scholarly journals Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica

2021 ◽  
Author(s):  
◽  
Rebecca Pretty
Keyword(s):  
Grain Size ◽  
Late Miocene ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ocean Current ◽  
Significant Advance ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Depositional Processes ◽  
Wilkes Land

<p>The middle Miocene Climatic Transition (~14 Ma) is commonly interpreted to represent the significant advance of the East Antarctic Ice Sheet (EAIS), and the transition to a hyper-arid climate and a stable polar-styled ice sheet. However, an increasing number of studies provide evidence for continued instability and abundant meltwater processes influencing the low-lying margins of the EAIS during the Late Miocene (~11.6-5.3 Ma). The history of the EAIS during this period remains ambiguous due to the sparse number of records, and those that do exist have poor age resolution. This thesis investigates Integrated Ocean Drilling Program Site U1361 (64°24.5°S 143°53.1°E), located on the lowermost continental rise of the Wilkes Land margin. It aims to assess the variability of the EAIS and associated changes in palaeoceanography offshore one of the largest marine-based sectors of East Antarctica, the Wilkes Subglacial Basin, and to establish if the EAIS was responding to orbital forcings during the Late Miocene.  The study period (~11.7 to 10.8 Ma) contains six intervals of nannofossil-rich mudstones, interbedded with laminated mudstones and diatom-rich mudstones. Nannofossils are absent elsewhere in core U1361A, which covers the past ~14 Ma. To identify the sedimentary and depositional processes which influenced this anomalous interval of calcareous biological productivity, a high-resolution record (using ~450 samples) of Iceberg Rafted Debris (IBRD), grain size analysis and bulk geochemistry XRF analysis have been developed.   A lithofacies scheme has been established and used to provide an interpretation of the shifting sedimentary processes through time. Repeating cycles of faintly laminated mudstones were interpreted to represent the influence of bottom current activity on overbank turbidites, that spill onto a channel leeve, during glacial periods. The contouritic nature of the facies is likely associated with the low-relief channel-levee system at this time. Interglacial sedimentation is characterised by an increase in biogenic content, IBRD and bioturbation, with deposition occurring during biologically productive open marine conditions. Two types of biogenic productivity are present over the interval (silica and/or carbonate). The intervals of diatom-rich mud were interpreted to be associated with enhanced upwelling of Circumpolar Deep Water (CDW). While, the nannofossil-rich mudstones suggest a significantly warmer climate, with coccolithophore production proposed to represent the influence of meltwater and shifting Southern Ocean frontal systems, acting to restrict nutrient upwelling and increase water temperatures.  Nannofossil-rich muds are only present for a short interval (700 kyr), suggesting that the anomalous depositional environment between ~11.7 to 11.0 Ma was potentially related to the significant retreat and surface meltwater processes at the EAIS margin. Interglacial sedimentation at Site U1361 is also accompanied by an increase in grain size (i.e. silt), interpreted to represent oceanic current intensification which acts to restrict the deposition of finer material, relative to glacial intervals. This intensification of ocean current strength may have resulted in increased heat delivery to the EAIS margin triggering a terrestrial based ice sheet, and the delivery of nutrients stimulating marine productivity.  Spectral analysis of the mean grain size (MGS) and IBRD Mass Accumulation Rate (MAR) records revealed that during the Late Miocene (~11.7 to 10.8 Ma), the ice sheet was paced by ~100 kyr eccentricity cycles, and a low frequency ~20 kyr processional component. This is consistent with two Late Miocene 𝛿¹⁸O records that are also paced by eccentricity, suggesting that the Antarctic Ice Sheet was contributing a significant signal to the global 𝛿¹⁸O record during this interval of the Late Miocene. However, the presence of nannofossil suggests a warmer world, rather than the colder climate state that are often inferred to lead to eccentricity/precession variability. A recent hypothesis proposed by Levy et al., (2019) invokes that a warmer climate may lead to surface melt processes which at high latitudes are dominated by eccentricity/precession. Although this style of climate is commonly thought to have occurred prior to ~14 Ma in East Antarctica, the evidence presented in this study suggests such a state existed at the Wilkes Land margin until at least ~11.0 Ma.</p>

scholarly journals Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica

2021 ◽  
Author(s):  
◽  
Rebecca Pretty
Keyword(s):  
Grain Size ◽  
Late Miocene ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ocean Current ◽  
Significant Advance ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Depositional Processes ◽  
Wilkes Land

