Final report on diamond drillhole NGDDH001

Abstract

This report summarises the provisional results from diamond drillhole NGDDH001 completed by Royal Resources Limited during 2010 within EL 24571 and partially funded by the Northern Territory Government under the 2009 Geophysics and Drilling Collaborations Agreement. The principal target commodity is uranium which was actively explored for in this area during the 1970s without success. There are no known uranium prospects within EL 24571. The Ngalia Project is located 40 kilometres southwest of the Bigrlyi Prospect. The principal exploration model is sandstone/structure hosted uranium deposits within the Carboniferous Mount Eclipse Sandstone of the Ngalia Basin, with secondary exploration models being surficial calcrete related mineralisation and Quaternary/Tertiary palaeochannel hosted uranium mineralisation. The Mount Eclipse Sandstone hosts the Bigrlyi Prospect where uranium enriched fluids have deposited uranium within a specific stratigraphic horizon. The Southwark Granite Suite located within the Arunta Block to the north is considered an ideal source rock. The Waite Creek Thrust Zone passes through the Licence sub-parallel to the boundary between the Ngalia Basin and the Arunta Block and the Vaughan Springs Quartzite is thrust over the Mount Eclipse Sandstone. Structures within the Mount Eclipse Sandstone are considered to be an ideal trap for mineralising fluids and were the focus of the exploration programme. Prior to NGDDH001, there had been no drilling conducted along this structure. The Ngalia Basin contains up to 6000m of sediments ranging in age from Neoproterozoic to Palaeozoic and preserved in an elongate structure, remnant of a much more extensive, polyphase intra-cratonic basin. The Neoproterozoic Vaughan Springs Quartzite is the oldest unit in the Ngalia Basin and forms ridges along the northern and southern margins. It unconformably overlies the Arunta Inlier basement and is in turn overlain conformably by carbonate units of the Albinia Formation. The Albinia Formation is unconformably overlain by glacial deposits of the Mount Doreen Formation and by the Carboniferous Mount Eclipse Sandstone. The Mount Eclipse Sandstone crops out widely in the Ngalia Basin and has a maximum thickness of over 3000m. Within the project area the Mount Eclipse Sandstone is exposed in patchy outcrops but is mostly masked by Cainozoic cover, which varies from 0-30m thick. Otherwise the Mount Eclipse Sandstone is poorly understood in this area. The provenance of the Mount Eclipse Sandstone is believed to be the older basement units of the Arunta Block. The Arunta Block is host to the Southwark Granite Suite, which is described in the literature as an undifferentiated megacrystic biotite and muscovite-biotite granite with minor microgranite, leucogranite, pegmatite and aplite dykes. The Southwark Granite Suite is considered to be the source of other metals besides uranium within the Mount Doreen area. Previous seismic survey data indicates that the basin is an asymmetrical synclinal structure which preserves a much thicker sedimentary succession on the northern margin, marked by northerly dipping thrusts (Waite Creek and Yuendumu Thrusts) and high angle reverse faults. The current basin configuration results from effects of the 300-400Ma Alice Springs Orogeny. This involved exhumation of the basement which became the provenance for the Mount Eclipse Sandstone, which is a medium to coarse-grained feldspathic sandstone, commonly cemented with carbonate with pebbles and shale clasts locally abundant and conglomeratic, arkosic and dolomitic sandstone and shale lenses. The Bigrlyi Prospect, within the Mount Eclipse Sandstone, was discovered by Central Pacific Minerals NL in 1971 from surface radiometric anomalies. Mapping by CPM sub-divided the basal zone of the Mount Eclipse Sandstone into eight units (Units A to H). The stratigraphic horizon of interest is the basal 500 metres of the Mount Eclipse Sandstone which contains all the uranium mineralisation encountered to date. CPM's Unit C of the Mount Eclipse Sandstone contains most of the known uranium mineralisation. Unit C tends to be white to grey in colour, while Unit D is commonly red-brown and purple in colour due to primary haematite. Uranium mineralisation is present at surface as carnotite, with uraninite present at depth below the water table. The Bigrlyi Prospect is currently