping subduction which means that they have the typical crustal thickening and thinning coupled with magma activity [4].
Figure 1: (a) Tasmanides of eastern Australia, after [2]. (b) The southern New England Orogen in NSW. Terminology of terranes from [3].(Source: [1])
The portion of the Fold Belt that is of interest to us at the moment is shown in Figure 1. It is the portion that is in New South Wales. Like most of Australia's geological corridors, the NEFB is another that has a history of being endowed in all sorts of metals.
According to [8], the use of high detail geophysics has identified the following:
potential magmatic diamond hosts,
controlling structures for orogenic gold and granite-related polymetallic veins,
unmapped and concealed deep leads,
accurately defining the extent of primary sapphire host rocks,
bauxitic laterites.
The survey was done in the western part of the NEFB but the reality is simple. The southern NEFB is basically a subduction zone that has proven to be producing metals (Figure 1). There is no secret that this area has substantial mineral discoveries. What is interesting for me is how the mineralisation relate to each other.
A Subduction Zone - Good Geology Never Disappoints
Before we go any further into the story, we need to have an appreciation of what is a Subduction Zone and why this is the key component of the Insights. I will not give a detailed description but I need to give some context.
The famous Ring Of Fire (Figure 2) is where we see the biggest and most endowed regions for mineralisation. On 22nd January 2020, I published an article - Copper Porphyry Districts - Chile & Associates - which talked about the mineral potential of deposits that are derived along these subduction margins.
When I talk about the mineral endowment, I am not just talking about the porphyries. Yes, these deposits are world class but I am really talking about the numerous "smaller" deposits that are in plague proportions because of the subduction zones.
Figure 2: The Ring of Fire - The Ring of Fire is a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean. Deep ocean trenches and high mountain ranges are also part of the Ring of Fire. (Source: The National Geographic)
In the western part of the USA you have a swarm of porphyries and volcanogenic massive Sulphide (VMS) mineralisation that is scattered randomly all over the place. This is where the Pacific plate is subducting into the Northern American continent and creating magma activity that is commonly seen in all these pate margins.
The volume of mineralisation is why the western margin of the Americas is swarming with deposits of all sizes. Have a look at this Insight that I published in May 2021:
When I wrote that Insight, I learned so much about the potential of provinces like that which are present all along the margin. So when we proceed with this Insight, think of these margins, think of the potential when we discuss the NEFB as a "miniature plate margin".
Remember, a subducting plate is always going to generate the same type and intensity of magmatic activity.
So Why the New England Fold Belt - The Brewing Pot
There is a lot of work being done in the NEFB and the New England Orogeny. What I have learnt in the long hours of reading is that the potential mineralising nature of the region is still at its infancy. There is no doubt that the rocks are tapping the mantle.
The presence of diamonds tells us that we are tapping the mantle, which makes complete sense as we are in a subduction zone. As you can see in Figure 3B, there is ample evidence of metal formation. The migration of volcanic activity Figure 3A over the subducted plate is clearly observed which supports Figure 3B where you can observe mineral deposition.
Figure 3: (A) Location of dated volcanic sites, northeastern New South Wales (map) with bistograms of older Mesozoic volcanism (190-95Ma, top) and younger Mesozoic-Cainozoic volcanism (95-OMa, bottom). Inset. Australian migration over Coral Sea-Cato Trough thermal rift system, (outer and inner margin lines) showing track positions from 65Ma to OMa, detailing positions at 45Ma and 20Ma relative to the Central Volcanic Province (CP). [10]
(B) . Geological subdivisions and metahydrothermal mineral deposits in the southern New England Fold Belt. [11]
The magmatic activities are key ingredients for all the metal deposit formations and this is very apparent in the research material. According to [5], the massive sulphides at Halls Peak are up to several metres across and up to 3m thick. Metal grades are high, averaging 3.5% Cu, 8% Pb, 24% Zn, 260ppm Ag and 0.42ppm Au. The bodies are associated with broad zones of weakly disseminated and stockwork sulphides in hydrothermally altered volcanics and sediments.
The Halls Peak massive sulphides is compared by [5] as similar to the Kuroko deposit in Japan. The Kuroko-Type deposits are usually accompanied by alteration zones with a distinct zonal arrangement. One of the similarities is the Kuroko type deposits are in the similar age range of deposition and they are in felsic lavas and pyroclastics.