<p>The middle Miocene Climatic Transition (~14 Ma) is commonly interpreted to represent the significant advance of the East Antarctic Ice Sheet (EAIS), and the transition to a hyper-arid climate and a stable polar-styled ice sheet. However, an increasing number of studies provide evidence for continued instability and abundant meltwater processes influencing the low-lying margins of the EAIS during the Late Miocene (~11.6-5.3 Ma). The history of the EAIS during this period remains ambiguous due to the sparse number of records, and those that do exist have poor age resolution. This thesis investigates Integrated Ocean Drilling Program Site U1361 (64°24.5°S 143°53.1°E), located on the lowermost continental rise of the Wilkes Land margin. It aims to assess the variability of the EAIS and associated changes in palaeoceanography offshore one of the largest marine-based sectors of East Antarctica, the Wilkes Subglacial Basin, and to establish if the EAIS was responding to orbital forcings during the Late Miocene.  The study period (~11.7 to 10.8 Ma) contains six intervals of nannofossil-rich mudstones, interbedded with laminated mudstones and diatom-rich mudstones. Nannofossils are absent elsewhere in core U1361A, which covers the past ~14 Ma. To identify the sedimentary and depositional processes which influenced this anomalous interval of calcareous biological productivity, a high-resolution record (using ~450 samples) of Iceberg Rafted Debris (IBRD), grain size analysis and bulk geochemistry XRF analysis have been developed.   A lithofacies scheme has been established and used to provide an interpretation of the shifting sedimentary processes through time. Repeating cycles of faintly laminated mudstones were interpreted to represent the influence of bottom current activity on overbank turbidites, that spill onto a channel leeve, during glacial periods. The contouritic nature of the facies is likely associated with the low-relief channel-levee system at this time. Interglacial sedimentation is characterised by an increase in biogenic content, IBRD and bioturbation, with deposition occurring during biologically productive open marine conditions. Two types of biogenic productivity are present over the interval (silica and/or carbonate). The intervals of diatom-rich mud were interpreted to be associated with enhanced upwelling of Circumpolar Deep Water (CDW). While, the nannofossil-rich mudstones suggest a significantly warmer climate, with coccolithophore production proposed to represent the influence of meltwater and shifting Southern Ocean frontal systems, acting to restrict nutrient upwelling and increase water temperatures.  Nannofossil-rich muds are only present for a short interval (700 kyr), suggesting that the anomalous depositional environment between ~11.7 to 11.0 Ma was potentially related to the significant retreat and surface meltwater processes at the EAIS margin. Interglacial sedimentation at Site U1361 is also accompanied by an increase in grain size (i.e. silt), interpreted to represent oceanic current intensification which acts to restrict the deposition of finer material, relative to glacial intervals. This intensification of ocean current strength may have resulted in increased heat delivery to the EAIS margin triggering a terrestrial based ice sheet, and the delivery of nutrients stimulating marine productivity.  Spectral analysis of the mean grain size (MGS) and IBRD Mass Accumulation Rate (MAR) records revealed that during the Late Miocene (~11.7 to 10.8 Ma), the ice sheet was paced by ~100 kyr eccentricity cycles, and a low frequency ~20 kyr processional component. This is consistent with two Late Miocene 𝛿¹⁸O records that are also paced by eccentricity, suggesting that the Antarctic Ice Sheet was contributing a significant signal to the global 𝛿¹⁸O record during this interval of the Late Miocene. However, the presence of nannofossil suggests a warmer world, rather than the colder climate state that are often inferred to lead to eccentricity/precession variability. A recent hypothesis proposed by Levy et al., (2019) invokes that a warmer climate may lead to surface melt processes which at high latitudes are dominated by eccentricity/precession. Although this style of climate is commonly thought to have occurred prior to ~14 Ma in East Antarctica, the evidence presented in this study suggests such a state existed at the Wilkes Land margin until at least ~11.0 Ma.</p>

scholarly journals Changes in ice dynamics and mass balance of the Antarctic ice sheet

2006 ◽  
Vol 364 (1844) ◽  
pp. 1637-1655 ◽  
Author(s):  
Eric Rignot
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
Ice Sheet ◽  
East Antarctica ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
The Antarctic

