Exploring till bed kinematics using AMS magnetic fabrics and pebble fabrics: North Central, New York.

摘要

The drumlins and flutes of the Weedsport Drumlin field in New York State provide an ideal location to study the development of macro and microfabrics in streamlined glacial landforms. Six drumlins and five flutes were sampled for pebble macrofabric and AMS microfabric analyses. At the site level, average orientations of maximum AMS principal axes (k1) are parallel to average pebble macrofabric maximum axis orientations. Based on rock magnetic measurements, the susceptibility is carried by maghemite grains. Macro and microfabrics are well developed in both the drumlins and flutes and are parallel to the ice flow direction that is inferred from the orientation of the landforms. This relationship suggests that the ice sheared the till bed so that elongate pebbles and magnetic particles became aligned parallel to the direction of ice movement. These results support the use of AMS as a fast, reliable and biased-free method to measure fabrics in natural tills.