Development of Williams Ridge (Kerguelen Plateau) and Broken Ridge: Tectonics, Hotspot Magmatism, Microcontinents, and Australias Extended Continental Shelf

摘要: Williams Ridge, an~ 300-km-long salient extending southeast from the Central Kerguelen Plateau, and Broken Ridge, located~ 2600 km to the north, are conjugate divergent margins in the southern Indian Ocean that separated at~ 43 Ma. In early 2020, we acquired multichannel seismic reflection (MCS), sub-bottom profiling, multibeam bathymetry, and gravity data on these margins, as well as dredged rock samples. Our project constitutes the first-ever case study of conjugate oceanic plateau end-members, with the goal of advancing knowledge of lithospheric rifting, breakup, and initial plate separation processes. The first dedicated multibeam mapping of Williams and Broken ridges encompassed~ 52,000 km2 and~ 43,000 km2, respectively. Seven new RV Investigator (4) and RV Sonne (3) MCS transects of Williams Ridge totalling 945 line-km complement one legacy RV Rig Seismic MCS transect (~ 150 line-km …