The concept that the Antarctic ice sheet changes with eternal slowness has been challenged by recent observations from satellites. Pronounced regional warming in the Antarctic Peninsula triggered ice shelf collapse, which led to a 10-fold increase in glacier flow and rapid ice sheet retreat. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of Antarctica. In West Antarctica, the Pine Island Bay sector is draining far more ice into the ocean than is stored upstream from snow accumulation. This sector could raise sea level by 1 m and trigger widespread retreat of ice in West Antarctica. Pine Island Glacier accelerated 38% since 1975, and most of the speed up took place over the last decade. Its neighbour Thwaites Glacier is widening up and may double its width when its weakened eastern ice shelf breaks up. Widespread acceleration in this sector may be caused by glacier ungrounding from ice shelf melting by an ocean that has recently warmed by 0.3 °C. In contrast, glaciers buffered from oceanic change by large ice shelves have only small contributions to sea level. In East Antarctica, many glaciers are close to a state of mass balance, but sectors grounded well below sea level, such as Cook Ice Shelf, Ninnis/Mertz, Frost and Totten glaciers, are thinning and losing mass. Hence, East Antarctica is not immune to changes.

Sedimentary signature of past West Antarctic Ice Sheet and ocean dynamics from deep sea drill cores in the Amundsen Sea (IODP Expedition 379)

2021 ◽  
Author(s):  
Delaney E. Robinson ◽  
Julia S. Wellner ◽  
Karsten Gohl ◽  
Benedict T.I. Reinardy ◽  
Keyword(s):  
Grain Size ◽  
Ice Sheet ◽  
Silty Clay ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Depositional Processes ◽  
Drill Cores

&lt;p&gt;Modern observations of the West Antarctic Ice Sheet (WAIS) show relatively warm ocean water causing negative changes in ice-sheet mass. The largest ice mass loss in the WAIS occurs in the Amundsen Sea region, where warm water flows onto the shelf and melts the marine-based ice shelves, a process with the potential to lead to full collapse of the WAIS. Geologic records from similar and warmer climate conditions than today are required to understand the role of changes affecting the Amundsen Sea drainage sector in steering past WAIS dynamics. International Ocean Discovery Program (IODP) Expedition 379 successfully recovered sediment drill cores from two sites on the continental rise in the Amundsen Sea, West Antarctica. Both sites are located on a large sediment drift that provides a continuous, long-term record of glacial history in a drainage basin that is fed exclusively by the WAIS. Sediments at both sites are associated with depositional processes related to glacial extent on the shelf. Repeated alternations of two major facies groups composed of dark-gray laminated silty clay and massive/bioturbated greenish-gray, clast-bearing mud are interpreted to represent cycles of glacial and interglacial periods. High-resolution sedimentological analyses define characteristics that vary within the two broad sedimentary facies, helping provide constraints on depositional processes of the sediments and controlling WAIS dynamics.&lt;/p&gt;&lt;p&gt;Detailed investigations were conducted on Miocene to Pliocene strata using grain size and shape analysis, combined with X-Ray Fluorescence data and computer tomography scans, as well as detailed thin section analysis. Laminated silty clay intervals contain consistently fine-grained sediments dominated by terrigenous components that were supplied by downslope transport during glacial periods. Massive/bioturbated muds with ice rafted debris (IRD) display variable grain size trends accompanied by changes in particular elemental ratios indicating increased supply of biogenic components and possibly reduced delivery of terrigenous detritus during interglacial periods. The boundaries between massive, interglacial facies and laminated, glacial facies are usually sharp; although occasionally, a more gradual interglacial-glacial transition is observed. Different sedimentation patterns suggest fluctuations in downslope transport and bottom current intensities that are connected to ice sheet extent on the West Antarctic continental shelf. Further analysis may reveal facies characteristics that vary with glacial-interglacial cycles and allow improved interpretation of past WAIS dynamics and Southern Ocean circulation.&lt;/p&gt;

scholarly journals East Antarctic Ice Sheet and Southern Ocean Response to Orbital Forcing from Late Miocene to Early Pliocene, Wilkes Land, East Antarctica

