scholarly journals Geology of the Sirius Group at Mount Feather and Table Mountain, South Victoria Land, Antarctica

2021 ◽  
Author(s):  
◽  
Nerida Lynn Bleakley
Keyword(s):  
Atmospheric Transport ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Table Mountain ◽  
Victoria Land ◽  
Transantarctic Mountains ◽  
High Elevations ◽  
The Antarctic ◽  
Marine Basins ◽  
Middle Pliocene

<p>The Sirius Group comprises of wet based glacial and related deposits found at high elevations throughout the Transantarctic Mountains. The discovery of marine Pliocene diatoms from within glacial till by Harwood (1983) led Webb et al. (1984) to propose that they were sourced from diatom bearing sediment eroded by glaciers from middle Pliocene marine basins inland of the Transantarctic Mountains. Others consider that temperatures during middle Pliocene times were not high enough to melt back the Antarctic ice sheet and expose these inland basins. They support the long held view of a stable Antarctic ice sheet since middle Miocene times, and insist that the Sirius Group is much older, explaining the diatoms as wind blown. This study was undertaken in order to determine whether the diatoms were incorporated into Sirius Group tills during or after their deposition. Sites were sampled at Mount Feather and Table Mountain in South Victoria Land. The distribution of diatoms through the upper 37 cm of the till were documented. Samples were also taken in snow and from other non Sirius Group surfaces (regolith) for comparison purposes. The geomorphic setting of the Sirius Group tills at Mt. Feather and Table Mountain suggests that their deposition predated the deep valleys that now run through the Transantarctic Mountains. Diatom abundances from within the tills are low (averaging about 1 diatom diatom per gram) and highly variable from site to site. Initially 184 diatoms were recovered from 10 samples at Mt. Feather and less than 7 diatoms were found from 4 samples of till at Table Mountain. At Mount Feather diatoms are concentrated in the surface few centimetres of the till and numbers generally decrease with depth. The pore size within the tills is highly variable but is on average ten times the size of the average diatom (10-15 microns) from within the deposits, allowing at least some diatoms to work their way into the tills from the surface. Diatoms from the snow and regolith from other rock surfaces have a similar diatom assemblage to the Sirius tills, containing many of the same common forms. Some non Sirius Group regolith samples have much larger concentrations of diatoms suggesting they have a much better trapping ability than the Sirius Group tills. These data indicate that most diatoms from the Sirius Group tills have been introduced from the atmosphere and have worked their way into the till. Thus the Sirius diatoms record not Pliocene marine basins of the Antarctic interior and subsequent extensive over riding glaciation, but the atmospheric transport and collection of both modern and ancient diatom bearing dust from within and beyond the continent. The Sirius Group tills do however have a phytolith (siliceous clasts from the cells of plant tissue) flora of glaciogenic origin, indicated by the lack of a vertical trend in abundance and very low levels of phytoliths in nearby snow and regolith samples.</p>

scholarly journals Geology of the Sirius Group at Mount Feather and Table Mountain, South Victoria Land, Antarctica

2021 ◽  
Author(s):  
◽  
Nerida Lynn Bleakley
Keyword(s):  
Atmospheric Transport ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Table Mountain ◽  
Victoria Land ◽  
Transantarctic Mountains ◽  
High Elevations ◽  
The Antarctic ◽  
Marine Basins ◽  
Middle Pliocene

