Abstract

New georaorphic, sedimentologic, and chronologic data are used to reconstruct late Quaternary ice-sheet flow patterns, deglaciation, and isostatic uplift along the largest marine trough connecting the Laurentide Ice Sheet with the North Atlantic Ocean. The Lake Harbour region was targeted for study given its potential to record flow from several ice-dispersal centers. Striations and sediment provenance indicators define flow patterns. Thirty-four radiocarbon dates constrain a chronology of events. Centuries or millennia(?) before deglaciation, a southeast-flowing ice stream impinged on southernmost Big Island, as recorded by a single striation site and delimited in extent by geomorphic evidence of cold-based ice. During the Cockburn Substagc (9000–8000 BP), the region was scoured by southward to southwestward flow from an ice cap on Meta Incognita Peninsula, as recorded by 60 striation sites along 200 km of coastline. Carbonate erratics are uncommon in till above the marine limit. Where present, they suggest that southward flow reworked older drift. At about 8200 BP, the area was dcglaciated, and the marine limit was established at elevations of 67–141 m above high tide. Iceberg calving and sediment discharge from an ice margin in Ungava Bay, Hudson Bay, or Foxe Basin then blanketed the area with limestone-rich glaciomarinc sediment. Afterward, the region experienced slow but sustained emergence. The data revise the maximum lateral extent of a Late Wisconsinan ice stream in Hudson Strait and emphasize the extent of a late-glacial ice cap on western Meta Incognita Peninsula.

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