Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

Swain, Christopher J.; Kirby, Jonathan

doi:10.1029/2020gl091576

Cited by 7 publications

(14 citation statements)

References 72 publications

(184 reference statements)

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“… (a) Gravity‐derived Moho depth and (b) crustal thickness. The purple solid lines exhibit the possible suture zones identified by Swain and Kirby (2021) based on a belt of weakened lithosphere. Green solid lines are the same as the orogenic belts in Figure 1.…”

Section: Resultsmentioning

confidence: 83%

Gravity‐Derived Antarctic Crustal Thickness Based on the Gauss‐FFT Method

Ji¹,

Zhang

2022

Geochem Geophys Geosyst

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The information on crustal thickness in Antarctica can provide significant constraints on its crustal deformation and tectonic evolution. To generate reliable images of crustal features, we investigate the model of Moho depth and crustal thickness beneath Antarctica by applying the Bott‐Parker's formulas based on the Gauss‐fast Fourier transform method through a comprehensive analysis of gravity data, ice and sediment thicknesses and bedrock elevation, combined with seismic constraints. Tests with synthetic data indicate that the iterative inversion algorithm can yield a highly accurate Moho topography. Ultimately, inverted crustal thickness reveals a more detailed crustal image by clearly identifying more tectonic elements at different scales than previous results and correlates well with major tectonic provinces. Airy isostasy and flexural isostasy models are used to assess the crustal isostatic compensation. The distinctive negative isostatic anomalies are observed in the Transantarctic Mountains and the East Antarctic areas of the great escarpment in the Dronning Maud Land and Aurora and Wilkes Subglacial Basin, indicating that the low density of the uppermost mantle and lithospheric strength may play important roles in compensating for their elevations. Variations in crustal thickness in interior East Antarctica are analyzed; the thickened crust from Dronning Maud Land to the Gamburtsev Subglacial Mountains may be associated with the collision of continental blocks and is interpreted as the fossil sutures. We compare the relationship between the Moho and Curie interfaces and find that the uppermost mantle is magnetized in some areas of East Antarctica, which may indicate preserved Precambrian cratonic roots.

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Section: Resultsmentioning

confidence: 83%

Gravity‐Derived Antarctic Crustal Thickness Based on the Gauss‐FFT Method

Ji¹,

Zhang

2022

Geochem Geophys Geosyst

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“…Black line shows the spatially variable T e scenario 16 , horizontal dashed lines show the three uniform T e values tested. ( f ) T e across Antarctica 17 . Colour notation is identical to panel e. ( g ) Greenland Ice Sheet (GrIS) and bed topography 14 .…”

Section: Resultsmentioning

confidence: 99%

“…We solved Eq. ( 1 ) for the laterally variable T e scenarios of Steffen et al (2018) 16 and Swain & Kirby (2021) 17 using a centred finite difference technique 25 . Steffen et al (2018) place uncertainties of up to 40 km on the spectral T e estimates for Greenland, but uncertainties are not quantified for the Antarctic estimates.…”

Section: Methodsmentioning

confidence: 99%

“…( e ) Effective elastic thickness ( T e ) model for Greenland 16 . ( f ) T e model for Antarctica 17 . Contour interval is 10 km.…”

Section: Datamentioning

confidence: 99%

“…Reliable estimates of T e have historically been difficult to establish in the polar regions, given the sparse coverage of geological and geophysical observations and poorly constrained crustal structure. However, we used laterally variable T e grids that have recently been derived using continental-scale spectral analysis of gravity and topography data in Antarctica 17 and Greenland 16 (Fig. 1 e,f).…”

Section: Datamentioning

confidence: 99%

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Total isostatic response to the complete unloading of the Greenland and Antarctic Ice Sheets

Paxman

Austermann

Hollyday

2022

Sci Rep

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The land surface beneath the Greenland and Antarctic Ice Sheets is isostatically suppressed by the mass of the overlying ice. Accurate computation of the land elevation in the absence of ice is important when considering, for example, regional geodynamics, geomorphology, and ice sheet behaviour. Here, we use contemporary compilations of ice thickness and lithospheric effective elastic thickness to calculate the fully re-equilibrated isostatic response of the solid Earth to the complete removal of the Greenland and Antarctic Ice Sheets. We use an elastic plate flexure model to compute the isostatic response to the unloading of the modern ice sheet loads, and a self-gravitating viscoelastic Earth model to make an adjustment for the remaining isostatic disequilibrium driven by ice mass loss since the Last Glacial Maximum. Feedbacks arising from water loading in areas situated below sea level after ice sheet removal are also taken into account. In addition, we quantify the uncertainties in the total isostatic response associated with a range of elastic and viscoelastic Earth properties. We find that the maximum change in bed elevation following full re-equilibration occurs over the centre of the landmasses and is +783 m in Greenland and +936 m in Antarctica. By contrast, areas around the ice margins experience up to 123 m of lowering due to a combination of sea level rise, peripheral bulge collapse, and water loading. The computed isostatic response fields are openly accessible and have a number of applications for studying regional geodynamics, landscape evolution, cryosphere dynamics, and relative sea level change.

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