Geological Setting

The underlying geological prospectivity of Rimfire’s tenement package is in part due to the presence and coalescence of major deep crustal scale structural trends; the Lachlan Transverse Zone (LTZ) and the Platina-Tresylva trend, which parallels the mineralised Gilmore Suture, within an interpreted Siluro-Devonian Rift Basin. The rift basin setting occurs in the back-arc to the World Class Macquarie Arc which hosts Newcrest’s Super Giant Cadia Valley Operations, and the World Class North Parkes porphyry systems, along with many other deposits including the McPhillamy’s deposit (REGIS).

The Fifield rift basin arguably overlies a terrain boundary between lower and upper Ordovician rocks and provides the backdrop for what appears to be carbonate base metal epithermal Au/Ag style mineralisation encountered to date at Sorpresa. The system is somewhat unique in geological terms.  Metal zonation across a large km scale is evidenced with diversity in deposit styles likely.

Rimfire has also revealed geological evidence for an additional target style at Fifield possibly akin to the high grade Tritton Cu Mine to the north. Similar stratigraphic and alteration assemblages have been observed at Fifield, particularly at the new Carlisle and Eclipse trend regional targets. The Tritton deposit is considered a Besshi style Volcanogenic Massive Sulphide (VMS) Cu-Au deposit, which is a very attractive target style for Rimfire.

The Fifield District is Australia’s largest Platinum producer with historical production reported at 20,000Oz Pt and 6,200Oz Au between 1880 to 1938. Platinum mineralisation is considered to be related to Alaskan-Ural ultramafic intrusives for which Fifield is the type locality in Australia. Rimfire’s tenement package not only contains the largest alluvial platinum deep lead in Australia, the Platina Lead, it also contains evidence for primary platinum mineralisation. Rimfire continues to search for the primary platinum source as well as looking at development scenarios for the Platina alluvial lead.

Modern day systematic exploration techniques applied by Rimfire has quickly resulted in the greenfields discovery of the Sorpresa Au/Ag Deposit. Given the lack of cover across the region, generally less than 10m, quick, simple and inexpensive exploration techniques such as rock chip, soil and auger geochemical sampling and shallow RAB and RC drilling generate targets. Broader application of these techniques on systematic grids, coupled with geophysical surveys such as aeromagnetics, gravity, and induced polarization (I.P.) has generated a significant pipeline of more than 30 exploration targets, (prospect pyramid) at various stages of assessment for drill testing.