Rock magnetism of Lower/Middle Pleistocene marine sediments, Wanganui Basin, New Zealand

Rock magnetic studies were carried out in order to identify the remanence carrying minerals and the domain state of magnetic grains in Lower/Middle Pleistocene marine sediments from the Wanganui Basin, southwestern North Island, New Zealand. Isothermal remanent magnetization (IRM) acquisition and stepwise thermal demagnetization of a three‐axis composite IRM suggest that titanomagnetite (or titanomaghaemite) is the dominant remanence carrier in these sediments. Other rock magnetic data suggest that these grains occur in a range of sizes in the superparamagnetic to pseudo‐single domain range, which helps account for the wide range of observed palaeomagnetic behaviour. Isolated occurrences of ferrimagnetic iron sulphides cannot be ruled out.