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First insights into the deep structure of the eastern Australian passive margin using wide-angle seismic data: Crustal segmentation from the Tasman Basin to the northern Lord Howe Rise

Created 16/10/2025

Updated 16/10/2025

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The eastern Australian margin was shaped by the fragmentation of eastern Gondwana during the Late Cretaceous. This led to the opening of the Tasman Basin and to the formation of sub-parallel ridges and basins, including the Lord Howe Rise continental ribbon. To image the deep structure of the region, a large-scale crustal experiment was conducted by JAMSTEC and Geoscience Australia onboard the R/V Kairei with the deployment of 100 ocean-bottom seismometers (OBS) along a 680 km profile at 27.2°S. The OBSs register clear refracted arrivals from the crust and the mantle that are recorded at very large offsets, as great as 300 km. Both pre- and post-critical reflected phases from the Moho (PmP) are also very clearly recorded by the OBSs. We performed first-arrival tomographic inversion to analyze the data. An initial layered P-wave velocity model was built using the two-way travel time reflection from the basement interpreted from coincident multi-channel seismic data to constrain the thickness of the sedimentary layer. During the inversion, the PmP arrivals are used to add constraints on the thickness of the crust. The uncertainty in the final P-wave velocity model is tested by applying Monte Carlo analysis. The final Vp model shows large variations in crustal thickness and allows the identification of distinct crustal domains along the profile from the Tasman Basin to the northern Lord Howe Rise: the Tasman Basin is an oceanic domain with 6 to 8 km thick crust; further east, thicker crust is present below the Dampier Ridge; the crust again thins to 8 km below the Middleton Basin; and the northern Lord Howe Rise is floored by a 23 km thick crust. Further work will compare the modeled P-wave velocities with previouslypublished results from the southwest Pacific region and well-known tectonic provinces to discuss to the nature of the crust within the crustal domains. This will help to better understand the processes that led to the fragmentation of eastern Gondwana. Abstract submitted and presented at 2017 IAG-IASPEI conference (https://www.zisin.jp/event/iag-iaspei-2017/)

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Title First insights into the deep structure of the eastern Australian passive margin using wide-angle seismic data: Crustal segmentation from the Tasman Basin to the northern Lord Howe Rise
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/35b39dcb-d1fa-41c6-9f96-a303fd5fe2c7
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period
Geospatial Coverage
Map data © OpenStreetMap contributors
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Data Portal Geoscience Australia

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This dataset was originally found on Geoscience Australia "First insights into the deep structure of the eastern Australian passive margin using wide-angle seismic data: Crustal segmentation from the Tasman Basin to the northern Lord Howe Rise". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/first-insights-into-the-deep-structure-of-the-eastern-australian-passive-margin-using-wide-angl