High-resolution seismic stratigraphy of late Quaternary deposits in Manitounouk Sound, northern Quebec: effects of rapid postglacial emergence

• Published in: Canadian journal of earth sciences Vol. 36; no. 4; pp. 549 - 563
• Main Authors: Hill, Philip R, Simard, Annie, Héquette, Arnaud
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.04.1999; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: America; Bgi / Prodig; Canada; Fault lines; Geological time; Geology; Glaciers; Physical geography; Quaternary; Sediments; Seismology; Stratigraphy; Canada; Hudson; Quebec; Hudson Bay region; Manitounouk Sound; Quebec Canada; Earthquake; Quaternary; Marine sediment; Mass movement; Marine seismic prospection; Stratigraphy; Bay; Deglaciation; Glaciolacustrine
• ISSN: 0008-4077; 1480-3313
• DOI: 10.1139/e99-003

Manitounouk Sound contains a succession of postglacial deposits consisting of three acoustic units separated by disconformities. From base to top, these are (1) a stratified draped unit interpreted as of glaciolacustrine and glaciomarine origin, (2) an onlapping basin-fill unit of thick transparent beds interpreted as gravity-flow deposits, and (3) a divergent fill unit of stratified and transparent modern marine deposits. The gravity-flow deposits of unit 2 pass laterally into slide scars that truncate unit 1. Pollen and dinoflagellate analysis of cores correlated with the acoustic sections indicate that unit 1 is of early Holocene age and confirms a glaciomarine environment. Unit 3 contains modern assemblages of pollen and dinoflagellates. The slide scar and gravity-flow deposits of unit 2 correspond to the period of transition from glaciomarine to modern conditions and are interpreted to result from a period of relatively intense earthquake activity due to stress release along faults during or shortly after the deglaciation of Hudson Bay.