Abstract
AbstractMega‐scale glacial lineations formed by the raking of ice shelves across the seafloor have been reported from multiple polar regions. Here, we present the first evidence of continental slope situated buried lineations in the southern Canadian Beaufort Sea in present‐day water depths of 220 to 800 m. Three separate surfaces with lineations are defined at sub‐seafloor depths of 40 m to 390 m. All lineations are mostly parallel to the general trend of slope contours. The uppermost surface is recognized over a distance of 56 km. In water depths > 500 m the lineations are parallel to each other at a consistent direction (43°–44°). The second lineated surface is a regionally occurring erosional unconformity. This event has two sub‐sets of lineations: mid‐slope situated lineations oriented at 42°–48°, and lineations closer to the continental shelf break at 55°–59°. The third lineated surface is an unconformable horizon buried up to 390 m below seafloor with lineaments oriented between 30° and 55°. All three sets of lineations are interpreted to have been produced by ice‐ploughing on the paleo‐seafloor through the grounding of an ice shelf. Our observations are similar to those documented along the slope off northern Alaska, Chukchi Rise, and Lomonosov Ridge. Collectively, these observations support the concept of an extensive ice shelf across the Arctic Ocean that grounded locally along its margins during multiple glaciations, including during the penultimate (or an earlier) glaciation. The youngest set of lineations indicates ice movement to the southwest with a suggested source in Amundsen Gulf and/or M'Clure Strait. Tentative age considerations for these youngest lineations indicate the first evidence for an analogous extensive ice shelf configuration for the Last Glacial Maximum.
Highlights
The glacial history of the Arctic Ocean is a topic of interest to Quaternary scientists, oceanographers, and environmental scientists who are studying glacial–interglacial cycles, ice shelf dynamics, and associated seabed processes (e.g., Engels et al, 2008; Grosswald &Hughes, 2008; Jakobsson et al, 2014; Niessen et al, 2013; Polyak et al, 2001)
These observations support the concept of an extensive ice shelf across the Arctic Ocean that grounded locally along its margins during multiple glaciations, including during the penultimate glaciation
As summarized by Jakobsson et al (2014), glacial-related lineations have been identified at greater water depths (800 to > 1000 m) on topographic highs in the Arctic Ocean. It remains a debate if these features should be called Mega-scale glacial lineations (MSGLs), since they were probably formed beneath an ice shelf and do not represent the same environment or conditions of a grounded ice stream
Summary
The glacial history of the Arctic Ocean is a topic of interest to Quaternary scientists, oceanographers, and environmental scientists who are studying glacial–interglacial cycles, ice shelf dynamics, and associated seabed processes As summarized by Jakobsson et al (2014), glacial-related lineations have been identified at greater water depths (800 to > 1000 m) on topographic highs in the Arctic Ocean It remains a debate if these features should be called MSGLs, since they were probably formed beneath an ice shelf and do not represent the same environment or conditions of a grounded ice stream. A previous examination of the industry 3D data set, conducted to assess seabed geohazards, identified two of these horizons which were considered to contain glacialrelated lineations (Woodworth-Lynas et al, 2016a, 2016b) These lineations were interpreted to have been formed by seabed scour from a possible melange of icebergs and thick sea ice moving in a southwest direction. Our interpretations broaden the expanse of regional observations of glacially produced seabed lineations observed elsewhere in the Arctic Ocean (e.g., Jakobsson et al, 2010, 2014, 2016), and provide evidence for their source of glacial ice from the western Canadian Arctic Archipelago
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