The Magnetic Properties and Fabrics of Upper Pleistocene Loess on La Motte, Jersey, and their Palaeoclimate Implications

Abstract: The island of Jersey is an interesting location for palaeoclimate reconstruction given the likely impact of variations in North Atlantic climate and European ice sheet extent during the last glacial period considering their proximal location. These last glacial climatic variations are recorded in the loess sequence from La Motte, Jersey and in order to reconstruct these changes, a detailed magnetic analysis was performed. This included measurements of magnetic susceptibility, the anisotropy of low field magnetic susceptibility (AMS) and temperature dependent magnetic susceptibility. Findings show that many models of magnetic enhancement apply to the loess of La Motte, which complicates the palaeoclimatic interpretation. Despite this, warmer and wetter conditions are shown to have prevailed during the deposition of older loess (~50 to 60 ka) considering more evidence of pedogenesis and reworking in comparison to during younger loess deposition (~40 to 20 ka) when it was relatively cooler and drier. From assessment of the magnetic fabric using AMS, there is also found to likely have been a dominance of westerly and northerly winds on Jersey during main period of younger loess deposition centred around ~23 ka, with varying wind strength. Variations in wind strength and direction at this time were likely a result of the changing configuration of the British Isles ice sheet which led to the changing influence of northerly katabatic winds.