- - Cenozoic Reconstructions of the Australia - New Zealand - South Pacific Sector of Antarctica Steven

Reconstructions are presented documenting the relative motion of the Australia. Antarctic and Pacific plates since Chron 27 (61.1 Ma). In addition to the motion of the major plates, the reconstructions show the relative motion between East and West Antarctica and the continental fragments that make up the South Tasman Rise. Recent observations that are used in making these reconstructions include the mapping of seafloor spreading magnetic anomalies in the Adare basin, northeast of Cape Adare, which recorded roughly 150 km of opening between East and West Antarctica between Chrons 20 (43.8 Ma) and 8 (26.6 Ma). In addition, magnetic and bathymetric observations from the lselin Rift, northeast of the lselin Bank, and from the Emerald Fracture Zone, along the western boundary of Pacific-Antarctic spreading, document the rotation of the Iselin Bank between Chrons 27 and 24 (53.3 Ma). Our reconstructions indicate that there was a total of about 200 km of separation between East and West Antarctica in the northern Ross Sea region in the Cenozoic. These reconstructions document the development of a deep-water passageway between Australia and Antarctica as the South Tasman Rise clears the final piece of the Antarctic continental margin around Chron 13 (33.5 Ma).