Perth, Sep 16, 2008 AEST (ABN Newswire) - Northern Mining Limited (ASX:NMI) has previously advised the uranium exploration potential of its Durack Range Project (see ASX announcements dated 14 February 2007 and 21 March 2007). However, the stated position of the previous Western Australian Labor Government led to Northern Mining taking the decision to suspend uranium exploration activities on this Project.
The recent agreement between the Western Australian Liberal and National parties to form a new Government in Western Australia, with a stated position of not being opposed to uranium mining in the state of Western Australia, has provided fresh impetus to Northern Mining to revisit the uranium potential of the Durack Range Project.
Exploration Licences 80/3848, 80/3849, 80/3865 and 80/3913 are located over the Durack Range in the Kimberley region of Western Australia and include known uranium, thorium and heavy mineral (HM) mineralization, containing tin, identified from the limited work completed in the 1960's and early 1970's by Planet Mining (Planet) and BHP Pty Ltd (BHP). The mineralization occurs in conglomerate beds located within the King Leopold Sandstone and the Warton Sandstone which have strike lengths within the NMI tenements of 80kms and 90kms respectively.
Highlights of the King Leopold Sandstone include:
- Three significant radiometric anomalies at Mt Lush, Mt Bedford and Lansdowne, identified by BHP in an extensive survey of the Kimberleys in 1968
- Uranium and high levels of thorium in the conglomerate bands
- Conglomerate bands up to 25m thick occurring throughout the 80km strike containing narrow bands of up to 3 to 5% heavy minerals (containing up to 0.21% tin at Mt Lush).
Highlights of the Warton Sandstone include narrow, impersistent heavy mineral bands which can aggregate up to 1.2m in thickness over 2m intersections, occurring throughout the 90km strike-length within the NMI tenements.
Limited sampling showed that these bands contain an average of 2.81% HM containing zircon, anatase, monazite and ilmenite with assays showing values of up to 0.136% uranium and 2% thorium.
Previous work by Planet, BHP and others was limited and sporadic, covering only small sections of the large strike length of the sandstones. Despite Planet and BHP recommending a substantial follow-up program, no systematic program has previously been undertaken to determine whether any potentially significant economic resources occur within these areas. Northern Mining plans to undertake the first such program to determine the extent of mineralisation in the Durack Range sandstone.
OVERVIEW OF THE DURACK RANGE TENEMENTS
The Durack Range tenements cover a large area of approximately 1,200 square kilometres in the Kimberley region of Western Australia. The King Leopold Sandstone, which outcrops between Mt Lush and Lansdowne on the northern fringe of the mobile zone, contains several conglomerate horizons. The Warton Sandstone unit also outcrops within the tenement areas, which contain some of the thickest HM bands.
URANIUM, THORIUM, HM AND TIN POTENTIAL IN THE KING LEOPOLD SANDSTONE
The King Leopold Sandstone contains several conglomerate horizons within the 80km strike-length occurring in the Northern Mining tenements. These range from less than one metre to a maximum of 25 metres in thickness.
Previous uranium exploration on Northern Mining's tenements, completed by BHP in the 1960's, comprised an extensive airborne radiometric survey which resulted in the discovery of three significant radiometric anomalies at Mt Lush, Mt Bedford and Lansdowne. These anomalous zones coincide with the conglomerate horizons in the King Leopold Sandstone.
Thin, laterally impersistent bands and lamellae of heavy minerals are common in these radioactive conglomerates. BHP estimated the HM content to range as high as 3 - 5% with significant amounts of zircon and tin, probably as cassiterite, in addition to ilmenite, anatase and monazite.
Uranium occurs in small amounts relative to thorium and it was concluded that there was leaching of uranium. This leads to the possibility of uranium enrichment in suitable traps, such as at unconformities, similar to Paladin's estimated 10,000 tonne uranium resource at Oobagooma in the west Kimberleys.
URANIUM, THORIUM, HM AND TIN POTENTIAL IN THE WARTON SANDSTONE
The Warton Sandstone conformably overlies the Carson Volcanics and consists of coarse grained, quartz sandstone and minor felspathic sandstone.
The Elgee Siltstone conformably overlies the Warton Sandstone and is about 200m thick. It consists predominantly of distinctive red brown siltstone with interbedded quartz sandstone. The Teronis member, near the top of the unit is a carbonate/siltstone unit with some stromatolitic dolomite, and contains widespread stratabound syngenetic copper mineralization.
Planet Mining conducted exploration on sections of the HM bands in the 1960's and early 1970's. Costeans dug through surface indications reveal that each outcrop occurrence contains two to three closely spaced, heavy mineral bands that may be up to 0.8 metres individually and 1.2 metres collectively over a two metres thick section.
Seventy five separate outcrop occurrences of uranium-bearing heavy mineral bands have been located over a strike length of 134kms, in a purple sandstone sequence above the Carson Volcanics in the overlying Warton Sandstone. The tenement areas cover approximately 96kms of some of the most prospective areas along this strike length.
These areas are under shallow cover and contain the thickest HM bands. Limited assays from Planet reveal that the highgrade heavy mineral band contains on average 2.81% HM comprising:
- 8% anatase (titanium oxide)
- 8% zircon
- 5% monazite
- 60% ilmenite
Assays returned up to 0.136% uranium and 2% thorium. The HM bands occur in a similar setting to the conglomerate hosted uranium mines in Blind River uranium fields in Canada, where monazite containing uranium is mined by Cameco and Rio Algom.
PROPOSED PROGRAM
The Exploration Licences contain significant targets. Northern Mining intends to focus its activities on exploration for uranium enrichment at the base of the unconformities below the conglomerate beds of the King Leopold Sandstone and an assessment of the potential of the heavy mineral bands of the Warton Sandstone, to host an economic resource of uranium, thorium and heavy mineral and of the King Leopold Sandstone to host an economic resource of heavy minerals including tin. Initial work will consist of mapping of the HM bands in the Warton Sandstone and detailed radiometric surveys.
Contact
CRAIG DAWSON
CHIEF EXECUTIVE OFFICER
Telephone (08) 9244 8499
Facsimile (08) 9244 3166
Website www.northernmining.com.au
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