Palaeomagnetism of cretaceous sediments from Misool, Northeastern Indonesia

Abstract

Palaeomagnetic analysis of Mesozoic pelagic sediments of the island of Misool, northeast Indonesia, showed that a large part of the sediments have very low initial remanence intensities. Progressive demagnetization both with alternating magnetic fields and with heating yielded characteristic remanence directions in two formations: the Waaf Formation of Santonian age revealed the following data: D = 318.10, I = -33.8 °, with ass = 4.9°; the Fafanlap Formation of middle Maastrichtian age gave: D = 176.10, I = 38.30, with ass = 5.1 =. The fold-test applied to the Wasf Formation was positive. Pole positions derived from the rocks of Misool do not coincide with those of Australian rocks of approximately the same age. Very probably, Misool formed part of the microcontinents that split off from Australia in late Triassic-Jurassic times. In the late Cretaceous Misool was positioned at a palaeolatitude of 20 ° south. At that time the crustal fragment of Misool was located at least 1000 km to the northnorthwest or northwest of Misool's present position, and thus far away from Australia. Since late Cretaceous time Mlsool has moved northwards, but not as fast as the Australian continent. Misool has undergone an anticlockwise rotation of approximately 20 ° relative to Australia.