Published on Monday December 13 2010
Deep Yellow Limited (ASX:DYL) is pleased to announce that follow-up infill drilling at Tumas Zone 3 of the Tubas-Tumas palaeochannel in Namibia, by DYL's wholly-owned subsidiary Reptile Uranium Namibia (Pty) Ltd (RUN), has identified high-grade uranium mineralisation in the basement rocks beneath the palaeochannel; mineralised Red Sand adjacent to the channel similar to the Tubas Red Sand (TRS) deposit material, as well as additional high-grade mineralisation within the palaeochannel.
Basement Hosted Mineralisation
In November 2010 RUN conducted follow-up infill drilling near Tumas Zone 3 of the Tubas-Tumas palaeochannel to investigate reverse circulation (RC) drilling results indicating the potential for basement mineralisation below a relatively high-grade section of the palaeochannel on RUN's EPL 3496.
The investigation confirmed that drillhole ORXR1 intercepted high-grade secondary uranium mineralisation hosted in granitic basement below the palaeochannel with a mineralised intercept of
47 metres at 830 ppm cU3O8 from 29 metres.
Three scissor holes drilled on the ORXR1 section suggests the mineralisation in ORXR1 may be limited in extent in the immediate area, but provides evidence for and may provide a model for new basement hosted targets.
A 60 degree angle hole ORXR3 also returned basement intercepts of
- 4 metres at 405 ppm cU3O8 from 30 metres
- 5 metres at 412 ppm cU3O8 from 43 metres
- 5 metres at 420 ppm cU3O8 from 53 metres
Mineralisation is carnotite in both holes.
The basement mineralisation appears to be associated with the contact zone between granite and gneiss (metasedimentary rocks). Microscopic studies show that the granite is a pegmatiticleucogranite phase (alaskite). Mineralisation is secondary carnotite. Diamond drilling will be carried out in 2011 to determine the potential of this contact zone.
Red Sand Mineralisation
Reverse Circulation infill drilling around ORXR1 also identified aeolian Red Sand hosted mineralisation with drill hole ORXR37 intercepting 8 metres at 516 ppm cU3O8 from 5 metres.
Mineralised aeolian red sand from ORXR37 has very similar characteristics to the Tubas Red Sand (TRS) deposit which is part of the Omahola Project located 20 kilometres to the west. The TRS deposit contains 13.9 million tonnes at 160 ppm U3O8 for 2,217 tonnes (4.9 million pounds) contained U3O8. This new discovery, on the flank of the palaeochannel, is consistent with mineralisation at the TRS deposit and further confirms the possible extent of this unique style of uranium mineralisation over 10's of kilometre of the main Tubas-Tumas palaeochannel system.
The red sand sample from 9 to 10 metres depth in ORXR37 assayed 249 ppm U3O8 and the TRS sample from 4 to 6 metres depth assayed 327 ppm U3O8.
Palaeochannel Mineralisation
Infill drilling on a 50 metre grid to the original reconnaissance drilling has outlined further highgrade palaeochannel mineralisation with an intercepts of
- 8 metres at 614 ppm cU3O8 from 7 metres
- 11 metres at 1,097 ppm cU3O8 from 5 metres
- 7 metres at 782 ppm cU3O8 from 3 metres
The earlier reconnaissance holes are unlabelled. Significant mineralised intercepts are given in Table 1 (see link at the bottom of the release). The palaeochannel mineralisation remains open upstream (east).
Only 49 holes were completed in this restricted campaign and the various modes of mineralisation (palaeochannel, aeolian and primary) remain open in most directions and will be subjected to further evaluation by drilling in 2011.
Tumas Zone 3 Exploration Target Range
The Tumas Zone 3 reconnaissance drill data was evaluated by Hellman & Schofield (H&S) as part of the upgraded Tumas JORC Resource estimate (ASX 28 October 2010). Due to the broadly and irregularly spaced lines of drillholes at the time, the calcrete-hosted mineralisation in Zone 3 was determined to be too poorly defined for inclusion in resource estimates. However when combined with geophysical survey results, the drill results provide an indication of the orientation and extent of the mineralised zone. Consequently a conceptual exploration target range was estimated at 10 to 30 million tonnes at a grade of 300 to 400 ppm U3O8 at 200 ppm cut-off. H&S stated that it is uncertain if future exploration will result in the determination of a Mineral Resource.
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