The 100%-owned Basin Creek Project is located near the Company’s Junee and Bogong Projects, further strengthening DevEx’s sizeable ground-holding in the Lachlan Fold Belt, host to several of Australia’s largest copper-gold mines.
The major geological province is known for world-class copper-gold deposits such as Cadia-Ridgeway (Newcrest Mining) and Northparkes (China Molybdenum Co Ltd) as well as several large- scale Silurian age deposits including the McPhillamys Gold Mine (Regis Resources Limited), a +2Moz gold deposit.
Despite its strategic location, no drilling has been conducted on the Basin Creek ground since the mid-1980’s, representing a fresh exploration opportunity.
In March 2020, DevEx commenced an exploration campaign at the northern part of Main Ridge Prospect which returned an extensive, near surface zone of gold in rock chips.
The compilation of Company exploration with historic rocks chips, associated lead-in-soil anomalism and alteration mapping supports the view that the broader gold system extends over a strike length of +4km.
Figure 1: Location of the Basin Creek Project, in close proximity to the Junee and Bogong Projects, NSW, within the Lachlan Fold Belt of New South Wales.
The Main Ridge Prospect was originally explored for base metals between 1973 to 1982 following the definition of an extensive lead-in-soil anomaly, together with other base metal occurrences within the tenement area. While extensive soil sampling was undertaken for copper, lead and zinc, no gold was analysed.
Regional mapping by AAA along this lead anomaly noted that the rocks were mixed argillic altered felsic volcanic and meta sediments with numerous quartz “gossan” veins (some chalcedonic) and overprinted by extensive silica, sericite and potassic alteration. Minor rock chip sampling for gold by AAA in the southern part of Prospect returned a peak gold assay of 2.75g/t Au.
Between 1985-1987, Shell Company of Australia Limited (Shell) explored the Main Ridge Prospect for gold. In 1986, Shell drilled eight shallow scout AirTrack holes designed to test limited parts of the 4km strike length where gold was encountered from their previous rock chip sampling.
Although broad spaced and reconnaissance by design, drilling intersected anomalous gold mineralisation on several traverses, encountering 33m @ 0.5g/t Au (including 6m @ 1.4g/t Au) from 19 metres within an altered felsic porphyry with fine quartz stockworks.
No further drilling has been conducted on the Project.
An initial program of rock chip sampling has identified anomalous gold in rock chips over a strike length of 1.2km with a >1g/t gold cluster located to north of the historical Shell drilling which remains open beneath shallow drainage cover.
These felsic to intermediate rocks are strongly silicified and partially brecciated, comprising thin stockwork quartz veins throughout with iron-oxide box-work textures indicating the presence of pyrite with the veins. Locally strong silica-pyrite alteration has been observed. Extensive potassic alteration is apparent in the majority of rocks observed within the gold zones.
The Company’s and historic rock chip sampling shows a close association with a historical lead-in-soil anomaly over the 1.2km trend tested so far (Figure 1).
Refer to ASX Announcement – 14 April 2020 for full details.
Figure 1: Northern part of Main Ridge Prospect where recent rock chips returned significant gold results over 1.2km of strike (open to the north and south). Gold shows a close association with pathfinder metals including molybdenum (Mo) and lead (Pb), with historical lead-in-soil anomalies mapping the broader system.
Compilation of historical exploration data over the entire Prospect, including the close association of gold with lead-in-soil geochemistry, supports the view that the gold system can be defined over a strike length of 4km within altered felsic volcanic and porphyry rocks (Figure 2).
Figure 2: Main Ridge Prospect showing recent rock chip results (northern area) in context with previous exploration highlights. Gold shows a close association with pathfinder metals including lead (Pb), with historical lead-in-soil anomalies and previously mapped sericite and potassic alteration mapping the broader system over 4km. The prospect remains open to the north and south.
The Company plans to carry out field investigations in the southern part of the Main Ridge Prospect next.
This close association with lead geochemistry suggests that the historical broad-spaced drilling has only partially tested the prospect (Figures 1 and 2) and further work to accurately map the scale of the gold system in advance of new drilling is required.
For the further project information, please view our latest Investor Presentation.