Antarctica‐Australia fit resolved by satellite mapping of oceanic fracture zones

Abstract

Sea floor spreading between Antarctica and Australia was resolved into two stages: (1) fast (27 mm/year), from the present to 49 Ma on a northerly azimuth constrained by well mapped fracture zones; and (2) slow (4.5 mm/year), from 49 Ma to break‐up at 96 Ma. A northwesterly azimuth was inferred by interpolation between the position of the continents at 49 Ma and the initial fit of the continents at break‐up at 96 Ma; during this stage, jumps to Australia of the spreading ridge west of the Spencer‐George V Fracture Zone were postulated to have transferred parts of the Australian Plate to Antarctica. Recently acquired satellite gravity trends confirm the inferred northwesterly azimuth and ridge jumps of the early spreading stage.

Key words:

• Antarctica‐Australia fit
• ridge jumps
• satellite gravity anomalies
• sea floor spreading pattern