A drilling programme at a sizeable anomaly beneath a dry salt lake in South Australia has been successfully completed with encouraging preliminary geology observations.
The Torrens project is located within the Stuart Shelf region of South Australia about 50 km from modern mining company Oz Minerals’ Carrapateena deposit and 75 km from multinational mining group BHP’s Olympic Dam mine, the world’s fourth largest copper resource. The iron oxide copper-gold target (IOCG) covers a large magnetic and gravity anomaly with a footprint greater than Olympic Dam.
The Torrens anomaly is one of the largest and most geologically prospective IOCG exploration targets in the world. The anomaly sits under a 250-km-long dry salt lake and is on the Torrens hinge zone, a continental scale zone of crustal weakness with the capacity to act as a conduit for mineralising mantle fluids.
The project is a joint venture between ore miner Aeris Resources (70% interest) and local mining company Kelaray – a wholly owned subsidiary of mining exploration company Argonaut Resources.
The first drillhole, TD7, was completed last month and targeted a coincident magnetic and gravity anomaly defined from the FALCON geophysical survey flown early in 2018.
TD7 was located about 1.5 km from the shoreline of Lake Torrens and was drilled to a total depth of 858.6 m. The unique drill setup and infrastructure requirements to allow drilling to occur on the salt crust surface of Lake Torrens have been successfully managed, says Aeris executive chairperson Andre Labuschagne.
Core samples from TD7 taken from 677.17 m downhole show dark grey hematite bands within a potassium feldspar and sericite-dominant alteration assemblage.
Drill core from TD7 will be transported to Adelaide, in Australia, for sample preparation and assaying, with assay results expected in towards the end of next month.
Following the completion of drillhole TD7, the drill rig and site infrastructure was safely demobilised and moved a further 7 km east from Lake Torrens’ western shoreline for commencement of drilling TD8.
This started on February 23 and was the first drillhole to be drilled more than 4 km from the Lake Torrens shoreline.
The next drillhole – TD9 – will be in close proximity to TD8 as the targeted deep gravity anomaly is still to be tested.
Stage 1 will involve 8 to 10 drill- holes to depths of 700 m to 1 500 m at priority drill targets. The drilling programme will be the first phase of a multiphase programme that is expected to take up to two years and comprise 20 to 30 deep drillholes.
“While it is early days and logging and assays are still pending, we are very encouraged with what we have seen from this first hole,” concludes Labuschagne.