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 flow till (thinly-bedded diamicton) was deposited in an apron (up to 1 km wide) along the ice margin. An upward gradient of porewater 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 pre-deposited sediments. The deforming bed is preserved as a massive diamicton layer, interpreted here as subglacially-deposited till.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author