<p>The Sirius Group comprises of wet based glacial and related deposits found at high elevations throughout the Transantarctic Mountains. The discovery of marine Pliocene diatoms from within glacial till by Harwood (1983) led Webb et al. (1984) to propose that they were sourced from diatom bearing sediment eroded by glaciers from middle Pliocene marine basins inland of the Transantarctic Mountains. Others consider that temperatures during middle Pliocene times were not high enough to melt back the Antarctic ice sheet and expose these inland basins. They support the long held view of a stable Antarctic ice sheet since middle Miocene times, and insist that the Sirius Group is much older, explaining the diatoms as wind blown. This study was undertaken in order to determine whether the diatoms were incorporated into Sirius Group tills during or after their deposition. Sites were sampled at Mount Feather and Table Mountain in South Victoria Land. The distribution of diatoms through the upper 37 cm of the till were documented. Samples were also taken in snow and from other non Sirius Group surfaces (regolith) for comparison purposes. The geomorphic setting of the Sirius Group tills at Mt. Feather and Table Mountain suggests that their deposition predated the deep valleys that now run through the Transantarctic Mountains. Diatom abundances from within the tills are low (averaging about 1 diatom diatom per gram) and highly variable from site to site. Initially 184 diatoms were recovered from 10 samples at Mt. Feather and less than 7 diatoms were found from 4 samples of till at Table Mountain. At Mount Feather diatoms are concentrated in the surface few centimetres of the till and numbers generally decrease with depth. The pore size within the tills is highly variable but is on average ten times the size of the average diatom (10-15 microns) from within the deposits, allowing at least some diatoms to work their way into the tills from the surface. Diatoms from the snow and regolith from other rock surfaces have a similar diatom assemblage to the Sirius tills, containing many of the same common forms. Some non Sirius Group regolith samples have much larger concentrations of diatoms suggesting they have a much better trapping ability than the Sirius Group tills. These data indicate that most diatoms from the Sirius Group tills have been introduced from the atmosphere and have worked their way into the till. Thus the Sirius diatoms record not Pliocene marine basins of the Antarctic interior and subsequent extensive over riding glaciation, but the atmospheric transport and collection of both modern and ancient diatom bearing dust from within and beyond the continent. The Sirius Group tills do however have a phytolith (siliceous clasts from the cells of plant tissue) flora of glaciogenic origin, indicated by the lack of a vertical trend in abundance and very low levels of phytoliths in nearby snow and regolith samples.</p>

scholarly journals Some Aspects of the Cenozoic Glaciation of Southern Victoria Land, Antarctica

1983 ◽  
Vol 29 (102) ◽  
pp. 343-349 ◽  
Author(s):  
Howard Brady ◽  
Barrie McKelvey
Keyword(s):  
Middle Miocene ◽  
Ice Sheet ◽  
Basement Complex ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
Transantarctic Mountains ◽  
East Antarctic Ice Sheet

AbstractPalaeoglacial evidence at three sites in southern Victoria Land has been examined to consider the possible uplift of the Transantarctic Mountains through the East Antarctic ice sheet prior to the Middle Miocene. A Cenozoic tillite at Mount Feather and a striated pavement at Mount Brooke pre-date uplift. Another tillite remnant adjacent to Odell Glacier near Mount Brooke post-dates the uplift and is locally derived. This tillite, together with the Mount Feather tillite, has been previously placed in the Sirius Formation, a term that the authors abandon as it covers tillites of varying ages. Basement complex derived clasts in the Mount Feather tillite. previously reported by these authors, could be inherited from the Jurassic Mawson Formation or the Permian Metschel Tillite but they still provide evidence that the Mount Feather tillite was deposited by a regional glaciation.

scholarly journals Uncertainty quantification of the multi-centennial response of the Antarctic ice sheet to climate change

2019 ◽  
Vol 13 (4) ◽  
pp. 1349-1380 ◽  
Author(s):  
Kevin Bulthuis ◽  
Maarten Arnst ◽  
Sainan Sun ◽  
Frank Pattyn
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Ice Sheet ◽  
Parametric Uncertainty ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Sources Of Uncertainty ◽  
West Antarctic ◽  
The Antarctic ◽  
Marine Basins

Abstract. Ice loss from the Antarctic ice sheet (AIS) is expected to become the major contributor to sea level in the next centuries. Projections of the AIS response to climate change based on numerical ice-sheet models remain challenging due to the complexity of physical processes involved in ice-sheet dynamics, including instability mechanisms that can destabilise marine basins with retrograde slopes. Moreover, uncertainties in ice-sheet models limit the ability to provide accurate sea-level rise projections. Here, we apply probabilistic methods to a hybrid ice-sheet model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology and bedrock relaxation, on the continental response of the Antarctic ice sheet to climate change over the next millennium. We provide probabilistic projections of sea-level rise and grounding-line retreat, and we carry out stochastic sensitivity analysis to determine the most influential sources of uncertainty. We find that all investigated sources of uncertainty, except bedrock relaxation time, contribute to the uncertainty in the projections. We show that the sensitivity of the projections to uncertainties increases and the contribution of the uncertainty in sub-shelf melting to the uncertainty in the projections becomes more and more dominant as atmospheric and oceanic temperatures rise, with a contribution to the uncertainty in sea-level rise projections that goes from 5 % to 25 % in RCP 2.6 to more than 90 % in RCP 8.5. We show that the significance of the AIS contribution to sea level is controlled by the marine ice-sheet instability (MISI) in marine basins, with the biggest contribution stemming from the more vulnerable West Antarctic ice sheet. We find that, irrespective of parametric uncertainty, the strongly mitigated RCP 2.6 scenario prevents the collapse of the West Antarctic ice sheet, that in both the RCP 4.5 and RCP 6.0 scenarios the occurrence of MISI in marine basins is more sensitive to parametric uncertainty, and that, almost irrespective of parametric uncertainty, RCP 8.5 triggers the collapse of the West Antarctic ice sheet.

