Australian Apparent Polar Wander Path
We have collected and analyzed a suite of volcanic rocks and weathered profiles from eastern Australia to constrain the Australian apparent polar wander path (APWP). The goal of the project has been to investigate the cause of the conflict between paleomagnetic results from sedimentary and igneous rocks, particularly those from the interval from 20-50 Ma, and ultimately to improve the Cenozoic portion of the Australian APWP. We attribute much of the scatter seen in prior paleomagnetic results from volcanic rocks to a high number of geomagnetic excursions that were fortuitously recorded by volcanic flows and to weathering and slumping, which makes sampling of unaltered and in situ exposures difficult. By taking numerous drill cores, rather than a few hand samples as was done in the past, we are better able to identify areas affected by weathering and slumping. Some of the results obtained so far are published in:

Acton, G.D. and Kettles, W.A., Geologic and palaeomagnetic constraints on the formation of weathered profiles near Inverell in New South Wales, Australia, Palaeogeography, Palaeoclimatology, Palaeoecology, 126, 211-226, 1996. [download pdf reprint]

Four versions of the Australian APWP:
(1) the Embleton APWP (yellow) derived mainly from basalts;
(2) the Musgrave APWP (green) derived from basalts and weathered profiles;
(3) the Idnurm APWP (orange) derived from sedimentary results; and
(4) the PEP APWP (dark blue with poles every 10 m.y from 10 to 70 Ma) derived from global data.
The PEP APWP is representative of reconstructed global paleomagnetic data whereas the other APWPs are based on data that are derived directly from Australia. In general, the PEP and Musgrave APWPs indicate more rapid APW from 40 to 20 Ma and slower APW from 20 to 0 Ma than the other paths. All the APWPs agree well from about 40 to 55 Ma, but diverge again for older intervals. These differences result in ambiguities when using the Australian APWP as a reference curve for other studies.