Ice-marginal sedimentation and processes of diamicton deposition in large proglacial lakes, Lake Erie, Ontario, Canada

Detailed studies of coastal cliff exposures through two end moraines form the basis for a model of ice-marginal sedimentation in large ice-contact glacier-fed lakes. The input to the ice-marginal environment directly from the glacier included subglacial till and subaquatic flow tills. The subaquatic...

Full description

Bibliographic Details
Published in:Canadian Journal of Earth Sciences
Main Authors: Barnett, Peter J., Karrow, Paul F.
Other Authors: Sharpe, David
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 2018
Subjects:
Online Access:http://dx.doi.org/10.1139/cjes-2017-0006
http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2017-0006
http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2017-0006
Description
Summary:Detailed studies of coastal cliff exposures through two end moraines form the basis for a model of ice-marginal sedimentation in large ice-contact glacier-fed lakes. The input to the ice-marginal environment directly from the glacier included subglacial till and subaquatic flow tills. The subaquatic flow till (thinly bedded diamicton) was deposited in an apron (up to 1 km wide) along the ice margin. An upward gradient of pore-water pressure immediately beyond the ice margin, causing heaving and dilation of the sediments, initiated debris flows of glacially derived debris (subaquatic flow tills). Most of the stratified sediments in the ice-marginal zone entered the lake by way of a large proglacial stream. Sedimentation was dominated by quasi- or near-continuous density underflows that resulted in the deposition of a sequence of thick rhythmites. The glacier in the Lake Erie basin most likely behaved like an ice stream, with its movement controlled predominantly by a deforming bed of glacial debris, separating the glacier sole from underlying predeposited sediments. The deforming bed is preserved as a massive diamicton layer, interpreted here as subglacially deposited till.