Toro Energy Limited (ASX:TOE) Release Western Australia And The Northern Territory 2010 Uranium Exploration Summary
Perth, Dec 21, 2010 AEST (ABN Newswire) - Toro Energy Limited (ASX:TOE) ("Toro") is pleased to provide the following summary of the Company's technical success with its mainstream 2010 uranium exploration programs across its Western Australian and Northern Territory projects.
The Company also owns exploration interests in uranium projects in South Australia, and Namibia in Africa.
Toro conducted more than 20,000m of drilling across Western Australia and the Northern Territory during the 2010 calendar year, despite one of the most adverse Winter/Spring rain seasons in 25 years in Central Australia. Due to localised flooding, Toro was unable to access and undertake follow-up drilling at our flagship 2009 discovery, the Theseus prospect at the Lake Mackay Project in WA. However, Toro made important discoveries in several other "greenfield" areas while continuing to consolidate a ground position in the vicinity of the Company's most advanced asset, the Wiluna Uranium Project in WA. These gains included:
- Discovery of uranium mineralisation in new areas of Lake Mackay, including within the older Carboniferous Amadeus Basin and Tertiary cover, thereby expanding the area of interest beyond the Theseus Prospect;
- Ground applications which contain uranium mineralised drill holes around the recently acquired Dawson-Hinkler Well project at Wiluna;
- Identification of an alteration "plume" within cover sandstones at the Birrindudu project that is consistent with the presence of a uranium mineral system at or near the underlying unconformity. This has confirmed the prospectivity of a major fault contained largely within the Cameco-Toro JV ground.
- Identification of a major palaeochannel system with redox interfaces and gamma anomalies in the Tertiary outwash fan of the Reynolds Range Project in the NT. This Basin has similar attributes to the Kazakhstan basins in terms of tectonic setting, sedimentary fill and exploration upside and which now produce in the order of 10,000t U3O8 per year. Toro has first mover advantage at Reynolds Range and has assembled a significant ground position there.
Following on from these technical successes, the Toro exploration team is now prioritising several exciting Stage 2 exploration leads for follow-up work in 2011.
ANTICIPATED 2011 EXPLORATION PROGRAM
- Priority and major Q1 drill program on Theseus Prospect at Lake Mackay
- Q2 drill start on Pokali East Prospect IOCGU targets at Lake Mackay
- Q2 completion of aircore drilling program on Reynolds Range
- Q3 exploration of Ventura prospect at the Birrindudu JV
- Q3 regional airborne EM and further aircore drilling at Reynolds Range
- Q3 drill testing at Sandover EM target
A detailed drilling summary, including all anomalous intervals and a current tenement map of all Toro's tenement holdings, is presented in Appendix 1 (see link at the bottom of the release).
Toro has applied for vacant ground surrounding the recently acquired U3O8 Ltd (ASX:UTO) Dawson-Hinkler Well Project near Wiluna (refer Toro's ASX release dated 13 December 2010). This project lies only 15km to the west of the Centipede deposit, part of Toro's Wiluna project.
Lake Mackay Project
The Lake Mackay Project, located 650 km west of Alice Springs but inside the WA border represents Toro's flagship exploration asset. During 2010, Toro undertook a regional aircore drilling program, before widespread and persistent rain systems denied access to the priority Theseus Prospect that was discovered during the Company's 2009 drilling program (refer Toro ASX release 28 October 2009).
An initial regional aircore program was undertaken at Lake Mackay in 2009 which resulted in the discovery of the Theseus uranium prospect within Tertiary palaeochannel sediments. Additional regional aircore drilling was undertaken in 2010 to expand exploration coverage of the palaeochannel system and any associated uranium mineralisation. This drilling resulted in a total of 120 holes for 10,637m. In addition, eight mud-rotary holes were also completed for 920m.
All drill holes were radiometrically probed and sampled for chemical assay. Radiometric anomalism was intersected in numerous holes, with two holes, LP0091 and LP0126, reporting results above 75ppm eU3O8 cut-off. Mud rotary hole LM0003, a twin of LP0091, recorded similar results. Significant gamma intersections at 75ppm eU3O8 cut-off are summarised in Table 1 (see link at the bottom of the release).
A palaeochannel map using depth-to-basement data from the 2009 and 2010 drilling programs is shown as Figure 3 (see link at the bottom of the release). This map depicts an extensive system of prospective northsouth connected Tertiary palaeochannels. Significant radiometric drill-hole intersections from 2009 and 2010 are also plotted on the map to illustrate the distribution of anomalous uranium in the area. Most of these intersections occur in palaeochannel sediments, and are spatially associated with interpreted palaeochannel margins. In addition, LP00165 encountered 0.24m @ 86ppm eU3O8 in basement Amadeus Basin sandstone. The Tertiary palaeochannel system remains the main target for further drilling and the newly mapped palaeochannels will guide future drill programs, planned to commence in March 2011. Results from the calcrete and Amadeus Basin systems are also encouraging and mirror uranium occurrences in the Ngalia Basin that are being actively explored.
