APPLICATION LOCATION & AREA:
The Ballarat Exploration Licence Application Victoria (Fig. 1) surrounds the city of Ballarat and Balmaine Gold Pty Ltd’s MIN5396 and lies entirely within the 1:100,000 map sheet of Ballarat (7622). The simplified geology of the project area is shown in figure 2 and the proposed work areas are shown in figure 3. The application area encapsulates the outer suburbs of Ballarat, farming land on basalt plains to the south and west and some Crown land to the east. There is good access to exploration sites from roads throughout the tenement area.
The tenement application is made by Mercator Gold Australia, an entirely owned subsidiary of ECR Minerals, a London-based mineral exploration company recently drilling in Victoria at Creswick (EL006184), Bailieston (EL5433), Avoca (EL5387) and with new applications at Swifts Creek (EL007484 and EL007486).
Devotion to the exploration licence
Considering the prospectivity and proximity to the Ballarat gold mine, exploration in the tenement area has been neglected for many decades while the greater mine area was held by the one company who focussed on the central lines. This means highly prospective brownfields potential rarely gets attention when the one company controls a district. Bendigo Mining recognised this dilemma and to address the problem they were making preparations to create a second separate company to explore the southern part of the field. Mercator Gold believe that a separate company is best suited to exploring the brownfields and greenfields area surrounding Ballarat to enable focus on the exploration programmes without the distractions and demands of the mine.
NATURE OF WORK TO BE UNDERTAKEN
There will be two styles of exploration work for brownfields and greenfields targets (Fig. 3). The brownfields targets are extensions of well-defined lines of the Ballarat East, Ballarat West and Nerrina fields. Brownfields exploration will be driven by diamond drilling. Greenfields exploration will initially be more regional in nature and commence on-ground with grass-roots geophysics and geochemistry to be followed by diamond drilling. As a result, two differing approaches will be adopted for the two types of exploration.
Successful community engagement will be paramount in the populated areas of the Ballarat suburbs. Mercator Gold have relationships with community engagement specialists such as Adam Place and Fiona Makin who will spend the first six months of the licence term developing good community relationships prior to drilling of the brownfield targets being considered and follow this up with ongoing community engagement. This will extend to include consultation and engagement with local indigenous, heritage and environmental groups.
Nature of office based activities
The office-based program proposed for the EL application area is expected to comprise:
- Review of open file exploration literature, historic mine and prospect production records;
- Review and appraisal of publicly available government geophysical surveys including gravity, radiometrics and magnetics;
- Incorporation of data surrounding the tenement to assist to evaluate the geology within the application area.
Nature of on-ground activities
- Ground geophysics, commencing with deep Ground Penetrating Radar (GPR) to map the basalt thickness and attempt to relate this to basement structures. Induced Polarisation (IP) will be conducted over priority areas and depending on the nature of the targets that are revealed, other geophysics such as gravity, magnetics, seismic and electrical methods will be considered where relevant. Depending on the success of the IP and other geophysics, their application over brownfields areas will be additionally considered.
- Modern Deep Penetrating Geochemistry (DPG) soil analysis techniques (such as ionic leach) will be applied which can detect pathfinder elements that have migrated through cover. Conventional soil geochemistry will be utilised in the northern and northeastern portion of the tenement where Ordovician basement outcrops.
- As there is no outcrop on the majority of the tenement, field mapping is not necessary to the west and south (area G1, Fig. 3). Some field mapping will be conducted on the northeastern (area N, Fig. 3) and eastern portion (area G2, Fig. 3) of the tenement to augment field mapping previously completed by Dr. Boucher.
Nature of sub-surface activities
- Mercator Gold have purchased their own diamond drill rig for exploration in Victoria. This diamond rig will be available to use year-round and can fit in a sound-proofed container for drilling in the vicinity of residents. The diamond rig is capable of drilling in excess of 1,000 m (NQ) which is deeper than the target depths for the first few years of the program. Mercator Gold have an excellent diamond driller who is experienced in drilling soft and hard rock. The application area has some hard rock (eg basalt) and a soft, deep weathering profile plus sub-basaltic lead gravels. Drilling such areas require careful hole planning and quality drilling.
- Other styles of drilling (eg RC or Air Core) are not considered suitable for testing the targets at this stage, but will be considered if targeting work demonstrates they may be justifiable. This may be more relevant in the greenfields portion of the licence.
LOCATION AND FOCUS OF THE PROPOSED EXPLORATION ACTIVITIES
The ELA surrounds MIN5396 and the city of Ballarat. The application area covers the northern extension of the Ballarat East line, the southern extensions of the Nerrina lines and the western, depth extensions of the Ballarat West lines. These areas will be the focus of the initial brownfields exploration work (Fig. 3).
The Ballarat East line is a complex series of faulted anticlines and deep diamond drilling is necessary to unravel the structures and mineralised systems. Suitable sites as far away from residents as possible will be selected for drill platforms to drill multiple holes from along the Ballarat East line. The northern extension of the Ballarat East line was lost by historic miners within the application area. Dr Boucher has previously conducted field mapping in this vicinity and has some insight into where the line may run and why the historic miners may have overlooked it. This can form some of the initial targeting. However, due to the likely proximity of drill sites to residents of the suburbs of Ballarat, drilling on the Ballarat East line will follow drilling on the Nerrina lines. Geophysics and geochemistry may be considered if relevant. The potential area for additional field mapping, geophysics and geochemistry is shown in Figure 3.
