2011 GSA Annual Meeting in Minneapolis (912 October 2011)
Paper No. 82-8
Presentation Time: 10:05 AM-10:20 AM

EXPLORING TILL BED KINEMATICS USING AMS MAGNETIC FABRICS AND PEBBLE FABRICS: NORTH CENTRAL, NEW YORK

EVENSON, Edward1, GENTOSO, Matt1, KODAMA, Kenneth1, IVERSON, Neal2, ALLEY, Richard B.3, BERTI, Claudio4, and KOZLOWSKI, Andrew L.5, (1) Earth and Environmental Sciences, Lehigh University, Bethlehem, PA 18015, ebe0@lehigh.edu, (2) Geological and Atmospheric Sciences, Iowa State Univ, 253 Science I, Ames, IA 50011, (3) Department of Geosciences, The Pennsylvania State Univ, Deike Builiding, University Park, PA 16802, (4) Earth and Environmental Sciences, Lehigh University, 1 West Packer Ave, Bethlehem, PA 18015, (5) Geologic Survey, New York State Museum, 3140 Cultural Education Center, Albany, NY 12230

The thick, relatively homogeneous, basal tills forming the drumlins and flutes of the Weedsport Drumlin field in New York State exhibit strong AMS (anisotropy of magnetic susceptibility) fabrics and pebble fabrics that are consistently oriented parallel to the streamlined bedforms. The pebble fabrics and the AMS fabrics are concordant. Thermally-induced, incremental reduction of isothermal remanent magnetization indicates that the AMS fabrics are caused primarily by oriented, elongate maghemite grains. The orientations of principal axes of maximum susceptibility (k1) are generally parallel to pebble long-axis orientations, and tend to plunge mildly up-glacier. Fabric directions are generally parallel to drumlin long-axis orientations but deviate 12-23º from flute directions. Fabrics of the flutes are stronger and more unidirectional than those of the drumlins. These results support the use of AMS as a fast and objective method for characterizing fabrics in tills and suggest hypotheses about basal processes linked to glacially streamlined landforms.

2011 GSA Annual Meeting in Minneapolis (912 October 2011)
General Information for this Meeting
Session No. 82
Processes of Subglacial Erosion, Sediment Transport, and Deposition
Minneapolis Convention Center: Room L100DE
8:00 AM-12:00 PM, Monday, 10 October 2011

Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 217

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