This study is based on about 4000 km of multi-channel seismic (MCS), magnetic and gravity data and 10 sonobuoys collected by the Russian Antarctic Expedition in the Mawson Sea and adjacent Australian-Antarctic basin between 102°E and 115°E. Major identified tectonic provinces and features of the study region include: 1) A marginal rift  about 300 km wide which developed as a result extreme crustal extension and unroofing of the upper mantle, and 2) An oceanic basin with  crust of not older than 81 Ma (anomaly 33) which is characterized by ultra-slow sea-floor spreading rates ranging from 3 to 11 mm/yr. Three major unconformities  identified in the sedimentary cover of the Mawson Sea are interpreted to be caused by break-up between Australia and Antarctica at about 81 Ma ago (WL1), the first arrival of the ice sheet to the Mawson Sea (WL3) and continental scale glaciation at about 34 Ma ago (WL4).