Deglacial and postglacial evolution of the Pingualuit Crater Lake basin, northern Québec (Canada) Pierre-Arnaud Desiage a,b, ⁎, Patrick Lajeunesse b,c , Guillaume St-Onge a,b , Alexandre Normandeau b , Grégoire Ledoux c , Hervé Guyard a,b,d , Reinhard Pienitz c a Institut des sciences de la mer de Rimouski (ISMER), Canada Research Chair in Marine Geology, Université du Québec à Rimouski, Rimouski, Canada b GEOTOP Research Center, Canada c Centre d'études Nordiques (CEN) & Département de Géographie, Université Laval, Québec, Canada d Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR CNRS 7154, Paris, France abstract article info Article history: Received 15 January 2015 Received in revised form 9 July 2015 Accepted 10 July 2015 Available online 29 July 2015 Keywords: lake levels Mass movements Laurentide Ice Sheet Sedimentological processes LiDAR Arctic The Pingualuit Crater, located in the Ungava Peninsula (northern Québec, Canada) is a 1.4-Ma-old impact crater hosting a ~245-m-deep lake. The lake has a great potential to preserve unique paleoclimatic and paleoecological sedimentary records of the last glacial/interglacial cycles in the terrestrial Canadian Arctic. In order to investigate the stratigraphy in the lake and the late Quaternary glacial history of the Pingualuit Crater, this study compiles data from three expeditions carried out in May 2007 (~9-m-long sediment core), in August 2010 (~50 km of seismic lines), and in September 2012 (high-resolution terrestrial LiDAR topography of the inner slopes). Despite the weak penetration (~10 m) of the 3.5-kHz subbottom profiling caused by the presence of boulders in the sedimentary column, seismic data coupled with the stratigraphy established from the sediment core enabled the identification of two glaciolacustrine units deposited during the final stages of the Laurentide Ice Sheet (LIS) retreat in the crater. Two episodes of postglacial mass wasting events were also identified on the slopes and in the deep basin of the crater. The high-resolution topography of the internal slopes of the crater generated from the LiDAR data permitted the confirmation of a paleolake level at 545 m and determination of the elevation of drainage outlets. Together with the mapping of glacial and deglacial landforms from air photographs, the LiDAR data allowed the development of a new deglaciation and drainage scenario for the Pingualuit Crater Lake and surrounding area. The model proposes three main phases of lake drainage, based on the activation of seven outlets following the retreat of the LIS front toward the southwest. Finally, as opposed to other high- latitude crater lake basins such as Lake El'gygytgyn or Laguna Potrok Aike where high-resolution paleoclimatic records were obtained owing to high sediment accumulation rates, the seismic data from the Pingualuit Crater Lake suggest extremely low sedimentation rates after the retreat of the LIS owing to the absence of tributaries. © 2015 Elsevier B.V. All rights reserved. 1. Introduction High-latitude lakes contain excellent archives of past climatic and environmental variations owing to the sediments they can preserve (Pienitz et al., 2004, 2008). In recent years, the Pingualuit Crater Lake (Nunavik; Fig. 1) has sparked a renewed interest in paleoclimatology re- search in the Ungava Peninsula (Black et al., 2010, 2012; Girard- Cloutier, 2011; Guyard et al., 2011, 2014; Luoto et al., 2013). Despite the presence of the Laurentide Ice Sheet during the Last Glacial Maxi- mum (~21,000 years ago; Clark et al., 2009), the morphology of the crater likely favored the existence of a subglacial lake in the Pingualuit Crater, precluding glacial erosion of the bottom sediments (Bouchard, 1989b; Guyard et al., 2011). These characteristics give the Pingualuit Crater Lake sediments the potential to record successions of glacial/in- terglacial periods in the Ungava Peninsula since its formation 1.4 Ma ago (Bouchard, 1989b). Furthermore, the Pingualuit Crater Lake has similar characteristics to lakes recently studied in the context of Interna- tional Continental scientific Drilling Program (ICDP) projects for their potential in paleoclimatic research, such as the El'gygytgyn Crater Lake in 2008/09 (e.g., Melles et al., 2012) and Laguna Potrok Aike in 2008 (e.g., Zolitschka et al., 2013, and papers in the special issue). El'gygytgyn Crater Lake, also a meteoritic impact basin located in the Arctic (67.5°N., 172°E.), escaped Northern Hemisphere glaciation because of its location in the center of Beringia (Brigham-Grette et al., 2007). Laguna Potrok Aike, located in southeastern Patagonia (Argentina), and the Pingualuit Crater Lake share a similar morphology with a high depth-to-area ratio, allowing the potential accumulation of a long sedimentary record Geomorphology 248 (2015) 327–343 ⁎ Corresponding author at: Institut des Sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada. E-mail address: Pierre-Arnaud.Desiage@uqar.ca (P.-A. Desiage). http://dx.doi.org/10.1016/j.geomorph.2015.07.023 0169-555X/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph