North Tuckabianna, near CUE
EL20/714, Cullen 100%
E20/714 lies approximately 30-50km east of Cue, covering the northern part of the Tuckabianna – Webbs Patch greenstone sequence, the eastern granite-greenstone contact, and possible greenstone enclaves within mapped granite. The principal exploration targets are gold and VMS-style base metal mineralisation in this under-explored northern section of the greenstone sequence, which is largely covered by colluvium and sand plain.
Silver Lake Resources Ltd (ASX:SLR) on 10 November 2011 announced significant drilling results (including 9.3 @ 15.4% Cu with 2.0 g/t Au and 29.0 g/t Ag from 61m) from its high-grade copper discovery at Hollandaire. The Hollandaire discovery is adjacent to Cullen’s EL20/714 (~ 600m) and is hosted by the prospective Eelya Felsic Complex which extends into Cullen’s North Tuckabianna project area. Cullen interprets the Hollandaire deposit as a probable volcanogenic massive sulphide deposit. Worldwide, such deposits frequently occur in clusters.
An earlier biogeochemical survey by Cullen has delineated an arcuate trend that consists of domains with anomalous arsenic, lead-cadmium and cobalt-manganese. This broad geochemically anomalous trend may encompass known base metal occurrences in the Eelya Felsic Complex such as Hollandaire, Colonel and Mt Eelya.
In light of the recent Hollandaire discovery and Cullen’s detection of broad geochemical anomalies, Cullen commissioned an extensive helicopter-borne EM survey (VTEM) to confirm the priorities for further base metals exploration across the Eelya Felsic Complex as well as test large areas of Cullen’s property where bedrock is obscured by transported cover rocks and has not been subjected to modern EM surveying or effective exploration (see Figure). The EM survey was flown in March 2012 with several targets delineated.
The company completed a 7-hole, ~1000m RC scout drilling programme at its North Tuckabianna copper/gold project which targeted three conductors identified by the VTEM survey (100-200m line spacing).
Cullen’s drilling intersected disseminated sulphide (mainly pyrite and pyrrhotite, 1-20% visually identified over intervals of 1-20m downhole) in mafic and felsic rocks at or near the modelled conductor plates from the VTEM survey in all holes drilled. The drill samples assays include a best result of 0.19% Cu and 0.21% Zn from 62-64m depth in drill hole TNRC14 at the target NT3. The best gold result is 0.12g/t from 66-68m in drill hole TNRC11 at target NT2.
RC drilling of the redefined conductor plates was completed in August 2012. A four hole, ~750m RC drilling programme (TNRC15-18) tested four EM conductors defined from the downhole surveying.
This drilling intersected semi-massive and disseminated sulphide (mainly pyrite and pyrrhotite) in three of four holes, close to the depths of the re-modelled conductor plates. The host is dominantly felsic to intermediate rock with strong quartz veining and alteration and thin units of mafic to ultramafic rocks and metasediment. Downhole surveying has been completed on these holes and indicates that in all but one hole, TNRC17, the conductor has been intersected. Drilling did not intersect significant sulphide mineralisation in TNRC 17 and may not have intersected the conductor.
The thick (7-12m) zones of disseminated sulphide together with strong alteration and quartz veining in holes TNRC15, 16 and 18 included only geochemically anomalous assay results. TNRC 15 shows anomalous copper (max.: 1980ppm) together with the following pathfinder elements maxima: As (147ppm), Bi (14ppm) and Mo (44 ppm). TNRC18 included anomalous Zn (max.: 1700ppm) and As (max.: 120ppm). The assay results for samples from these four holes did not include any significant gold values.
Regional magnetics suggest that holes TRC16-18 lie along the “Tuckabianna shear zone”, whereas TRC15 tested an EM anomaly within the felsic Eelya Complex. Given the favourable structural and stratigraphic settings of the “strong” VTEM anomalies at these sites, there may be parts of these sulphide systems intersected by the drilling that warrant further drill testing. Further, the interpreted shear zone corridor within E20/714 is considered by Cullen to be prospective for gold in general.
In addition, several lower-order VTEM anomalies remain to be tested, initially using A/C drilling, and/or ground EM. In particular two “weak” VTEM anomalies located just east of Silver Lake Resources’ (ASX : SLR) Hollandaire deposit (2.8Mt @ 1.6% Cu, 0.4 g/t Au, 5 g/t Ag, Inferred Resources), appear to be along strike and in the same stratigraphy. These anomalies may be deeper-seated conductors.
A group of “moderate” VTEM anomalies also occur on the eastern margin of the greenstone belt and close to or within an interpreted Banded Iron Formation and warrant further exploration as gold targets.
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