Todd River Resources plans to get busy on the ground this quarter at its Nerramyne project in WA’s Murchison region after applying for further ground next to its large, granted exploration licence covering a 40km-by-6km copper soil anomaly. The company says a newly defined mafic intrusive will be one target worth investigating further in the expanded Nerramyne project area.
The Nerramyne area, about 130km north-east of Geraldton port, is considered prospective for platinum, palladium and copper.
With a 30 square kilometre tenement applied for next to its 462sq.km Nerramyne project, Todd River expects to control a massive area along the margin of the mineral-rich Yilgarn Craton and the Perth Basin Narryer terrane. Regional regolith surface sampling by the Geological Survey of WA, or “GSWA”, on a 4km-by-4km grid over the area has identified a broad low-level copper-platinum-palladium anomaly that stretches over a 40km-by-6km area, Todd River has reported.
Management said the best result from the GSWA sampling was from the northern part of the project area, coincident with a large magnetic feature, where a significant 228ppm copper, 21ppb palladium and 8ppb platinum was returned. This compared with background levels of 2-30 ppm copper and mostly below detection levels for palladium and platinum.
Todd River says the geochemical anomalism uncovered by the GSWA sampling appeared to be connected with up to five magnetic features covering a combined 40sq.km. Its planned wide-spaced geochemical sampling over the “interpreted mafic/ultramafic intrusions” – either auger or surface lag sampling – will be aimed at generating priority targets for more sampling, geophysics and drilling.
Todd River secured the main Nerramyne tenement package via its 2020 acquisition of Marlee Base Metals.
Management said detailed desk top studies and exploration planning work had highlighted the “presence of an unpegged probable mafic-ultramafic intrusive body adjacent to the original tenement”. They said the applied-for ground was considered “highly prospective for copper and precious metals”.
Platinum minerals are commonly associated with these types of intrusions.
The current Nerramyne project covers an 8-10km-by-45km-long stretch along the margin of the Yilgarn Craton where the Archean craton is juxtaposed against the Narryer terrane. The Yilgarn and Narryer rocks are mapped predominantly as gneissic terrane, with mafic rocks in the south. The north south trending Darling Fault transects the project area.
However, a portion of the project area is covered by wind-blown sands and alluvial sediments which potentially mask any surface expression of mineralisation and render simple soil geochemistry unreliable. Previous exploration has been limited and concentrated entirely in an area of around 6km in the northern portion of the tenement, where a total of five soil sampling lines and 11 lag sampling lines have been completed, with soils taken to 30cm depth and lag collected at surface. As expected, more than half the soil samples collected were reported as being transported sand, suggesting that the shallow soil sampling completed was ineffective.
Despite this the sampling did return substantial anomalous results, with up to 29.1ppb palladium, 18.2ppb platinum and 416ppm copper in lag sampling. Mapping and petrological studies by Todd River also confirmed the presence of poorly exposed gabbro and amphibolite associated with the magnetic features and geochemical anomalism.
Todd River’s neighbours at Nerramyne include Chalice Mining, S2 Resources and AusQuest.
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By Matt Birney
