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Stratigraphic drilling completed in the East Tennant and South Nicholson

The Australian Government’s $225 million Exploring for the Future Program, led by Geoscience Australia, has enabled the completion of MinEx CRC’s first National Drilling Initiative campaigns.

In late 2020 the National Drilling Initiative (NDI) completed two stratigraphic drilling projects in the highly prospective East Tennant and South Nicholson regions of the Barkly Tableland, Northern Territory. Ten drill holes in the East Tennant and one in the South Nicholson collected some of the first ever samples in underexplored regions that are prospective for mineral and energy resources.

Geoscience Australia’s Chief of the Minerals, Energy and Groundwater Division, Dr Andrew Heap, said the scientific importance of and potential resource wealth to come from these drilling activities cannot be understated.

“These drill holes will provide a whole new generation of geological knowledge and will support future resource exploration and discovery in these geological frontiers,” Dr Heap said.

“The Exploring for the Future Program played a key role in identifying the East Tennant and South Nicholson regions as high priorities for stratigraphic drilling through combining and interpreting historical data with newly acquired innovative geoscientific data.

“This new innovative data included seismic and magnetotelluric data, which provided clues that these were potentially prospective areas. Each drill hole was then designed to enable characterisation of the stratigraphy and improve our understanding of its geological evolution and resource potential.”

Dr Heap noted the initial samples from the drilling look very promising, with the interpreted age of the rocks supporting previous assumptions about their prospectivity.

“For example, the 1750m-deep NDI Carrara 1 drill hole in the South Nicholson was designed to capture geological and stratigraphic information from a previously unknown sedimentary basin,” he said.

“Initial results indicate NDI Carrara 1 intersected rocks of the Georgina Basin, possibly the South Nicholson Basin, and terminated in the Paleoproterozoic Isa Superbasin package.

“These rocks have the potential to host both mineral and energy resources.”

Drilling at East Tennant was designed to test basement rocks, concealed by hundreds of meters of younger sedimentary rocks, interpreted to be an undercover extension of the rocks that host copper-gold mineralisation in Tennant Creek further to the west.

“The East Tennant drilling campaign has unearthed samples from a range of igneous and metasedimentary rocks. Preliminary interpretations indicate that the rocks are age equivalent to those in Tennant Creek and support our earlier interpretations of the region’s prospectivity,” Dr Heap said.

MinEx CRC CEO Andrew Bailey said the NDI's first stage had seen great collaboration between MinEx CRC, Geoscience Australia, and the Northern Territory Geological Survey (NTGS). Lessons learned from the East Tennant and South Nicholson will assist in future NDI campaigns moving forward.

“In addition to utilising conventional drilling methods, the NDI will deploy innovative mineral exploration technologies currently being developed by MinEx CRC and sponsoring organisations,” Mr Bailey said.

“These technologies will reduce the environmental footprint of the drill program (smaller drill site, lower water and energy usage), improve safety and deliver greater volume and detail of information at a lower cost.”

The NDI will provide a testing platform to refine and optimise these technologies, bringing them closer to market.

Executive Director NTGS Dr Ian Scrimgeour said the stratigraphic knowledge gained in this campaign will be used by geoscience agencies in future work.

“The NTGS was proud to provide direct contributions to the program and we’re looking forward to the new interpretations to come from this work,” Dr Scrimgeour said.

“The range of datasets and ongoing research activities on the drill holes will transform our understanding of mineral systems in the region, leading to better targeted exploration activities in the Barkly Tableland.”

The drilling data is expected to be released in early 2021 and a range of analyses to comprehensively characterise the drill holes will follow.

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