scholarly journals Remote Sensing of Antarctic Glacier and Ice-Shelf Front Dynamics—A Review

2018 ◽  
Vol 10 (9) ◽  
pp. 1445 ◽  
Author(s):  
Celia Baumhoer ◽  
Andreas Dietz ◽  
Stefan Dech ◽  
Claudia Kuenzer
Keyword(s):  
Remote Sensing ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Clear Trend ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
The Antarctic ◽  
Front Dynamics

The contribution of Antarctica’s ice sheet to global sea-level rise depends on the very dynamic behavior of glaciers and ice shelves. One important parameter of ice-sheet dynamics is the location of glacier and ice-shelf fronts. Numerous remote sensing studies on Antarctic glacier and ice-shelf front positions exist, but no long-term record on circum-Antarctic front dynamics has been established so far. The article outlines the potential of remote sensing to map, extract, and measure calving front dynamics. Furthermore, this review provides an overview of the spatial and temporal availability of Antarctic calving front observations for the first time. Single measurements are compiled to a circum-Antarctic record of glacier and ice shelf retreat/advance. We find sufficient frontal records for the Antarctic Peninsula and Victoria Land, whereas on the West Antarctic Ice Sheet (WAIS), measurements only concentrate on specific glaciers and ice sheets. Frontal records for the East Antarctic Ice Sheet exist since the 1970s. Studies agree on the general retreat of calving fronts along the Antarctic Peninsula. East Antarctic calving fronts also showed retreating tendencies between 1970s until the early 1990s, but have advanced since the 2000s. Exceptions of this general trend are Victoria Land, Wilkes Land, and the northernmost Dronning Maud Land. For the WAIS, no clear trend in long-term front fluctuations could be identified, as observations of different studies vary in space and time, and fronts highly fluctuate. For further calving front analysis, regular mapping intervals as well as glacier morphology should be included. We propose to exploit current and future developments in Earth observations to create frequent standardized measurements for circum-Antarctic assessments of glacier and ice-shelf front dynamics in regard to ice-sheet mass balance and climate forcing.

scholarly journals Some Aspects of the Cenozoic Glaciation of Southern Victoria Land, Antarctica

1983 ◽  
Vol 29 (102) ◽  
pp. 343-349 ◽  
Author(s):  
Howard Brady ◽  
Barrie McKelvey
Keyword(s):  
Middle Miocene ◽  
Ice Sheet ◽  
Basement Complex ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
Transantarctic Mountains ◽  
East Antarctic Ice Sheet

AbstractPalaeoglacial evidence at three sites in southern Victoria Land has been examined to consider the possible uplift of the Transantarctic Mountains through the East Antarctic ice sheet prior to the Middle Miocene. A Cenozoic tillite at Mount Feather and a striated pavement at Mount Brooke pre-date uplift. Another tillite remnant adjacent to Odell Glacier near Mount Brooke post-dates the uplift and is locally derived. This tillite, together with the Mount Feather tillite, has been previously placed in the Sirius Formation, a term that the authors abandon as it covers tillites of varying ages. Basement complex derived clasts in the Mount Feather tillite. previously reported by these authors, could be inherited from the Jurassic Mawson Formation or the Permian Metschel Tillite but they still provide evidence that the Mount Feather tillite was deposited by a regional glaciation.

Modern and Holocene aeolian dust variability from Talos Dome (Northern Victoria Land) to the interior of the Antarctic ice sheet

2013 ◽  
Vol 64 ◽  
pp. 76-89 ◽  
Author(s):  
B. Delmonte ◽  
C. Baroni ◽  
P.S. Andersson ◽  
B. Narcisi ◽  
M.C. Salvatore ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Aeolian Dust ◽  
Victoria Land ◽  
The Antarctic

scholarly journals A Joint Inversion Estimate of Antarctic Ice Sheet Mass Balance Using Multi-Geodetic Data Sets

2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi
Keyword(s):  
Mass Balance ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Mass Change ◽  
West Antarctica ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
Uplift Rates ◽  
The Antarctic

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.

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