During 2010, Toro contracted Haines Surveys to collect detailed gravity data over the Theseus Prospect area. Figure 4 (see link at the bottom of the release) depicts the gridded gravity data and significant radiometric intersections from the 2009 drilling. The distribution of radiometric intersections suggests there is a correlation between the edges of gravity highs (basement inliers in the palaeochannel) as a control on mineralisation, although this is based on limited data points.
This concept will be tested in Q1 2011, with a major drill program planned in the Theseus area as a priority. All approvals, access and heritage clearances for this drilling are in place.
Pokali East Area
Detailed gravity data was also collected by Haines Surveys over the southern part of the Lake Mackay Project, covering areas interpreted to be Mount Webb Complex, analogous with South Australia's Gawler Craton that hosts world-class Iron Oxide Copper Gold Uranium ("IOCGU") style deposits including Olympic Dam. This dataset has been integrated with data collected during 2009, providing seamless coverage over the prospective geological domain, with the exception of sensitive heritage zones. Interpretation of the data indicates a number of discrete large gravity anomalies, related spatially to magnetic highs.
Magnetic alteration overprints early structures, suggesting it relates to late magmatism associated with the Mount Webb Complex. These zones are favourable sites for magnetitehematite alteration, and potentially, base metal and uranium deposition. The adjacent Pokali Cu prospect owned by Ashburton Minerals (ASX:ATN) has thus far been shown to have extensive (<0.5%) copper mineralisation associated with chlorite and magnetite.
Toro believes that hematite-dominated end-members and structural upgraded zones exist in the area and these have been targeted for drilling by Toro in Q2 2011. Importantly, the basement in this area is covered by a thin 10-20m veneer of sediment and drill targets are relatively shallow compared to the Gawler Craton. Any deposit discovered is likely to be amenable to cheap open pit mining, overcoming the negative impact of the remote location and lack of infrastructure.
The Birrindudu Project is a joint venture between Toro and Cameco Australia, whereby Toro is currently earning a 51% interest. It encompasses the regional unconformity between the Tanami Domain and the Birrindudu Basin, analogous with the Alligator Rivers uranium field in the Northern Territory that hosts Ranger and Jabiluka. Toro is exploring for high grade uranium near the unconformity using a modified Athabasca Basin model, focussing exploration on conductive basement structures and alteration plumes evident in electromagnetic data. Of secondary interest are interpreted palaeochannels in the western part of the project area.
Thirteen aircore holes for 950m were drilled in the western part of the project area, designed to test airborne electromagnetic trends indicative of a large palaeochannel system. Drilling showed that there are no significant permeable sands and that the conductive character can be adequately explained by shallow saline (>10000ppm TDS) groundwater present in the Tertiary clays. This 100m thick cover sequence is underlain by ubiquitous grey siltstones of the Canning Basin.
During 2010, Toro also undertook Reverse Circulation (RC) drilling of unconformity targets in the eastern and central parts of the project area (Ringer Soak and Ventura respectively). A total of five holes for 804m were drilled. The most encouraging results were from drill holes BR0001 and BR0003 at the Ventura prospect, coincident with a major WNW structure defined in magnetic data.
Dark grey, sulphidic and possibly graphitic alteration was intersected in Gardiner Sandstone over a 30m interval at approximately 45m depth in both holes. Various elements are elevated up to 10 times background in this zone including K, Al, U, Cu, Zn, Pb, Ag, As, Se and Tl. The mineralogy is currently being investigated. This zone is interpreted to be an alteration plume from a deeper source, perhaps at or near the unconformity.
Hole BR0002, drilled only 200m to the north of this alteration zone, intersected silicified sandstone to 149.5m then felsic volcanics and quartzite of the Killi Killi Beds to the end of hole at 253m. Minor uranium anomalism to 22ppm U3O8 in chemical assays was encountered in the volcanics. The lateral distribution of the alteration zone is currently not constrained by drilling or electromagnetics and will be a focus of exploration in Q3 2011. RC drilling at Ringer Soak was only partially completed due to start of the wet season rains.
During the year, Toro also collected soil samples from unconformity target areas throughout the Birrindudu Project, the results for which are expected in Q1 2011. These are expected to constrain the anomalism at Ventura and generate further targets for drill testing in 2011. Toro will complete the Earn-In expenditure requirement early in the New Year.
