Surface Grids, Isochron Grids, and Fault Maps, Offshore Otway Basin (Updated September 2024)

During 2021–2024 Geoscience Australia conducted regional seismic mapping across the offshore Otway Basin that extended into the frontier deep-water region. This work was part of a broader pre-competitive study undertaken in support of petroleum exploration. Seismic horizons and faults were interpreted on three regional data sets, including: over 18 000 line-km of new and reprocessed data compiled for the 2020 offshore Otway Basin seismic program; over 40 000 line-km of legacy 2D seismic data; and the Otway 3D Megamerge dataset. This digital dataset (publication date 5 August 2024) updates and replaces a previously released dataset (publication date 16 May 2022). This updated dataset includes 8 surface grids and 11 isochron grids generated from the following seismic horizons (in ascending stratigraphic order); MOHO (Mohorovičić discontinuity), TLLCC (top laminated lower continental crust), Base (base Crayfish Supersequence), EC2 (base Eumeralla Supersequence), LC1 (base Shipwreck Supersequence), LC1.2 (base LC1.2 Sequence), LC2 (base Sherbrook Supersequence), and T1 (base Wangerrip Supersequence). Fault polygons created for all surfaces (except for MOHO, TLLCC, and LC1.2) are also included in the dataset. Maps generated from the dataset depict deep-water Cretaceous depocentres, and trends in crustal thinning and rifting during the Cretaceous. This revised map package has underpinned updates to regional structural elements, including a revision of the boundary between the Otway and Sorell basins.