Aileron Project EL 24741 Woodforde Annual report for the period ending 20 April 2010

Abstract

Woodforde (EL 24741) was granted on 21 April 2006 and transferred to NuPower Resources Ltd on 14 March 2007 as a result of the demerger of Arafura's uranium assets into the newly formed company focussed on uranium. There are only two known mineral prospects in the area; an occurrence of copper at Mt Airy and of tin at White Yard Hill, both in the northwest. Rare earths are reported from the Mt Finnis area immediately west of the northernmost part of the area and the Nolan's Bore polymetallic deposit lies south of the central part. The area was selected by Arafura Resources NL because of the potential for secondary uranium mineralisation, derived from the erosion of adjacent uraniferous basement granites and gneisses, and hosted by unconsolidated Cainozoic basin sediments of the Ti-Tree Basin. The Woodforde region is underlain by rocks of the Arunta Region, a complex basement inlier in central Australia that has undergone a prolonged history of sedimentation, magmatism and tectonism extending from the Palaeoproterozoic to the Palaeozoic that is subdivided into three, largely fault bounded terrains with distinct geological histories; the Aileron, Warumpi and Irindina Provinces. The basement geology of Woodforde comprises units of the Aileron Province consisting of greenschist to granulite facies metamorphic rocks with protolith ages in the range 1865-1710 Ma. It forms part of the North Australian Craton and is geologically continuous with the gold-bearing Tanami and Tennant Regions to the north. Because of the high grade of metamorphism and the paucity of continuous outcrop across the Arunta Province, a reliable stratigraphy has not yet been constructed for the metasedimentary sequences and instead, the Early-Mid Proterozoic metamorphosed rocks have been subdivided into three Divisions, intruded by granites, on the basis of broad lithological correlations, in which Division 1 is regarded as the oldest and Division 3 as the youngest. Division I rocks comprise mafic and felsic granulites and minor metapsammite and calcareous lithologies that are typified by granulite facies metamorphic mineral assemblages. They are faulted against rocks of Division 2 or form enclaves surrounded by granite, orthogneiss or granitic gneiss. In the Woodforde area they include the Tyson Creek Granulite, Weldon Metamorphics and Possum Creek Charnockite confined to the north-western corner and Aileron Metamorphics in the central western part of the area. Division 2 comprises mostly metamorphosed pelitic, calcareous, or psammitic rocks and minor mafic-intermediate meta-igneous rocks. They range from low greenschist to low granulite facies and are usually faulted against Division 1 and overlain with an angular unconformity by Division 3. Units of Division 2 are confined to the headwaters of Woodforde River in the north-western part of the area although rocks of this Division are the most extensive of the three divisions in the Reynolds Ranges region. Subdivided into 6 units they all appear to be lithological facies of one enormous flood of terrigenous detritus. Represented here by two lithologies of the Lander Rock Beds they comprise highly folded pelitic and impure metasediments ranging in grade from high amphibolite to low granulite facies that appear to have originated from a granitic terrain. Division 3 consists of a basal conglomerate or arkose overlain by a mature quartzite followed by metamorphosed pelitic and calcareous rocks. Similar to Division 2 they grade from low greenschist to low granulite. This Division is represented here by rocks of the Reynolds Range Group, a conformable sequence of quartzite, shale and carbonate. Eleven intrusive granitic units, Mid Proterozoic in age, have been mapped in the Reynolds Ranges region, grouped into 7 older granitic gneisses and orthogneisses dated at 1500-1600m.y and three younger gneisses and unmetamorphosed porphyritic granite dated at 1350-1400m.y. Five of the older granitic rocks, the Anmatjira, Boothby, Yaningidjara, and Aloolya Orthogneisses and an un-named gneiss are represented here. The Anmatjira and Aloolya Gneisses, and the un-named gneiss intrude Tyson Creek Granulite and Weldon Metamorphics in the Mt Weldon-Mt Finniss area in the northwest corner of the license where the Anmatjira Gneiss contains a small occurrence of rare earths near Mt Finniss. Boothby Gneiss outcrops in the headwaters of Woodforde River in the central-eastern part of the area and is associated with the Nolan's Bore rare earths deposit. Yaningidjara Gneiss underlies the Yaningidjara Hills in the northwest part of the area. The Orthogneisses are granitic in composition, contain xenoliths of the surrounding metamorphic rocks, locally send dykes into the surrounding country rocks and are therefore interpreted as pre-syn tectonic granites. The Arunta Block is traversed by a series of WNE-NW trending faults that locally widen into extensive zones of shearing and retrogression comprising muscovite-quartz schist with extensive quartz veins and epidote-bearing rocks. One of these, the Aileron Shear, passes through the southwestern corner of the tenement. The southern NT forms a 'basin and range' province in which Proterozoic and Palaeozoic rocks form prominent ranges separated by broad valleys in which at least twenty major Cainozoic sedimentary basins have developed of which the Ti Tree Basin underlies the eastern half of the Woodforde area. The stratigraphy of these basins is generally poorly known due to a lack of outcrop, strong weathering overprints, the paucity of drillholes and a lack of attention paid to the 'cover' overlying crystalline basement. Limited stratigraphic drilling by both the BMR and the NTGS during the 1960's and 1970's provides much of the regional stratigraphic information of the Cainozoic Basins. During the late 1970's and early 1980's the Hale Basin southeast of Woodforde was explored extensively for coal and sedimentary uranium and has therefore become the best known Cainozoic Basin in the NT and although the succession is relatively thin it is considered to represent a generalised Tertiary stratigraphy for the region. Here a broad two-fold stratigraphic subdivision comprises