Palaeomagnetic dating of haematite genesis in Orcadian Basin sediments
Synopsis Stable directions of remanence in samples of the red facies of the Old Red Sandstone in the Caithness region correspond to a complex magnetisation mainly acquired in Carbo-Permian times. This indicates that haematite in these sediments formed or passed through a growth stage in late Palaeozoic Permian times that obscured most pre-existing magnetisation and was not seriously affected by any later chemical changes. The timing of this period of haematite growth illustrates the application of palaeomagnetic techniques to the dating of certain post depositional processes in sedimentary rocks and raises problems about the mechanism involved in such changes in the case of the Old Red Sandstones of northern Scotland.