LOCATION AND ACCESS

The Reynolds Range Uranium Project covers a group of granted tenements and applications, 250km north-northwest of Alice Springs (Figure 1) in the Reynolds Range province. Access to the region is via the Stuart Highway or Tanami Highway. Tenements are evenly spread between pastoral (native title affected) and Aboriginal freehold (ALRA affected) land and Toro has been able to develop a good relationship with the various stakeholders.

Figure 1:  Location of Reynolds Range Project tenements. Granted tenements have no pattern fill, while applications are stippled.

GEOLOGICAL SETTING

This project lies within the Arunta-Ngalia region of the Northern Territory (Figure 2). Basement is comprised of Palaeoproterozoic to Mesoproterozoic metasedimentary and granitic rocks assigned to the Aileron Province, including the Reynolds Range Group. These granites and orthogneisses are notably radiogenic (Figure 3), hosting numerous phosphatic veins and pegmatites with anomalous uranium and thorium. Basement rocks are overlain by Neoproterozoic to Carboniferous sediments of the Ngalia Basin to the south of the tenements and Wiso/Georgina Basins to the north. Locally, the Aileron Province rocks are overlain by a veneer of Tertiary to Recent clastics, derived from erosion of the radiogenic granites in the Reynolds Range. This situation is analogous with the Frome Embayment in South Australia, which hosts the Beverley and Four Mile uranium deposits, the former of which has been in production since 2000.

Uranium mineralisation is known in the region and is restricted (thus far) to the Proterozoic Aileron Province and the Devonian to Carboniferous parts of the Ngalia Basin. Uranium at Nolans Bore (Arafura Resources), to the south-east, occurs in phosphatic and REE-enriched metasomatic pods and veins within the high-metamorphic-grade Lander Rock beds. This deposit is the subject of ongoing feasibility studies. Uranium is also present in high grades at Bigrlyi (Energy Metals-Paladin JV) to the west, within carbonaceous sandstones of the Mt Eclipse Sandstone. The deposit is a roll-front style formed during uplift and deformation of the basin in the Carboniferous Alice Springs Orogeny. Uranium has also been identified by Thundelarra to the southwest in Tertiary lignite-bearing palaeochannel sands.

Palaeochannels are interpreted to have developed during the Tertiary within the foreland outwash fans north of the Reynolds Ranges, carrying immature detritus into locally reduced settings, perhaps sites where lignite may accumulate (Figure 4). Subsequent uplift events in the ranges generated topographic head and forced oxidised uranium-carrying fluids from the hinterland northward into the reduced palaeochannels. Uranium was likely to be dropped out of solution as the chemical ‘roll-front’ moved northward. The hydrodynamics of the region may also support the view that the ‘roll-front’ system is currently active and any uranium deposits that are present are actually forming and dispersing within the modern timeframe. The Beverley ISL uranium mine in South Australia is a good example of this type of deposit and is the analogue for Toro Energy’s exploration on this project.

Figure 2: Geological setting of the Reynolds Range Project. The brown tone depicts Aileron basement and the pink tone indicates Neoproterozoic to Carboniferous basin cover. A small Archaean inlier is interpreted in the northwest by NTGS.

Figure 3: Radiometrics ratio U2/Th draped on DEM showing the anomalous radiometric signature of the Reynolds Range basement outcrops in the south.

Figure 4:  Regional radiometric image (uranium channel) showing the redistribution of radionucleiides from the Reynolds Ranges north into the Tertiary and Recent sedimentary fans. The inset maps are Tempest EM collected in 2009 and highlight the difference in trends of Tertiary versus Modern outwash channels.

PREVIOUS EXPLORATION

Although uranium has been explored for in the area, the nature of the exploration has been restricted to bore water sampling, hard rock and limited near surface calcrete sampling, in search of calcrete styles of uranium within or proximal to outcropping terrains. The area outboard of the outcrop belt warrants further work within the cover sequences and palaeochannels.

EXPLORATION OBJECTIVES

After reviewing of the available data and reports, Toro composed the following objectives for this project:

 •   Determine the nature of anomalous radiometric and AEM responses in outcrop.
•    Determine the likelihood of economic ‘hard-rock’ U mineralisation in the Palaeoproterozoic granites and
     gneisses under cover. This should include identification of labile uranium species and phosphatic facies.
•    Identify potential palaeochannel sediments and determine if there is reduced facies or evidence of redox
     changes.
•    Assess the amenability of the sediment package to in situ leaching (‘ISL’), an efficient mechanism of uranium
     extraction, as used extensively in Kazakhstan.