"Largely stratiform Kuroko deposits, stockwork ores and fissure-filling veins are widespread in the so-called Green Tuff basins of Tertiary age in Japan. They are the youngest, least modified examples known of base metal sulfide deposits associated with felsic lavas and pyroclastics, and familiarization with their features should lead to a more detailed appreciation of how and where other deposits of the same general types were formed."
- [12]
The report went on to name the Paleozoic deposits in eastern Australia like Rosebery, Mount Lyell, Captain Flat, Woodlawn, and Mount Morgan.
Why Zinc?
In January 2019, I published a couple of articles related to zinc. I was feeling optimistic about the Zinc market and was struggling to understand why there is no price surge. There was supposed to be a potential supply shortage but the so called imbalance of demand vs. supply was not forthcoming.
The Samso Insights are as follows,
What is interesting is that since that time, there has not been an economical discovery. If I am not mistaken, there have been discoveries but none that have gone to production. It is because of this lack of success that I am still keen on Zinc.
What is a Zinc Discovery - The Earaheedy
In July 2020, I learned about Rumble Resources and their Earaheedy Project and was instantly attracted to the potential. At that time, the company was focused on the Western Queen Gold project. In my previous dealings with associates, I was already a fan of the Earaheedy area. I have learned that the Gascoyne was the place to find a lead-zinc project.
To cut a long story short, I was not able to convince Rumble Resources to share the story on Coffee with Samso and history will show that they have made a good discovery on their Chinook Zn-Pb-Ag-Mn-Cu project.
For one who has declined a Coffee with Samso, it looks like another discovery is on the way in the Kimberley.
Halls Peak Project - Southern New England Fold Belt
This brings us to the Halls Peak project - a very interesting project in an area that is well know for mineralisation. The Halls Peak project is 100% owned by Critical Resources Limited (ASX:CRR) and is located 45km south-east of the town of Armidale.
It is well documented that there are massive sulphides in this area. It sits in the Tasmanides accretionary orogenic system [4]. It has historical workings and was previously mined for zinc. A historical high-grade zinc mine is as good a place to start to look for more zinc.
According to [5], historical workings discovered a series of gossanous outcrops in the halls Creek area. Mining for Cu, Ag, Pb and Zn commenced in 1916 through to the 1970s. The massive sulphide deposits are located 50km SE of Armidale and 500km North of Sydney.
* An extract form Critical Resources Limited noting some highlights of the Halls Peak Project.
One of these massive sulphide location is shown in Figure 4. The area lies towards the eastern edge of the New England plateau on the steep upper slopes of the Chandler River valley.
Figure 4: Halls Peak area, NSW, showing location (inset) and position of mine waste landslide, sulphide stockpile and polluted area, and drainage into Chandler River.[7]
Conclusions
When I set out to write this Insight, I was going to talk about Zinc mineralisation. As I progressed into the researching stage of the Insight, I started to realise that the real story is the New England Fold Belt and that the geological history or understanding of the NEFB is the key.
I have some knowledge of this area due mainly to my previous work in the diamond industry way back in the early1990s. However, my current research has definitely made me think about the mineral exploration potential of the eastern part of Australia.
Limited Working Knowledge
My geological career is very limited to Western Australia and I am now understanding why there are so many explorers on the other side of Australia. The geology is so intense and the potential for discoveries is a surprise for me. I know it should not be as there are numerous discoveries and world class mines on this side of the continent.
My ignorance is largely due to the fact that I have only worked in a limited capacity in a small highly focused industry, and there is little opportunity to work elsewhere. Small companies tend to focus on projects in a do or die program.
Learning about Halls Peak
When I came across the Halls Peak project with Critical Resources Limited (ASX: CRR), I immediately took a liking to the geology and the potential. I did not know much but I was definitely thinking that this is worth some further research.
Exploration at the project has been busy and there have been several announcements updating the ASX on exploration activities:
3rd December 2021: Visual Massive Sulphides Intersected in First Drill Hole
7th December 2021: More Mineralisation and Visual Massive Sulphides at Gibsons
15th December 2021: Massive Sulphides Intersected in Second Drill Hole - Gibsons
21 December 2021: Massive & Disseminated Sulphide Intersection- 4th Drill Hole
7th January 2022: Drilling Recommences at Halls Peak Project
As this Insight is being written, the company has gone into a Trading Halt (10th January 2022) and the anticipation is for further drilling results.
