Rift processes and crustal structure of the Amundsen Sea Embayment, West Antarctica, from 3D potential field modelling

Kalberg, Thomas; Gohl, Karsten; Eagles, Graeme; Spiegel, Cornelia

doi:10.1007/s11001-015-9261-0

Cited by 10 publications

(10 citation statements)

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“…The absolute values of DBMS can be expected to contain significant error (Figure 7) due to interpretational subjectivity in the method and inhomogeneous data distribution [Gohl et al, 2013a]. Despite this, we can have confidence in the relative values and their trends because they reliably reproduce the spatial variability in magnetization of the crust that can be expected to result from known details of the crustal structure [Gohl et al, 2013a;Kalberg et al, 2015]. For example, a steep gradient that can be followed offshore Thwaites Glacier toward Thurston Island (Figure 10a) potentially reflects a boundary between the Marie Byrd Land block and Thurston Island crustal blocks.…”

Section: Depth To the Bottom Of The Magnetic Sourcementioning

confidence: 99%

“…In a last step, we implemented a yet more realistic crustal model (Figure 10c) taking into account recent interpretations of gravimetric, magnetic anomaly and seismic data for the ASE [Kalberg et al, 2015]. The model features suites of felsic and mafic intrusions, for instance emplaced at the Dorrel Rock intrusive complex during a period of increased magmatic activity at about 30 Ma [Rocchi et al, 2006] to 18 Ma [Spiegel et al, 2016], which disturb the thermal field of the region due to their contrasting thermal conductivity and radiogenic heat production.…”

Section: Fvm 3-d Numerical Model 2 With Further Crustal Parameterizationmentioning

confidence: 99%

“…Geochemistry, Geophysics, Geosystems 10.1002/2016GC006755 when stretching of the crust ceases and the distribution volcanic activity along the complex branching geometry of the WARS, which reflects its multi-stage history and structural inheritance [Kalberg et al, 2015]. Geothermal heat flux strongly influences ice flow rates, basal friction, deformation rates, and/or hydrological systems, which in turn control ice-bed coupling, and therefore the height and dynamics of ice sheets [Hughes, 2009].…”

Section: Introductionmentioning

confidence: 99%

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Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling

Dziadek

Gohl

Diehl

et al. 2017

Geochem Geophys Geosyst

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Focused research on the Pine Island and Thwaites glaciers, which drain the West Antarctic Ice Shelf (WAIS) into the Amundsen Sea Embayment (ASE), revealed strong signs of instability in recent decades that result from variety of reasons, such as inflow of warmer ocean currents and reverse bedrock topography, and has been established as the Marine Ice Sheet Instability hypothesis. Geothermal heat flux (GHF) is a poorly constrained parameter in Antarctica and suspected to affect basal conditions of ice sheets, i.e., basal melting and subglacial hydrology. Thermomechanical models demonstrate the influential boundary condition of geothermal heat flux for (paleo) ice sheet stability. Due to a complex tectonic and magmatic history of West Antarctica, the region is suspected to exhibit strong heterogeneous geothermal heat flux variations. We present an approach to investigate ranges of realistic heat fluxes in the ASE by different methods, discuss direct observations, and 3‐D numerical models that incorporate boundary conditions derived from various geophysical studies, including our new Depth to the Bottom of the Magnetic Source (DBMS) estimates. Our in situ temperature measurements at 26 sites in the ASE more than triples the number of direct GHF observations in West Antarctica. We demonstrate by our numerical 3‐D models that GHF spatially varies from 68 up to 110 mW m−2.

