Todd River Resources has expanded its footprint in WA, picking up close to 900 sq.km of ground in the Edmund Basin immediately south of the Pilbara Craton. The company’s new Pingandy tenure covers a package of rocks similar to the stratigraphy hosting Rumble Resources’ recent Earaheedy lead-zinc discovery.
The company’s new ground is considered prospective for copper, lead, zinc and silver mineralisation.
The original Pingandy tenure was acquired as part of a transaction with Marlee Base Metals late last year. However, as the company began its evaluation of the tenure it quickly recognised that much of the surrounding ground was highly prospective and remained open, resulting in Todd River pegging three new lease applications that stretch across more than 100km of strike.
A review of the historical exploration data indicated the Pingandy project ground hosted a plethora of targets, with much of the sediment-hosted, or “SEDEX” base metal mineralisation in the region associated with the Blue Billy Formation that stretches across the basin.
The Blue Billy Formation is a sulphide-bearing carbon-rich shale unit which is an ideal geological host for a SEDEX deposit. The formation varies in thickness but can be up to 500 metres wide in the middle of the basin, providing the volume and space to accommodate a significant mineral deposit.
Interestingly, the stratigraphy within Todd River’s new ground is also geologically similar to that hosting Galena Mining’s world-class Abra deposit. Abra is currently being developed by Galena and tips the scales at an impressive 34.5 million tonnes at 7.2 per cent lead and 16 grams per silver, demonstrating the potential endowment of the region.
The company says previous exploration across the Pingandy region has been largely limited to the outcrop of the Blue Billy unit, leaving the down-dip, fresh rock extensions largely untouched. However, a desktop review of this work has already turned up historical drill intercepts of highly anomalous zinc mineralisation varying in thickness from 5m to 50m and with grades between 0.1 per cent to 1.2 per cent zinc, providing added encouragement for an expanded exploration program.
Assaying of both surface and drill samples has also returned anomalous levels of copper, lead, arsenic, manganese and uranium which perhaps points towards the presence of a large base metal deposit lurking within the company’s tenure. However, the added presence of the element thallium in the sedimentary pile has raised eyebrows within Todd River’s management team as it is regarded as a key pathfinder for SEDEX mineralisation.
SEDEX base metal deposits are regarded as globally important sources of lead and zinc mineralisation and often contain significant quantities of silver that is extracted as a by-product. Australian examples of this style of deposit include the McArthur River and Mount Isa mining complexes in north-western Queensland, providing an enviable mineralisation model for Todd River’s evolving exploration program.
The company says that due to the peculiarities of SEDEX deposits many geophysical methods that are now regularly used to fast-track base metal sulphide discoveries are of limited use, leaving the company to get back to the old hammer and boots methodologies that have been so successful over time. Initial exploration programs at Pingandy will likely including mapping and sampling in the led up to systematic geochemical sampling and drilling.
The acquisition of the Pingandy project appears to be in line with Todd River’s company-developing strategy to leverage off its considerable in-house geological expertise and gain a first-mover advantage in some of Western Australia’s overlooked but potentially highly fertile mineral fields.
The approach is on display with the company's hunt for intrusive-related nickel-copper mineralisation in the Berkshire Valley north of Perth underway. Now Todd River is getting ready to begin tracking down a SEDEX lead-zinc discovery in the terrane south of the Pilbara.
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