DETERMINING GLACIAL SEDIMENT DEPOSITIONAL MECHANISMS THROUGH ANISOTROPY OF MAGNETIC SUSCEPTIBILITY

Patterns of sediment deposition provide insight into the dynamics of past glacial systems and their impact on cryosphere landscapes. Anisotropy of magnetic susceptibility (AMS) is a technique that measures the magnetic alignment of sediment particles that accumulates during strain and thus is a powerful diagnostic tool for identifying the processes of glacial sedimentation. Specifically, it may help distinguish between sediments that melted out of basal ice or lodgment till that was deposited during deformation. A lack of defined AMS fabric is commonly ascribed to melt out tills; however, this criterion becomes less straightforward when sediment is entrained during active deformation, potentially preserving developed fabrics. In this study, we conduct a comparative analysis of in situ AMS measurements obtained from the Copper Falls till unit in Wisconsin, believed to have been deposited through melt out by the Laurentide Ice Sheet, with analogous measurements performed under controlled laboratory conditions. We acquire AMS data with a Kappabridge KLY-3, recording the magnetic alignment of particles within the sediment for both in situ and laboratory settings. Our preliminary findings reveal distinctive AMS signatures, indicating common magnetic fabrics between in situ melt out till and our laboratory-based measurements. These results shed light into glacial depositional mechanisms and underscore the significance of AMS analysis in unravelling past environmental conditions and glacial dynamics.