GBM Resources Limited (ASX:GBZ) has defined a significant high-grade vein target at Yandan via a new geological model for East Hill and the broader Yandan mineral system in Queensland, Australia.
The model has identified aa tilted low sulphidation epithermal hot spring system with the top of the system truncated and off-set from possible high-grade veins by a fault.
New East Hill Geology Model and Exploration Target
The East Hill deposit is a clear example of a hot spring low sulphidation epithermal system. Volcanic facies contacts at a high angle to the overall stratigraphy suggests that the deposit likely formed in a graben or half graben within the broader Yandan Trough. The style of mineralization is partly controlled by host rock with breccias generally formed in coarse tuffs and fine-grained tuff and lava hosting veins. The Epiphany Conglomerate with clasts of silica-illite altered andesite, sinter and epithermal veins suggests hydrothermal eruption breccia was present and forms a distinct marker horizon.
“Work by our geological team to interpret the Yandan geological setting following drilling in FY22 has identified compelling targets with the potential to yield a new project-making discovery,” Managing Director and CEO, Peter Rohner, said.
“Our confidence is supported by the geological evidence in several of the holes that penetrated the underlying fault and strong geological parallels that Yandan has with several large, well known, world class epithermal gold deposits. Further work will be focussed on geological characterisation, additional geophysics and spatial definition, to enable us to efficiently drill to maximise our probability of success.”
Vein composition and textures at East Hill clearly demonstrate that the known mineralization represents the top half of the hot spring and vein texture model.
The presence of hydrothermal alteration and epithermal veins below the Generator Fault together with gold grades that increase down plunge suggest that the Yandan system remains open at depth with potential for better grades and significantly more ounces.
With strong similarities to well know epithermal deposits Favona in New Zealand and Golden Promise in USA, it appears likely that high-grade veins exist below the Generator Fault. These high-grade veins are our key exploration target at Yandan.
Target Location
Yandan mineralization (Yandan Main to East Hill) defines a one km trend that contains 900,000 oz Au (historic and current resources). Hot spring epithermal systems often have better grades and more ounces at depth with high-grade veins present underneath similar epithermal systems at Favona and Golden Promise.
The geological model developed for East Hill implies that the Generator Fault off-sets mineralization to the south. Initial drilling will likely target locations immediately to the north of known mineralization.
Forward Plans
Yandan continues to be a key project for GBM. Future exploration will initially focus on confirming the new geological model and establishing vein texture, alteration, and metal zoning patterns to reconstruct the system and vector to the centre and feeder veins. The results of this work will be used to define the most effective geophysics method and confirm then to confirm drill targets.
For further information please visit: https://www.gbmr.com.au/