12 FEBRUARY 2019
THICK, HIGH-GRADE EXTENSIONAL RESULTS AT ZOROASTRIAN CONFIRM SIGNIFICANT GROWTH OPPORTUNITIES AT BARDOC
High-grade hits of up to 17g/t Au confirm down-plunge extensions as successful testing of new exploration model opens up an important new resource growth opportunity
• Significant results received from extensional drilling at Zoroastrian South, with the first drill-hole KNCD180013, completed late last year and a further four holes completed in January. Assay results include:
2.14m @ 11.44g/t Au from 393.4m in KNCD180013
7.55m @ 6.52g/t Au from 198.5m in KND190001 including 3.15m @ 13.16g/t Au from 203.25m
19.07m @ 6.38g/t Au from 296.93m in KND190001 including 3.55m @ 17.0g/t Au from 310.30m 5.53m @ 4.47g/t Au from 368.75m in KND190001
• The 1,800m RC and diamond drilling program was extended due to the visual identification of multiple mineralised lodes in KND190001. An additional hole, KND190002 was drilled to 477m, assay results are pending.
• This drilling tested the high-grade plunge along the newly-defined fractionated dolerite, which has potential to add significantly to the understanding of the deposit and the Bardoc production profile.
• Successful testing of the exploration model confirms the presence of an additional mineralised structure at depth, with the mineralisation still open in all directions.
• Diamond drilling is now underway at the high-grade Mulwarrie satellite deposit, with three holes planned for both geotechnical and structural analysis, ensuring that future Reverse Circulation drilling can be designed to deliver optimal results.
Bardoc Gold Limited (ASX: BDC, Bardoc or the Company) is pleased to advise that it has received highly encouraging initial results from a program of extensional drilling at the Zoroastrian deposit, part of its 100%-owned 2.6Moz Bardoc Gold Project, located 55km north of Kalgoorlie in Western Australia.
The results are significant because they have confirmed immediate opportunities to grow the existing Resource inventory at Bardoc, highlighting the significant exploration upside within the Project area.
Bardoc Gold Limited | ABN 40 125 578 743
130 Stirling Highway, North Fremantle WA 6159 | Locked Bag 4, North Fremantle WA 6159 | Australia
Tel +61 (0)8 6215 0090 | Fax +61 (0)8 6215 0091www.bardocgold.com
Resource extension and upgrade drilling programs commenced at the Zoroastrian South and Blueys South deposits during the December quarter, as part of the Company's strategy to expand and upgrade the existing Resources within the newly-consolidated Bardoc Gold Project.
Results have now been received for the first four holes of the program and are reported in this announcement.
Following completion of this program, the rig has moved to the high-grade Mulwarrie deposit (located 10km north of the Davyhurst mining centre and 65km from Bardoc), to complete three diamond holes designed to upgrade the Resource category to Indicated.
Bardoc Gold Managing Director, Mr John Young, said the successful drilling program followed the application of a new geological model based on the analysis of historical datasets and the application of state-of-the-art computer modelling.
"We have been able to transform our thinking about the Zoroastrian deposit compared with the original interpretation based on limited open pit mining undertaken at the deposit by Excelsior Gold," he said.
"This recent work has allowed us to successfully define and explore the target host dolerite unit at depth, resulting in a decision to change the angle of our drilling in order to intersect all of the mineralised lodes at depth, within the favourable host dolerite.
"This is a very exciting development, which suggests that this deposit could well and truly open up down-plunge with multiple high-grade lodes. In light of this, we have decided to extend the current drilling program in order to lay the foundations to expand the Bardoc Resource in this area."
Zoroastrian Extensional Drilling
Drilling was planned to target potential down-plunge extensions for two of the multiple high-grade lodes at the Zoroastrian deposit. The first three diamond holes were drilled towards the east targeting the Zoroastrian South Lode, which daylights some 500m to the south of the recently completed Zoroastrian Central Pit and plunges to the north at about 40-50 degrees (see Figure 2).The fourth diamond hole was drilled towards the south-east (145o azimuth) targeting all potentially mineralised structures of the Zoroastrian system within the recently defined fractionated dolerite host unit.
An additional hole was added to the program after the drilling of KND190001.
The hole was successful in intersecting all lodes (Pearl, Blueys South, Zoroastrian South and Bank of England) as well as the multiple footwall and flat lodes, and the hole was completed at a down-hole depth of 477m.
The original program of four diamond drill holes for 1,800m was extended to include an additional hole. KND190002 was collared 55m to the south-east of KND190001, as shown in Figure 1 which is a plan view of the two drill holes and their orientation designed to drill within the differentiated dolerite unit.
Figure 2 is the oblique section 55°S of grid east (145°S).
Results have been received for holes KNCD180013, KNCD180014, KNCD180015 and KND190001.
KND190001 is a significant hole for the Zoroastrian deposit. Not only has it intersected significant gold mineralisation, returning, amongst others, a thick intercept of 19.07m @ 6.38g/t Au from 296.93m, it is also the first hole that has targeted multiple lodes within the now defined preferentially mineralised fractionated dolerite host unit. It should be noted that the drill orientation of KND190001 is designed to remain within the favourable dolerite host targeting successive mineralised structures with depth. As suchthe steep west dipping lodes are intersected at an oblique angle and true lode widths are approximately 40% of the downhole intercept widths. Drill intercepts through flat lying lodes could approach true width.