The Nerrina (or Little Bendigo) goldfield comprises three main lines (described below). The favoured of the three lines is the central Grey Horse line containing the Dimocks Main Shale (DMS, Fig. 2). The DMS has been previously mapped to run down the tenement boundary before it extends into the application area. However, it dips to the west and the target lies at depth inside the licence application area. The DMS is likely to extend further southwards than the most southerly workings and exploration is planned on these extensions through field mapping, geochemistry, geophysics and drilling. The Temperance line was worked very early in the exploration history of Ballarat and very little effort has been made to follow it southwards, especially in the modern era. Similar works of field mapping, geochemistry and geophysics will be conducted here. The Monte Christo line dies out before the tenement area. However, some exploration will be considered to seek extensions of this line.
The Ballarat West lines have been worked to depths beyond the planned drilling depths in the first few years of the project. Deep drilling for lateral and depth extensions of the lines will be considered in later years. As with the Nerrina lines, the Ballarat West lines dip to the west into the application area.
The focussed areas for brownfields exploration related to the three main goldfields are shown in figure 3. These will primarily be diamond-drilling based work but may include some field mapping, geochemistry and geophysics. The greenfields portion of the tenement will be explored through geophysics and geochemistry to delineate drill targets for later diamond drilling. Exploration in the eastern portion of the tenement (G2) will additionally include some field mapping. The greenfields areas are shown in figure 3.
NATURE OF TARGETS
There are two types of opportunities sought in the application area (Fig. 3):
- Brownfields exploration along strike and beneath existing mines on the portion of the Ballarat East line to the north of MIN5396, portions of the Ballarat West lines and portions of the Nerrina lines.
- Greenfields exploration under cover in the southern, western and eastern portions of the tenement area.
A full description of the targets is given in the exploration rationale below.
Basement to the ELA is Ordovician Castlemaine Supergroup deep marine turbidites that are tightly folded into asymmetrical, disharmonic and discontinuous sub-parallel anticlines and synclines. The folds have been complexly faulted by strike-parallel reverse faults and upright conjugate (crosscourse) faults. The high strain, folding and faulting is indicative of more complex geology than most other goldfields around the state. Additionally, there is a strong lithological control on the location of mineralisation where intercepted by key faults. The western and southern portions of the tenement are covered by basalt. The Ballarat West line was discovered through sub-basaltic deep lead mining and demonstrates the potential for additional lines in the unexplored portions of the tenement under cover.
The differing target models are shown in figure 4. At Ballarat East, channel sands, notably the ‘Big Sandstone’ are a brittle host for vein development on and adjacent to faults and provide competency contrast for layer parallel shearing on the margins and accompanying veining. Conversely, locations where thick shales develop, most notably the 25 m wide Dimocks Main Shale on the Grey Horse line at Nerrina contain stratabound bedding- and cleavage- parallel auriferous veins. The third portion to the goldfield, Ballarat West, is dominated by layer-parallel laminated quartz veins. This host style additionally occurs on the Temperance Line at Nerrina. Understanding the geological controls on mineralisation is critical for the exploration and evaluation of the Ballarat District, particularly to explore the greenfields area under cover in the western and southern portions of the tenement. Given the lateral repetition of multiple lines in the Ballarat district, Mercator Gold consider there is a high probability of locating new lines under the basalt cover to the west of Ballarat West.
PROPOSED TIMING SCHEDULE
The proposed exploration program is listed in Table 1:
|Year||Description of Activity|
|Year 1||Community/environmental/indigenous liaison. Literature review. Magnetic/gravity/satellite imagery interpretations. Field mapping. Geochemistry: DPG & conventional soil sampling. Geophysics: deep GPR & IP|
|Year 2||Community/environmental/indigenous liaison. Field mapping. Geochemistry: DPG & conventional soil sampling. Geophysics: IP. Diamond drilling of brownfields targets|
|Year 3||Community/environmental/indigenous liaison. Geochemistry & infill geochemistry: DPG & conventional soil sampling. Geophysics as warranted. Diamond drilling of brownfields and greenfields targets|
|Year 4||Community/environmental/indigenous liaison. Geophysics as warranted. Diamond drilling of brownfields and greenfields targets|
|Year 5||Community/environmental/indigenous liaison. Diamond drilling of brownfields and greenfields targets|
Table 1. Proposed exploration program
Mercator’s specified annual budget presented in the application is not intended as a firm figure, since the company recognises that significantly more expenditure may ultimately be justified. The company is confident in the likelihood of its ability to finance a higher figure, depending on the opportunities for drilling. These will be determined by the findings of preliminary work earlier in the term of the licence, and on the response of the community to consultations. The specified annual budget is considered to be sufficient to underpin the non-drilling activities discussed in this application, as well as community consultations and limited diamond drilling later in the term of the licence.