Drilling Deep into Australia’s Ancient Coral Past Reveals Devonian Secrets

On 29 September 2026, Geoscience Australia released a report on a federal drilling programme in the Adelvale Basin, outback Queensland. The initiative, costing $31 million, aimed to explore deep geological structures and assess the feasibility of storing hydrogen in a thick subsurface salt deposit. A 3 km borehole was drilled, extending through over two kilometres of crust to intersect a fossil reef that dates back to the Devonian period, roughly 400 million years ago.

The retrieved core sections revealed a complex assemblage of sponges and early‑stage corals that built a reef framework in warm, high‑sea‑level seas. Hundreds of rock samples and fossils were extracted, providing a continuous record of reef growth and the surrounding sedimentary environment. Among the recovered material, 975 metres of coral‑rich rock were identified, confirming the presence of a substantial reef system at depth.

In addition to the biological evidence, the drill team encountered evaporative rocks that point to periods when the basin experienced lake‑to‑ocean transitions. These rocks are interpreted as signatures of fluctuating water bodies that may have contributed to episodic rises in atmospheric oxygen during the early to mid‑Devonian. Researchers note that while the data hint at a possible global oxygen increase, the signal remains ambiguous and requires broader investigation.

A key objective of the project was to locate a thick salt layer suitable for an underground hydrogen battery—a concept that could store renewable energy in geological formations. Despite the extensive drilling and detailed mineral mapping, no such salt deposit was found in the surveyed section. The absence of the targeted salt horizon means the hydrogen storage concept will need to be reassessed or redirected to alternative sites.

The findings were featured in an ABC News broadcast titled “Unlocking the secrets to ancient coral reefs”, where scientists such as Crispian Yeomans, Espen Knutsen, Mitchell Bouma, Jeffrey Gilleaudeau, Holly Richardson, and Rachel Mealey discussed the implications for understanding reef evolution and ancient climate dynamics. While the project did not achieve its primary engineering goal, the geological and palaeontological insights contribute valuable context for reconstructing Devonian marine environments.

Future work will focus on determining whether the observed oxygen rise signal is a localized phenomenon or part of a worldwide trend during the Devonian. Additional drilling campaigns and comparative analyses with other global sites are planned to resolve this question. The outcomes also inform broader discussions about deep‑earth resource exploitation, carbon capture, and the potential for using ancient geological formations in modern energy strategies.

Overall, the Adelvale Basin expedition underscores the dual nature of deep‑earth research: while engineering ambitions may falter, the scientific dividends can reshape our understanding of Earth’s ancient biosphere and climate. The data gathered lay groundwork for both future energy storage concepts and refined models of early reef ecosystems, offering a richer picture of the planet’s deep past.