2021 ◽  
Author(s):  
◽  
Nikita Anne Turton
Keyword(s):  
Southern Ocean ◽  
Late Miocene ◽  
Ice Sheet ◽  
Orbital Forcing ◽  
Sea Ice Extent ◽  
Antarctic Ice Sheet ◽  
Early Pliocene ◽  
Wilkes Land ◽  
Marine Productivity ◽  
East Antarctic Ice Sheet

<p>Geological and ice sheet models indicate that marine-based sectors of the East Antarctic Ice Sheet (EAIS) were unstable during periods of moderate climatic warmth in the past. While geological records from the Middle to Late Pliocene indicate a dynamic ice sheet, records of ice sheet variability from the comparatively warmer Late Miocene to Early Pliocene are sparse, and there are few direct records of Antarctic ice sheet variability during this time period. Sediment recovered in Integrated Ocean Drilling Program U1361 drill core from the Wilkes Land margin provides a distal but continuous glacially-influenced record of the behaviour of Antarctic Ice Sheets.  This thesis presents marine sedimentological and x-ray fluorescence geochemical datasets in order to assess changes in the dynamic response of the EAIS and Southern Ocean productivity in the Wilkes Land sector during Late Miocene and Early Pliocene to climatic warming and orbital forcing between 6.2 and 4.4 Ma. Two primary lithofacies are identified which can be directly related to glacial–interglacial cycles; enhanced sedimentation during glacials is represented by low-density turbidity flows that occurred in unison with low marine productivity and reduced iceberg rafted debris. Interglacial sediments contain diatomaceous muds with short-lived, large fluxes of iceberg rafted debris preceding a more prolonged phase of enhanced marine productivity. Interglacial sediments coincide with a more mafic source of terrigenous sediment, interfered to be associated with an inland retreat of the ice margin resulting in erosion of lithologies that are currently located beneath the grounded EAIS. Poleward invigoration of the Antarctic Circumpolar Current during glacial–interglacial transitions is proposed to have intensified upwelling, enhancing nutrient availability for marine productivity, and increasing oceanic heat flux at the ice margin acting to erode marine ice sheet grounding lines and triggering retreat.  Spectral analysis of the datasets indicated orbital frequencies are present in the iceberg rafted debris mass accumulation rates at all three Milankovitch frequencies, with a dominant 100 kyr eccentricity driven ice discharge. Prolonged intervals of marine productivity correlate to 100 kyr cyclicity occurring at peaks in obliquity. The response of both ice sheet and biological systems to 100 kyr cyclicity may indicate eccentricity-modulated sea ice extent controls the influx of warm water onto the continental shelf.</p>

scholarly journals Pliocene-Pleistocene Orbital Cyclostratigraphy and Glacial Evolution of the East Antarctic Ice Sheet from Continental Rise IODP Site U1361, Wilkes Land Margin, East Antarctica

2021 ◽  
Author(s):  
◽  
Georgia Rose Grant
Keyword(s):  
Spectral Analysis ◽  
Late Pleistocene ◽  
Gamma Ray ◽  
Physical Property ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Continental Rise ◽  
Depositional Processes ◽  
Core Site ◽  
Wilkes Land