thought of as a traditional sandstone type deposit with the uranium sourced from the Southwark Granite, transported in oxidising solutions and precipitated in reduced sandstones containing carbonaceous material and pyrite such as the Mount Eclipse Sandstone. Uranium minerals include carnotite in the oxidised zone and uraninite +- montroseite in the fresh rock below the water table. Montroseite is a vanadium-iron hydroxide mineral. Diagnostic alteration in the Bigrlyi Prospect includes haematitisation, chloritisation and kaolinisation. The mineralisation is amenable to acid leaching with 98-99% of the uranium and 70% of the vanadium recovered. This drilling programme was specifically designed to target the Mount Eclipse Sandstone and its intersection with the Waite Creek Thrust, where uranium mineralisation has been predicted. The aim of the drilling was to provide knowledge on the nature of the Waite Creek Thrust along the regional north-western contact of the Ngalia Basin and the Arunta Block. Royal and Aldershot believe the understanding of the tectonics of this region is essential in refining target areas and models. With most of the Mount Eclipse Sandstone overlain by cover Tertiary/Quaternary units, drilling also provided input into refinement of a regolith thickness map for future reference and input for future geophysical and/or geochemical surveys. Three drill profiles were designed based on interpretations from the known geology and results of a detailed airborne survey (magnetics and radiometrics) flown by Aldershot in 2007. The three drill profiles were spread regionally along EL 24571 and were designed to examine the variations and development of the Waite Creek Thrust Zone along a strike length of about 18 km. Drilling commenced on 26 October 2010 after repeated flooding caused abandonments and rebuilding of access roads. NGDDH001 was commenced on 28 November 2010 and completed on 1 December 2010. Initially a twenty hole aircore program was completed on three profiles to locate the Waite Creek Thrust, separating the Mount Doreen Quartzite and older formations from the Carboniferous Mount Eclipse Sandstone. It was anticipated that one diamond hole would be drilled on each profile. The aircore drilling on profiles A and B did not locate the targeted contact so no diamond drilling was undertaken on these two profiles. The third area (Line C) proposed for testing by a drill profile, crosses the southern boundary of the Vaughan Springs Syncline. Mapping identified Vaughan Springs Quartzite outcrop within 200m of Mount Eclipse Sandstone outcrop, suggesting a near vertical sequence of faulted contacts analogous to the model for the Bigrlyi mineralisation. Interpretation of the airborne magnetic survey imagery (TMI 1VD) suggested the Waite Creek Thrust is SW of the Mount Eclipse Sandstone outcrop. The aircore drilling identified the contact between the Treuer Member of the Vaughan Springs Quartzite and the Mount Eclipse Sandstone. The Treuer Member is comprised of interbedded, dark grey, micaceous siltstone and sandstone and minor, pale grey quartzitic layers. The Mount Eclipse Sandstone is a red, haematite stained, moderately sorted sandstone, distinct in appearance due to its colouring and is thought to be Unit A, based on CPM's unit descriptions. On identifying the contact, a single angled NQ diamond hole (NGDDH001) was drilled (67.6m) to intersect the contact. Approximately 7m of cover sediments were drilled before the hole entered weathered basement. Drilling intersected a weathered, fine to very fine-grained brown-grey siltstone/sandstone sequence from 7.14m to 50.85m, interpreted as the Truer Member of the Vaughan Springs Quartzite, before entering a medium-grained red sandstone, interpreted as Mount Eclipse Sandstone. A downhole gamma log shows only weak radioactivity with a slight increase (x3bg) over a 40cm interval, between 41.42 - 41.82m. No other significant gamma anomalism was observed. As a consequence, no samples were taken or submitted for analysis from NGDDH001. Magnetic susceptibility readings on the core were uniformly low with no magnetic intervals identified. The program was successful in intersecting the Waite Creek Thrust and providing drill core for future reference. It showed that the structure was not mineralised in this area. Aircore drilling on the two other profiles suggest the Waite Creek Thrust, if developed, is wholly within the Mt Eclipse Sandstone.