KNCD180013 intersected the Zoroastrian South Lode at 393.4m, returning 2.14m @ 11.44g/t.
Results from holes KNCD180014 and KNCD180015 were lower grade in nature, however they all intersected their main target in the Zoroastrian South and Blueys Lodes, encountering reasonable mineralised widths but outside of the preferred dolerite unit as the holes lifted.
Figure 1: Zoroastrian Plan View showing recent drilling locations. Note drill orientation of KND190001 and
KND190002 designed to remain within the favourable host dolerite unit
Figure 2: Zoroastrian Oblique Section showing KND19001 drill intercepts and interpreted mineralised lodes
There are a number of exploration opportunities and concepts that will be tested in the coming months within the Bardoc Gold Project, including:
• Current drilling may increase the Zoroastrian UG Mineral Resource and hence Ore Reserve, as currently only two of the five known lodes are in the mine plan.
• Drilling is planned to extend the resource at Aphrodite.
• Data from the drilling at Mulwarrie will provide key data to target the high grade shoots and provide data to allow a possible upgrade of resource category.
• The current Zoroastrian geological model using the known position of the fractionated dolerite and the semi-regular spacing of north-south striking, west-dipping, shears, has the potential for additional shears that do not reach the surface, beneath the Bank of England shear. Hence there is significant gold potential at depth that is yet to be tested.
• Drilling that can intersect multiple lodes within the one hole saves both time and money, making it more cost effective. The learnings and techniques from the work completed at Zoroastrian are now being applied at other significant prospects within the Bardoc Project, in particular at Aphrodite and Bulletin South to enable the next round of drilling to focus on high quality, geologically-driven targets.
THE ZOROASTRIAN DOLERITE AND MACHINE LEARNING
After the cessation of mining at Zoroastrian (August 2017), the Company embarked on an exploration program that was based on using the best available technical data to enable the optimal use of Company funds by minimising the drilling of low chance of success drill holes.
Through working with external consultants (Greg Wilson, Scott Halley, CSIRO), initial characterisation of the
Pleasurebound Dolerite, located just 500m west, was applied and modified by BDC's geologists and data scientist to suit the Zoroastrian Dolerite.
Through an iterative process of machine learning using whole rock multi-element portable XRF (pXRF) data, application of mapped geological structures (from drill core and pit mapping) and 3D modelling, it is now possible to identify and map the preferred host unit of the Zoroastrian Dolerite both quickly and cheaply.
A classification tree was developed in house by using the lowest error rate through recursive partitioning. At each decision node pXRF analyses of V, Zr, Nb, Fe and P are considered with Cu and Sc in the surrogate splits. In the later nodes, Mg comes into play.
The analysis of large datasets via machine learning and data science has enabled Bardoc Gold to successfully define and explore the preferred dolerite unit at depth.
Additionally, with a much better understanding of the geology, the drilling direction has been adjusted to enable drill holes to now intersect multiple lodes within the preferred host unit.
KND190001 has confirmed the exploration model used by Bardoc's geologists and gives the Company confidence to explore deeper, targeting structures parallel to the known lodes that may be blind to any surface expression.
GEOLOGY OF THE ZOROASTRIAN DOLERITE
The Zoroastrian gold deposit is situated along the Bardoc Tectonic Zone and is structurally related to the giant (Golden Mile) and other world-class deposits (St Ives Goldfield Camp). It is classified as an orogenic gold system with gold being hosted by the Zoroastrian Dolerite. Portable X-ray fluorescence (pXRF), whole rock multi-element analysis and geological logging were used to construct and model the Zoroastrian Dolerite mineral zonation patterns and related fluid pathways.
The litho-geochemical signature of the Zoroastrian Dolerite has been determined through immobile element geochemistry and mapping mineral zonation patterns. This has led to a better understanding of (1) fluid pathways and (2) spatial controls on hydrothermal alteration and gold deposition and now enables the Company to focus its efforts in areas more likely to contain larger tonnages of high-grade gold.
Based on the geological and geochemical classification, new lithological boundaries within the dolerite have been identified. It appears that the last phase of dolerite magmatism was more fractionated and ascended via a pathway through the crust which may have been also exploited by auriferous fluids explaining the association of gold with fractionated or chemically distinct dolerite within the dolerites at Zoroastrian.
In addition to work on the Zoroastrian Dolerite, different alteration events (Stages 1 - 6) are identified within Zoroastrian such as calcic-sodic, sodic-potassic-carbonate, silica and chlorite alteration. A Ti-mineral zonation pattern is present with titanite occurring in the least altered wall-rocks and ilmenite and rutile occurring close to, or within the high-grade gold zones. A replacement of ilmenite by rutile is a common characteristic within these high-grade gold zones not only at Zoroastrian, but also at Athena (St Ives) and East Repulse (St Ives).
A second set of mineral zonation pattern is related to sulfide minerals such as arsenopyrite, pyrrhotite and pyrite. The arsenopyrite population is paragenetically related to gold mineralization and shows mass independent fractionation. The pyrite analysis shows fractionation that suggests a deeper mantle source,