<p>Stability of the East Antarctic Ice Sheet (EAIS), in response to the orbitally-paced cooling climate of the Late Neogene, is largely unknown. The Wilkes Land margin of East Antarctica, largely grounded below sea level, has previously been proposed to respond dynamically during the warmer climate of the Pliocene, similarly to other marine based sectors of Antarctica (i.e. West Antarctica). Sediment deposition on the Wilkes Land continental rise, recovered in Integrated Ocean Drilling Program U1361A drillcore provides a distal but continuous record of EAIS fluctuations. Changes in sedimentary depositional environments at U1361A core site, were determined through analysis of lithofacies and physical property logs: natural gamma-ray (NGR), gamma-ray attenuation bulk density (GRA), magnetic susceptibility (MS) and L* colour reflectance. NGR primarily reflected biogenic content and a synchronous relationship between NGR, GRA and MS was used to identify interglacial and glacial phases, whereby decreased NGR, GRA and MS values indicated an increase in biogenic material. L* colour reflectance was more variable through time, displayed higher frequency fluctuations and a changing relationship with the other physical property logs down core. Two depositional models, based on facies interpretations and the defined physical property relationships, were produced for the Middle Late Pleistocene (last ~550 kyr; model A) and mid-Pliocene (~4.2-3.6 Ma; model B), which represent end members. Depositional processes common to both models occurred in the intervening core, spanning the Late Pliocene-Early Pleistocene (3-1 Ma). Model A, applied to the Middle Late Pleistocene, shows that alternating diatom-rich clays to silty clays in the upper 9 m of core U1361A, reflect the large amplitude ~100 kyr paced glacial-interglacial cycles, which is confirmed by spectral analysis of the physical properties for this interval. Model B, applied to the Early Pliocene, suggest that the depositional processes recorded by facies may have been less sensitive to EAIS fluctuations, probably due to the fact that the ice margin was generally more distal to the core site during glacial-interglacial cycles of advance and retreat. Nevertheless, these more subtle changes in lithology were characterised by variations in the physical property logs, and spectral analysis of these time series implied orbital pacing was still influential on depositional processes at this time (displaying power in precession and obliquity frequencies). Spectral analysis of the physical property logs and visual correlations to the benthic δ18O stack, confirmed the 4.2-1 Ma interval was paced by ~40 kyr and implies obliquity-paced oscillations of the margin of the EAIS. Precession periodicities, significant in spectra throughout the 4.2 Myr record, are proposed to be the response of phytoplankton productivity in response to seasonal insolation controlling sea-ice extent.</p>

scholarly journals East Antarctic Ice Sheet and Southern Ocean Response to Orbital Forcing from Late Miocene to Early Pliocene, Wilkes Land, East Antarctica

2021 ◽  
Author(s):  
◽  
Nikita Anne Turton
Keyword(s):  
Southern Ocean ◽  
Late Miocene ◽  
Ice Sheet ◽  
Orbital Forcing ◽  
Sea Ice Extent ◽  
Antarctic Ice Sheet ◽  
Early Pliocene ◽  
Wilkes Land ◽  
Marine Productivity ◽  
East Antarctic Ice Sheet

<p>Geological and ice sheet models indicate that marine-based sectors of the East Antarctic Ice Sheet (EAIS) were unstable during periods of moderate climatic warmth in the past. While geological records from the Middle to Late Pliocene indicate a dynamic ice sheet, records of ice sheet variability from the comparatively warmer Late Miocene to Early Pliocene are sparse, and there are few direct records of Antarctic ice sheet variability during this time period. Sediment recovered in Integrated Ocean Drilling Program U1361 drill core from the Wilkes Land margin provides a distal but continuous glacially-influenced record of the behaviour of Antarctic Ice Sheets.  This thesis presents marine sedimentological and x-ray fluorescence geochemical datasets in order to assess changes in the dynamic response of the EAIS and Southern Ocean productivity in the Wilkes Land sector during Late Miocene and Early Pliocene to climatic warming and orbital forcing between 6.2 and 4.4 Ma. Two primary lithofacies are identified which can be directly related to glacial–interglacial cycles; enhanced sedimentation during glacials is represented by low-density turbidity flows that occurred in unison with low marine productivity and reduced iceberg rafted debris. Interglacial sediments contain diatomaceous muds with short-lived, large fluxes of iceberg rafted debris preceding a more prolonged phase of enhanced marine productivity. Interglacial sediments coincide with a more mafic source of terrigenous sediment, interfered to be associated with an inland retreat of the ice margin resulting in erosion of lithologies that are currently located beneath the grounded EAIS. Poleward invigoration of the Antarctic Circumpolar Current during glacial–interglacial transitions is proposed to have intensified upwelling, enhancing nutrient availability for marine productivity, and increasing oceanic heat flux at the ice margin acting to erode marine ice sheet grounding lines and triggering retreat.  Spectral analysis of the datasets indicated orbital frequencies are present in the iceberg rafted debris mass accumulation rates at all three Milankovitch frequencies, with a dominant 100 kyr eccentricity driven ice discharge. Prolonged intervals of marine productivity correlate to 100 kyr cyclicity occurring at peaks in obliquity. The response of both ice sheet and biological systems to 100 kyr cyclicity may indicate eccentricity-modulated sea ice extent controls the influx of warm water onto the continental shelf.</p>

scholarly journals Pliocene-Pleistocene Orbital Cyclostratigraphy and Glacial Evolution of the East Antarctic Ice Sheet from Continental Rise IODP Site U1361, Wilkes Land Margin, East Antarctica

