Single mantle plume explains twin volcanic chains off eastern Australia
Research published in Gondwana Research reveals that a single mantle plume created both the Lord Howe and Tasmantid seamount chains, which run parallel off Australia's east coast. The plume remained stable for 40 million years despite being close to another potential plume, and the lava chemistry matches. This explains the unusual side-by-side arrangement of the two chains.
The research team combined three independent lines of evidence to confirm their model. A global simulation of Earth's interior, not designed to reproduce this specific region, naturally generated a splitting plume with the same 650–900-kilometer spacing observed between the chains. Plate reconstructions spanning 200 million years identified a stalled slab of subducted seafloor with gaps on either side, matching where each branch would rise.
Chemical analysis provided the final confirmation. Lead isotope signatures in lava from both chains require over a billion years to develop, ruling out separate mantle sources. This fingerprint indicates both branches tapped the same deep reservoir, confirming they share a single origin.
This research could reshape how geoscientists interpret parallel volcanic chains worldwide, potentially leading to re-evaluation of other paired seamount systems. It may also refine models of mantle dynamics and plate tectonics, with implications for understanding volcanic hazards and the geological history of the southwest Pacific region. For the public, it offers a clearer picture of how Australia's offshore landscape formed, though direct societal impact remains limited to scientific and educational spheres.