The Imbin Project (Lodestar 100%)
The Imbin project is located 170 kilometres north east of Wiluna, Lodestar’s tenements cover 70 kilometres of strike along the northern margin of the Earaheedy Basin. Dating of rocks near the base of the Earaheedy Basin by the GSWA gave an age similar to that expected for the upper Bryah Basin, implying that the rocks stratigraphically below the Frere Formation may be Bryah Basin age equivalents. The Bryah Basin hosts a number of significant copper and gold deposits, including the DeGrussa mine, and equivalent age rocks along the northern margin of the Yilgarn Craton may have similar exploration potential.
Lodestar’s tenements include prominent gravity anomalies aligned with the prevailing west northwest structural trend. The gravity anomalies suggest the presence of a large volume of buried mafic rocks within a rift setting comprised predominantly of sedimentary rocks. The interpreted “Imbin Rift” is defined by the gravity anomalies, interpreted Bryah age felsic intrusive and volcanic rocks and probable mafic-ultramafic intrusive and volcanic rocks within a thick sedimentary sequence and is prospective for volcanic-hosted massive sulphide, sediment-hosted copper and orogenic gold. The rift sequence is generally poorly exposed and concealed beneath a thin veneer of transported sand.
The western half of the Imbin project includes the known historic base metal and gold prospects of Main Gossan, North Chert, Murilla and Catalina. Historic drilling reported strong copper and gold anomalies over a wide area. In the Bryah Basin gold has proven an important vector to base metal mineralisation and the gold anomalies at Imbin have not received intensive follow-up.
Figure 1 Interpreted Bryah-age Imbin palaeo-rift at the northern margin of the Yilgarn Craton
Imbin - Exploration
The Imbin area has been subjected to sporadic exploration dating back to 1990. Exploration completed by Sons of Gwalia, Aztec Exploration, Stockdale and Mount Isa Mines targeted sediment-hosted base metal (Cu-Pb-Zn-Au), diamonds, shear-hosted lode gold, shale-hosted Au-PGM and IOCG (Cu-U-Au) deposits.
Historic exploration identified a number of gossanous ironstones developed in pyritic carbonaceous shale, dolomitic siltstone and pyritic chert. The gossans are associated with steeply-dipping shear zones and where drill tested, display silica-sericite-carbonate-sulphide alteration. Exploration has focussed on the Main Gossan prospect, which is anomalous in Au, As, Cu, Ag and Pt. Widely spaced diamond drilling of the prospect by Aztec intersected disseminated and massive sulphide mineralisation anomalous in copper and gold. Results from the Main Gossan area provide strong justification for exploration of the broader region and include;
70m at 0.52% Cu from 60m in TCRC09-06
36m at 0.76% Cu from 91m in TCRC08-02, (including 2m at 4.65% Cu and 17g/t Ag and 3m at 1.97% Cu and 3g/t Ag)
21m at 0.63% Cu from 69m in TCZRC06
Collectively the histroic prospects at Imbin extend over a distance of 14 kilometres and are evidence of a large mineralised system (Figures 2 and 3) related to the northwest-trending tectonic margin of the northern Yilgarn Craton.
Figure 2 Imbin Project - Historic Drill Results (formerly Troy Creek project) MGA Zone 51
Figure 3 Anamalous gold reported in first-pass drilling at the Catalina prospect
- aeromagnetic background image, MGA zone 51