The Myall project consists of one licence (EL 6913) which covers 244km2 of one of the largest volcano-intrusive complexes in the East Lachlan. The project is located in the Junee-Narromine Volcanic Belt 18km southwest of Narromine and is prospective for porphyry Cu-Au and related epithermal deposits. The intrusives have the same age as the Cadia Valley (9.2Mt Cu and 52Moz Au) and Northparkes (3.7Mt Cu and 4Moz Au) intrusives. The project has a similar geological setting to Evolution’s Cowal Gold Mine (7.8Moz Au) with intermediate calc-alkaline intrusives, volcanics and volcaniclastics.
The area is underexplored due to post-mineral cover in general >50m in thickness. Systematic air-core drilling at 500m x 500m spacing has been completed over the project, with some infill down to 250m x 250m. This drilling has identified a number of porphyry Cu-Au alteration systems with associated mineralization or anomalous geochemistry, a number of which have undergone initial diamond drilling.
Magmatic believe that due to a poorly preserved residual saprolite at Myall, these anomalies are only partly tested and scope remains for a major discovery of 2 to 5 Moz Au, 2 to 5Mt Cu deposits: i.e. Northparkes-sized targets.
Magmatic has completed data analysis and targeting at Myall which has resulted in four new untested high order geological-geochemical-geophysical targets for priority follow-up: SLR, Calais East, Kingswood and Northern High.
Latest ASX Release
The porphyry copper-gold system at Kingswood has chalcopyrite-pyrite-bornite-molybdenite sulphide mineralisation hosted in potassic altered, magmatic-hydrothermal breccias, quartz stockwork vein arrays, and sheeted and massive magnetite vein systems. The best intercept at Kingswood is:
- 121m t 0.4% Cu, 0.09/t Au (from 103m), including:
- 70m at 0.54% Cu, 0.15g/t Au (from 141m)
in MYACD001. The area to the north of this hole is untested for over 250m and open towards early reconnaissance hole NACD089 (14m at 0.14% Cu, 0.05 g/t Au from 130m) with only 1 DD hole following up (NACD156: e.g. 22m at 0.21% Cu and 0.2 g/t Au, from 374m).
SLR is to the east of Kingswood and near a regional fault. Inspection of drill chips has found altered monzodiorite with minor pyrite and trace chalcopyrite in hole MYAC153. Magmatic believe that this sample is close to a possible porphyry source and further testing is required. Two previously drilled AC holes at SLR ended in copper mineralisation, with visible chalcopyrite at the end of MYAC153:
- 1m at 0.22% Cu, 0.053ppm Au, 3.59ppm Mo, 0.48 ppm Te (MYAC153, from 146m, eoh), not followed up
- 9m at 0.11% Cu (MYAC152 from 153m, eoh), including:
- 1m at 0.16% Cu, 0.62 g/t Au, 4.33ppm Mo, 0.2ppm Te (from 161m eoh), followed up by MYACD366 (wide anomalous ~300-1000ppm Cu) zone of copper, maximum 0.29% Cu, 0.26ppm Au). Due to drilling conditions and equipment at the time, the weathered rock below the base of the transported cover was not sampled. Magmatic believe that this weathered rock is a critical part of assisting in defining these complex anomalies and are working with our drilling contractors to resolve this sampling issue.
Other notable intercepts include:
- 3m at 1.02% Cu 0.34ppm Au, 32.7ppm Mo, 13.2ppm Te (MYACD367, from 302m)
The molybdenum and tellurium in MYACD367 are some of the highest in the Myall geochemical database. The high-grade intercept reported in MYACD367 is at a structure related to an alteration margin with magnetite-altered monzodiorite to the west and unaltered monzodiorite to the east. This highlights the area as having both porphyry-style geochemical signature and porphyry-style alteration products which are believed to make this area very prospective for multiple porphyry copper-gold deposits.
A three-hole AC gold anomaly east of Calais has end-of-hole anomalous gold. Review of chip trays shows the chips are weakly altered and porphyritic. Intersections include:
- 1m at 0.11 g/t Au, 261ppm Cu (MYAC125, from 124m, eoh)
- 2m at 0.1 g/t Au, 167ppm Cu (MYAC160, from 137m, eoh), and
- 2m at 0.143 g/t Au, 282ppm Cu (MYAC161, from 142m, hole is 145m deep).
AC drilling is on 250m spacing and there is no diamond drilling. Although the pathfinder elements and copper values are low, this is considered a high-order gold anomaly and further work is required.
End of hole anomalies of 1m at 0.22% Cu (MYAC153, from 146m) and 1m at 0.16% Cu and 0.62g/t Au (MYAC152, from 161m).
Magmatic has carried out re-mapping of the depth of the transported cover by looking at previous explorer’s drill data and defining the depth of the transported cover. The depth has been mapped out to show a palaeochannel with two distinct palaeo-highs: Kingswood High and Northern High. The northern high which is a similar paleo topographical feature to the one found at the mineralised Kingswood target may be related to alteration and is poorly tested.