“…This applies whether retreat progressed rapidly southward along the mountain front or shoreward from the central Ross Sea (Figure ). The latter scenario is supported by (i) 14 C ages of foraminifera in marine sediment retrieved from ∼60 km east of Ross Island [ McKay et al , ], which predate deglaciation ages from farther west along the Scott Coast (Figure c), and (ii) seafloor geomorphic features in the central Ross Sea [ Halberstadt et al , ] and near Ross Island [ Lee et al , ], which also indicate shoreward grounding‐line retreat.…”
Section: Discussionmentioning
confidence: 94%
“…[ McKay et al , ]. This is older than deglaciation ages from farther to the west and may imply that the grounding line retreated shoreward, resulting in open‐water conditions at the core site before sites closer to the coast became ice free [ McKay et al , ; Lee et al , ]. Taken together, these ages indicate that grounded ice withdrew from the Scott Coast region between ∼8.6 and 7 kyr B.P.…”
Deglaciation of the Ross Sea following the last ice age provides an important opportunity to examine the stability of marine ice sheets and their susceptibility to changing environmental conditions. Insufficient chronology for Ross Sea deglaciation has helped sustain (i) the theory that this region contributed significantly to Meltwater Pulse 1A (MWP‐1A) and (ii) the idea that Ross Sea grounding‐line retreat occurred in a “swinging gate” pattern hinged north of Roosevelt Island. We present deglaciation records from southern Transantarctic Mountain glaciers, which delivered ice to the central Ross Sea. Abrupt thinning of these glaciers 9–8 kyr B.P. coincided with deglaciation of the Scott Coast, ∼800 km to the north, and ended with the Ross Sea grounding line near Shackleton Glacier. This deglaciation removed grounded ice from most of the central and western Ross Sea in less than 2 kyr. The Ross Sea Sector neither contributed nor responded significantly to MWP‐1A.
“…This applies whether retreat progressed rapidly southward along the mountain front or shoreward from the central Ross Sea (Figure ). The latter scenario is supported by (i) 14 C ages of foraminifera in marine sediment retrieved from ∼60 km east of Ross Island [ McKay et al , ], which predate deglaciation ages from farther west along the Scott Coast (Figure c), and (ii) seafloor geomorphic features in the central Ross Sea [ Halberstadt et al , ] and near Ross Island [ Lee et al , ], which also indicate shoreward grounding‐line retreat.…”
Section: Discussionmentioning
confidence: 94%
“…[ McKay et al , ]. This is older than deglaciation ages from farther to the west and may imply that the grounding line retreated shoreward, resulting in open‐water conditions at the core site before sites closer to the coast became ice free [ McKay et al , ; Lee et al , ]. Taken together, these ages indicate that grounded ice withdrew from the Scott Coast region between ∼8.6 and 7 kyr B.P.…”
Deglaciation of the Ross Sea following the last ice age provides an important opportunity to examine the stability of marine ice sheets and their susceptibility to changing environmental conditions. Insufficient chronology for Ross Sea deglaciation has helped sustain (i) the theory that this region contributed significantly to Meltwater Pulse 1A (MWP‐1A) and (ii) the idea that Ross Sea grounding‐line retreat occurred in a “swinging gate” pattern hinged north of Roosevelt Island. We present deglaciation records from southern Transantarctic Mountain glaciers, which delivered ice to the central Ross Sea. Abrupt thinning of these glaciers 9–8 kyr B.P. coincided with deglaciation of the Scott Coast, ∼800 km to the north, and ended with the Ross Sea grounding line near Shackleton Glacier. This deglaciation removed grounded ice from most of the central and western Ross Sea in less than 2 kyr. The Ross Sea Sector neither contributed nor responded significantly to MWP‐1A.
“…Attempts to reconcile opposing flow directions in the McMurdo area call upon a reorganisation of flow in the south-western Ross Sea during deglaciation 19 – 21 . Recent interpretations of seafloor glacial geomorphology 20 , 22 , terrestrial outlet glacier ice surface histories 23 and Antarctic-wide numerical ice sheet modelling 5 , 24 suggest a significant role of the Southern Victoria Land (SVL) sector of the EAIS in governing, and responding to, ice sheet and ice shelf dynamics in the western Ross Sea. Fig.…”
How ice sheets respond to changes in their grounding line is important in understanding ice sheet vulnerability to climate and ocean changes. The interplay between regional grounding line change and potentially diverse ice flow behaviour of contributing catchments is relevant to an ice sheet’s stability and resilience to change. At the last glacial maximum, marine-based ice streams in the western Ross Sea were fed by numerous catchments draining the East Antarctic Ice Sheet. Here we present geomorphological and acoustic stratigraphic evidence of ice sheet reorganisation in the South Victoria Land (SVL) sector of the western Ross Sea. The opening of a grounding line embayment unzipped ice sheet sub-sectors, enabled an ice flow direction change and triggered enhanced flow from SVL outlet glaciers. These relatively small catchments behaved independently of regional grounding line retreat, instead driving an ice sheet readvance that delivered a significant volume of ice to the ocean and was sustained for centuries.
“…Previous work suggests that deglaciation in the Ross Sea could have started before the LGM (Bart & Cone, 2012; Mosola & Anderson, 2006), while a more recent review on the topic led to the interpretation that significant acceleration of the post‐LGM deglaciation took place around 10,000 yr ago (Anderson et al, 2014). More recent investigations have revealed a complex retreat scenario with individual ice streams showing different retreat patterns, timing, and sensitivity to different forcings (Greenwood et al, 2012, 2018; Halberstadt et al, 2016; Jones et al, 2015; Lee et al, 2017; Prothro et al, 2020; Simkins et al, 2018; Spector et al, 2017). The post‐LGM glacial retreat in Pennell and JOIDES troughs, which are in the scope of this study, was also diachronous beginning at 15.1 and 13 calendar thousand years before present (cal ka BP), respectively (Prothro et al, 2020).…”
Section: Introductionmentioning
confidence: 99%
“…During the LGM, large ice streams flowing through these troughs formed glacial lineations that record paleodrainage of the expanded ice sheet (e.g., Bart & Cone, 2012; Halberstadt et al, 2016). 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).…”
Improved multibeam swath bathymetry allows targeted coring of glacial landforms aiming at improving our understanding of sedimentary facies that developed in glacimarine settings during the post-Last Glacial Maximum (LGM) deglaciation. Coupled with radiocarbon dates, we explore foraminiferal records from 18 sediment cores from the western Ross Sea largely from sites near paleo-grounding lines. We investigate post-LGM foraminiferal assemblages from glacimarine environments, including those proximal and more distal to paleo-grounding lines, including environments influenced by subglacial meltwater outflow and further removed from direct glacial influence and subject to different oceanographic conditions. Agglutinated benthic foraminiferal assemblages dominate open marine facies deposited under the presence of High Salinity Shelf Water and significant primary production, while calcareous foraminiferal assemblages characterize grounding line-proximal settings, some of which were potentially influenced by Modified Circumpolar Deep Water. Rapid deposition of meltwater plume deposits inhibited and, in some cases, significantly altered foraminifera abundance and diversity. Broadly in the Ross Sea, it appears that the high bathymetric gradient of grounding zone wedges is a key factor promoting rich benthic foraminiferal communities in habitats proximal to grounding lines. Therefore, we demonstrate that paleo-grounding line settings may archive high quality in situ foraminiferal data, which is imperative for paleoenvironmental and geochemical studies on glaciated continental margins worldwide.
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