On the influence of post-LGM ice shelf loss and grounding zone sedimentation on West Antarctic ice sheet stability

Sedimentary processes at ice sheet grounding‐zone wedges revealed by outcrops, Washington State (USA)

“…Foraminiferal analyses revealed both reworked and in situ foraminiferal assemblages, indicating that the diamictons include both proximal glacimarine sediments and debris flows. Detailed sediment facies analysis of similar strategically placed cores from a large composite GZW in Whales Deep Basin on the outer continental shelf of the eastern Ross Sea revealed a stratigraphic succession consisting of diamictons overlain by proximal glacimarine sediments, including a sub-ice shelf facies, and capped by open marine sediments (McGlannan et al, 2017). An abundance of reworked diatoms within diamictons was interpreted as indicating a combination of glacial and sediment gravity flow processes acting near the grounding line.…”

“…An abundance of GZW research from the Ross Sea (Antarctica) provides a framework whereby sediment deposition patterns are used to infer ice dynamics and transport processes. Detailed sediment facies analysis of similar strategically placed cores from a large composite GZW in Whales Deep Basin on the outer continental shelf of the eastern Ross Sea revealed a stratigraphic succession consisting of diamictons overlain by proximal glacimarine sediments, including a sub-ice shelf facies, and capped by open marine sediments (McGlannan et al, 2017). Bart and Cone (2012) and Bart and Owolana (2012) examined cores recovered from topset, foreset and bottomset strata of a large composite GZW of the central Ross Sea continental shelf.…”

Foraminiferal Patterns in Deglacial Sediment in the Western Ross Sea, Antarctica: Life Near Grounding Lines

“…Complicating issues with such reconstructions stem from difficulties in obtaining precise age control due to poor understanding of sedimentary facies as they relate to specific glacial settings during ice sheet retreat, widespread reworking of sediments either during older glaciations or iceberg scouring of the seafloor (e.g., Andrews et al, 1999; Licht & Andrews, 2002; Mosola & Anderson, 2006) and limited preservation of carbonate (Kennett, 1968). Recent studies have focused on enhancing our understanding of sedimentary facies using improved multibeam swath bathymetry and targeted coring of glacial landforms that have not been scoured by icebergs and yield important information about the glacial setting during retreat (McGlannan et al, 2017; Prothro et al, 2018). Along with improvements to sediment facies distinctions, we must also understand foraminiferal assemblages (FAs) and their habitats, as well as be able to distinguish in situ versus reworked specimens.…”

“…To fill this gap, studies relating FAs to glacial landforms and sedimentary facies, which provide context for the glacial setting (e.g., Bart & Cone, 2012; Prothro et al, 2018), have successfully been used. A study conducted in the Whales Deep Basin in eastern Ross Sea (McGlannan et al, 2017) provided a robust paleoenvironmental framework for relating FAs to near grounding line and sub–ice shelf settings. Majewski et al (2018, 2019) found distinct agglutinated and calcareous assemblages in clearly different paleoenvironments and two rarely encountered morphotypes of pustulose Globocassidulina biora and spinose Trifarina earlandi benthic foraminifera were found in abundance.…”

“…As the ice sheet retreated across the continental shelf, it left a geomorphic record of complex grounding line retreat patterns (Greenwood et al, 2012, 2018; Halberstadt et al, 2016; Lee et al, 2017; Shipp et al, 1999; Simkins et al, 2018) and a sedimentary succession composed of till overlain by glacimarine facies that document a temporal shift from ice‐contact to ice‐proximal to open‐marine conditions (e.g., Domack et al, 1999). With the use of high‐resolution multibeam bathymetry surveys, targeted sediment coring has shed light on distinct depositional changes with increasing distance from paleo–grounding lines and major refinements to sedimentary facies models (McGlannan et al, 2017; Prothro et al, 2018).…”