Preprints
https://doi.org/10.5194/cp-2021-132
https://doi.org/10.5194/cp-2021-132

  18 Oct 2021

18 Oct 2021

Review status: this preprint is currently under review for the journal CP.

Was there a glacial outburst flood in the Torngat Mountains during Marine Isotope Stage 3?

Tamara Pico1, Jane Willenbring2, April S. Dalton3, and Sidney Hemming4 Tamara Pico et al.
  • 1Earth & Planetary Sciences, 1156 High St, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA
  • 2Earth, Energy, & Environmental Sciences, 50 Jane Stanford Way, Building 320, Room 325, Stanford University, Stanford, CA, 94305-2215, USA
  • 3Department of Physical Geography, Opletalova 38, 110 00 Staré Město,Charles University, Prague, Czech Republic
  • 4413 Comer, Columbia/Lamont-Doherty Earth Observatory, 61 Rte 9W, Palisades,NY, 10964, USA

Abstract. We report previously unpublished evidence for a Marine Isotope Stage 3 (MIS 3; 60–26 ka) glacial outburst flood in the Torngat Mountains (northern Quebec/Labrador, Canada). We present 10Be cosmogenic exposure ages from legacy fieldwork for a glacial lake shoreline with evidence for outburst flooding in the Torngat Mountains, with a minimum age of 36 ± 3 ka (we consider the most likely age, corrected for burial, to be ~56 ± 3 ka). This shoreline position and age can potentially constrain the Laurentide Ice Sheet margin in the Torngat Mountains. This region, considered a site of glacial inception, has no published dated geologic constraints for high-elevation MIS 3 ice margins. We estimate the freshwater flux associated with the inferred glacial outburst flood using high-resolution digital elevation maps corrected for glacial isostatic adjustment. Using assumptions about the ice-dammed locations we find that a freshwater flood volume of 1.14 × 1012 m3 could have entered the Hudson Strait. This glacial outburst flood volume could have contributed to surface ocean freshening to cause a measurable meltwater signal in δ18O records, but would not necessarily have been associated with substantial ice rafted debris. Future work is required to refine estimates of the size and timing of such a glacial outburst flood. Nevertheless, we outline testable hypotheses about the Laurentide Ice Sheet and glacial outburst floods, including possible implications for Heinrich events and glacial inception in North America, that can be assessed with additional fieldwork and cosmogenic measurements.

Tamara Pico et al.

Status: open (until 13 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-132', Anonymous Referee #1, 29 Oct 2021 reply
  • CC1: 'Comment on cp-2021-132', Nicolas Young, 01 Nov 2021 reply
  • RC2: 'Comment on cp-2021-132', Anonymous Referee #2, 05 Nov 2021 reply
  • CC2: 'Comment on cp-2021-132', Martin Roy, 10 Nov 2021 reply
  • EC1: 'Responding to comments/reviews', Alberto Reyes, 29 Nov 2021 reply
  • CC3: 'Comment on cp-2021-132', Jessey Rice, 24 Nov 2021 reply
  • CC4: 'Comment on cp-2021-132', Jakob Heyman, 26 Nov 2021 reply

Tamara Pico et al.

Tamara Pico et al.

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Short summary
We present data from fieldwork completed in 2002 for a glacial lake in the Torngat Mountains (Northern Quebec and Labrador, Canada). We dated the lake to ~56 ± 3 ka and estimated the freshwater volume that may have been released during an outburst flood. The location of this glacial lake is surprising because the Torngat Mountains are considered a site of glacial inception, and this shoreline suggests the region was not ice-covered throughout the North American ice sheet growth phase.