YENEENA (100% Encounter)
The Yeneena project covers a 1,300km 2 tenement package in the Paterson Province of WA located between the Nifty copper mine, the Woodie Woodie manganese mine and the Kintyre uranium deposit (Figure 1). The project is considered highly prospective for sedimentary copper mineralisation, silver-lead-zinc mineralisation, Woodie Woodie style manganese mineralisation and unconformity related uranium mineralisation.
Figure 1: Yeneena targets and major structures over magnetics
Simplified geological stratigraphy for the region comprises the Palaeo-Proterozoic Rudall Complex as the lowermost unit, overlain by the Neo-Proterozoic Coolbro Sandstone. The Broadhurst Formation sits stratigraphically above the Coolbro Sandstone and is the host to the base metals targets and the Nifty copper mine.
The Kintyre uranium deposit sits directly below the unconformity between the Coolbro Sandstone and the Rudall Complex.
The $5M 2011 exploration program at the Yeneena project is a major escalation of activity at this exciting greenfield copper exploration project.
BM1 Copper Discovery
The BM1 Copper Discovery (" BM1") is located along the McKay Fault approximately 60km south of the Nifty copper mine (Figure 1).
The copper regolith anomaly at BM1 extends over 3.5km and remains open to the north and south.
The BM1 copper mineralisation is hosted within the Broadhurst Formation and is almost entirely overlain by 2-10 metres of transported cover. The exploration target at this prospect is for a Zambian Copper Belt style, sediment-hosted copper deposit.
High grade copper mineralisation was first discovered in aircore drilling at BM1 in June 2010. Further drilling confirmed a coherent zone of high grade, near surface copper mineralisation defined over a large area in the northern section of BM1 (" Northern Area") (Figures 2 and 3).
Figure 2: BM1 Discovery - Maximum Copper in Hole over 0.75mg Gravity Shell
Figure 3: BM1 Northern Area - Maximum Copper in Hole, Red labels = 2011 drill holes
Diamond drill hole EPT751 was collared within the Northern Area oxide position and drilled south to intersect the King Fault at depth (Figure 3). The hole intersected 10.1m @ 6.8% copper from 31.9m, including an interval of 2.8m @ 12.3% copper and 156 g/t silver. A 70cm zone of black shale from 34m returned an assay result of 28.8% copper and 178 g/t silver (see Photo 1). XRD analysis from the 70cm zone confirmed the dominant copper mineral is chalcocite.
Photo 1 & 2: EPT 751 32.6m to 38.8m (Copper and Silver assay results shown along sampled intervals)
A systematic program of north-south RC drill traverses to a depth of 120m was completed in July 2011 to determine the orientation and extent of the mineralised horizon intersected in EPT751.
High grade intercepts from assay results to date include
- 6m @ 3.6% Cu from 16m incl. 2m @ 5.6% Cu (oxide)
- 20m @ 2.2% Cu from 16m incl. 2m @ 3.6% Cu (oxide)
- 10m @ 1.4% Cu from 20m incl. 4m @ 2.4% Cu (oxide)
- 18m @ 1.1% Cu from 26m (oxide)
- 10m @ 1.1% Cu from 68m (supergene)
- 4m @ 2.1% Cu from 110m incl. 2m @ 3.4% Cu (supergene and native copper)
The mineralisation encountered in the RC drilling is hosted within the black shales of the Broadhurst Formation that have undergone varying degrees of weathering. This ranges from subtle oxidation within the supergene zone to complete leaching within sections of the oxide zone. The higher grade intercepts within the oxide zone are coincident with areas of greater silicification where the mineralised horizon is more resistant to surface weathering and leaching.
The drilling has confirmed the mineralised horizon is generally flat lying through the central core of the Northern Area and then dips off to the west and to the east. This observation supports an earlier interpretation that the overall geology of the BM1 area is dominated by an open antiform that appears to plunge gently to the north. A schematic cross section has been drafted to illustrate the overall geology across the Northern Area mineralisation (Figure 4).
Figure 4: BM1 Schematic Oblique Section - Northern Area
The western line of RC drilling has intersected significant copper mineralisation below the carbon oxidation front at depths between 50-95m from surface (Figure 5). This indicates the western limb of the antiform is dipping to the west. The mineralisation along this section is dominated by chalcocite and native copper. The progression from malachite dominated mineralisation in the oxide zone to chalcocite and native copper in the supergene zone is typical of the weathering profile of a copper sulphide deposit. This provides a vector to a possible copper sulphide zone further west and at depth.