11th January 2022 - Outstanding High Grade Zinc, Copper and Silver Assays
Final Thoughts
Mineral exploration is all about finding a needle in a hay stack. Most investors think that X marks the spot but are often disappointed in reality. At best, all that X marks is a good place to look. It is good to remember that a drill hole is at best 10 inches in diameter (most are not) and you can miss a lot when you are exploring.
Whenever we talk about a prospective place to find minerals, it is always good to know that the place has good genes. A good genetic signature goes a long way. Hence, when I think about what Critical Resources are doing at Halls Peak, it does make me prick up my ears. I would not go so far as to say that I am excited. I will be excited when I see more drilling results that are consistent with the historical grades and intercept depths.
What I like is the evidence of multi metal mineralisation that is consistent with magmatic activity synonymous with a subduction zone. The Hillgrove SB-Au project, which is just north of the area, is a case in point. As you can see in Figure 3B, there are numerous known sites of mineralisation.
From an investor point of view, I like Halls Peak because the historical numbers are very encouraging. I like the regional setting and how the known mineralisation supports the tectonic setting and potential metal endowment. One can never say anything is a sure thing, but this has got good points for a decent DYOR.
Reference:
Manton, Ryan & Buckman, Solomon & Nutman, Allen. (2019). Early Permian strike-slip basin formation and felsic volcanism in the Manning Group, southern New England Orogen, eastern Australia. Australian Journal of Earth Sciences. 66. 1-19. 10.1080/08120099.2019.1566932.
Glen, R. A. (2005). The Tasmanides of eastern Australia. Geological Society, London, Special Publications, 246(1), 23–96. doi:10.1144/ GSL.SP.2005.246.01.02
Flood, P. G., & Aitchison, J. C. (1988). Tectonostratigraphic Terranes of the Southern Part of the New England Orogen. In Flood, P. G., Aitchison, J. C. (Eds.), New England Orogen: Tectonics and metallogenesis (pp. 7–10). Armidale, NSW: University of New England.
McKibbin, Seann J., Landenberger, Bill, and Fanning, c. Mark. 2017. First magmatism in the New England Batholith, Australia: forearc and arc-back-arc components in the Bakers Creek Suite gabbros. Solid Earth, 8, pp421-434.
Ashley and Wolfenden, B.J., 2004. Halls Peak Massive Sulphide Deposits, New England, NSW. CRC LEME.
Murray, C.G. 1987. Tectonic Evolution and Metallogenesus of the New England Fold Belt, Eastern Australia. Pacific Rim Congress
Lottermoser, B.G., Ashley, P.M. and Muller, M. 1995 Environmental geochemistry of the Halls Peak massive sulphide ZnPbCuAg deposits, New South Wales, Australia.
BRown, R.E. 2010. Potential exploration uses of high resolution geophysical data in the southern New England Orogen, NSW. NEO 2010 Conference Proceedings. pp55-61.
Henderson, R.A., Fergusson, C.L., Morand, V.J., Reinhardy, J.J. & Carr, P.F. 1993. Tectonics of the Northern New Fold Belt. NEO 93 Conference Proceedings. pp505-515.
Sutherland, F.L. 1999 Volcanism, Geotherms, Gemstones and Lithosphere, since orogenesis, N.E. New South Wales: A synthesis New England Orogen 1999 Conference. pp355-364.
Stroud, W.J., Barnes, R.G., Brown, R.E., Bronwnlow, J.W. & Henley, H.F. 1999. Some aspects of the metallogenesis of the Southern New England Fold Belt. New England Orogen 1999 Conference. pp365-371.
Lambert, Ian B. & Sato, Takeo. 1974. The Kuroko and Associated Ore Deposits of Japan: A Review of Their Features and Metallogenes. Economic Geology, Vol 69, pp1215-1236
Disclaimer
The information or opinions provided herein do not constitute investment advice, an offer or solicitation to subscribe for, purchase or sell the investment product(s) mentioned herein. It does not take into consideration, nor have any regard to your specific investment objectives, financial situation, risk profile, tax position and particular, or unique needs and constraints. Read full Disclaimer.
About Samso
Samso is a renowned resource among the investment community for keen market analysis and insights into the companies and business trends that matter.