The Surveyor deposits are located about 150 km from Mt Garnet via the sealed Kennedy Developmental Road. A bitumen sealed road extends from the highway to the mine site.
The Surveyor deposits are base metal deposits of copper, gold, lead, silver and zinc.
Base metal mineralisation within the Surveyor Project area was first identified with the discovery of the Surveyor gossan by Geopeko in 1975 where, as a result, the original Surveyor Mining Lease (ML 1393) was pegged in 1978.
Carpentaria Exploration was granted an exploration tenement around the Surveyor ML and, in late-1978, discovered the Balcooma zinc-rich and copper-rich massive sulphide deposits 2 km north-east of Surveyor.
In 1985, Carpentaria tested an electromagnetic (EM) conductor about 1 km south of Surveyor Mine and intersected zinc-rich polymetallic massive sulphides in hole DRS15, the discovery hole, which was the fifteenth hole drilled in the DRS area.
The DRS deposit was mined by Kagara between 2004 and 2008. The mine was closed in 2008 when preference was given to the Balcooma underground copper project. A total of 0.85 Mt at 9.0% Zn, 3.1 % Pb and 1.0% Cu was produced during this time from the DRS deposit and 3.5 Mt at 3.0% Cu was produced from the Balcooma underground mine.
A significant quantity of high-grade remnant material remains in the DRS mine adjacent to the historically mined stopes. This is the area currently being mined by CSD.
CSD commenced dewatering and rehabilitation of the existing DRS Mine decline in early 2017 with refurbishment completed in 2018. Mining activities commenced immediately in the upper production zone with the mining of the remnant high grade pillars.
Dry River South Current Mining Activity
Rehabilitation of the existing DRS decline and upper level access is ongoing. The rehabilitation includes the installation of cable bolts and fibrecrete using the existing mining fleet. Mining of ore from the remnants within the 200 Panel is completed and the focus is now the 400 Level.
Extraction of Dry River South underground employs Longhole Open Stoping as the mining method in the upper remnant zones with Modified Avoca Stoping to be used to extract the DRS deeps orebody. Development and rehabilitation is achieved using CSD owned Atlas Copco M2D twin boom Jumbos. Longhole production drilling is achieved using CSD owned Sandvik DL432i Production Drill. Teleremote loading in stope is done by CSD CAT R1700 and R2900 loaders and ore is trucked to surface using CSD CAT AD55 articulated dump trucks. Fibrecrete is used throughout the mine, with contractor run batching plant, sprayer and ancillary equipment on site. Ore from the Dry River South Mine is hauled 150 km to Mount Garnet by road-train for processing at the Mount Garnet Processing Plant.
Dry River South Resources
Mineral Resources for Dry River South estimated by Mining Associates as of 30th August 2019 in accordance with the JORC Code 2012 are summarised below:
Dry River South – Indicated and Inferred Resources (As at August 2019)
Located on ML 1393 & 30156, the Surveyor Projects consist of DRS extensions and extensions/repeats at Balcooma.
The Surveyor project area lies within the Balcooma Metavolcanic Group (BMG) of the Greenvale Province comprising marine or possibly subaerial rhyolitic metavolcanics, metasediments and minor mafic volcaniclastics and lava. The Balcooma Metavolcanic Group was metamorphosed to lower to middle amphibolite facies and preserves a steep schistosity that may be a second-generation fabric. The metavolcanics were intruded by small microgranite and granite plutons, and porphyry dykes and sills before being deformed. The Balcooma Metavolcanics host the significant volcanic-hosted massive sulphide (VHMS) resources of the Surveyor Project.
The Surveyor, Balcooma and DRS deposits are within a NNE trending 8 km x 40 km belt of strongly deformed and metamorphosed Cambrian-Ordovician volcanics and sediments of the Balcooma Metamorphics. To the east, the Balcooma metamorphics are intruded by the Silurian Dido granodiorite.
The local stratigraphy comprises from the oldest to the youngest:
- Highway Metavolcanics – interbedded metatuffs and metavolcanics;
- Lochlea Volcanics – dacitic volcaniclastics and volcanics;
- Lochlea Metarhyolite;
- Clayhole Schist – metagreywacke with minor interbedded metapelites and metavolcanics, which in part interfingers with the overlying; and
- Dry River Volcanics – massive quartz-feldspar porphyry, volcaniclastics and metasediments.
These are intruded by the Cambro-Ordovician Ringwood Park Microgranite.
The Balcooma deposit is hosted by a meta-pelite lens within the Clayhole Creek Beds, which has been divided into a lower and upper greywacke, separated by the metapelite which comprises two varieties of staurolite bearing schist with a number of intercalated volcanoclastic lenses. Five separate massive sulphide lenses were outlined. Two of these contained the main Cu resource, while two others were more Zn-Pb rich and the fifth has been largely eroded and weathered to eventually be represented as a high lead enriched gossan. These five lenses were interpreted to represent three stratigraphic levels. (Note: These lenses were mostly already mined by Kagara before 2012.)
