Preliminary Afmex mineralogical and geochronological studies of the pitchblende mineralisation and accompanying alteration confirm that the Gardiner-Tanami region displays similarities with the highly productive Athabasca and Alligator Rivers uranium provinces.
Pitchblende mineralisation associated with well defined graphitic conductors which a new airborne VTEM2 survey shows extending over a distance of about 8km.
Series of new priority drill targets with potential for higher grades of uranium now being defined where fault structures transect the conductors; such as:
– at Soma A1 and
– within adjacent Manhattan Corporation Limited’s exploration licence where Northern Uranium is earning 60% interest.
Additional conductors identified at depth at The Don prospect (Northern Uranium earning 60%, Manhattan 40%) and extending below sandstone cover towards Northern Uranium’s 100%-owned licence.
The drilling follows two years of extensive geophysical exploration across 6,000km2 of Northern Uranium’s tenements by its strategic partner and project operator Afmeco Mining and Exploration Pty Ltd (Afmex) – the Australian subsidiary of French nuclear group Areva NC (Areva).
The principal target at Gardiner-Tanami is the high grade unconformity-style uranium deposit type similar to the ore deposits mined by Areva and its joint venture partners in the Athabasca Basin, Saskatchewan, Canada.
Diamond drilling at the Gardiner-Tanami project commenced in August, with the objective of testing the Company’s highest priority exploration target areas at Lewis Creek North, Oracle and Soma. Results of the drilling at Lewis Creek North target area, which were encouraging, have been announced previously.
Kevin Schultz, Northern Uranium’s executive chairman said the latest results from Soma were further confirmation of the uranium potential of the Gardiner-Tanami project, and a validation of the company’s exploration strategy. “This is very promising for shareholders, as we have observed uranium mineralisation in the unconformity-type setting and have identified a host of new targets with potential for high grade uranium deposits,” Schultz said.
“Testing has also now observed the similarities between the Gardiner-Tanami and the world class uranium provinces at Athabasca and Alligator Rivers,” Schultz said. “These latest results greatly increase our confidence as we plan our follow up work programs, not only at Lewis Creek and Soma but also in the Manhattan Gardner Range joint venture area, and the 5,000 square kilometres of new tenements in the Northern Territory that we expect to be granted in 2010.”
“Northern Uranium has a unique opportunity with such a vast and strategically important land holding, similar to the opportunity that was available for uranium exploration in the Alligator Rivers when Narbalek, Ranger and Jabiluka were discovered in the 1970s,” Schultz said.
“The follow up at Soma and along the conductor extending into the Manhattan Gardner Range joint venture area will involve on-ground mapping and other surveys to pinpoint structures likely to host an ore deposit which will be tested by drilling. This work has already commenced around Soma A1 and will be continued as seasonal conditions allow early in 2010,” Schultz said. “We would hope to be drilling much earlier next year than was the case this year, when our program was delayed by the difficult financial situation that was common to all mining and exploration companies.”
“We are obviously very pleased with the way our flagship project is shaping up,” Schultz said.
Soma Drilling Results
As a first pass test of the uranium potential of the Oracle Soma target area, one diamond core hole was drilled into the Soma A3 VTEM conductor and five diamond core holes were drilled on a single cross section across the Soma A1 VTEM conductor.
To test the Soma A1 VTEM conductor holes GT04-GT08 were located on an elevated plateau of Gardiner Sandstone and drilled through to the unconformity into a basement of metasediments that are referred to as Killi Killi Beds.
As a generalisation, the holes encountered Gardiner Sandstone to depths varying from 35 to 60m. The Gardiner Sandstone display localised weak to moderate bleaching, presence of quartz dissolution features and drusy quartz along fractures.
The unconformity is characterised by a strong argillisation and bleaching overprinting a 25- 50m thick zone of intensely hematised (iron oxide enriched) Killi Killi Beds. At depths ranging from 80-250m three of the holes intersected meta-pelite with “conductive” graphite and associated 0.4m-3.0m wide radiometrically anomalous zones with disseminated sulphides (pyrite and chalcopyrite) and thin siderite veins. A high degree of fracturing associated with immature brecciation is observed within some graphitic zones, such as in Hole GT04 between 134m and 146m. An apparent east-southeasterly trending fault zone is interpreted to be the cause of a 12m offset of the unconformity.
Hand-held XRF measurements on the drill core located the following significant anomalous uranium concentrations with disseminated sulphides:
GT04 144.5m – 145.6m: spot measurements up to 113ppm U (0.013% U3O8)
155.9m – 156.3m: spot measurements up to 2,100ppm U (0.252% U3O8)
GT06 102.6m – 103.4m: spot measurements up to 219ppm U (0.026% U3O8)
GT07 164.45m – 165.6m: spot measurements up to 1,469ppm U (0.176% U3O8)
Downhole gamma logging only returned values up to a maximum of 125ppm eU3O8 and selected intervals of the diamond drill core are currently being sampled for chemical assay.
The uranium concentrations in the drill cores were determined by Afmex to be due to the presence of the minerals pitchblende and autunite (a calcium uranyl phosphate mineral). Preliminary Afmex mineralogical and geochronological studies of the pitchblende mineralisation and accompanying alteration confirm that the Gardiner-Tanami region displays similarities with the Athabasca and Alligator Rivers uranium provinces.
Mineralogical and Age Dating Studies
The initial results of the scientific studies of the Soma diamond drill cores by Afmex show that the uranium mineralisation is related to pitchblende–siderite–sulphide veinlets associated to hydrothermal alteration. Secondary uranium remobilisation as autunite is disseminated in the surrounding host rocks (Figure 5). Preliminary primary uranium deposition age was determined at approximately 1400-1500 million years (Ma), in the geological time scale. This age is younger than the age of deposition of the overlying Gardiner Sandstone (1750-1640Ma). Further age determination on pitchblende will be done to better constrain the model.
Such observations of age range link the primary uranium mineralisation in the Killi Killi basement rocks with hydrothermal fluid movement that took place after the Gardiner Sandstone deposition. This reinforces the comparisons that have been made between the Gardiner-Tanami region and the Athabasca and Alligator Rivers uranium provinces, which host the world’s largest high grade unconformity-style uranium deposits.
New Airborne VTEM Survey
As announced on 16 October 2009 Northern Uranium has reached an agreement with Manhattan providing an exclusive right for Northern Uranium to earn 60% interest in Manhattan’s Gardner Range Project by spending A$1.05m within four years.
Manhattan’s Gardner Range Project comprises exploration licences which are adjacent to some of Northern Uranium’s Gardiner-Tanami tenements, most notably E80/3275 which is contiguous with a Northern Uranium tenement covering the Oracle and Soma target areas.
