Pilot mineral magnetic data from the fine-sand fraction of glacial sediments from north Norfolk suggest that two magnetic parameters, the Absolute Saturation Isothermal Remanent Magnetism (A1000 mT) and the Median Destructive Field (MDF) may help discriminate glacial sediments of Anglian and Devensian age. Samples are most obviously separated by the large range in A1000 mT values. One group of glacial sediments have A1000 mT values between 170-340, implying a high concentration of magnetic minerals. MDF variability is low in this group, around 40-50, probably indicating the presence of easily magnetised magnetite. This group might represent a magnetically distinct Devensian 'Hunstanton Till'. The second group of glacial sediments has A1000 mT values mostly below 40, implying low concentrations of magnetic minerals, but with variable MDF values (45-70). This second group has A1000 mT and MDF values within error of previously published data for Anglian tills elsewhere in Norfolk In some localities, particularly in the Cley-Blakeney-Warham area, these magnetically distinct sediments are in close juxtaposition. The identification of glacial sediments with 'Hunstanton Till' and 'Anglian till' magnetic character supports earlier work which suggested that at least two groups of glacial sediments are present on the north Norfolk coast. A more complete study of glacial sediments in north Norfolk, using the techniques outlined here along with traditional sedimentological and mineralogical data, is needed to confirm these initial findings and extend the geographic coverage.
|Number of pages||15|
|Journal||Bulletin of the Geological Society of Norfolk|
|Publication status||Published - 2002|