2021 ◽  
Author(s):  
◽  
Georgia Rose Grant
Keyword(s):  
Spectral Analysis ◽  
Late Pleistocene ◽  
Gamma Ray ◽  
Physical Property ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Continental Rise ◽  
Depositional Processes ◽  
Core Site ◽  
Wilkes Land

<p>Stability of the East Antarctic Ice Sheet (EAIS), in response to the orbitally-paced cooling climate of the Late Neogene, is largely unknown. The Wilkes Land margin of East Antarctica, largely grounded below sea level, has previously been proposed to respond dynamically during the warmer climate of the Pliocene, similarly to other marine based sectors of Antarctica (i.e. West Antarctica). Sediment deposition on the Wilkes Land continental rise, recovered in Integrated Ocean Drilling Program U1361A drillcore provides a distal but continuous record of EAIS fluctuations. Changes in sedimentary depositional environments at U1361A core site, were determined through analysis of lithofacies and physical property logs: natural gamma-ray (NGR), gamma-ray attenuation bulk density (GRA), magnetic susceptibility (MS) and L* colour reflectance. NGR primarily reflected biogenic content and a synchronous relationship between NGR, GRA and MS was used to identify interglacial and glacial phases, whereby decreased NGR, GRA and MS values indicated an increase in biogenic material. L* colour reflectance was more variable through time, displayed higher frequency fluctuations and a changing relationship with the other physical property logs down core. Two depositional models, based on facies interpretations and the defined physical property relationships, were produced for the Middle Late Pleistocene (last ~550 kyr; model A) and mid-Pliocene (~4.2-3.6 Ma; model B), which represent end members. Depositional processes common to both models occurred in the intervening core, spanning the Late Pliocene-Early Pleistocene (3-1 Ma). Model A, applied to the Middle Late Pleistocene, shows that alternating diatom-rich clays to silty clays in the upper 9 m of core U1361A, reflect the large amplitude ~100 kyr paced glacial-interglacial cycles, which is confirmed by spectral analysis of the physical properties for this interval. Model B, applied to the Early Pliocene, suggest that the depositional processes recorded by facies may have been less sensitive to EAIS fluctuations, probably due to the fact that the ice margin was generally more distal to the core site during glacial-interglacial cycles of advance and retreat. Nevertheless, these more subtle changes in lithology were characterised by variations in the physical property logs, and spectral analysis of these time series implied orbital pacing was still influential on depositional processes at this time (displaying power in precession and obliquity frequencies). Spectral analysis of the physical property logs and visual correlations to the benthic δ18O stack, confirmed the 4.2-1 Ma interval was paced by ~40 kyr and implies obliquity-paced oscillations of the margin of the EAIS. Precession periodicities, significant in spectra throughout the 4.2 Myr record, are proposed to be the response of phytoplankton productivity in response to seasonal insolation controlling sea-ice extent.</p>

scholarly journals Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme

2011 ◽  
Vol 5 (3) ◽  
pp. 551-560 ◽  
Author(s):  
J. L. Roberts ◽  
R. C. Warner ◽  
D. Young ◽  
A. Wright ◽  
T. D. van Ommen ◽  
...  
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
East Antarctica ◽  
Geometric Constraints ◽  
Ice Thickness ◽  
Interpolation Scheme ◽  
Ice Dynamics ◽  
High Resolution Data ◽  
Physically Based ◽  
Glacial Morphology

Abstract. Ice thickness data over much of East Antarctica are sparse and irregularly distributed. This poses difficulties for reconstructing the homogeneous coverage needed to properly assess underlying sub-glacial morphology and fundamental geometric constraints on sea level rise. Here we introduce a new physically-based ice thickness interpolation scheme and apply this to existing ice thickness data in the Aurora Subglacial Basin region. The skill and robustness of the new reconstruction is demonstrated by comparison with new data from the ICECAP project. The interpolated morphology shows an extensive marine-based ice sheet, with considerably more area below sea-level than shown by prior studies. It also shows deep features connecting the coastal grounding zone with the deepest regions in the interior. This has implications for ice sheet response to a warming ocean and underscores the importance of obtaining additional high resolution data in these marginal zones for modelling ice sheet evolution.

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