Figure 5: BM1 Northern Area - Cross Section 368300mE
A detailed helicopter EM survey (" VTEM") was completed at BM1 in June 2011. Early interpretation of this data has highlighted a series of potentially important structural controls to the copper mineralisation as well as providing greater detail on bedrock conductors. Bedrock conductors located down dip of the western and eastern mineralised limbs will be modelled and are considered high priority drill targets.
The VTEM survey has also identified two regional scale targets to the north and east of BM1 (Figure 6). These areas show similar structural and conductivity response to the main BM1 copper discovery.
Figure 6: BM1 Regional Prospects - VTEM B-Field Channel 35 (NW sun angle)
The BM2 prospect is located 50km south-east of the Nifty copper deposit and 34km north-east of the BM1 copper discovery at the intersection of a north-south trending, westerly dipping fault and the regionally extensive Tabletop Fault (Figure 1).
Three east-west aircore drill traverses were completed at BM2 in September 2010. These traverses outlined a broad area of regolith copper anomalism. The central line (Figure 7 ) included multiple thick, highly anomalous copper intersections including:
- EPT561 30m @ 0.14% Cu from 42m to end of hole incl. 2m @ 0.88% Cu
- EPT563 28m @ 0.18% Cu from 54m incl. 4m @ 0.48% Cu & 2m @ 0.41% Cu
- EPT564 36m @ 0.17% Cu from 76m to end of hole incl. 6m @ 0.37% Cu
- EPT588 20m @ 0.27% Cu from 62m incl. 4m @ 0.57% Cu
Figure 7: BM2 -Cross Section 7570470N
In June 2011 a program of north-south aircore traverses was completed at BM2. This program was designed to confirm the orientation of the mineralised trend and define any higher grade zones within the extensive area of regolith anomalism.
Field XRF, and the limited analytical results received to date, have confirmed copper regolith anomalism trending parallel to the Tabletop Fault and extending over a strike length of 1.2kms.
The aircore drill program is currently being followed up with a two hole diamond drill program (both holes drilled on the same section). Visual inspection of the drill core from BM2 has highlighted a 100m thick zone containing base metal bearing sulphide veins. The base metal sulphides observed occur within thin carbonate / quartz veinlets and narrow breccia zones and appear to be predominately sphalerite with minor galena and chalcopyrite (Photos 4 & 5). The quantity of base metals sulphides observed in the core is considered unlikely to represent an economic concentration however the wide extent of mineralised veining intersected in the first diamond holes at this prospect is highly encouraging. Significantly, the observed intensity of copper sulphide mineralisation in these holes is considered unlikely to be sufficient to account for the scale of the observed copper regolith anomalism at BM2. This interpretation suggests the potential primary source of the regolith copper anomalism is along strike from the current drill section.
Photo 4 and 5: EPT 799 - Examples of base metal sulphide veins at BM2
Encounter has confirmed the presence of a horst block of Palaeo-Proterozoic basement rocks (5.5km x 3.5km) in an area of no outcrop at the T4 Prospect which is located approximately 5kms north of the BM5 Prospect. The block was observed in three independent datasets (magnetics, gravity and AEM).
Sedimentary units on the margins of the horst block are considered highly prospective for SEDEX Cu and Pb-Zn mineralisation.
A VTEM survey was completed over the T4 region to assist in the definition of drill targets along the margin of the Rudall Complex metamorphics. The results of the airborne EM survey have been received and are currently being modelled. An initial review of the data has identified a series of basement conductors along the margin of the horst block. The conductors appear as both subparallel to interpreted dip of the stratigraphy as well as steeply discordant.
The BM5 Prospect (" BM5") is located along the regionally extensive Kintyre Fault (Figure 1). During the June 2010 quarter two diamond drill holes were completed at the prospect to test a downhole EM conductor beneath a gossanous iron manganese horizon, associated with copper-lead-zinc-silver geochemical anomalism. The drill holes were designed to test to the west of a vein of massive sulphide containing sphalerite and galena that was intersected by Encounter in drill hole EPT062 in late 2009. Assay results for the interval of massive sulphide returned 0.1m @ 28.5% zinc, 2.3% lead and 33.9g/t silver.
Additional RC drilling is planned towards the north of BM5 in the second half of 2011 where it is interpreted that the prospective geological contact is trending closer to surface.