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An anisotropy of magnetic susceptibility (AMS) investigation of the till fabric of drumlins: support for an accretionary origin

TitleAn anisotropy of magnetic susceptibility (AMS) investigation of the till fabric of drumlins: support for an accretionary origin
Publication TypeJournal Article
Year of Publication2016
AuthorsHopkins, NR, Evenson, EB, Kodama, KP, Kozlowski, AL
JournalBoreas
Volume45
Issue1
Pagination100-108
Date Published09/2015
Keywordsanisotropy magnetic susceptibility, drumlin, New York state, till fabric, Weedsport Drumlin Field
Abstract

This paper describes the results of a spatially dense anisotropy of magnetic susceptibility (AMS) till fabric study of a single drumlin in the Weedsport Drumlin Field, New York State, USA. AMS till fabrics provide a robust, quantitative and unbiased approach to assess subglacial till kinematics and infer ice-flow dynamics. The drumlin selected for this detailed investigation was systematically sampled at 18 locations to evaluate the patterns of ice flow and associated till kinematics within a drumlin and to test erosional vs. depositional models for its formation. AMS till fabric analysis yielded strong fabrics that increase in strength towards the drumlin crest, indicating that bed deformation occurred during till deposition and that deformation within the drumlin was greater than that in the interdrumlin low. Fabric orientations reveal drumlin convergent, divergent and parallel ice-flow paths that illustrate a complex interaction between ice flow and the drumlin form; fabric strength and shape reveal systematic differences in bed deformation between the interdrumlin and drumlin regions. These observations are inconsistent with purely erosional models of drumlin genesis; instead, these observations are more consistent with syndepositional streamlining of till transported, probably locally as a deforming bed, from the interdrumlin low towards the drumlin locality.

URLhttp://doi.wiley.com/10.1111/bor.12138
DOI10.1111/bor.12138
Short TitleBoreas