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| Tasmantid hotspot | |
|---|---|
| Name | Tasmantid hotspot |
| Type | Hotspot track |
| Location | Tasman Sea, Australia, South Pacific Ocean |
| Coordinates | ~24°S 155°E to 40°S 160°E |
| Age | ~33–7 million years |
| Last eruption | Miocene–Pliocene (onshore remnants) |
Tasmantid hotspot The Tasmantid hotspot is an inferred mantle plume track responsible for a north–south chain of volcanic seamounts, islands, and volcanic provinces in the Tasman Sea off eastern Australia and along the eastern margin of the Australian Plate. It underlies a linear array of extinct volcanic centers linked by consistent age progression and geochemical signatures, and its study connects research in plate tectonics, mantle dynamics, and marine geology involving institutions such as the Australian National University, CSIRO, Geoscience Australia, and international collaborators from Scripps Institution of Oceanography and the British Geological Survey.
The Tasmantid hotspot track crosses the continental margin of eastern Australia and extends into the South Pacific Ocean along the Tasman Sea with seamounts and ridges aligned roughly north–south parallel to the Lord Howe Rise and the New Caledonia Basin. Its position with respect to the Australian Plate, the Pacific Plate, and the Antarctic Plate places it adjacent to features like the Lord Howe Island province, the Tasmantid Seamounts, and the Larne Seamount chain, and it is mapped in marine geophysical surveys by agencies including Geoscience Australia and research vessels from CSIRO.
Interpretations of the Tasmantid hotspot invoke a mantle plume origin comparable to models developed for Hawaii and Iceland, yet alternative explanations involve shallow mantle melting influenced by lithospheric structures such as the Lord Howe Rise and reactivated zones from the breakup of Gondwana. Evolutionary scenarios reference events like the opening of the Tasman Sea, the motion of the Australian Plate since the Oligocene, and interactions with nearby volcanic chains including the Lord Howe Seamount Chain and the New England Seamounts. Geological syntheses cite stratigraphic correlations with onshore units such as those at Ballina and Coffs Harbour.
Volcanic outputs attributed to the track include tholeiitic to alkaline basalts, minor basanites, and evolved phonolitic to trachytic suites preserved on islands and seamounts including Lord Howe Island, the Vanuatu-proximal seamounts, and submerged edifices mapped by multibeam surveys. Petrographic and geochemical comparisons have been made with lavas from onshore occurrences at Young, Grafton, and Nambucca Heads, and with ocean island basalts studied at Scripps Institution of Oceanography and described in compilations by Geoscience Australia.
Radiometric dating, including K–Ar and Ar–Ar methods applied to dredged samples and onshore flows, shows an age progression from older Miocene seamounts in the north to younger Pliocene centers to the south, consistent with northeastward absolute motion of the Australian Plate relative to the deep mantle. Chronologies link to regional stratigraphy such as the Eocene–Oligocene transition and to seismic reflection profiles across features like the Lord Howe Rise. Correlations have been drawn with global plate reconstructions produced by groups at the University of Sydney, the University of Queensland, and the University of Wollongong.
The hotspot track is situated on the eastern margin of the Australian Plate where interactions occur with major structures formed during the breakup of Gondwana and the opening of the Tasman Sea. Tectonic influences include flexural responses of the continental shelf, stress regimes related to motion with respect to the Pacific Plate, and reactivation of basement lineaments recognized in work by the Australian Geological Survey Organisation and university research groups. The hotspot has been implicated in intraplate volcanism that affected basins such as the Newcastle Basin and the Great Artesian Basin margin.
Geophysical investigations using multichannel seismic reflection, gravity, magnetic anomaly mapping, and marine geophysical campaigns by vessels operated by CSIRO and international partners have imaged seamount edifices, volcanic rift structures, and crustal thickness variations beneath the track. Geochemical fingerprinting—major, trace element, and isotope studies (Sr–Nd–Pb–Hf)—has compared Tasmantid lavas with those from Hawaii, Reunion, and Galápagos, showing enriched mantle signatures interpreted in mantle plume frameworks developed at institutions such as Scripps Institution of Oceanography, Oxford University, and the University of Cambridge.
Seamounts of the track provide habitats for diverse marine biota studied by researchers from University of New South Wales, Australian Museum, and international organizations such as the International Seabed Authority and the Convention on Biological Diversity. Fisheries, benthic ecology, and biodiversity on seamounts intersect with conservation policy discussions involving DAFF and regional stakeholders. Economic considerations include potential mineral resources mapped by Geoscience Australia and hydrocarbon provincial implications for offshore basins assessed by companies like Woodside Petroleum and research consortia at the Australian Institute of Marine Science.
Category:Volcanism of Australia Category:Seamounts of the Pacific Ocean