a restricted, fluvial palaeochannel dominated Palaeogene succession (Hale Formation) overlain by a more widespread, dominantly lacustrine Neogene succession (Waite Formation). Although the Cainozoic stratigraphic units were initially defined in separate, small and isolated Tertiary Basins, these units are now recognised as components of a much larger Tertiary palaeodrainage system, the extent and size of which has until now been vastly underappreciated. Elsewhere historic and recent drilling results indicate that the basins may contain very thick sedimentary packages. The Cainozoic fill of the Burt Basin exceeds 200m and the Sixteen-Mile Basin contains at least 180m of sediment. Similarly, the Whitcherry Basin and Waite Basins are known to exceed 250m in thickness in some locations, whilst minor tributaries feeding the Ti-Tree basin contain up to 140m of sediments. The maximum thickness of the Cainozoic sediments in the Ti-Tree Basin is not currently known as exploration drillholes to date by NuPower after drilling through a minimum of 320m of sediment, have locally failed to penetrate to basement and thicknesses of 400-500m of sediments are considered to be likely in the deeper portions of the basin. Deposition of Cainozoic sediments was episodic and punctuated by hiatuses during which prolonged periods of weathering resulted in the formation of well-developed weathered profiles (palaeosols and duricrusts). Deep weathering was an ongoing process during the Tertiary but was enhanced at particular times during this time by the combination of periods of warm, humid climates, non-deposition and surface exposure. Three Palaeogene weathering events affecting the Arunta igneous and metamorphic basement rocks and the overlying Tertiary successions and two weathering events affecting the overlying Neogene successions have been recognised. Overlying these sediments are unconsolidated Quaternary sediments including quartz sands, silts, red earths and clayey and sandy soils that record a complex history of deposition, erosion and redeposition due to climate changes and gentle tilting. The formation of calcretes, particularly within drainage channels overlying the Waite Formation, was also widespread during the Quaternary. NuPower carried out an airborne electromagnetic (AEM) survey in June-July 2007 over most of the area as part of a larger survey of NuPower's tenements in the Aileron region. The survey was designed to explore for buried palaeochannels within the Cainozoic sedimentary package as potential hosts for secondary uranium. Concurrently, water from station stock water bores was sampled and assayed for a suite of major and trace elements the results of which are expected to assist with targeting potential sites of uranium accumulation within the palaeochannel systems. AEM survey results indicated that the technique was very successful; revealing that the Tertiary palaeodrainage system is far more extensive and better developed than previously thought and indicating that the Ti-Tree Basin infills a deep structural feature developed in two NW-SE trending grabens immediately to the northeast of the Ti-Tree Fault. Several major palaeochannels flow into the basin from the southwest, north and east. NuPower also contributed to the NTGS Central Australia Gravity Survey over the Central Arunta region in the Woodforde region to acquire higher quality data for regional basement interpretation that confirmed the crustal significance of the Ti-Tree Fault. Eight water samples from seven station bores were reassayed for additional elements and a further 36 water samples were taken from NUP drillholes. Interpretation of the water geochemistry is in progress. Twelve, broadly spaced, reconnaissance drillholes were completed on Woodforde during 2008 for a total of 2,919m, from which 1459 samples were collected, of which 102 were sent for chemical assay. The drilling showed that the Tertiary palaeodrainage system on Woodforde is very well developed, reaching thicknesses in excess of 320m and NuPower has been able to establish a preliminary stratigraphic model for the Tertiary Ti-Tree Basin. One drillhole (WF004) intersected uranium mineralisation exceeding 0.01% eU3O8 and indications of anomalous gamma were detected in another six holes. Chemical assays of drill hole cuttings were very disappointing but not unexpected in view of the drilling and sampling methods employed. Composite samples from two drill holes downstream from the Nolan's Bore deposit showed no evidence of secondary accumulations of uranium, thorium or rare earth elements. Tertiary sediments were intersected in all holes, thereby validating the airborne EM data and the mineralisation intersected by reconnaissance drilling is hosted by a flat-lying, regionally widespread stratigraphic horizon that appears to occur throughout the Ti-Tree Basin. This work validated NuPower's exploration model and demonstrated that all the necessary elements for the formation of a sizeable sandstone hosted secondary uranium deposit occur on the Woodforde tenement. Stream sediment samples from the Woodforde River-Kerosene Creek area down stream from the Nolan's Bore deposit were assayed to determine the geochemical signature of the mineralisation but contained no elevated values suggesting that this type of deposit lies undetectable by stream sediment geochemistry at 10-15km down stream from source. Reconnaissance rock chip sampling of four isolated U-Th radiometric anomalies associated with small bodies of Boothby Orthogneiss and Aileron Metamorphics showed no significant anomalies, but that Ce, Nb, P and Rb are apparently elevated and may be typical of the Boothby Orthogneiss. Rock chip, stream sediment and soil samples from a prominent U-Th radiometric anomaly in the NW extremity of the tenement 5km southeast of the Mt Finniss area where there is a recorded occurrence of Ce-Th-U-Nd-La mineralisation are anomalous in Ce, Hf, La, Nb, Th, Sn and Ta. These results are considered sufficiently important for further reconnaissance work here. Rehabilitation of the drill sites and access tracks was completed in early 2009. The final round of drillhole water samples was completed in late 2009 but assay results are still awaited. The drill holes were rehabilitated at that time.