MinEx CRC has drilled 5 holes through the thick and challenging cover of the Eucla Basin on the Nullarbor. This retrieved new samples of the cover sequence, adding to previous stratigraphic drilling in the region, with one hole reaching 501m depth.

The National Drilling Initiative aims to provide precompetitive data to help exploration success in under-cover terranes, and retrieve new rock samples from never-studied areas. The Nullarbor is one of the most challenging drilling locations in Western Australia, and we have successfully demonstrated the use of the CT technology to provide both chip and core material down to beyond 500 m.

Over the past few months, the 500m RoXplorer CT rig has been operating near the Moonera pastoral station on the Nullarbor plain in south-eastern Western Australia. With the thick, limestone-dominated cover of the Eucla Basin obscuring the basement, drilling is critical to testing geophysical interpretations of basement geology.

This program under the NDI fills in a gap in the stratigraphic drilling program undertaken by GSWA in 2014–2015 which showed significant basement prospectivity for nickel and other critical minerals. GSWA tested the ability of the novel CT technology to drill through the ~500 m of cover in order to see if basement could be intersected.

The program has not been without its challenges. Unprecedented rainfall of nearly 300 mm in a week – what the area normally receives over a whole year! – flooded out the drilling. The cover sequence has also presented difficulties with a hard near-surface cap, numerous cavities, and a tendency to fracture behind the bit.

This program drilled two deep holes by the RoXplorer, plus 3 others to nearly 100 m each. The deepest hole reached 501 m, and from ~100 m depth core was selectively retrieved through the cover sequence to the bottom of the hole. These samples provide a unique perspective on the cover sequence and provide unprecedented insight to help explorers reach basement targets.