Late Mesozoic and Cenozoic palaeomagnetism of Australia–I. A redetermined apparent polar wander path

Summary. Palaeomagnetic measurements have been carried out on one Cretaceous and five Cenozoic sedimentary sequences of Australia; of those, one is in the Carnarvon Basin of north‐western Australia, and the others are in the Otway Basin of south‐eastern Australia. The new results are used together with those published previously to define a revised late Mesozoic–Cenozoic apparent polar wander path for Australia. This path differs from earlier, basalt‐derived paths by the absence of a large westward excursion and zig‐zag irregularities. It is characterized instead by a substantially straight Cenozoic trajectory, a sharp bend in the Late Cretaceous, and a non‐uniform rate of apparent polar wander. The early Tertiary segment of the new path lies north of the original paths, thus eliminating a discrepancy that has been noted previously between the Indian and Australian palaeomagnetic data (Luyendyk & Rennick, Peirce and Klootwyk & Peirce). A re‐examination of the original data suggests that this discrepancy, as well as two others in the Australian results, may have been caused principally by incomplete time‐averaging of remanence directions, because the volcanics on which the results were based had been extruded episodically.