30th May 2008 08:49
30 May 2008
INITIAL DRILLING AT THE NEW OJARANZO PROJECT CONFIRMS HISTORICAL INDICATIONS OF WIDESPREAD, SHALLOW URANIUM MINERALISATION
The Directors of Berkeley Resources Limited (AIM: BKY.L) are pleased to provide initial results of the first stage of exploration at the Ojaranzo prospect in Cáceres Province, Spain.
Two diamond core holes, located about 300m apart, have been drilled to confirm the validity of results from historical roto-percussion drilling within a northeast trending radiometric anomaly measuring approximately 1,200m by 550m. Both holes intersected significant shallow uranium mineralisation including (at a cut off grade of 0.01% U3O8):
These results indicate extensive, near surface uranium mineralisation, at potentially economic grades, within the radiometric anomaly and are consistent with available information from shallow historical drilling. Importantly, this anomaly coincides with strongly deformed shales close to the contact of a granite pluton. This favourable geological setting is enhanced by the presence of overlying Tertiary cover, both within the area and along strike.
These encouraging initial results will be followed by a Reverse Circulation drilling program later in the year, after the conclusion of the high risk fire season.
Enquiries - Managing Director: Matt Syme Tel: +61 417 906 717
RBC Capital Markets: Martin Eales Tel: +44 20 7029 7881
Background
The Ojaranzo project is located 4-5km southwest of the village of Puente del Arzobispo in the eastern part of Berkeley's Cáceres VI Almendro license area. This license contains a number of perigranitic uranium mineral occurrences of which Ojaranzo is a typical example. Other prospects include the encouraging Gambuta project located about 15km to the west, where RC drilling is in progress, and El Zarzal.
The initial discovery of uranium mineralisation at Ojaranzo was made by the Junta Energia Nuclear ("JEN") during the 1960's in a work program that included over 1,000 shallow wagon drill holes, up to depths of 25m, 129 trenches and 10 small shafts. Further work by CISA (a joint venture between ENUSA - the Spanish State uranium company - and AREVA) during the early 1990's included a programme of geological mapping, detailed ground radiometrics and 21 trenches.
CISA's initial assessment of the JEN results indicated a 600m x 400m anomaly at Ojaranzo with encouraging values in trenches and wagon drilling. For example:
Hole # Intersection* Hole # Intersection
C59 9.5m @ 0.16% U3O8 C36 12.0m @ 0.12% U3O8
C9 12.0m @ 0.07% U3O8 C20 12.0m @ 0.06% U3O8
C33 21.6m @ 0.06% U3O8 C37 12.0m @ 0.10% U3O8
C44 9.6m @ 0.06% U3O8 C42 14.4m @ 0.08% U3O8
C35 10.6m @ 0.07% U3O8 C41 7.2m @ 0.09% U3O8
B7 7.2m @ 0.07% U3O8 C53 12.0m @ 0.05% U3O8
C54 14.4m @ 0.08% U3O8 E3 10.6m @ 0.2% U3O8
*A 1992 CISA report states that minimum widths of 2.4m were applied to mineralised intersections, which were determined from JEN radiometric logs and therefore probably represent radiometric equivalent grades, as no assay values were determined by JEN or CISA. Berkeley is unable to verify the accuracy of these results without additional drilling
CISA then targeted a program of 23 roto-percussion drillholes. Fifteen of these holes recorded significant anomalous radiometric response in the downhole logs, which CISA believed equated to uranium mineralisation. These positive holes were located within a 400m long section of the anomaly. No chemical assays were completed, and only summarized downhole gamma readings are available. CISA's radiometric and geological logs broadly define the magnitude and tenor of the anomaly and the degree of weathering and differentiate between intrusive and metasedimentary material. Several historic drill collars have now been located and their positions are within acceptable limits (1-2m).
Aerial Survey
In late 2007 Berkeley completed a helicopter-borne radiometric and magnetic survey over the Caceres VI license area to better define the extent of the known uranium occurrences and to identify potential extensions and possible new occurrences.
The survey comprised 1,468 line kilometres on 100m spaced north - south lines using a towed magnetic sensor at a nominal height of 35m, with a spectrometer positioned inside the aircraft. The survey specifications, supervision, quality control and data interpretation were undertaken in conjunction with Berkeley's senior geophysical consultant, Bob White.
The results show the Ojaranzo uranium mineralisation to occur within a strong, northwesterly trending magnetic feature. Although the source of the magnetic anomaly and its relation to uranium mineralisation is not yet known, a second, untested radiometric anomaly occurs about 1km to the southeast of Ojaranzo (Ojaranzo Sur) in a similar stratigraphic position to Ojaranzo and within the same magnetic feature.
The Ojaranzo radiometric anomaly appears to be partially blanketed by Tertiary cover to the north and east. Similarly, southeast of Ojaranzo the radiometric anomaly decreases in strength and this may also represent the influence of Tertiary cover. Preliminary surface mapping indicates some areas of Tertiary deposits and areas of outcropping weakly radiometric shales.
The magnetics suggest east-west, northwest and northeast orientated structures, but their relationship to mineralisation is currently unknown.
Berkeley Drilling
Two angled diamond core holes have been drilled to confirm the results of historical percussion drilling and to clarify geological and structural controls on the mineralisation.
Drill Hole Details and Intersections (200ppm cut-off)
|
HOLE_ID |
UTM_E (m) |
UTM_N (m) |
RL |
Inclination |
EOH |
From |
To |
Interval |
%U3O8 |
|
OJA-001 |
310,831 |
4,404,185 |
437 |
-60 to 230 |
125.5 |
6.15 |
6.7 |
0.55 |
0.0244 |
|
9.0 |
10.0 |
1.0 |
0.0327 |
||||||
|
13.3 |
13.8 |
0.5 |
0.0545 |
||||||
|
16.3 |
18.6 |
2.3 |
0.0650 |
||||||
|
22.0 |
23.0 |
1.0 |
0.0237 |
||||||
|
47.0 |
51.0 |
4.0 |
0.0790 |
||||||
|
55.0 |
56.0 |
1.0 |
0.0343 |
||||||
|
58.5 |
59.5 |
1.0 |
0.0338 |
||||||
|
OJA-002 |
310,860 |
4,403,860 |
443 |
-60 to 230 |
59.65 |
18.0 |
22.0 |
4.0 |
0.0708 |
|
23.0 |
23.85 |
0.85 |
0.0881 |
The Grid has a datum of UTM 30N ED50.
These results confirm the significance of the results obtained in the previous CISA roto-percussion drilling and indicate the potential for extensive shallow mineralisation. A Reverse Circulation drilling program to test the broader extent of the anomaly will commence later this year after the high fire-risk season.
Geology
A basement of thermally altered Cambrian to Precambrian metasediments (originally shales and greywackes) has been intruded by extensive Hercynian granites. At Ojaranzo, recent erosion has exposed windows of poorly outcropping metasediments consisting dominantly of spotted and finely banded dark grey phyllites with near-surface, litho-structurally controlled uranium mineralisation.
Although no primary mineralisation has been observed, high radiometric values are associated with closely spaced sub-vertical, bedding parallel shears and fractures (1400), often with quartz, pyrite/Fe-oxides grains and secondary autunite and gummites. This shear zone can be traced using radiometrics for over 600m.
A genetic model, similar to that developed for the Retortillo deposit, appears to also apply at Ojaranzo. Oxidized ground waters carrying dissolved uranium species came in contact with a reducing metasedimentary package, resulting in deposition of the uranium as pitchblende and coffinite.
Radiometric anomalies coincide with topographically lower areas where recent erosion has created windows in the Tertiary cover.
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