Great Boulder defines new targets at Ironbark using sub-audio magnetics

Great Boulder Resources (ASX:GBR) has defined multiple new targets through a sub-audio magnetics (SAM) survey at the Ironbark deposit, within the Side Well Gold Project in Western Australia.

The $39.83 million market capitalisation company says the SAM survey was completed over a 2.2km area centred on the Ironbark deposit, which produced high-resolution images of conductivity and magnetic susceptibility in the regolith and bedrock. 

This is intended to provide further context to the position of mineralisation at Ironbark and generate new targets by extrapolation. It’s the first time Great Boulder has used SAM at Side Well.

Great Boulder reports the gold mineralisation at Ironbark occurs within a relatively resistive zone, which may be associated with silica alteration during the mineralising event. 

A conductive zone interpreted to represent a sheared contact is located proximal to the deposits’ mineralisation. This shear zone is traceable north of Ironbark where it is offset to the east, and to the south where it flexes to a southerly easterly strike. 

The company notes there may be potential for further mineralisation in the offset zone to the north. The company is planning an aircore (AC) drilling program to test this new ‘high priority’ target area. 

“This survey is the first time we’ve used SAM at Side Well. It’s given us a lot of useful data as well as a couple of immediate targets close to Ironbark”

Commenting on the new targets, Great Boulder Resources Managing Director Andrew Paterson says: “This survey is the first time we’ve used SAM at Side Well. It’s given us a lot of useful data as well as a couple of immediate targets close to Ironbark. 

The conductivity data shows Ironbark mineralisation sits in a resistive zone adjacent to a linear conductor which is probably a shear zone. The images also confirm our theory that Ironbark is offset to the north by a cross-cutting fault, with potential for strike extensions to the northeast.

Secondly, we have identified an unexplained and untested conductor northeast of Ironbark that may be caused by sulphides. We plan to test that with a small AC program in the near future. 

The data also shows interesting deformation in the shear south of Ironbark where the conductive trends bend from north-northeast to a north-northwest strike orientation. That’s the area we’re currently testing with AC drilling, so we’re looking forward to seeing the results from that program.”

Great Boulder adds that a previously unrecognised bedrock conductor immediately northeast of Ironbark is unexplained by geology and untested by drilling or surface geochemistry. This conductive feature is adjacent to a resistor similar to that at Ironbark. 

The company says AC drilling will be planned to test this area. 

Great Boulder is a mineral exploration company with a portfolio of ‘highly prospective’ gold and base metals assets in Western Australia ranging from greenfields through to advanced exploration. 

As of 31 March 2023, the company had a cash at hand of $2.3 million, according to its latest quarterly report published on 27 April 2023.

Write to Aaliyah Rogan at

Images: Great Boulder Resources Ltd
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Written By Aaliyah Rogan
Relocated from the East Coast in New Zealand to Queensland Australia, Aaliyah is a fervent journalist who has a passion for storytelling. When Aaliyah isn’t writing stories, she is either spending time with friends and family or down at the beach.