SMOKEBUSH – M3
Smokebush is one of the highest-ranking Milestone 3 targets at Yamarna, comprising a mineralised shear zone intersecting a high conducive quartz dolerite unit within the Smokebush Dolerite. Differentiated dolerites are a very prospective mafic rock type and host many large gold deposits throughout the Yilgarn province (e.g. Junction and Argo at St Ives, and The Golden Mile in Kalgoorlie). Previous drilling (2014 to 2015) confirmed high-grade gold mineralisation over a strike length of approximately 1,300 metres associated with quartz veining and biotite-arsenopyrite-pyrrhotite alteration in discrete lode structures, with a best intersection of 6.76 metres at 31.13 g/t Au in hole 15SYDD0008.
The acquisition of 100% of the South Yamarna Project has allowed priority focus on this highly ranked target. Recent diamond drilling targeted extensions to the high-grade mineralisation intersected in 2015. Gold assays returned from the first two diamond holes confirmed high-grade gold mineralisation in similar alteration and lode structures to previous intersections (see captioned figure).
Plan view of simplified interpreted geology at Smokebush
A 13-hole RC and diamond programme designed to test strike and dip continuity and extensions to high-grade mineralisation intersected during 2014 and 2015 has been completed at the Smokebush Dolerite prospect. The results reported here comprise four diamond holes for 1,088 metres and nine RC holes for 1,429 metres. The first two holes from the programme were reported earlier this year2. The new high-grade intersections adding to the previous results include:
- 0.51 metres at 22.49 g/t Au from 157.50 metres (18SMDD0006) internal to 2.74 metres at 4.40 g/t Au from 156.61 metres at 0.1 g/t Au cut-off
- 2 metres at 4.71 g/t Au from 61 metres (18SMRC0006)
- 5.38 metres at 1.59 g/t Au from 147.03 metres (18SMDD0002)
Gold mineralisation at Smokebush has been confirmed over a strike length of more than 1.3 kilometres and remains open both along strike and down-dip. The differentiated dolerite host rock is analogous to other dolerite hosted gold deposits in the Eastern Yilgarn, such as Cave Rocks (>500 koz gold) and Argo (>1.5 Moz gold) at St Ives in Kambalda. The highest gold grades occur in shear zones which intersect the most fractionated quartz rich zones of the dolerite host. The high iron content and brittle nature of the host unit provides a chemical and competency contrast ideal for classic lode style gold mineralisation to develop, and which comprises visible gold associated with quartz veining, and biotite-arsenopyrite ± pyrrhotite alteration at Smokebush.
Three diamond intersections with visible gold at Smokebush are of particular interest as they display the geological features described above and are interpreted to form a potential continuous ore shoot over at least a 250 metre strike length within the greater 1.3 kilometre strike of the identified shear zone. These intersections, illustrated in Figures 4 and 5, are listed from north to south as:
- 0.51 metres at 22.49 g/t Au
- 6.76 metres at 31.13 g/t Au
- 7.73 metres at 5.45 g/t Au,
and include individual gold assays of 191.36, 50.83, 22.49, 13.10 and 10.34 g/t Au over varying lengths.
Gold Road is highly encouraged by the high-grade mineralisation and the emerging geological model at Smokebush. Detailed interpretation of the geology and structural controls is in progress. Follow-up drilling will commence in the second half of 2018 focussing on proving the continuity of the high-grade shoots and targeting down-dip extensions to mineralisation. The objective will be to define the mineralisation and the geological framework allowing more detailed infill drilling to promote the discovery of additional ore shoots within the prospective dolerite zones. If successful, this drilling will allow detailed geological modelling and economic assessment to support a possible resource drill out in 2019.