Abstract: Drainage of the Laurentide Icecap into the Labrador Sea through Hudson Strait, Inferred from Sidescan Sonar Imagery, Seismic Profiles and Piston Cores

F. Reinhard Hesse, William B. F. Ryan, Chris Keely, Ingo Klaucke, David J. W. Piper, L. A. Mayer

Glacial waste products from the late Pleistocene Laurentide icecap were transferred to the slope and deep basins of the Labrador Sea by a variety of mechanisms: (1) hemipelagic settling from turbid surface plumes and nepheloid layers formed by glacial flour-laden meltwater; (2) turbidity currents formed by sand-laden subglacial and supraglacial meltwater; (3) ice rafting; (4) debris flows caused by slumps on the canyon walls of the upper slope and in front of the ice margin; and (5) turbidity currents developing from debris flows. Mechanisms 1-3 form part of the primary delivery system of the glacial detritus and include particularly powerful, large turbidity currents that must have generated the low-amplitude ridge-and-furrow topography on the braided sandy flood plains adjacent to t e main channel of NAMOC seen on sidescan images. These may have resulted from catastrophic subglacial-lake outburst flooding. Hemipelagic settling and ice rafting deposited the well-stratified, seismically transparent sediments on the high-relief slope south of Hudson Strait. The redistribution processes (mechanisms 4 and 5) dominate on the lower slope and rise, but are also important on the upper slope immediately in front of Hudson Strait.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994