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Section: Depth To the Bottom Of The Magnetic Sourcementioning

confidence: 99%

Section: Fvm 3-d Numerical Model 2 With Further Crustal Parameterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling

Dziadek

Gohl

Diehl

et al. 2017

Geochem Geophys Geosyst

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“…Because the ASE shelf and its hinterland are underlain by relatively thin crust [e.g., Gohl et al, 2007;Jordan et al, 2010;Kalberg et al, 2015] and recent volcanic activity has been recorded in the region [Wilch et al, 1999;Corr and Vaughan, 2008], the role of enhanced geothermal heat flow for mass loss of the glaciers draining into the ASE has also been considered [e.g., Joughin et al, 2009;Schroeder et al, 2014]. However, its effect on basal sliding conditions is not well understood since we have little knowledge of the composition and hydrological processes at the ice-to-bed of most ice streams.…”

Section: Attribution Of Recent Changes In the Asementioning

confidence: 99%

Atmosphere‐ocean‐ice interactions in the Amundsen Sea Embayment, West Antarctica

Turner

Orr

Gudmundsson

et al. 2017

Reviews of Geophysics

120

125

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Over recent decades outlet glaciers of the Amundsen Sea Embayment (ASE), West Antarctica, have accelerated, thinned, and retreated, and are now contributing approximately 10% to global sea level rise. All the ASE glaciers flow into ice shelves, and it is the thinning of these since the 1970s, and their ungrounding from “pinning points” that is widely held to be responsible for triggering the glaciers' decline. These changes have been linked to the inflow of warm Circumpolar Deep Water (CPDW) onto the ASE's continental shelf. CPDW delivery is highly variable and is closely related to the regional atmospheric circulation. The ASE is south of the Amundsen Sea Low (ASL), which has a large variability and which has deepened in recent decades. The ASL is influenced by the phase of the Southern Annular Mode, along with tropical climate variability. It is not currently possible to simulate such complex atmosphere‐ocean‐ice interactions in models, hampering prediction of future change. The current retreat could mark the beginning of an unstable phase of the ASE glaciers that, if continued, will result in collapse of the West Antarctic Ice Sheet, but numerical ice sheet models currently lack the predictive power to answer this question. It is equally possible that the recent retreat will be short‐lived and that the ASE will find a new stable state. Progress is hindered by incomplete knowledge of bed topography in the vicinity of the grounding line. Furthermore, a number of key processes are still missing or poorly represented in models of ice‐flow.

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“…The Amundsen Sea Embayment is part of the West Antarctic Rift System (WARS, Fig. 1), which is the second largest continental rift system on earth (LeMasurier, 2008), and a key study area for GHF. Young, continental rift systems are regions with significantly elevated GHF (Morgan, 1983), because the transient thermal perturbation to the lithosphere caused by rifting requires ∼100 myrs to reach long term thermal equilibrium (McKenzie, 1978;Jaupart and Mareschal, 2007).…”

Section: Introductionmentioning

confidence: 99%

Elevated geothermal surface heat flow in the Amundsen Sea Embayment, West Antarctica

Dziadek

Gohl

Kaul

2019

Earth and Planetary Science Letters

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Keywords: skin depth for geothermal gradients spatial variation of geothermal heat flow on small scales in situ temperature measurements geotherm transitionThe thermal state of polar continental crust plays a crucial role for understanding the stability and thickness of large ice sheets, the visco-elastic response of the solid Earth due to unloading when large ice caps melt and, in turn, the accuracy of future sea-level rise prediction. Various studies demonstrate the need for precise measurements and estimation of geothermal heat flow (GHF) in Antarctica for better constrained boundary conditions to enhance the ice sheet model performance. This study provides ground-truth for regional indirect GHF estimates in the Amundsen Sea Embayment, which is part of the West Antarctic Rift System, by presenting in situ temperature measurements in continental shelf sediments. Our results show regionally elevated and heterogeneous GHF (mean of 65 mW m −2 ) in the Amundsen Sea Embayment. Considering thermal blanketing effects, induced by inflow of warmer water and sedimentary processes, the estimated GHF ranges between 65 mW m −2 and 95 mW m −2 .

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Rift processes and crustal structure of the Amundsen Sea Embayment, West Antarctica, from 3D potential field modelling

Abstract: The Amundsen Sea Embayment of West

Cited by 10 publications

References 65 publications

Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling

Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling

Atmosphere‐ocean‐ice interactions in the Amundsen Sea Embayment, West Antarctica

Elevated geothermal surface heat flow in the Amundsen Sea Embayment, West Antarctica

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