THE AUSTRALIA-PACIFIC BOUNDARY AND CENOZOIC PLATE MOTIONS IN THE SW PACIFIC - SOME CONSTRAINTS FROM GEOSAT DATA

Finite poles of Australia-Pacific rotation are calculated using a thre e-plate (Australia-Antarctica-Pacific) model and published Geosat data analyses of the Indian and Pacific Oceans (GEOS-3P solution). Feature s identified on maps of Geosat data from SW of New Zealand are used to determine a new best fit finite pole for the prerift (mid Eocene; sim ilar to 45 Ma) configuration of the Australia-Pacific plate boundary a nd to refine Eocene-Miocene motions on the plate boundary (similar to 45-20 Ma; GEOS-NZ results). Inverting the Australia-Pacific best fit f inite rotation to find relative displacements between east and west An tarctica since the Eocene implies dextral oblique extension in the Ros s Embayment and almost pure dextral movement in the Queen Maud Range. Early-mid Eocene convergence predicted through Antarctica conflicts wi th geological evidence and remains an unresolved problem.