Commodities, Features, Gold

The Lachlan Fold Belt: A Legacy of exploration

Legacy Lachlan Fold Belt

Legacy Minerals holds six wholly owned tenements in NSW, but one project in the Lachlan Fold Belt presents the most compelling value-creation opportunity.

The Lachlan Fold Belt is home to Australia’s largest underground gold mine – Newcrest Mining’s 50-million-ounce (Moz) Cadia Ridgeway operation – as well as Evolution Mining’s 15Moz Cowal gold project, and the New South Wales region continues to demonstrate its endowment with recent exploration successes including Alkane Resources’ 5.21-million-ounce Boda gold project.

Legacy Minerals holds one of the largest under-explored tenures in the Lachlan Fold Belt, a foothold it has gradually cultivated since the company’s genesis in 2017.

Seeing significant untapped potential in the region, Legacy’s founders, Christopher Byrne and Thomas Wall, went to work entrepreneurially and built a portfolio before the rush.

“In 2017, there was a lot of open ground, and we’ve acquired all of our projects through pegging licences,” Byrne told Australian Resources & Investment. 

“This involved looking at public, pre-competitive data made available by the Geological Survey of NSW, examining legacy projects and reinterpreting them with a modern-day view.”

In the years since, the Lachlan Fold Belt has become a hive for mineral exploration as companies came to understand the potential of the region. 

“We built up a critical mass in the Lachlan Fold Belt and then saw a rush of exploration in the region, and we were left with a really strong position in the district as a result,” Byrne said.

“That includes spaces out at Cobar, some good porphyry ground in central New South Wales and our most exciting project at the moment, Bauloora, where we’ve essentially pegged a district-scale control over a large epithermal system.”

Legacy Minerals considers Bauloora to be the largest under-explored low-sulphidation epithermal gold system in NSW, which gives the project significant discovery potential.

“Low-sulphidation epithermal mines are operated across the world and make up a significant portion of the gold resource globally,” Byrne said. “What makes these systems so attractive is, if the system is preserved, they’re shallowly emplaced and gold mineralisation is on the surface.

“This can lead to a bulk-tonnage, relatively high-grade system where it can essentially be mined at a very cheap all-in sustaining cost.”

Bauloora epithermal
Legacy Minerals holds one of the largest under-explored exploration tenures in the Lachlan Fold Belt.

Legacy Minerals is advancing an accelerated exploration program to further understand Bauloora.

In early November, the company announced promising geophysical results from Bauloora, where analysis of ASTER (advanced spaceborne thermal emission) data identified nine new ‘lookalike’ hydrothermal alteration anomalies.

These are interpreted to be consistent with known gold-silver bearing low-sulphidation epithermal veins mapped elsewhere at Bauloora.

“This is the first time satellite spectral data has been acquired and interpreted over Bauloora and we are greatly impressed with the results,” Legacy Minerals technical director Thomas Wall said in a press statement.

“Legacy Minerals has employed modern ‘smarter’ exploration techniques across its tenure to screen the whole project systematically for unidentified opportunities and to focus on the key targets, reducing time and expenditure.

“The results from the ASTER data have supported the interpretation of the Bauloora epithermal project’s potential to host significant gold-silver epithermal deposits.”

Other ‘smarter’ exploration techniques conducted at Bauloora include petrographic examination, which has determined the presence of sinter-related lithology over 5.6km of the project.

Sinter is a sedimentary rock primarily composed of silica that is precipitated at or near the surface from hot waters at the vents of hot springs and geysers. The presence of sinter is synonymous with other operating epithermal gold mines.

Identifying sinter preservation, Byrne said, further bolstered Legacy’s confidence in Bauloora.

“This is the first-time petrography has been completed on these prospects and the results, along with the high-grade gold found in previous rock chip sampling, have strongly reinforced our belief that we are sitting on a large, preserved epithermal gold system,” he said.

In early December, Legacy announced its maiden diamond drill campaign at the fancied Mee Mar trend at Bauloora, after securing a drill rig and the relevant approvals.

With 15 diamond drill holes approved by the New South Wales Resources Regulator, Legacy plans to complete an initial six-hole program for approximately 1000m. The campaign is set to begin in January.

Legacy will be following up highly anomalous soil and rock chip sampling across an extensive 2km strike at Mee Mar, with grades up to 55.5 grams per tonne (g/t) gold, 904g/t silver and 1810 parts per million (ppm) antimony.

The company has been exploring Bauloora from various angles to not only expedite the process but also enhance the analysis. Given so much of the tenure is under-tested, there is still so much to discover.

“We’re looking across an area of geochemical gold mineralisation which is about 14 square kilometres, where one drill hole has been completed every 72 hectares,” Byrne said. 

“From more than 100 Bauloora targets, we’re looking to select the best prospects and essentially make them into drill campaigns, targeting areas that haven’t been tested before.”

Byrne said the drill campaigns would then feed Legacy Minerals’ geological work and system modelling to create robust datasets and analysis of Bauloora’s seldom-explored tenure.

“People don’t understand how this district was formed, or understand what happened geologically,” Byrne said. “This is where a new frontier mindset needs to come in.

“We’re trying to balance getting those discovery holes in with building a broader picture of the project, and by early next year we hope to have completed at least one diamond campaign.”

Legacy Minerals is advancing an accelerated exploration program to further understand its Bauloora project.

The expansive nature of epithermal systems, where there is often kilometres of strike and many potential prospects, means Legacy Minerals will need to be discerning about the targets it hits.

But if the success of early geophysical and petrographic analysis is anything to go by, Legacy Minerals has a fascinating journey ahead of it.

“You consider some of the companies that have explored this region – such as Shell, BHP etcetera in the 1980s – and spend the time looking through the old reports, look through their exploration programs, you start to see some pretty glaring holes,” Byrne said.

“There are some pieces of the puzzle they couldn’t find, so you start devising a strategy around where they didn’t look and build it from there.

“We’re picking up rocks in prospects that no one’s been to before. It almost feels like we’re in remote Papua New Guinea, but instead we’re in central New South Wales, 15 minutes outside of a regional town. 

“So we have a pretty amazing opportunity to explore an area which has been tightly held for 40 years.”

Legacy Minerals is completing large-scale soil sampling and reconnaissance rock chip sampling campaigns to accompany its drilling ambitions. The company has also engaged Cobre Nuevo Consulting to complete a third-party report on Bauloora’s exploration potential and strategy.

By the end of 2023, when Legacy hopes to have several drill campaigns under its belt, the company will have an even stronger picture of the burgeoning project. 

This feature appeared in the December issue of Australian Resources & Investment.

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