An analysis of gravity measurements on the Ross Ice Shelf, Antarctica

Greischar, Lawrence L.; Bentley, Charles R.; Whiting, Larry R.

doi:10.1029/ar057p0105

Cited by 15 publications

(40 citation statements)

References 28 publications

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“…We model our study area as a layer of snow and ice overlying a water column, sedimentary layer, and basement rock. This approach is consistent with inversion of subglacial structures in various parts of Antarctica [e.g., Greischar et al ., ; Studinger et al ., ; Muto et al ., ].…”

Section: Gravity Inversionmentioning

confidence: 96%

“…Available data indicate that this general crustal structure extends beneath the Ross Ice Shelf and to the inner Ross Embayment. The dominant features mapped by the 55 km grid gravity data of RIGGS, as well as small‐scale local gravity surveys at several locations with 10 to 20 km profiles [ Greischar et al ., ], were long‐wavelength (>100 km) gravity anomalies paralleling the Transantarctic Mountains. Greischar et al .…”

Section: Study Areamentioning

confidence: 99%

“…Greischar et al . [] suggested that the negative anomalies in both free‐air gravity and Airy isostatic anomaly maps that cover parts of the Siple Coast, including our survey area (note that RIGGS gravity survey extended up to 150 km inland from the grounding zones in WIS and Kamb Ice Stream (KIS) regions), likely arise from thick glacial‐marine sediments. A sediment‐filled graben approximately 2500 m deep and 20 km wide has also been imaged by a combined seismic‐refraction and gravity survey near Ridge BC between WIS and KIS, approximately 250 km inland of the current grounding line [ Munson and Bentley , ].…”

Section: Study Areamentioning

confidence: 99%

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Bathymetry and geological structures beneath the Ross Ice Shelf at the mouth of Whillans Ice Stream, West Antarctica, modeled from ground‐based gravity measurements

et al. 2013

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[1] New gravity data reveal important geologic controls on the location and behavior of the grounding zone of Whillans Ice Stream (WIS), West Antarctica. Grounding zones of ice sheets and contiguous ice shelves are important for understanding ice sheet dynamics, as key processes that influence the grounded ice and its discharge into the ocean occur in these regions. Here, we model the bathymetry and shallow geological structures beneath the Ross Ice Shelf in an embayment of the WIS grounding zone using gravity data collected on the ground, in conjunction with seismic and radar data. We find that the region of shallow ocean water (<~50 m) is extensive; oceanographic models suggest that grounding zones exhibiting thin ocean cavities with gently sloping ice-ocean interfaces are likely to be tidally well mixed, leading to slower basal melting than would occur in a thicker, stratified water column. Beneath the ocean water column, we model a fault and a sedimentary basin in a half-graben, filled with two layers of sediments. The total thickness of the sediment layer is 900 to 1250 m in the half-graben, and 600 to 800 m on the upthrown block, and the basement depth is no more than 2000 m. We observe that the upper, softer sediment is thinnest near the modern grounding line and may possibly pinch out near our grid, and that the modeled fault is roughly parallel to part the grounding. We therefore hypothesize that the WIS grounding line stabilized in its current location in part due to the subglacial geology.

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Section: Gravity Inversionmentioning

confidence: 96%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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Bathymetry and geological structures beneath the Ross Ice Shelf at the mouth of Whillans Ice Stream, West Antarctica, modeled from ground‐based gravity measurements

et al. 2013

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“…1B). Although several other gravity surveys have sampled this area (Stern et al, 1991;Greischar et al, 1992;Brancolini et al, 1995), these data were not incorporated due to the difficulties in establishing accurate elevation, ice thickness and bathymetry measurements to accompany these. This means that our model is unconstrained beyond the limits of the collected data, which cover a fairly small area (Fig.…”

Section: Gravity Datamentioning

confidence: 98%

Reprint of: Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

Aitken

Wilson

Jordan

et al. 2012

Global and Planetary Change

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“…Bottom topography is from Smith and Sandwell (1997) north of 72°S, and ETOPO5 data south of 72°S. Ice shelf and water column thicknesses for the large ice shelf cavities are from Greischar et al (1992) (Ross) and Johnson and Smith (1997) (Filchner-Ronne). Ice shelf thickness is set to 200 m for the smaller ice shelves, George VI, Abbot and Getz in the South East Pacific.…”

Section: Model Descriptionmentioning

confidence: 99%

Variability of dense water formation in the Ross Sea

Assmann

Timmermann

2005

Ocean Dynamics

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This paper presents results from a model study of the interannual variability of high salinity shelf water (HSSW) properties in the Ross Sea. Salinity and potential temperature of HSSW formed in the western Ross Sea show oscillatory behaviour at periods of 5-6 and 9 years superimposed on long-term fluctuations. While the shorter oscillations are induced by wind variability, variability on the scale of decades appears to be related to air temperature fluctuations. At least part of the strong decrease of HSSW salinities deduced from observations for the period 1963-2000 is shown to be an aliasing artefact due to an undersampling of the periodic signal. While sea ice formation is responsible for the yearly salinity increase that triggers the formation of HSSW, interannual variability of net freezing rates hardly affects changes in the properties of the resulting water mass. Instead, results from model experiments indicate that the interannual variability of dense water characteristics is predominantly controlled by variations in the shelf inflow through a sub-surface salinity and a deep temperature signal. The origin of the variability of inflow characteristics to the Ross Sea continental shelf can be traced into the Amundsen and Bellingshausen Seas. The temperature anomalies are induced at the continental shelf break in the western Bellingshausen Sea by fluctuations of the meridional transport of circumpolar deep water with the eastern cell of the Ross Gyre. In the Amundsen Sea, upwelling due to a persistently cyclonic wind field carries the signal into the surface mixed layer, leading to fluctuations of the vertical heat flux, anomalies of brine release near the sea ice edge, and consequently to a sub-surface salinity anomaly. With the westward flowing coastal current, both the sub-surface salinity and deep temperature signals are advected onto the Ross Sea continental shelf. Convection carries the signal of salinity variability into the deep ocean, where it interacts with modified circumpolar deep water upwelled onto the continental shelf as the second source water mass of HSSW. Sea ice formation on the Ross Sea continental shelf thus drives the vertical propagation of the signal rather than determining the signal itself.

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An analysis of gravity measurements on the Ross Ice Shelf, Antarctica

Cited by 15 publications

References 28 publications

Bathymetry and geological structures beneath the Ross Ice Shelf at the mouth of Whillans Ice Stream, West Antarctica, modeled from ground‐based gravity measurements

Bathymetry and geological structures beneath the Ross Ice Shelf at the mouth of Whillans Ice Stream, West Antarctica, modeled from ground‐based gravity measurements

Reprint of: Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

Variability of dense water formation in the Ross Sea

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