All deposits plunged gently to the south, with ore-grade mineralisation extending for 1.1 km down-plunge. The deepest of the polymetallic lenses extended to about 350 m below surface.
The massive sulphide lenses were vertically stacked about 100 m apart in cross section and, with depth, each lies to the north of the overlying lens. With increasing depth, the lenses were called Upper, No.1 and No.2 zinc lenses. The main copper-rich massive and stockwork sulphide lens, referred to as Main Copper, was centred roughly between and about 100 m east of the Upper and No 1 lens and was the largest of the Balcooma group of deposits and the largest deposit found to date in the BMG belt. A small copper lens immediately to the north of Main Copper, called Balcooma North, (not yet mined) is connected to Main Copper by low-grade mineralisation and may represent a structurally displaced portion of the Main Copper orebody. The copper mineralisation is interpreted as a footwall feeder zone to the polymetallic mineralisation.
The Balcooma polymetallic deposits extended for about 100 m to 150 m down-dip, ranged from 300 m down plunge (No.2 Lens) to 500 m down-plunge (Upper Lens) and were generally 5 m to 10 m thick. The Main Copper lens had a down-dip extent of approximately 100 m, and extended down-plunge for one kilometre and was up to 50 metres thick. Both the Upper Lens and Main Copper lens outcropped, and their original sizes were indeterminable. Due to the repeating nature of the Balcooma deposit there remains potential to discover additional lenses.
Dry River South Deposit (DRS)
The DRS zinc, lead-rich polymetallic orebody is a sheet of massive pyritic sulphides that dips at a shallow angle to the ESE and plunges gently to the SSW. Massive pyritic sulphides lie along, and just below, the upper contact between highly altered felsic volcanics and relatively unaltered hanging-wall metasediments and extend for up to 250 m down-dip and approximately 800 m down-plunge. The orebody reaches a maximum thickness of about 15 m in structurally thickened domains. The orebody is delimited to the west by late faulting and an extensive body of quartz feldspar porphyry. Down-dip and down-plunge limits are defined by a decrease in sulphides. To the north, the DRS orebody is cut by a complex array of late faults including the NE-trending Andesite Fault. This is interpreted to represent the first stage of structural separation of the DRS orebody from the Surveyor orebody, which lies about 600 m to the north. Access is via a portal and decline from the Surveyor Mine open pit.
Surveyor Project – Resources and Exploration Targets
Dry River South – Exploration Targets
Several targets have been identified near the DRS mine. These targets represent either extensions to the currently defined mineralised domains or sub-parallel lenses or splays to the main mineralised domain.
The upper targets within the DRS deposit have been subject to drilling during 2018. Four targets are shown in Figure 4‑3 labelled A, B, C and D. Targets A and B were drilled during 2018, key intercepts are summarised in the table within Figure 4‑4.
Significant results such as in DSDD002: 5.7 m at 4.94% Zn, 1.72% Pb, 0.69% Cu, 36.83 ppm Ag and 0.38 ppm Au were intersected in target zone A and may represent material that could be accessed from the current underground operations. Further drilling will be required to define the extent and grade of the mineralised domains intersected within this drilling program.
Dry River South – Exploration Target/Exploration Upside Targets
Dry River South Deposit Exploration – 2018 Drilling Results
Balcooma – Exploration Targets
Several near mine targets have been identified adjacent to the historically mined Balcooma deposit. The primary target for drilling programs completed in 2018 is known as the Lens 2 Upper target. A total of 21 reverse circulation holes were drilled during 2018.
The drilling was designed to target the Lens 2 Upper zone that exists approximately 50 m above the historically mined Lens 2. The Lens 2 Upper has a sigmoidal shape that dips east, plunges moderately to the south and has been subject to shearing and deformation.
Key drilling results that intersected the Lens 2 Upper domain include;
- BARD 011 – 25.1 m at 6.09% Zn from 96.2 m (including 11.7 m at 10.9% Zn)
- BARD 013 – 21.7 m at 7.43% Zn from 118 m (including 4.8 m @ 14.86% Zn)
- BARD 020 – 31 m at 2.28% Cu from 149.7 m (including 2.7 m @ 7.97% Cu)
The location of the Lens 2 Upper target is shown below (coloured magenta).
Balcooma Mineralisation Model Showing Lens 2 Area (Magenta) – Looking East
Surveyor Regional Exploration Project – Prospects
Numerous exploration targets exist within the Surveyor regional project area. Anomalies have been identified based on soil geochemistry, geophysical surveys and shallow drilling, see below. Seventeen priority regional targets have been identified and are summarized in the table below.
Surveyor Project – Regional Exploration Prospects
Surveyor Regional Prospects – Cu & Zn in Surface Soil Anomalies