GBM has substantially improved the confidence and quality of gold resources at its Yandan project within the Drummond Basin following a key update.

Almost half (47%) of the resource of 15.9Mt grading 1 gram per tonne (g/t) gold, or 514,500oz of contained gold, is now in the higher confidence Indicated category where it had previously all been contained in the Inferred category.

Along with an increase in grade from 0.8g/t to 1g/t – due to the increased cut-off grade, this effectively offset the 5.6Mt reduction in overall tonnage.

GBM Resources (ASX:GBZ) resource update was the result of combining its FY2022 drill results with the updated geological model on the main deposit at East Hill.

East Hill itself now has a resource of 12.8Mt at 1.1g/t gold for 443,000oz of contained gold that includes a high-grade core of 1.1Mt at 5.7g/t gold, or 201,000oz of contained gold.

The company also delivered a maiden resource of 2.19Mt at 0.8g/t gold, or 55,500oz of contained gold, for the Illamahta deposit. This includes an oxide ore component of 1.15Mt at 0.73g/t gold.

Overall resources at the Drummond Basin in northern Queensland now stands at 45.6Mt at 1.26g/t gold for 1.84Moz of contained gold.

“Converting more than half of the East Hill Deposit gold ounces to Indicated status is very pleasing and an important advancement for the Yandan project,” managing director Peter Rohner said.

“Recent interpretative work on the formation of the East Hill deposit in conjunction with the high-grade core mineralisation provides significant encouragement for future drilling.”

He added that small Illamahta deposit is similar to the Yandan Main deposit, which represents the very top of the system, and that it is located at one end of a large, mineralised alteration system that represents a significant exploration gold target for the future.

Growth potential

East Hill mineralisation is hosted in the Yandan andesite volcanic unit at the base of the Saint Anns Formation with the highest density veining and highest gold grades are developed in the hanging wall of the moderately NW dipping Generator Fault.

However, the latest drilling has demonstrated that low sulphidation style veining and alteration are present under the fault.

Along with a re-interpreted geology model, GBM believes that the Generator Fault crosscuts and offsets mineralisation and that there is potential to find higher grade mineralisation at depth.

Its technical team is working through the reinterpreted geological model to generate priority exploration targets to extend the mineralised zones at East Hill.

Exploration at East Hill this year will initially focus on confirming the new geological model and establishing vein texture, alteration, and metal zoning patterns in order to reconstruct the system and vector to the centre.

Meanwhile, Illamahta is located about 15km southwest of the Yandan Main and East Hill deposits.

Gold mineralisation occurs in several bedding parallel layers that dip shallowly to the northwest with resources defined for more than 330m along a northwest strike, a typical width of 160m and to a depth of about 80m.

Illamahta mineralisation is similar to Yandan Main and is interpreted to represent the upper and perhaps distal part of an epithermal system.

It is considered to be part of a much larger system, with the potential for higher grades and more ounces in permissive structural settings and key lithological units at depth.

Exploration will initially involve IP or CSAMT type geophysics across key structural zones and the mapped silicification to identify targets followed by drilling.

This article was developed in collaboration with GBM Resources, a Stockhead advertiser at the time of publishing.

This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.