Reynolds Range Project
Since listing on the ASX in 2006, Toro has steadily built up an extensive land holding in the Tertiary alluvial outwash fan north of the Reynolds Range, 250km northwest of Alice Springs. This area is viewed as analogous with the Chu-Sarysu Basin of Kazakhstan and the Frome Embayment of South Australia, with central tectonic uplift zones of radiogenic crust and a widespread multi-phase sedimentary apron containing organic units and permeable sands. Both these analogous regions host significant resources of uranium and are potential burgeoning mining provinces.
In 2010, Toro undertook an aircore drilling program over granted parts of the Reynolds Range project area where there is existing electromagnetic coverage. During this program, Toro discovered distinctive redox interfaces and moderate uranium mineralisation in Tertiary unconsolidated sands and clays in the NE corner of Toro's Mt Denison tenements. A total of 39 aircore holes were completed for 3,501m. Similar interbedded reduced coarse sands and clays have been intersected 70km east on Anningie Station in two holes but at this stage, no oxidised facies have been encountered. Heavy rainfall disrupted the drilling program and completion of the program is planned for Q2 2011.
Figure 10 (see link at the bottom of the release) is a drill section from the uranium anomalous area of the Mt Denison tenement and illustrates the lateral change in redox conditions observed, grading over several kilometres from reduced interbedded sands and clays in the east, to an oxidised sequence in the west. This is typical of a sedimentary redox front where uranium is likely to be concentrated. The orientation and continuity of the redox front is unknown, but will be a focus of drilling in 2011. Based on the interpreted extent of Tertiary sands north of the Reynolds Range, Toro is hopeful that the front continues over hundreds of kilometres, presenting numerous exploration targets.
As had been hoped, the sediments drilled at Reynolds Range exhibit similar geological-host and redox characteristics compared to the "Kazakhstan style" roll front deposits, vindicating Toro's exploration model and the acquisition of ground in this area. The Chu-Sarysu Basin in Kazakhstan is a world-class uranium province, with numerous operating ISR uranium mines scattered along regional redox fronts hundreds of kilometres long. Toro has an extensive ground position in the Reynolds Range region that equates in area to just one of the Kazak redox fronts. On this basis, exploration upside in the poorly-explored Reynolds Range and surrounding Tertiary basins of central Australia is considered immense.
Toro will also move to progress agreements with traditional owners for the tenements to the north, which are on Aboriginal Freehold Land and we are hopeful of a resolution by March next year. This would enable Toro to undertake regional airborne electromagnetics in Q3 of 2011 followed by aircore drilling.
The Sandover Project lies 250km northeast of Alice Springs along the boundary between the Georgina Basin and Aileron Province, where Toro is exploring for sedimentary uranium within various cover sequences of Palaeozoic age and IOCGU mineralisation in the basement. Wide-spaced regional aircore drilling was undertaken in 2010, primarily focussed on palaeochannel targets in the northern part of the tenement package (ELs 27052 and 27531), where a thick sequence of Cretaceous and Tertiary sediments was interpreted.
In total, 47 holes for 3,314m were drilled, all of which were radiometrically probed and assayed. These proved to be unsuccessful in defining significant sand units in the cover sequence, and no significant uranium anomalies were identified. Most radiometric anomalies relate to thorium, possibly in the form of detrital monazite in the sediments. The best gamma intersection attributable to uranium was 1.9m @ 76ppm eU3O8 using a 75ppm cutoff, from a redox interface in clay at 96m in SP0034. A pronounced calcrete or travertine unit was intersected in the eastern part of EL27052, but this had no associated radiometric signature. Minor nickel (locally above 500ppm detection limit; currently subject to follow-up analysis) and copper were identified at redox interfaces in the clay cover sequence, but these are likely to have a supergene origin.
During the year, SkyTEM heliborne electromagnetics was acquired over the southern tenement, EL26542. This dataset has now been interpreted and a number of conductive anomalies have been identified for follow-up. These are thought to relate to pervasive alteration along a regional structure, the Delny-Sainthill Fault. The presence of hematite alteration and weak copper mineralisation along strike at the historic Perenti prospect, suggests that an IOCGU alteration system may exist within Toro's tenement. Drill testing is proposed for Q3 2011.
YEAR IN REVIEW
COMMENT BY TORO MANAGING DIRECTOR, GREG HALL
"While weather events and conditions in the field have been extremely challenging this year, the Toro exploration team can be proud of its achievements. First pass results from several grassroots projects demonstrate a compelling technical success story and leave Toro with some very exciting exploration leads to follow up in 2011. We look forward to getting back out on the ground in WA and the NT early in the New Year."
For the complete Toro Energy announcement including figures and tables, please refer to the following link: