(Nickel-Copper, Zinc-Copper-Silver & Gold)
The Rockford Project is located in the highly prospective Fraser Range district of Western Australia and covers a total area of 3,088km2 (see Figure 1). Exploration is primarily focussed on Nova-Bollinger style nickel-copper, along with volcanogenic massive sulphide (VMS) style zinc-copper-silver and Tropicana style structurally controlled gold mineralisation.
The Project comprises 14 contiguous granted exploration licences covering a total area of 3,088km2 (see Figure 2).
A detailed breakdown of ownership, area and manager is given below:
- Legend (100%) 238km2;
- Legend (70%)/Creasy Group (30%) Two JVs covering 2,192km2 with Legend manager;
- IGO (60%)/Creasy Group (30%)/Legend (10% free carry) JV covering 634km2 with IGO manager;
- IGO (70%)/Legend (30% free carry) JV covering 24km2 with IGO manager.
Importantly, the Project tenure covers a strike length of 100km over a regional gravity high “ridge” associated with dense mafic/ultramafic intrusive rocks of the Fraser Zone, within the larger Albany-Fraser Orogen. The Nova-Bollinger deposit and the recently discovered Silver Knight nickel-copper deposit, both of which lie within the Fraser Zone, are situated on a similar tenor gravity ridge to that of the Rockford Project, (see Figure 3).
In 2015 Legend acquired an extensive exploration dataset over the entire Rockford Project, which is constantly being added to by Legend’s activities and reinterpreted/interrogated to identify specific areas for follow up exploration. These high quality datasets include:
- Project wide high resolution aeromagnetic data at 50m line spacing
- Detailed gravity data over an 800m/400m x 100m grid, comprising 35,600 stations
- Aircore drilling with multi-element analysis of bottom-of-hole samples
- Detailed petrological descriptions of bottom-of-hole aircore samples
- Project wide soil and calcrete geochemical sampling over an 800m x 400m grid.
Exploration activities completed by Legend to January 2020 over the Rockford Project since the commencement of the JV on 23 September 2015 include:
- Project wide aeromagnetic data interpretation
- 3D inversion modelling of the aeromagnetic and gravity data
- Moving loop electromagnetic surveys over 27 target areas, 245km2
- Fixed loop electromagnetic surveys over seven target areas, 6.6km2
- Aircore drilling 735 holes totalling 51,717m
- Ten RC drillholes targeting EM conductors, totalling 2,266m
- Seven diamond drillholes targeting EM conductors, totalling 4,075.3m
- Downhole electromagnetic surveys in nine drillholes
- Three detailed infill aeromagnetic surveys, 1,039km2
- Three detailed gravity surveys, 10,294 stations
- Target selection and evaluation.
Exploration results to date by both Legend and Creasy Group have highlighted six priority prospects as shown on Figure 2. These include; magmatic nickel-copper sulphide style targets at Mawson, Octagonal, Magnus and Crean and VMS style zinc-copper-silver targets at Shackleton and Worsley.
Legend achieved a watershed milestone in December 2019 at the Mawson prospect at its Fraser Range Rockford Project with the discovery of massive nickel-copper sulphides in diamond drillhole RKDD007. (See Figures 4 & 5)
A structural report from analysis of the core from the discovery hole and the final assays in January 2020 supported the Company’s view that the hole was part of a large mineralised system. Subsequent review and modelling of the downhole EM survey data and geological input has identified an off hole conductor which is a compelling drill target for the first diamond drillhole in the March 2020 programme.
Meanwhile the regional aircore and innovative moving loop EM surveys will be ongoing throughout the project area.